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Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
533
Chapter 19 Marineprotected areas
Graham J. Edgar1,2, Garry R. Russ3 & Russ C. Babcock4
1 Marine Research Laboratory, Tasmanian Aquaculture and Fisheries Institute,
University of Tasmania, Private Bag 49, Hobart 7001, Tasmania, Australia.
2 Center for Applied Biodiversity Science, Conservation International, 1919 M Street
NW, Suite 600, Washington, D.C. 20036, USA
3 Centre for Coral Reef Biodiversity, School of Marine Biology and Aquaculture,
James Cook University, Townsville, Queensland 4811, Australia
4 CSIRO Marine and Atmospheric Research, PO Box 5, Wembley, WA 6913,
Australia
Marine Protected Areas (MPAs) are spatially-delimited areas of the marine
environment that are managed, at least in part, for conservation of biodiversity. The
number of MPAs declared worldwide is increasing exponentially. Because MPAs can
be declared for a variety of reasons, the specific goals of each MPA needs to be
specified to allow management agencies to assess the success of the MPA, and to
guide monitoring and research activitieswithin. Because of thecomplexity of
processes within marine ecosystems, ecologicalchanges associated with the
declaration of MPAs vary greatly from one region to another and are difficult to
accurately predict. Important factors that affect the way plants and animals respond to
MPAs include distribution of habitat types,level of connectivityto nearby fished
habitats, wave exposure, depth distribution,prior level of resource extraction,
regulations, and level of compliance to regulations.
The value of MPAs primarily relates to biodiversity conservation, fisheries, and as
research and management tools, but they can also generate recreational, aesthetic and
educational benefits. Conservation benefits are evident through increased habitat
heterogeneity at the seascape level, increased abundance of threatened species and
habitats, and maintenance of a full range of genotypes. Fisheries can benefit through
spillover, increased dispersal of egg and larval propagules, and as insurance against
stock collapse. Scientific benefits primarily relate to the use of MPAs as reference
areas to assess the scale of human impacts on the environment, and as locations for
the collection of data that are unobtainable in fished systems. Nevertheless, MPAs can
also involve costs to human society through displaced fishing effort, short-term
reductions in catches, false security, andthrough undesirable interactions within the
biota. MPAs do not represent the universal panacea for all threats affecting marine
ecosystems, but are best regarded asarguably the most important tool in the marine
manager’s toolbox
Key concepts: marine conservation, biodiversity, effects of fishing, spillover,
threatening processes, trophic cascades
Introduction
Marine Protected Areas or “MPA”s can be defined in various ways, but generally
speaking they are areas that afford some level of special protection to parts of the
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
534
ocean for conservation purposes. Such areas may range in nature from seasonal
closures of spawning sites, to areas permanently closed to fishing, and include marine
parks with multiple levels of zoning that allow different types of activities in different
areas.
Expected benefits of MPAs
MPAs have been established to achieve a wide range of goals in response to a
plethora of threats now faced by marine and coastal environments. Among the
commonly stated goals of MPAs are protecting and conserving biodiversity, including
threatened species, and allowing for the recovery of species depleted by human
activities. The most commonly perceived threat to marine ecosystems against which
MPAs are meant to protect is overfishing, but protection from other threats has also
provided stimulus for MPA creation. For example, the initial declaration of the Great
Barrier Reef Marine Park was as a result of fears that the Great Barrier Reef might
suffer from the effects of proposed oil drilling and limestone mining. While the
potential benefits of MPAs as a management tool are well accepted, there is general
agreement that while they are useful formany things, in thecontext of the wider
marine environment they cannot do everything, and must be employed in conjunction
with a range of other, more “traditional” management approaches (Allisonet al. 1998)
(see also Chapter 18, Fisheries and their management).
The fact that MPAs are designed to produce benefits or outcomes for particular issues
or problems means that during the establishment of an MPA it is essential to identify
specific goals or expectations that the MPA is intended to achieve. These goals should
be clearly expressed when MPAs are established, something that assists greatly in
determining their effectiveness. For example, if an MPA is set up to protect a
threatened species then clearly this will guide not only the design of the MPA but also
scientific work, which should include population monitoring to assess whether the
threatened species has been adequately safeguarded. Similarly, if the goal of the MPA
is to protect more general biodiversity values then MPA effectiveness will have to be
assessed using different more general criteria, for example species number,
biodiversity indices or some measure of habitat or trophic diversity (Halpern &
Warner 2002).
The fact that MPAs are often established for general conservation reasons but
expectations often include increased fishery catches, frequently leads to an overlap of
conservation and fisheries goals.In such cases the spatial scales relevant to fisheries
issues and local conservation may be quite different, particularly where industrial-
scale fisheries are involved (Parrish 1999). In such casesthere will also be a mismatch
of the methodologies needed to study conservation versus fisheries-scale effects.
Where fisheries are of an artisanal or subsistence nature there is less of a mismatch,
and it is in such situations that the best examples of fisheries benefits from MPAs can
be found (Russ & Alcala 1996).
Unexpected effects of MPAs
Experience has shown that even though MPAs may be set up with particular goals in
mind, they frequently produce unexpected results and insights. Following MPA
declaration, particular species may responddirectly or indirectly, showing responses
in ways not predicted at the outset (Babcock et al. 1999, Edgar & Barrett 1999,
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
535
Langlois & Ballantine 2005). Even more commonly, indirect effects are observed that
arise through interactions of several speciesat different trophic levels, and that were
unforseen when an MPA was established (Edgar & Barrett 1999, Shears & Babcock
2002, Willis & Anderson 2003). These resultscan be viewed as serendipitous insights
into the function of marine ecosystems, but given the complexity of interactions in
marine ecosystems such insights should not be unexpected, even if their details can’t
be accurately predicted.
One of the reasons that MPAs have provided unexpected results is that human
activities in the marine environment arenow so ubiquitous that some ecological
components of these natural systems are functionally absent. Thus, even though
species are not extinct they may be present at such low densities that their populations
no longer fulfil the same role in the ecosystem that they formerly did, or are no longer
viable as a fisheries target, a condition sometimes referred to as “commercial
extinction” or “extirpation” (Friedlander & DeMartini 2002). Under such
circumstances we may be unaware that such species and their functions are missing,
since there is no longer any reference point against which to assess them. This has
been referred to as the shifting baseline syndrome (Daytonet al. 1998). MPAs have
special usefulness as a natural reference point for determining what is natural, or at
least as natural as we may now be able to achieve.
Inherent ecosystem complexity means thatspecific responses of systems to MPAs or
other changes in management cannot easily be extrapolated from one region to
another, and have to be assessed empirically. Generally, exploited species respond
positively to reductions in fishing effort, and attempts to generalise and derive a mean
figure for trends in exploited populations or overall biodiversity have supported this
(Halpern & Warner 2002). While such simplifications may be useful in terms of
illustrating the overall value of MPAs forprotecting exploited species, they are to
some extent stating the obvious; that is if you stop killing fish you will probably have
more and/or bigger fish. Perhaps more importantly, such meta-analyses may not
utilise the full information content of original data, including species that do not
respond positively to protection, in order to understand more about the mechanisms at
work in marine ecosystems. Therefore, much can be gained in terms of our general
understanding of marine ecosystem function by paying attention to negative as well as
positive results from MPAs. The use of MPAs as large scale experiments will greatly
advance our understanding of marine ecosystems and our ability to manage and utilise
them on an ongoing basis without irrevocably compromising their utility, ecological
integrity, and biodiversity values.
Factors influencing MPA effectiveness
The effectiveness of MPAs for protecting any particular species can be influenced by
numerous factors. Basic consideration of the function of MPAs as areas closed to
fishing suggests that small MPAs are likely to be less effective at protecting fished
populations than large ones, and that the size of an effective MPA will be different for
species with different movement patterns since wide-ranging species will be more
vulnerable to fishing thanhighly site-attached species. While modelling studies
support this conclusion, meta-analysis suggests that the level of recovery of fished
populations is not correlated with the size of the MPA (Halpern 2003). Clearly, we
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
536
need more data and/or better models of how MPAs of varying sizes interact with
different species.
Among factors critical to an understanding of this question are assumptions about
species mobility, variations in boundary permeability, and the levelof fishing pressure
in surrounding waters. Other factors that may influence the rate and speed ofrecovery
include the availability of individuals to migrate into sanctuaries (e.g. Denny et al.
2004). Recruitment into MPAs may be critical in this regard, so overfished
populations may be slow to recover in MPAs. At the same time, species that are not
overfished, or not fished at all, may show no difference between fished and unfished
areas. A further factor to consider is the potential for recovering species to interact
negatively with other species through competition or predation (Willis & Anderson
2003) (see also Chapter 5, Negative interactions). Finally, recovery depends on
adherence to or effective enforcement of no-take principals – poaching can greatly
compromise the success of MPAs for conservation outcomes.
Monitoring MPA effectiveness
In order to assess whether management aims are achieved, and to understand
ecological processes that determine MPA success, it is necessary to implement a
program of research and monitoring of the systems in question. Management agencies
should put in place programs to monitor compliance with regulations, ecological
condition of MPAs, and socio-economic factors. Ecological monitoring of subtidal
marine ecosystems to evaluate their statusand the direction of their responses cannot
be achieved by casual observation. To a much greater extent than their terrestrial
equivalents, MPAs require special sampling programs to assess even the abundance of
common marine algae, plants or invertebrates such as corals. Specialised sampling
protocols are particularly required for mobile organisms such as fishes and larger
invertebrates. Management agencies also commonly need to understand the socio-
economic implications of their decisions, in which case monitoring should include
assessment of human interactions with the ecosystem. The effectiveness of research
and monitoring, either to achieve management goals or in the assessment of MPAs as
large scale ecosystem-level experiments, is dependent on the application of scientific
method, but this is often compromised by the MPA creation process.
Because MPAs are generally created through social and political processes rather than
as scientific experiments, funding supportis rarely available for rigorous quantitative
field surveys of target populations priorto MPA declaration at sites inside and
adjacent to the MPA: a ‘Before-After Control-Impact’ experimental design (Williset
al. 2003b). MPA research must often wait until MPAs have been successfully
established and funding is available, leading to reduced confidence in any conclusions
that may be drawn from such research. For example, persons opposed to the creation
of MPAs frequently remark that the reason for apparent success of a particular reserve
(e.g. increased numbers of fish, higher diversity etc.) is that the reserve had always
had higher populations of certain species and was simply different to start with. Since
MPAs are often selected through political processes that bias their location, they are
frequently not representative of the wider coast; hence it is difficult for anyone to
evaluate the success of such MPAs for management.
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
537
The Galapagos Marine Reserve provides an example of biases in site selection that
would greatly affect interpretation of effects of the MPA if surveys prior to protection
had not been undertaken. The major fishery species – rock lobster and sea cucumbers
– had baseline densities three times higher in fished areas compared to sanctuary
zones at the time that sanctuary zones were declared (Edgaret al. 2004b). Without
baseline surveys, the assumption would be made that population densities were
initially equivalent in the different zones and the magnitude of any subsequent
population recovery would be greatly underestimated.
Baselines and long-term monitoring perspectives
Monitoring, by its nature, represents a commitment to collect a consistent data set that
can be used to inform management. This commitment needs to continue beyond the
first few years after an MPA is created, to the medium and long term. Populations of
some species may take time to recover, particularly if they are rare or long-lived, or
have irregular or low recruitment (perhaps because of overfishing). Populations of
lobsters in the Leigh Marine Reserve (NZ) required eight years to recover to a stable
level (MacDiarmid & Breen 1993), and at Maria Island (Tasmania) lobster numbers
were still increasing after six years (Edgar & Barrett 1999). These recovery rates are
likely to result from steady recruitment into the MPA populations.
Predatory fish populations at several MPAs in the Philippines took 3-4 years to show
measurable increases in biomass; however, at Apo Island, for example, biomass of
these species was still increasing rapidly after 18 years (Russ & Alcala 2004). In
contrast, major recruitment of bastard trumpeter (Latridopsis forsteri) was recorded
only once in 6 years of monitoring of the Maria Island marine reserve (Edgar &
Barrett 1999). For such species, monitoring has to take place over time periods
sufficiently long that at least one recruitment period is included in the time series.
Indirect ecological effects can take much longer to become apparent. In the Leigh
Marine reserve in northeastern New Zealand, predator-urchin-algal trophic cascades
took more than 20 years to become evident and habitats were still in transition from
barrens to kelp forest after 25 years (Shears & Babcock 2003).
In contrast to the long time-lags found in the response to protection of some species,
others may respond very quickly, in fact so quickly that there is little possibility that
this could take place through recruitment alone. A case in point is the increase in the
abundance of the snapperPagrus auratus in the Leigh Marine Reserve. After only 4
years snapper biomass had increased by over 7 times, but themodal length of fishes
was 410 mm, indicative of an age over 14 yrs (Denny et al. 2004). Most likely, large
animals immigrated to the reserve from a pool of nomadic individuals present in the
regional snapper stock (Denny, et al. 2004). No such accumulation of snapper in
reserves has been seen in other parts of New Zealand with depleted snapper stocks
(Babcock 2003), further emphasising that MPAs do not exist in isolation and that
populations in fished areas have the potential to be an important component of MPA
dynamics.
Another example of re-colonisation that may perhaps more correctly be called “spill-
in” comes from lobster (Panulirus argus) populations in Florida MPAs, where an
increase in lobster density occurs each year at the beginning of the commercial lobster
season (Parsons & Eggleston 2005). Thismovement results from a combination of
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
538
chemical signals and behavioural responses that disturb fished lobsters and make them
more mobile and less gregarious. Consequently, the disturbed animals are more likely
to move across an MPA boundary, and will often then remain in response to the
stronger gregarious chemical cues released by undisturbed resident lobsters (Parsons
& Eggleston 2005).
Connectivity of MPA networks
The examples above indicate strong connections between MPAs and adjacent areas,
and how population recovery within MPAs can depend on movement of adults and
larvae. This is a characteristic of marine systems, whichare typically open systems
that show high levels of connectivity. Because seascapes are composed of numerous
patches of habitat (islands or reefs), species have evolved mechanisms that allow
widely-separated populations to maintain connections despite large intervening
distances, thereby forming a larger regional meta-population. Such concepts are well
established in marine ecology and have also been applied to MPAs, which can be
regarded as “islands” of safety for exploited populations. A good deal of discussion
and theory has been applied to the concept of connectivity among MPAs to try and
ensure that MPAs are sufficiently wellconnected that meta-populations will be
maintained through the interchange of adults or larvae (Sala et al. 2002, Bode et al.
2006). This would be particularly important if stochastic risk is large and one or more
subpopulations suffer catastrophic mortality.
Such ideas have led to the concept of MPA networks, in which a number of MPAs are
distributed along a coastline. MPA networks have several advantages over single
MPAs through: (i) spreading the risk that might be borne by a single MPA, (ii)
encompassing a wider range of species and habitats, and (iii) providing replicate
observations and broadening inferences that may be drawn from monitoring or other
scientific studies. The concept of MPA networks sits well within the practice of
multiple use zoning, in whichthe uses of a marine region are divided up so that some
areas are devoted to conservation (e.g. no-take MPAs) while others may be devoted to
recreational activities, commercial fishing, shipping and so on. This is a useful
approach in that it takes into account all of the values and uses of an area and attempts
to balance them in order to optimise the outcomes for the system or region as a whole.
Multiple Use marine parks
The Great Barrier Reef Marine Park (GBRMP) is perhaps the best example of such
multiple-use zoning put into effect on the world’s largest coral reef ecosystem. The
GBRMP is zoned into 8 different zone types, ranging from no-take to general use
zones where all but high-risk activities are permitted. This approach to zoning marine
parks has been applied elsewhere in Australia, for example in the Ningaloo Marine
Park on Australia’s west coast. However, a more piecemeal approach to declaring
marine protected areas remains the norm, and it should be remembered that even
multiple-use areas such as Ningaloo are in a sense islands of integrated management
in a sea that is still managed largely on a “commons” basis.
Because there are many legitimate uses of marine resources, including their
conservation, multiple use zoning has resulted in a proliferationof different zoning
types. A level of flexibility in zoning is,in principal, a useful way to accommodate
diverse uses and habitats found in marine ecosystems; however there is growing
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
539
evidence that some of these do not achieve their intended goals. For example, some
areas are zoned to allow all formsof fishing, others for recreational fishingor for
restricted gear types, and still others to provide total protection from fishing. A
comparison of no-take, recreational fishing, and open fishing areas in northeastern
New Zealand has shown that a recreational fishing area was no different to a nearby
area open to all forms of fishing, and that only no-take areas had higher levels of
exploited fish species (Denny & Babcock 2004) and lobsters (Shearset al. 2006) for
that region. Further research is clearly needed to assess what forms of fishing
restrictions are generally useful and which are ineffective for species conservation.
Significance of no-take marine protected areas in fisheries
management
Most marine protected areas in the world are established to conserve species,
ecosystems, habitats, bioregions and biodiversity (Robertset al. 2005). State,
Territory and National governments of Australia and New Zealand, for example, have
jointly agreed to establish a National Representative System of Marine Protected
Areas with the primary goal “To contribute to the long-term ecological viability of
marine and estuarine systems, to maintain ecological processes and systems, and to
protect Australia’s biological diversity at all levels” (ANZECC 1998, 1999). Thus, in
contrast to most discussionabout MPAs, which relates to fisheries issues, the majority
are not declared with fisheries enhancement as a primary goal.
The best-known MPA is Australia’s Great Barrier Reef Marine Park (GBRMP) in
Queensland (Day et al. 2003). In 2004 the GBRMP was rezoned under the
Representative Areas Program (RAP), a Commonwealth government initiative. The
objective of RAP was to protect at least 20% of each of 70 major bioregions in the
GBRMP (Day, et al. 2003). While the RAP was not established for fisheries
management purposes, which are the responsibility of the Queensland state
government, it increased the no-take (no fishing) zones from 4.5% to 33.4% of the
GBRMP, closing an area of approximately 115,000 km2. This is the largest single
spatial closure to fishing in the world. Furthermore, for the first time, many of the no-
take zones are now close to the coast, where many people fish, particularly for
recreation. Not surprisingly, the public debate over the implementation of RAP
centred on fishing, not biodiversity, issues. The debate helped to bring into sharper
public focus the potential benefits of no-take zones as fisheries management tools,
particularly the potential benefits for reef fisheries.
Many fish stocks worldwide are currently over-exploited by marine capture fisheries
(Pauly et al. 2002). No-take marine protected areas, often referred to as marine
reserves, are areas of the marine environment permanently closed to fishing. To many
they represent one potential solution to enhance the long-term sustainability of many
of these fisheries. To others they represent a “fencing off of the seas” attitude, a denial
of people’s “rights” to fish. Thus, the use of no-take reserves as fisheries management
tools is a highly controversial topic in fisheries science and fisheries management.
The popularity of marine reserves as fisheries management tools, at least in the
literature, stems partly from a frequent failure of “traditional” catch and effort controls
to prevent overfishing in many developed nations, and the difficulty in applying such
“traditional” options in many developing nations. It also reflects a growing interest in
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
540
a more holistic approach to fisheries management, particularly the concept of
protecting the habitats and ecosystems on which fish productivity depends. MPAs
have attracted a great deal of interest from a remarkably broad cross section of
disciplines e.g. conservation, ecology, economics, environmental science, fisheries
science, fisheries management, mathematical modelling, and social science. The topic
is popular since it offers, simultaneously, conservation and sustainable exploitation,
two objectives that many have viewed in the past as almost conflicting. It proverbially
offers us a chance to have our fish and eat them too.
Expectations of no-take marine protectedareas as fisheries
management tools
There are seven expectations of the effects of no-take marine reserves on organisms
targeted by fisheries (Russ 2002):
Effects Inside Reserves
1. Lower Fishing Mortality.
2. Higher density.
3. Higher mean size/age.
4. Higher biomass.
5. Higher production of propagules (eggs/larvae) per unit area.
Effects Outside Reserves
6. Net export of adult (post-settlement) fish (the “Spillover” Effect)
7. Net export of eggs/larvae (“Recruitment Subsidy”).
Good evidence indicates that the abundance and average size of organisms targeted by
fisheries increases inside no-take marine reserves. However, to be usefulas fisheries
management tools, no-take marine reserves need to become net exporters of targeted
fish biomass (export of both adults and/or propagules) to fished areas. The use of
marine reserves as fisheries management tools remains controversial, since clear
demonstrations of such export functions are technically and logistically difficult to
demonstrate.
Examples of expected effects ofno-take marine protected areas.
Higher density, average size and biomass
(Williamson et al. 2004) demonstrated that no-take zones on inshore coral reefs of the
Great Barrier Reef (GBR) increased the density and biomass of coral trout, the major
target of the recreational and commercial line fisheries on the GBR, 2-4 fold over a
period of around 13 years (Figure 19.1). Coral trout were on average, much larger in
no-take zones. No-take zoning was the likely cause of these differences between no-
take and fished areas, since Williamson et al. (2004) had data on density, biomass and
average size before zoning was implemented in 1987. Edgar and Barrett (1999)
surveyed reef biota in four Tasmanian no-take marine reserves, and at various control
(fished) sites. They also collected data atthe time these reserves were established and
then monitored the changes over a six year period. In the largest of these reserves,
Maria Island (7 km in length), rock lobster increased in biomass 10-fold, and
trumpeter (a reef fish) 100-fold. The number of fish, densities of larger (>325 mm
TL) fish, mean size of blue-throat wrasse and mean size of abalone, increased in this
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
541
reserve. Such changes were not as obvious in smaller reserves. Similar large increases
in abundance of spiny lobster and snapper have been recorded in northern New
Zealand no-take reserves over more than two decades (Babcock 2003).
A key question regarding no-take marine reserves is what duration of protection is
required for full recovery of abundance of species targeted by fishing. Some authors
have suggested that many targeted species may display significant levels of recovery
in no-take reserves in just a few years (Halpern & Warner 2002). Other evidence
suggests that duration to full recovery of large predatory reef fish in Philippine no-
take reserves may take 3 to 4 decades (Russ & Alcala 2004, Russ et al. 2005) (Figure
19.2).
-------------------------------------------------------------------
Box
Box 19. 1 The Maria Island MPA, Tasmania
The ideal field investigation of MPAs should include: (i) baseline information
collected prior to protection from fishing, (ii) surveys undertaken at least annually for
many years following MPA declaration, (iii)the use of standardised methods targeted
at a large range of plant and animal species, (iv) data obtained from replicated sites
inside and outside MPAs, and (v) data obtained from numerous MPAs distributed
over a large geographic span. To date, no such comprehensive study has been
reported; however, one study with many of these elements has been undertaken at
Maria Island, Tasmania (Edgaret al. 1999).
Since fishing was prohibited within a 7 km section of Maria Island coast in 1991,
underwater visual census transects have been undertaken annually at six sites
distributed both inside the MPA and along the adjacent coast. The primary aim of this
monitoring project has been to identify ecological changes through time inside the
MPA relative to changes outside.
Results of the Maria Island study over the first decade indicate that while some
marine species respond quickly to protection (Figure 19.3), changes in population
numbers of others take many years to become evident. Also, that some ecological
changes are unpredictable and quite variable; hence field monitoring of a wide range
of taxa within MPAs is necessary to properly understand ecosystem effects of fishing.
Following protection, some species at Maria Island increasedin numbers, other
species decreased, while the majority of species such as the most abundant fish
Trachinops caudimaculatus showed no clear population trends inside the MPA
relative to outside. Densities of the rock lobsterJasus edwardsii and large exploited
fishes such as the latrid trumpeterLatridopsis forsteri increased substantively over the
first decade (Figure 19.3). By contrast, densities of medium-sized abalone (Haliotis
rubra), a heavily-exploited species, unexpectedly declined (Figures 19.3 and 19.4).
Densities of the abundant sea urchinHeliocidaris erythrogramma remained stable for
the first five years of protection, but then commenced a gradual decline (Figure 19.3).
Increasing numbers of rock lobsters and fish predators within the Maria Island MPA
have probably caused a general decline in densities of large herbivorousinvertebrates.
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
542
Algal vegetation has not changed significantly following restrictions on fishing;
nevertheless, a longer time series of data is necessary to assess whether declining
levels of herbivorous invertebrates within the MPA ultimately generates a cascading
habitat effect involving plants. Such an interactive effect involving increased lobster
and fish predator numbers, decreased urchin and herbivorous invertebrate numbers,
and increased macroalgae canopy cover, known as a trophic cascade was observed
after 20 years protection in the Leigh Marine Reserve, New Zealand (Shears &
Babcock 2002, Shears & Babcock 2003).
<End of Box>
---------------------------------------------
Higher propagule production
A key requirement for no-take reserves to become net exporters of propagules (and
thus net exporters of potential recruits to fisheries) is that the per unit area production
of propagules is substantially higher in reserves well protected in the long-term. Since
density and average size of targeted speciesshould increase in well-protected
reserves, egg production per unit area also should increase. Evidence for this simple
expectation remains fairly limited, despite it being a reasonable expectation. Some of
the best evidence for this comes from New Zealand no-take reserves. Snapper (Pagrus
auratus) egg production was estimated to be 18 times higher inside than outside 3
New Zealand reserves over 3 years (Williset al. 2003a). (Kelly et al. 2002) used
empirical data to predict that egg production of lobster,Jasus edwardsii, would be 4.4
times higher in New Zealand no-take reserves after 25 years of protection. (Paddack
& Estes 2000) showed that egg production ofrockfish were often 2-3 times higher in
no-take than fished reefs in California. While these differences in egg production are
substantial it is far less clear whether they translate into measurable differences in
recruitment, either locally or to the wider stock.
Spillover
Do no-take reserves, well protected in the long-term, become net exporters of adult
targeted organisms? Some of the best evidence for such export (spillover) comes from
studies that have demonstrated increased abundance of targeted fish inside reserves
and in adjacent fished areas over time (McClanahan & Mangi 2000, Roberts et al.
2001, Russ et al. 2003, Abesamis & Russ 2005). Many of these studies report the
development of gradients (from higher inside reserves to lower outside reserves) of
abundance and catch rates. However, not all studies indicate the potential for
spillover. Kelly et al. (2002), for example, could not detect any enhanced catch rate of
lobsters adjacent to a well-protected marine reserve in New Zealand; however, their
results also showed that there was no reduction in catch in the region. This suggests
that conservation goals were being achieved without negatively affecting local
fisheries.
A substantial literature on movements ofmarine fish and some invertebrates
establishes the strong potential for spillover (Gell &Roberts 2003). Computer
modelling studies suggest that if spillover occurs, its contribution to overall fishery
yield will likely be very modest (Russ 2002).Most models of spillover suggestthat
such a process will rarely, if ever, compensate for the loss of fishery catch caused by
the loss of fishing area required to set up the reserve in the first place.
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The key question is what happens to local fishery catch, in both the short- and long-
term, when part of the area is declared no-take? One of the few studies to address this
question was that of (Alcala et al. 2005) at two small Philippine islands. They
demonstrated that closure to fishing of 10-25% of fishing area of these two islands did
not reduce total fishery catch at the islandsin the long-term (two decades), similar to
the results for lobsters in New Zealand (Kelly et al. 2002). On the contrary, the
experimental evidence suggested that the total catch was sustained, or even enhanced,
in the long-term. These results are particularly significant, given that municipal
(subsistence) fishing is such a major human activity at each island.
If spillover does occur in some cases, it islikely to have a fairly modest impact on
local fish yields. However, the potential still exists for net export of propagules from
reserve to fished areas, the “recruitment subsidy” effect.
Recruitment subsidy
Evidence for recruitment subsidy (net export of propagules from no-take marine
reserves) is still extremely limited. The main reasons for this are that propagules
(eggs, larvae) are extremely difficult to sample, tag and track (see Chapter 2, Early
life histories of marine invertebrates and fishes). Marine ecologists still have very
limited knowledge of the “dispersal kernels” of most marine larvae. Furthermore,
recruitment of marine organisms is notoriouslyvariable, making both the
identification and statistical testing of trends in recruitment difficult. Some empirical
evidence for recruitment subsidy comes from a scallop fishery in the Northern
Hemisphere, although a good deal of disagreement remains about the interpretation of
the evidence. The abundance of scallops (Placopecten magellanicus) increased
substantially following the 1994 closure to fishing of three large areas of the Georges
Bank, northeastern USA (Murawski et al. 2000). Total catch of the scallop fishery
increased between 1994 and 1998, despite the reduced fishing area. Fishing effort
concentrated outside the boundaries of the closed areas, particularly in places most
likely to receive scallop larvae exported from the closed areas (Gell & Roberts 2003).
These results suggest that the no-take reserves may have had a positive effect on total
yield of scallops on the Georges Bank, by exporting propagules to fished areas.
Recruitment subsidy from no-take reserves to fished areas is by far the mostlikely
mechanism to sustain, or even enhance, fisheries outside the boundaries of the no-take
reserves. Whilst many marine ecologists believe that such an expectation is
reasonable, given that marine larvae can often disperse distances much greater than
the spatial scale of most no-take marine reserves(e.g. 10’s of km), empirical evidence
in support of this export process is still rare.
Insurance against management failure and unpredictable stochastic events
A particularly powerful argument in support of establishing no-take marine protected
areas or reserves is that they serve as insurance policy against future fisheries
management failure and unpredictable stochastic events. The record of “traditional”
fisheries management to maintain spawning stocks of exploited organisms at levels
most marine scientists would consider to be sufficient to ensure long-term sustainable
harvest is fairly dismal (Pauly, et al. 2002). Many people now argue that the only way
to ensure sufficient spawners is to set aside a reasonable proportion of the stock in no-
take zones. Some argue that the economic and social cost of such an insurance policy
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is too high. Such arguments have to be weighed against the considerable economic
and social hardships that occur if a fishery is so depleted that it is no longer
economically viable. Such a debate is one of trade-offs between short and long-term
costs and benefits, and the ability of “traditional” fisheries management to maintain
enough spawning fish in the water.
Information on important parameters for stock assessment
A very clear benefit of no-take reserves, protected properly in the long-term, is that
they provide scientists with sites for study of unexploited populations, communities,
and ecosystems. They are some of the few places where scientists can directly make
reasonable estimates of such key parametersas natural mortality rates or growth rates
(Buxton et al. 2005). They are also places that show us what natural marine
communities and ecosystems actually look like, and how they function. No-take
reserves can also provide novel means of independently estimating parameters, such
as fishing mortality, that are vital for theeffective management of fisheries. For
example, by comparing seasonal fluctuations in abundance of snapper in reserves and
fished areas on coastal reefs it has been estimated that between 70 and 96% of legal-
sized snapper are being taken, mostly by recreational fishers (Willis & Millar 2005).
Costs of no-take marineprotected areas as fisheries management tools
Displaced effort
A compelling argument against the use of no-take MPAs as fisheries management
tools, at least at first sight, is that reserves will simply move fishing effort away from
the no-take area and concentrate it in the remaining fished area (see also Chapter 18,
Fisheries and their management). The short-term cost is likelyto be very real,
particularly if the fishery is fully exploited or over-exploited.In many cases, the
implementation of no-take reserves involves financial compensation to some
displaced fishers. This was certainlythe case in Queensland, following the
implementation of the Representative Areas Program on the Great Barrier Reef. The
amount of compensation paid out by the Federal government to commercial fishers
was considerable, more in fact than initially estimated. But such short-term costs must
always be weighed up against the longer-term benefits likely to flow from recruitment
subsidy (at least for coral reef fisheries on the GBR), insurance against management
failure and tourism income generated by Australia having one of the few well-
protected coral reef ecosystems in the world. The key point with respect to displaced
effort is weighing up short-term costs against long-term gains.
Locked-up resources
Another argument against no-take MPAs as fisheries management tools is that they
simply make part of the resource unavailable to the fishery, and thus make that
portion of the resource useless to the fishery. Such an argument ignores two things.
First, that export functions may, in the long-term, compensate for initial loss of
“locked-up” resources. Such export functions may even enhance fishery yields,
particularly if the resource is already heavily fished. Second, those “locked-up”
resources are possibly one of the best insurance policies we can have against the
possibility of future fisheries management failures.
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False sense of security
If no-take MPAs are poorly protected (e.g. poor compliance to no-take regulations) or,
due to specific life history characteristics of some target species, do not develop
export functions, they may well create afalse sense of security for fisheriesmanagers
and the public. The simple remedy to this problem is to ensure appropriate and
effective monitoring of reserve performance with respect to the stated goals of the
MPA. It is important to avoid setting MPAsup with the assumptions that they will act
as an insurance policy (albeitthis situation is likely) or they will develop a net export
function (an untested assumption).
Benefits of MPAs for biodiversity conservation
A primary objective of most MPAs declared to date is the conservation of biological
diversity. This may be expressed in terms of the protection of threatened species, the
preservation of important species, communities or habitats, or the conservation of
representative ecosystems.
The term “biological diversity” or “biodiversity” describes the variety of life on earth,
encompassing genetic, species and ecosystem levels. MPAs should safeguard and
enhance biodiversity at all three levels; however, the act of declaration of an MPA is
no guarantee that this will happen, in part because the MPA maybe ineffectual, in
part because human behaviour may change, and in part because of the complexity of
natural interactions between species.
Conservation of ecosystems
One clear conservation benefit of effective no-take MPAs is that they increase
ecosystem diversity at large geographic scales. Modern advances in boats, GPS and
other fishing technologies have created the situation where fish and large invertebrates
are captured from virtually all open-access coastal areas of the planet and trawlable
seabeds to over 1000 m depth. The removal of large carnivorous species targeted by
fishers in turn affects populations of prey species, with consequent flow-on effects
throughout the food web (Paulyet al. 1998, Pauly et al. 2000, Okey et al. 2004).
Creation of an effective MPA thus adds a new ecosystem component to the regional
seascape mosaic in the form of a patch that is ecologically structured by the large
commercially-exploited fishes that are virtually absent elsewhere.
The second clear conservation benefit of MPAs is that they protect habitats from
physical damage caused by fishing gear. Trawls and dredges, in particular, and to a
lesser extent anchors, traps and pots, directly scrape and modify the seabed. Scarring
by propellers, boat hulls and anchor chains can also degrade shallow seagrass beds
and sandbanks (see also Chapter 16, Seagrass). Until recently, impacts of trawls and
dredges were largely out-of-sight and overlooked; however, these fishing techniques
are now known to affect huge areas of seabed (Jenkins et al. 2001, Hall-Spencer et al.
2002, Thrush & Dayton 2002). An extreme example of physical damage to seabed
habitats relates to the trawl fishery fororange roughy on deepwater seamounts off
southeastern Tasmania. The complex coral matrix that provided habitat for numerous
species on all investigated seamounts shallower than 1000 m depth has been found
destroyed by trawl chains and nets, with some small seamounts trawled up to 3000
times during the initial ‘goldrush’ period (Koslow & Gowlett-Holmes 1998, Koslow
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et al. 2001). A subset of seamounts, including areas with coral >1000 m depth, has
now been protected from benthic trawling within the Tasmanian Seamounts MPA.
Another impact of fishing excluded from MPAs is the effect of bycatchand bait
discards. Populations of some scavenging species increase significantly in fishing
grounds as a consequence of the captureand discard from boats of dead unwanted
organisms, plus animals killed or woundedby trawls or dredges passing over the
seabed (Wassenberg & Hill 1987, Bradshaw et al. 2002).
In theory, MPAs should also assist efforts to safeguard biodiversity through
increasing local ecosystem resilience to invasive species and climate change. Human-
induced stresses that affect biologicalcommunities rarely operate on their own but
often act in a synergistic manner, such thatthe net impact of threats such as fishing
plus catchment nutrification, sedimentation, invasive species and climate change is
greater than the sum of these threats if acting individually (see also Chapters 20, 21
and 22). Modelling studies support this view, indicating that communities with the
full complement of species should possess greater stability and resistance to threats
such as invasive species than disturbed communities (Case 1990, Stachowicz et al.
1999, Stachowicz et al. 2002, Occhipinti-Ambrogi & Savini 2003), including those
affected by intense fishing.
Field studies on this topic are, however, limited; hence general support for theoretical
predictions that MPAs increase ecosystem resistance requires more data, particularly
on the scale of ecosystem response to threats. Work from the California coast has
shown that fished areas are less stablethan adjacent marine reserves, since high
density populations of urchins are much more susceptible to disease epidemics
(Behrens & Lafferty 2004). In another example, populations of the invasive, habitat-
modifying sea urchinCentrostephanus rodgersii appear to be rapidly expanding
through the eastern Tasmanian region as a consequence of warming water
temperatures (Crawford et al. 2000); however, the presence of high densities of
predatory lobsters has the potential to constrain recruitment and survival within the
Maria Island MPA (see Box 19.1). Thus, the Maria Island MPA is likely to resist sea
urchin invasion better than adjacent fished coasts (Buxton et al. 2005). Because of a
paucity of sea urchin barrens, this MPA is also likely to better resist invasion by the
exotic kelpUndaria pinnatifida (Valentine & Johnson 2003, Edgar et al. 2004a).
Conservation of species
The most obvious conservation benefit of MPAs is the protection of exploited
animals, including both targeted andbycatch species. For the majority of exploited
species, this benefit translates to increased local abundance inside MPAs relative to
outside rather than the persistence of a species that is fished elsewhere to extinction.
Once populations of targeted fishery species decline below a certain point then
continuation of the fishery is no longer economically viable (“commercial
extinction”), and that species generally continues to persist at low levels.
Nevertheless, extinction of local populations and even species is possible in
circumstances where the target is highly-valuable and lacks arefuge from hunting, as
in the case of Steller’s sea cow, or where an animal concentrates in a small area to
breed. For this reason, boundaries of MPAs are often delineated to include and protect
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spawning aggregations of fishes, such as Nassau grouper (Chiappone & Sealey 2000,
Sala et al. 2001).
The major conservation benefit of MPAs at the species level relates to bycatch.
Exploitation of species caught incidentally during fishing operations does not
necessarily decline as their populations decline, providing that the fishery for the main
target species remains economically profitable. Thus, populations of albatross caught
incidentally in the tuna long-line fishery (Brothers 1991), for example, could decline
to extinction, as long as the tuna population persists and fishers actively continue to
set baited lines.
Perhaps the most effective use of MPAs to protect bycatch species relates to trawling
grounds, where the ratio of target to non-target species killed by fishing can exceed
1:10 (Andrew & Pepperell 1992). Shark and ray species appear particularly
vulnerable to trawl bycatch threats because of very low fecundity, slow growth, and
late onset of sexual maturity. During the first 20 years of fishing on the New South
Wales continental slope trawl grounds, for example, the catch per unit effort declined
from 681 to 216 kg/hour (68%) for all fish species combined, but from 139 to 0.6
kg/hour (99.6%) for slow-growing dogshark (Centrophorus spp.) (Grahamet al.
2001). Populations of dogshark continue to decline towards extinction because the
NSW trawl fishery remains viable for other species (see also Chapter 18, Fisheries
and their management).
MPAs will also indirectly benefit some species because of the complexity of food web
interactions. Declaration of the Leigh Marine Reserve (NZ) indirectly benefits
Sargassum plants, for example, because sea urchin grazing pressure declined as a
consequence of increased numbers of lobsters and other predators within the MPA
(Figure 19.5), and these predators consumed most local sea urchins (Shears &
Babcock 2002). Similarly, predation pressure exerted by abundant lobsters in a South
African protected area caused a major ecosystem shift, with resultant higher
abundance of some invertebrate species (Barkai & Branch 1988).
On the other hand, some species will show declining populations following the
declaration of MPAs. In general, for every positive response shown by species to
protection from fishing, some prey species will show a negative response, with ripple
effects through the ecosystem. As a consequence of summing negative as wellas
positive responses, changes in species richness measured at the site scale are rarely
predictable, other than the minor increase caused by the addition to fish and
invertebrate counts of large exploited species that become common in the seascape,
and species greatly affected by fishing-related damage to habitat structures.
The prevalence of indirect effects within MPAs highlights the importance of
ecological monitoring programs for assessing MPA effectiveness. As an example,
MPAs may not provide the best mechanismto protect critically-endangered white
abalone (Haliotis sorenseni) in California (Tegner 2000) because of increased
predation risk from sea otters and other shellfish consumers. Abalone populations
declined following declaration of Tasmanian MPAs (see Box 19.1, Edgar & Barrett,
1999), possibly as a result of increase in abundance of rock lobsters and other large
predators.
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Conservation of genotypes
When fishing mortality is greater than natural mortality, as occurs for the majority of
fished stocks, then fishing exerts a very strong evolutionary pressure on populations.
For example, individuals of fishedpopulations that grow slowly and reach maturity at
a relatively small size, particularly if that size is below the minimum legal size of
capture, will have a greater chance of spawning and passing their genetic code to the
next generation than fast growing individuals. Fishing mortality can cause the mean
size of maturity of fished populations tosignificantly decline within less than four
generations (Conover & Munch 2002, Conover et al. 2005).
Because declining growth rate and size at maturity negatively affects fishery
production, fishery-induced selectionis sometimes counterbalanced by specific
management actions, such as maximum as well as minimum size limits, which allow
some large spawners to pass on their genes. However, new regulations directed at
individual species cannot counteract the full range of selective pressures induced by
fishing, such as behavioural adaptations that decrease probability of capture.
Effective no-take MPAs provide the best management tool for conserving genetic
diversity because populations within MPAs are not affected by fishing mortality or
fishery-induced evolutionary pressures. In most situations, populations within MPAs
will be genetically fitter than fished populations because thepopulation has evolved
specific characteristics through millenia that maximise long-term survival of the
species in the natural environment. Populations consisting of slow-growing
individuals as a result of fishing selection, for example, will suffer higher rates of
natural mortality than populations of fast-growing individuals because animals take
longer to reach spawning size. Populations with reduced size at maturity tend to have
lower total egg production than an unfished population where individuals spawn at a
large size with many more eggs released per female. Populations where individuals
forage less often because they stay longer in crevices to avoid capture by divers will
have reduced food consumption rates, growth rates and net egg production.
Maintenance of genetic diversity within anetwork of MPAs should prove particularly
important for the persistence of species in the face of changing environmental
conditions, such as during a period of rapid climate change (see also Chapter 22,
Climate change in marine ecosystem).
Costs of no-take marine protected areas for biodiversity conservation
In addition to benefits, managers andscientists must recognise that MPA
establishment can negatively affect biodiversity in some circumstances, and should try
to minimise any such losses. As discussed above, populations of species such as
abalone may decline within MPAs as a result of increases in populations of fished
predatory species. More importantly, the declaration of MPAs results in changed
human behaviour, with potential negative consequences.
As discussed above, exclusion of fishersfrom MPAs can result in displacement of
fishing effort and greater fishing pressure within open access areas outside. If the total
fishing catch is finely regulated using total allowable catches, then such displaced
effort could potentially cause overfishing and a gradual decline in fish populations
within the open-access areas, ultimately resulting in protected ‘islands’ of high
biodiversity that are surrounded by a ‘sea’ of low fish production (Buxton, et al.
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2005). Such a scenario is clearly undesirable from a resource management
perspective, and also from a conservation perspective for species with little
connectivity between the MPAs.
The declaration of MPAs can also concentrate divers and other users of the marine
environment into localised areas. Whereas accidental damage to corals and other
organisms caused by diver contact may have little environmental impact when spread
over a large area, such impacts can be catastrophic when localised along popular dive
trails. Clearly, management prescriptionswithin MPAs must take into account the
potential impacts on marine biodiversityof concentrations of ‘passive’ users.
Management planning should also pre-empt any race by fishers to extract as many
fishes as possible before MPA regulations come into force, and recognise that
spawning aggregation and other important sites may be targeted for illegal fishing if
locations are advertised within MPAs.
One pervasive threat to biodiversity that accompanies MPA creation is a false sense of
security. Everything is frequently assumed tobe fine once a MPA is declared
regardless of level of poaching and fish movement across boundaries. Field
monitoring studies should quickly indicate whether the MPA is actually working or
not, alleviating the threat of false belief.
Scientific benefits ofmarine protected areas
MPAs represent a management tool that interacts with human society at many levels.
In addition to much-debated economic impacts, MPAsprovide opportunities and
potential benefits for education and recreation, and can enhance aestheticexperiences.
They also generate scientific benefits of importance to fishery and conservation
managers, and to the wider community.
The immediate scientific value of effective MPAs is that they act as reference areas
for understanding effects of fishing on marine communities. Our present
understanding of this topic is poor, hence information on the unexpected population
changes that almost inevitably occur within MPAs (see Box 19.1) greatly enhances
our comprehension of ecosystem processes and provides new insights. To date, a
general understanding of effects of fishing has been severely compromised by
complexities of interactionsbetween species and by the‘sliding baseline syndrome’ –
the phenomenon whereby slow incremental changes may amount to massive
environmental changes over several human generations but are not noticed because
each generation starts with a different, albeit slightly worse, conception of the
‘natural’ state of the environment (Dayton et al. 1998).
In this context, it is important to recognise that the study of MPAs not only provides
information on how fishing affects the environment, but can also alleviate concerns
about fishing where this activity has little effect. For example, fisheries for a variety
of southeastern Australian species – including school shark, striped trumpeter, jack
mackerel, barracouta, gemfish and warehou – collapsed during the second half of the
20th century. In some cases the collapse was probably due to overfishing; however,
fisheries may also have declined as a consequence of increasing water temperatures,
coastal degradation, or a combination of factors. Without MPAs as reference areas,
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the contributing factors can only be speculated on, and fishing blamed in some cases
when not a major contributing factor.
An additional scientific benefit of MPAs is that they provide access to subjects that
are so rare that they cannot be rigorously studied elsewhere. For example, if large
predators have been overfished across the coastal seascape, then without study of
protected populations their potential role in the ecosystem cannot be assessed.
Similarly, without MPAs it is often impossible to accurately measure basic parameters
used for modelling stock dynamics of fished species, such as rates of natural
mortality, growth rates of large individuals, and size at maturity for unfished stocks.
MPAs are also useful in providing acontrolled environment for scientific
experiments, particularly when public access is restricted and experiments can be
undertaken without interference. The Leigh Marine Reserve in New Zealand was
originally planned with this scientific aim as its primary goal, although the reserve
was subsequently found to also generate many conservation-, fishery- and recreation-
related benefits over the long term.
From an ecological perspective, MPAs represent a large-scale manipulative
experiment where predation by humans is excluded from particular plots (Walters &
Holling 1990). If appropriately monitored, results can provide profound insights into
structural connections within food webs at regional, continental and global scales.
These spatial scales differ markedly from those traditionally studied in ecological
investigations, such as when plant and animal densities are modified at the scale of
metres on patches of shore. Processes operating at small scales often differ from those
operating at larger scales (Andrew & Choat 1982, Andrew & MacDiarmid 1991,
Babcock, et al. 1999), so conclusions reached cannot be extrapolated tothe more-
interesting larger domains without validation (Eberhardt & Thomas 1991, Menge
1992). MPAs provide prime opportunities to validate experiments at scales relevant to
management intervention.
Conclusions
Marine protected areas are not a universal panacea for all threats affecting marine
ecosystems. They provide one very important tool in the marine manager’s toolbox,
but need to be complemented with other management strategies.
Ecological changes associated with the declaration of MPAs will vary from location
to location, depending on such factors as the type and variety of habitats present,
extent of connectivity to adjacent habitats, wave exposure, depth distribution, level of
poaching, and extent of fishing impacts prior to protection. Similarly, each species
inhabiting the MPA will respond differently to protection, depending on level ofprior
exploitation and interactions with other species. For these reasons, biological
responses to MPA declaration are sometimes unpredictable at our present state of
ecological knowledge. Scientific research into the effects of MPAs represents a
rapidly expanding field with huge potential to increase general understanding of
marine processes at large geographic scales. With respect to research, we have passed
the stage where the question is “Will MPAs increase fish numbers” to questions of
how they affect individual species with particular life-history characteristics and how
to optimise MPA networks so that they maximise conservation and fishery benefits.
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The scientific jury is still out on thequestion of whether no-take MPAs will be
generally-effective fisheries management tools(Sale et al. 2005), although it is clear
that they will be more effective for some species than others. Many fisheries scientists
and managers, in Australia and around the world, view no-take reserves as a
conservation tool, but not as a fisheries management tool. Many of these fisheries
scientists and managers have, in a sense, backed themselves into a corner by
managing the world’s fisheries so poorly. There is no doubt that Australia has and
does manage its fisheries far better than most places in the world; yet we are not
immune to overfishing problems (e.g. gemfish, southern bluefin tuna, school shark,
orange roughy). On November 23, 2005, the Commonwealth Fisheries Minister
announced a plan to halve the number of commercial fishers fishing Commonwealth
managed fish stocks. Such an announcement does not reduce fleet sizes of state
managed fisheries. Furthermore, recreational fishing can be more difficult than
commercial fishing to monitor and regulate, an increasingly important issue for
fishery managers in the Australian context as well as in other parts of the world
(Cooke & Cowx 2004). The question is, if we have allowed far too much fishing in
the past, will simply trying to reduce fishing effort ensure sustainable fisheries and
return marine ecosystems to more natural conditions? Given past performances and
ever-increasing efficiency of fishing technologies, we need some insurance against
future failures of “traditional” fisheries management. No-take marine protected areas
will, at the bare minimum, provide that. In the fisheries context, nations and states
need to decide whether the long-term benefits will outweigh the short-term costs.
Questions & problems
1. Which life history traits are most associated with species that generate spillover
benefits to fisheries following the declaration of MPAs?
2. Do populations of many species benefit from the dispersal of eggs and larvae from
MPAs, and which species most benefit?
3. How can we best improve predictions of the trophic interactions that accompany
declaration of MPAs?
4. What general relationships exist between the size and spatialconfiguration of no-
take MPAs and their effectiveness for biodiversity conservation and fishery
management?
5. Which social considerations contribute most to the ecological success or failure of
MPAs?
Key references
Abesamis, R.A. and G.R. Russ, 2005. 'Density-dependent spillover from a marine
reserve: long-term evidence'.Ecological Applications 15: 1798-1812.
Allison, G.W., J. Lubchenco and M.H. Carr,1998. 'Marine reserves are necessary but
not sufficient for marine conservation.'Ecological Applications 8: S79-S92.
Babcock, R.C., S. Kelly, N.T. Shears, J.W. Walker and T.J. Willis, 1999. 'Changes in
community structure in temperate marine reserves'.Marine Ecology Progress
Series 189: 125-134.
Comment [RB1]:These are
excellent topics for discussion,
(which would be good title for the
section if the format of the book
allows) but I consider them
problematic in the context of the
usual textbook questions section –
where people may expect there to
be a “right” and “wrong” answers.
We have some empirical data for
1 thanks to garry, but answers for
2. (we don’t know, there is no
evidence); 3. (experience shows
that its really hard to predict and
you need local empirical
experience); 4. (confliciting data
on size, data conficiting with
theoretical predictions on size,
only theoretical predictions for
spatial configuration); 5. (it
depends…..)
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
552
Edgar, G.J. and N.S. Barrett, 1999. 'Effectsof the declaration of marine reserves on
Tasmanian reef fishes, invertebrates and plants'.Journal of Experimental
Marine Biology and Ecology 242: 107-144.
McClanahan, T.R. and S. Mangi, 2000. 'Spillover of exploitable fishes from a marine
park and its effect on the adjacent fishery'.Ecological Applications 10: 1792-
1805.
Roberts, C.M., J.P. Hawkins and F.R. Gell, 2005. 'The role of marine reserves in
achieving sustainable fisheries.'Philosophical Transactions - Royal Society of
London, B 360: 123-132.
Russ, G.R. and A.C. Alcala, 2004. 'Marine reserves: long-term protection is required
for full recovery of predatory fish populations'.Oecologia 138: 622-627.
Shears, N.T. and R.C. Babcock, 2003. 'Continuing trophic cascade effects after 25
years of no-take marine reserve protection.'Marine Ecology Progress Series
246: 1-16.
Walters, C.J. and C.S. Holling, 1990. 'Large-scale management experiments and
learning by doing.'Ecology 71: 2060-2068.
Willis, T.J., R.B. Millar, R.C. Babcock andN. Tolimieri, 2003. 'Burdens of evidence
and the benefits of marine reserves:putting Descartes before des horse?'
Environmental Conservation 30: 97-103.
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
0
2
4
6
8
10
12
14
16
18
Pre-protected ProtectedFished
No. / 1000
m
2 +/- SE
ZONE
0
2
4
6
8
10
12
14
16
18
Pre-protected ProtectedFished
No. / 1000
m
2 +/- SE
ZONE
0
2
4
6
8
10
12
14
16
18
Pre-protected ProtectedFished
Biomass (kg. / 1000
m
2) +/- SE
ZONE
0
2
4
6
8
10
12
14
16
18
Pre-protected ProtectedFished
Biomass (kg. / 1000m2) +/- SE
ZONE
Whitsunday Islands
Palm Islands
Density (/1000 m2)
Density (/1000 m2)
Biomass (kg/1000 m2)Biomass (kg/1000 m2)
Figure 19. 1 Mean (± 1 SE) density (number / 1000m2) and biomass (kg / 1000m2) of
coral trout,Plectropomusspp., within pre-protected (1983-1984), protected (1999-
2000) and fished (1999-2000) zones of the Palm (top) and Whitsunday (bottom)
Island groups.Island groups.
Reprinted with permission from Williamson et al. (2004)Reprinted with permission from Williamson et al. (2004)
553
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
Figure 19. 2 Mean biomass (g/m2) of large predatory reef fish (Families: Serranidae:
Epinephelinae, Lutjanidae, Lethrinidae) plotted against duration of reserve protection
(years) for Philippine no-take reserves.
Top figure - 13 no-take reservesof varying age (0.5-13 years) and12 nearby
nonreserve (fished) sites sampled at the one time. Middle and lower figures –
temporal monitoring (1983-2001) at Sumilon and Apo islands, respectively.
Exponential and linear models, respectively, fitted to reserve and nonreserve data.
Negative years of protection at Sumilon indicate years open to fishing. Vertical
arrows indicate duration at first significant difference between reserve and nonreserve
biomass (Tukey’s tests - 0.05 significance level). Closed circles = reserve, open
circles = nonreserve. Significance levels of regressions are ns > 0.05, * < 0.05, ** <
0.01, *** < 0.001. Reprinted with permission from Russ et al. (2005).
554
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
S.D. Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
555
Density (/500 m2)
Figure 19. 3 Changes through time in densities per transect of two fishes and four
invertebrate species in the Maria Island MPA and external referencesites
(after Buxton et al. 2005).
Reserve
External
Heliocidaris erythrogramma
0
200
400
600
800
0
200
400
600
800
92 93 94 95 9697 98 99 00 01 0292 93 94 95 9697 98 99 00 01 02
Centrostephanus rodgersii
0
10
20
30
0
10
20
30
92 93 94 95 96 97 98 99 00 01 0292 93 94 95 96 97 98 99 00 01 02
Haliotis rubra
0
50
100
0
50
100
9293 94 95 96 97 9899 00 01029293 94 95 96 97 9899 00 0102
Year
Trachinops caudimaculatus
0
1000
2000
09293 94 95 96 97 9899 00 01029293 94 95 96 97 9899 00 0102
9293 94 95 96 97 9899 00 01029293 94 95 96 97 9899 00 0102
0
10
20
30
40Latridopsis forsteri
0
10
20
30
40
Density (/500 m2)
Density (/50 m2)
Density (/50 m2)Density (/50 m2)
0
10
20
92 93 94 9596 97 9899 0001 02
Jasus edwardsii
92 93 94 9596 97 9899 0001 02
Density (/50 m2)
Year
Edg
S.D. C
ar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds
onnell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
556
Figure 19. 4 Abundance in three size categories of black-lip abalone (Haliotis rubra)
within the Maria Island marine reserve and at external reference sites between 1992
and 2002 (Buxton, et al. 2005).
ure 19. 4 Abundance in three size categories of black-lip abalone (Haliotis rubra)
within the Maria Island marine reserve and at external reference sites between 1992
and 2002 (Buxton, et al. 2005).
Reserve
0
100
200
300
400
1992 1993 1994 1995 1996 19971998 1999 2000 2001 2002
135-200 mm
85-134 mm
35-84 mm
External
0
100
200
300
400
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Reserve
0
100
200
300
400
1992 1993 1994 1995 1996 19971998 1999 2000 2001 2002
135-200 mm
85-134 mm
35-84 mm
External
0
100
200
300
400
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Year
Abundance
Reserve
0
100
200
300
400
1992 1993 1994 1995 1996 19971998 1999 2000 2001 2002
135-200 mm
85-134 mm
35-84 mm
External
0
100
200
300
400
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Reserve
0
100
200
300
400
1992 1993 1994 1995 1996 19971998 1999 2000 2001 2002
135-200 mm
85-134 mm
35-84 mm
External
0
100
200
300
400
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Year
Abundance (/300 m2)
gar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds S.D. Connell and B.M. Gillanders. Oxford University
s.ISBN: 0195553020.
557
Ed
Pres
Open Coast of NE
New Zealand
Unprotected MarineReserve
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds S.D.
Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
558
Figure 19. 5 Changes observed inside marine reserves in northeastern New Zealand
reflect the indirect and unanticipated changes to coastal reef ecosystems as a consequence
of fishing.
Such changes go beyond the species that are directly exploited (lobsters and fish) to
impact indirectly on their prey (urchins) and the primary producers in the system (large
habitat-forming brown algae). Such large-scale changes to habitat may have many other
cascading effects on the trophic structure of affected reef systems. Figure by T. Langlois
Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds S.D.
Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
559
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Edgar G.J., Russ G.R, Babcock R.C 2007 Marine protected areas. pp 534-565 InMarine EcologyEds S.D.
Connell and B.M. Gillanders. Oxford University Press.ISBN: 0195553020.
564
Chapter 19 Marine protected areas................................................................................. 533
Chapter overview...........................................................Error! Bookmark not defined.
Introduction................................................................................................................. 533
Significance of no-take marine protected areas in fisheries management.................. 539
Expectations of no-take marine protected areas as fisheries management tools.... 540
Examples of expected effects of no-take marine protected areas........................... 540
Costs of no-take marine protected areas as fisheries management tools................ 544
Benefits of MPAs for biodiversity conservation........................................................ 545
Conservation of ecosystems.................................................................................... 545
Conservation of species.......................................................................................... 546
Conservation of genotypes...................................................................................... 548
Costs of no-take marine protected areas for biodiversity conservation.................. 548
Scientific benefits of marine protected areas.............................................................. 549
Conclusions................................................................................................................. 550
Questions & problems................................................................................................. 551
Key references............................................................................................................ 551
Boxes........................................................................................................................... 551
References................................................................................................................... 559
Box 19. 1 The Maria Island MPA, Tasmania............................................................. 541
Figure 19. 1 Mean (± 1 SE) density (number / 1000m2) and biomass (kg / 1000m2) of
coral trout,Plectropomusspp., within pre-protected (1983-1984), protected (1999-
2000) and fished (1999-2000) zones of the Palm (top) and Whitsunday (bottom)
Island groups........................................................................................................... 553
Figure 19. 2 Mean biomass (g/m2) of large predatory reef fish (Families: Serranidae:
Epinephelinae, Lutjanidae, Lethrinidae) plotted against duration of reserve
protection (years) for Philippine no-take reserves.................................................. 554
Figure 19. 3 Changes through time in densities per transect of two fishes and four
invertebrate species in the Maria Island MPA and external reference sites........... 555
Figure 19. 4 Abundance in three size categories of black-lip abalone (Haliotis rubra)
within the Maria Island marine reserve and at external reference sites between 1992
and 2002 (Buxton, et al. 2005)................................................................................ 556
Figure 19. 5 Changes observed inside marine reserves in northeastern New Zealand
reflect the indirect and unanticipated changes to coastal reef ecosystems as a
consequence of fishing............................................................................................ 558
  • ... There is growing recognition that local communities and their actions have a much more dynamic relationship with marine and coastal resources than merely causing negative impacts (Kittinger et al 2014;Cinner, David 2011;Christie et al 2003;Edgar, Russ, Babcock, 2007;Pollnac et al 2010;Ban et al 2017). In focussing solely on the human impacts on the GBR, managers may miss valuable opportunities to empower people to work in partnership with management, harnessing powerful sources of custodianship, and deepening social, cultural and economic ties to the GBR. ...
  • ... There is growing recognition that local communities and their actions have a much more dynamic relationship with marine and coastal resources than merely causing negative impacts ( Ban et al., 2017;Christie et al., 2003;Cinner & David, 2011;Edgar, Russ & Babcock, 2007;Kittinger et al., 2014;Pollnac et al., 2010). In focussing solely on the human impacts on the GBR, managers may miss valuable opportunities to empower people to work in partnership with management, harnessing powerful sources of custodianship, and deepening social, cultural and economic ties to the GBR. ...
  • ... There is growing recognition that local communities and their actions have a much more dynamic relationship with marine and coastal resources than merely causing negative impacts ( Ban et al., 2017;Christie et al., 2003;Cinner & David, 2011;Edgar, Russ & Babcock, 2007;Kittinger et al., 2014;Pollnac et al., 2010). In focussing solely on the human impacts on the GBR, managers may miss valuable opportunities to empower people to work in partnership with management, harnessing powerful sources of custodianship, and deepening social, cultural and economic ties to the GBR. ...
  • ... By their very nature, MPA are spatially-delimited areas of the marine environment with special management policies to achieve, among other possible goals, the conservation of biodiversity (Edgar et al., 2007). They are usually structured in order to allow different types of activities, usually termed as uses, in different areas with the help of a zoning of the area. ...
  • ... An emerging multidisciplinary consensus stresses the importance of assessing and actively promoting ecosystem resilience ( Peterson et al., 1998;Folke et al., 2004), to achieve which it will be key to establish deep-sea reference areas in the proximity of the deep-sea mining areas. In addition, it is now widely accepted that for the effective protection of marine biodiversity and marine resources the establishment of marine protected areas (MPAs) is essential ( Tundi Agardy, 1994;Margules and Pressey, 2000;Roberts et al., 2001;Edgar et al., 2007). The numbers and extent of MPAs has increased rapidly over recent decades, with a target of protecting 10% of ocean areas incorporated in the Convention on Biological Diversity and a target of 30% recommended by the 2014 Sydney World Parks Congress. ...
  • ... Marine protected areas (MPAs) are usually established for conservation of biodiversity, and are often used as reference areas to assess the scale of human impacts on marine and coastal environments(Edgar, Russ, and Babcock 2007). Although catchment and coastal communi- ties are highly complex, their role tends to be oversimplified by marine managers ( Christie et al. 2003), and local people are often identified as a major source of problems in MPA management, resulting in their actions becoming targets for external management interventions (Shackeroff, Campbell, and Crowder 2011). ...
    ... This brings a social justice obligation on protected area managers to ensure community well-being is enhanced through conservation (De Santo 2013), rather than simply being displaced by wider societal or political needs ( Adger et al. 2003;Breslow et al. 2016;Jones, McGinlay, and Dimitrakopoulos 2017;Devillers et al. 2015). In focussing solely on the human impacts on the biophysical condition of an MPA at the expense of other human dimensions, managers may miss valuable opportunities to harness powerful sources of MPA custodianship, and deepen social, cultural, and economic ties ( Christie et al. 2003;Edgar, Russ and Babcock 2007). ...
  • ... The protection of essential fish habitat by means of marine protected areas (MPAs) might improve the current status of both habitats and stocks, and ensure the long-term sustainability of fisheries resources (Giannoulaki et al. 2011). However, given the complexity of the processes within marine ecosystems, the ecological changes that an MPA creation might bring about vary greatly from one region to another and are difficult to predict accurately (Edgar et al. 2007). The outcomes of the present study may assist in the identification of areas where the protection of juveniles is imperative, but more studies to analyse the impacts on the entire ecosystem are recommended. ...
  • ... Usually they operate either close to or in a nature reserve or Marine Protected Area ( Buckley, 2010). As such, the ecosystems are highly sensitive and of national, if not international, importance (Edgar et al, 2007). Secondly, the tour operator is offering 'close encounters' with various iconic species such as whales, dolphins, seals, sharks, chimpanzees, gorillas and elephants ( Kopnina, 2016;Moorhouse et al, 2016). ...
  • ... Οι Θαλάσσιες Προστατευόμενες Περιοχές αποτελούν πόλο έλξης για πολλές δραστηριότητες που σχετίζονται με την αναψυχή, ανάμεσα τους και το ερασιτεχνικό ψάρεμα, με αποτέλεσμα να δημιουργούνται πολλές φορές προβλήματα. Καθότι είναι περιοχές προσβάσιμες με σκάφος είναι δεδομένο ότι μεγαλύτερος αριθμός σκαφών κοντά σε τέτοιες περιοχές μπορεί να δημιουργήσει και μεγαλύτερες συνθήκες πίεσης και να διαταράξει το προστατευόμενο ενδιαίτημα (Edgar et al. 2007). Οι Θαλάσσιες Προστατευόμενες Περιοχές είναι χαρακτηριστικά παραδείγματα των κινδύνων που μπορεί να προκαλεί η, έστω και μικρής κλίμακας, ερασιτεχνική αλιεία (Lynch 2006). ...
  • ... This is contrary to the trend of declining (or in some cases stable) relative biomass of exploited fish and invertebrate stocks observed in many regions of the world ( Costello et al. 2012, Worm andBranch 2012). To stop overfishing, counter measures of marine protected areas and annual catch limits (e.g., "catch shares") have been proposed and implemented over the past decades (e.g., Roberts 1997, Edgar et al. 2007, Costello et al. 2008). However, neither of these management measures was applied to these two lobster fisheries. ...

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