Why marine protected areas are often not where they should be



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Piers Dunstan, CSIRO; Natalie Dowling, CSIRO; Simone Stevenson, Deakin University, and Skipton Woolley, CSIRO

There’s no denying the grandeur and allure of a nature reserve or marine protected area. The concept is easy to understand: limit human activity there and marine ecosystems will thrive.

But while the number of marine protected areas is increasing, so too is the number of threatened species, and the health of marine ecosystems is in decline.

Why? Our research shows it’s because marine protected areas are often placed where there’s already low human activity, rather than in places with high biodiversity that need it most.

Not where they should be

Many parts of the world’s protected areas, in both terrestrial and marine environments, are placed in locations with no form of manageable human activity or development occurring, such as fishing or infrastructure. These places are often remote, such as in the centres of oceans.




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And where marine protected areas have been increasing, they’re placed where pressures cannot be managed, such as areas where there is increased ocean acidification or dispersed pollution.

Limestone islands in the Coral Triangle. The marine protected areas.
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But biodiversity is often highest in the places with human activity – we use these locations in the ocean to generate income and livelihoods, from tourism to fishing. This includes coastal areas in the tropics, such as the Coral Triangle (across six countries including Indonesia, the Philippines and Malaysia), which has almost 2,000 marine protected areas, yet is also home to one of the largest shipping routes in the world and high fishing activity.




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What’s more, many marine industries are already regulated through licences and quotas, so it’s hard to establish a new marine protected area that adds a different type of management on top of what already exists.

This leaves us with an important paradox: the places where biodiversity is under the most pressure are also the places humanity is most reluctant to relinquish, due to their social or economic value. Because of those values, people and industry resist changes to behaviour, leaving governments to try to find solutions that avoid conflict.

Lessons from the fishing industry

How can we resolve the paradox of marine protected areas? A strategy used in the fishing industry may show the way.

Fisheries have had experience in going beyond the limits of sustainability and then stepping back, changing their approach to managing species and ecosystems for better sustainability, while still protecting economic, social and environmental values.




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In the past, many of the world’s fisheries regularly exceeded the sustainable limit of catches, and many species such as southern bluefin tuna declined significantly in number. But strong rules around how a fishery should operate mean declines have since been reversed.

Changes to fishery management have reversed population declines in southern bluefin tuna.
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So how did they do it? In recent decades, many of the world’s large-scale fisheries implemented formal “harvest strategies”. These strategies can flip downward trends of marine species in places not designated a marine protected area.

Harvest strategies have three steps. First is pre-agreed monitoring of species and ecosystems by fishers, regulators and other stakeholders. Second, regulators and scientists assess their impact on the species and ecosystems. And last, all stakeholders agree to put management measures in place to improve the status of the monitored species and ecosystems.

These measures may include changing how fishing is done or how much is done. It’s a commonsense strategy that’s delivered successful results with many fished species either recovering or recovered.




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In Australia, the federal government introduced a formal harvest strategy policy to manage fisheries in 2007. It was evaluated in 2014, and the report found many (but not all) fish stocks are no longer overfished. This includes species such as orange roughy and southern bluefin tuna in Australia, which were overfished but are no longer so.

But unfortunately, this positive trend has not been replicated for biodiversity hit by the combinations of other human activities such as coastal development, transport, oil and gas extraction and marine debris.

A consistent strategy

We need to adapt the experience from fisheries and apply a single, formal, transparent and agreed biodiversity strategy that outlines sustainable management objectives for the places we can’t put marine protected areas.

This would look like a harvest strategy, but be applied more broadly to threatened species and ecosystems. What might be sustainable from a single species point of view as used in the fisheries might not sustainable for multiple species.




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This would mean for our threatened species, we would be monitoring their status, assessing whether the total population was changing and agreeing on when and how we would change the way that they are impacted.

Such a strategy would also allow monitoring of whole marine ecosystems, even when information is limited. Information on trends in species and ecosystems often exists, but is hidden as commercial-in-confidence or kept privately within government, research or commercial organisations.

Looking ahead

Still, a lack of data shouldn’t limit decision making. Experience in fisheries without much data shows even rules of thumb can be effective management tools. Rules of thumb can include simple measures like gear restrictions or spatial or temporal closures that don’t change through time.

Moving forward, all stakeholders need to agree to implement the key parts of harvest strategies for all marine places with high biodiversity that aren’t protected. This will complement existing marine protected area networks without limiting economic activity, while also delivering social and environmental outcomes that support human well-being.

Our marine ecosystems provide fish, enjoyment, resources and and simple beauty. They must survive for generations to come.The Conversation

Piers Dunstan, Principal Research Scientist, CSIRO; Natalie Dowling, Researcher, CSIRO; Simone Stevenson, PhD Candidate, Deakin University, and Skipton Woolley, Research scientist, CSIRO

This article is republished from The Conversation under a Creative Commons license. Read the original article.

No-take marine areas help fishers (and fish) far more than we thought



A juvenile Plectropomus leopardus from the Whitsundays.
David Williamson/James Cook University

Dustin Marshall, Monash University and Liz Morris, Monash University

One hectare of ocean in which fishing is not allowed (a marine protected area) produces at least five times the amount of fish as an equivalent unprotected hectare, according to new research published today.

This outsized effect means marine protected areas, or MPAs, are more valuable than we previously thought for conservation and increasing fishing catches in nearby areas.

Previous research has found the number of offspring from a fish increases exponentially as they grow larger, a disparity that had not been taken into account in earlier modelling of fish populations. By revising this basic assumption, the true value of MPAs is clearer.




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Marine Protected Areas

Marine protected areas are ocean areas where human activity is restricted and at their best are “no take” zones, where removing animals and plants is banned. Fish populations within these areas can grow with limited human interference and potentially “spill-over” to replenish fished populations outside.

Obviously MPAs are designed to protect ecological communities, but scientists have long hoped they can play another role: contributing to the replenishment and maintenance of species that are targeted by fisheries.

Wild fisheries globally are under intense pressure and the size fish catches have levelled off or declined despite an ever-increasing fishing effort.

Yet fishers remain sceptical that any spillover will offset the loss of fishing grounds, and the role of MPAs in fisheries remains contentious. A key issue is the number of offspring that fish inside MPAs produce. If their fecundity is similar to that of fish outside the MPA, then obviously there will be no benefit and only costs to fishers.




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Big fish have far more babies

Traditional models assume that fish reproductive output is proportional to mass, that is, doubling the mass of a fish doubles its reproductive output. Thus, the size of fish within a population is assumed to be less important than the total biomass when calculating population growth.

But a paper recently published in Science demonstrated this assumption is incorrect for 95% of fish species: larger fish actually have disproportionately higher reproductive outputs. That means doubling a fish’s mass more than doubles its reproductive output.

When we feed this newly revised assumption into models of fish reproduction, predictions about the value of MPAs change dramatically.


Author provided

Fish are, on average, 25% longer inside protected areas than outside. This doesn’t sound like much, but it translates into a big difference in reproductive output – an MPA fish produces almost 3 times more offspring on average. This, coupled with higher fish populations because of the no-take rule means MPAs produce between 5 and 200 times (depending on the species) more offspring per unit area than unprotected areas.

Put another way, one hectare of MPA is worth at least 5 hectares of unprotected area in terms of the number of offspring produced.

We have to remember though, just because MPAs produce disproportionately more offspring it doesn’t necessarily mean they enhance fisheries yields.

For protected areas to increase catch sizes, offspring need to move to fished areas. To calculate fisheries yields, we need to model – among other things – larval dispersal between protected and unprotected areas. This information is only available for a few species.

We explored the consequences of disproportionate reproduction for fisheries yields with and without MPAs for one iconic fish, the coral trout on the Great Barrier Reef. This is one of the few species for which we had data for most of the key parameters, including decent estimates of larval dispersal and how connected different populations are.

No-take protected areas increased the amount of common coral trout caught in nearby areas by 12%.
Paul Asman and Jill Lenoble/Flickr, CC BY

We found MPAs do in fact enhance yields to fisheries when disproportionate reproduction is included in relatively realistic models of fish populations. For the coral trout, we saw a roughly 12% increase in tonnes of caught fish.

There are two lessons here. First, a fivefold increase in the production of eggs inside MPAs results in only modest increases in yield. This is because limited dispersal and higher death rates in the protected areas dampen the benefits.




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However the exciting second lesson is these results suggest MPAs are not in conflict with the interests of fishers, as is often argued.

While MPAs restrict access to an entire population of fish, fishers still benefit from from their disproportionate affect on fish numbers. MPAs are a rare win-win strategy.

It’s unclear whether our results will hold for all species. What’s more, these effects rely on strict no-take rules being well-enforced, otherwise the essential differences in the sizes of fish will never be established.

We think that the value of MPAs as a fisheries management tool has been systematically underestimated. Including disproportionate reproduction in our assessments of MPAs should correct this view and partly resolve the debate about their value. Well-designed networks of MPAs could increase much-needed yields from wild-caught fish.The Conversation

Dustin Marshall, Professor, Marine Evolutionary Ecology, Monash University and Liz Morris, Administration Manager, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Article: Australia – Marine Protected Areas


The following link is to an article about Australia’s Marine Protected Areas.

For more visit:
http://www.wwf.org.au/our_work/saving_the_natural_world/oceans_and_marine/marine_solutions/protected_areas/