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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More fish, more fishing: why strategic marine park placement is a win-win


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.

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More fish, more fishing: why strategic marine park placement is a win-win



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Marine parks are good for fish – especially if they’re in the right areas.
Epstock/Shutterstock

Kerstin Jantke, University of Hamburg; Alienor Chauvenet, Griffith University; Hugh Possingham, The University of Queensland; James Allan, The University of Queensland; James Watson, The University of Queensland, and Kendall Jones, The University of Queensland

Australia has some of the most spectacular marine ecosystems on the planet – including, of course, the world-famous Great Barrier Reef. Many of these places are safe in protected areas, and support a myriad of leisure activities such as recreational fishing, diving and surfing. No wonder eight in ten Aussies live near the beach.

Yet threats to marine ecosystems are becoming more intense and widespread the world over. New maps show that only 13% of the oceans are still truly wild. Industrial fishing now covers an area four times that of agriculture, including the farthest reaches of international waters. Marine protected areas that restrict harmful activities are some of the last places where marine species can escape. They also support healthy fisheries and increase the ability of coral reefs to resist bleaching.




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Most recreational fishers in Australia support marine sanctuaries


One hundred and ninety-six nations, including Australia, agreed to international conservation targets under the United Nations Convention on Biological Diversity. One target calls for nations to protect at least 10% of the world’s oceans. An important but often overlooked aspect of this target is the requirement to protect a portion of each of Earth’s unique marine ecosystems.

How are we tracking?

The world is on course to achieve the 10% target by 2020, with more than 7.5% of the ocean already protected. However, our research shows that many marine protected areas are located poorly, leaving many ecosystems underprotected or not protected at all.

What’s more, this inefficient placement of marine parks has an unnecessary impact on fishers. While marine reserves typically improve fisheries’ profitability in the long run, they need to be placed in the most effective locations.

We found that since 1982, the year nations first agreed on international conservation targets, an area of the ocean almost three times the size of Australia has been designated as protected areas in national waters. This is an impressive 20-fold increase on the amount of protection that was in place beforehand.

But when we looked at specific marine ecosystems, we found that half of them fall short of the target level of protection, and that ten ecosystems are entirely unprotected. For example, the Guinea Current off the tropical West African coast has no marine protected areas, and thus nowhere for its wildlife to exist free from human pressure. Other unprotected ecosystems include the Malvinas Current off the southeast coast of South America, Southeast Madagascar, and the North Pacific Transitional off Canada’s west coast.

Marine park coverage of global ecosystems. Light grey: more than 10% protection; dark grey: less than 10% protection; red: zero protection.
Author provided

Australia performs comparatively well, with more than 3 million square km of marine reserves covering 41% of its national waters. Australia’s Coral Sea Marine Park is one of the largest marine protected areas in the world, at 1 million km². However, a recent study by our research group found that several unique ecosystems in Australia’s northern and eastern waters are lacking protection.

Furthermore, the federal government’s plan to halve the area of strict “no-take” protection inside marine parks does not bode well for the future.

How much better can we do?

To assess the scope for improvement to the world’s marine parks, we predicted how the protected area network could have been expanded from 1982.

With a bit more strategic planning since 1982, the world would only need to conserve 10% of national waters to protect all marine ecosystems at the 10% level. If we had planned strategically from as recently as 2011, we would only need to conserve 13% of national waters. If we plan strategically from now on, we will need to protect more than 16% of national waters.

If nations had planned strategically since 1982, the world’s marine protected area network could be a third smaller than today, cost half as much, and still meet the international target of protecting 10% of every ecosystem. In other words, we could have much more comprehensive and less costly marine protection today if planning had been more strategic over the past few decades.

The lack of strategic planning in previous marine park expansions is a lost opportunity for conservation. We could have met international conservation targets long ago, with far lower costs to people – measured in terms of a short-term loss of fishing catch inside new protected areas.

This is not to discount the progress made in marine conservation over the past three decades. The massive increase of marine protected areas, from a few sites in 1982, to more than 3 million km² today, is one of Australia’s greatest conservation success stories. However, it is important to recognise where we could have done better, so we can improve in the future.

Australia’s marine park network.
Author provided

This is also not to discount protected areas. They are important but can be placed better. Furthermore, long-term increases in fish populations often outweigh the short-term cost to fisheries of no-take protected areas.

Two steps to get back on track

In 2020, nations will negotiate new conservation targets for 2020-30 at a UN summit in China. Targets are expected to increase above the current 10% of every nation’s marine area.

We urge governments to rigorously assess their progress towards conservation targets so far. When the targets increase, we suggest they take a tactical approach from the outset. This will deliver better outcomes for nature conservation, and have less short-term impact on the fishing industry.




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Strategic planning is only one prerequisite for marine protected areas to effectively protect unique and threatened species, habitats and ecosystems. Governments also need to ensure protected areas are well funded and properly managed.

These steps will give protected areas the best shot at halting the threats driving species to extinction and ecosystems to collapse. It also means these incredible places will remain available for us and future generations to enjoy.The Conversation

Kerstin Jantke, Postdoctoral Researcher on conservation biology, University of Hamburg; Alienor Chauvenet, Lecturer, Griffith University; Hugh Possingham, Professor, The University of Queensland; James Allan, Postdoctoral research fellow, School of Biological Sciences, The University of Queensland; James Watson, Professor, The University of Queensland, and Kendall Jones, PhD candidate, Geography, Planning and Environmental Management, The University of Queensland

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

Most recreational fishers in Australia support marine sanctuaries


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Recreational fishers adjacent to an established marine park in NSW.
Author provided

Matt Navarro, University of Western Australia; Marit E. Kragt, and Tim Langlois, University of Western Australia

More than 70% of recreational fishers support no-take marine sanctuaries according to our research, published recently in Marine Policy.

This study contradicts the popular perception that fishers are against establishing no-take marine reserves to protect marine life. In fact, the vast majority of fishers we surveyed agreed that no-take sanctuaries improve marine environmental values, and do not impair their fishing.




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No-take marine sanctuaries, which ban taking or disturbing any marine life, are widely recognised as vital for conservation. However, recent media coverage and policy decisions in Australia suggest recreational fishers are opposed to no-take sanctuary zones created within marine parks.

This perceived opposition has been reinforced by recreational fishing interest groups who aim to represent fishers’ opinions in policy decisions. However, it was unclear whether the opinions expressed by these groups matches those of fishers on-the-ground in established marine parks.

To answer this, we visited ten state-managed marine parks across Western Australia, South Australia, Queensland and New South Wales. We spoke to 778 fishers at boat ramps that were launching or retrieving their boats to investigate their attitudes towards no-take sanctuary zones.

Our findings debunk the myth that recreational fishers oppose marine sanctuaries. We found 72% of active recreational fishers in established marine parks (more than 10 years old) support their no-take marine sanctuaries. Only 9% were opposed, and the remainder were neutral.

We also found that support rapidly increases (and opposition rapidly decreases) after no-take marine sanctuaries are established, suggesting that once fishers have a chance to experience sanctuaries, they come to support them.

Recreational fishers support for marine sanctuaries increases with marine park age.

Fishers in established marine parks were also overwhelmingly positive towards marine sanctuaries. Most thought no-take marine sanctuaries benefited the marine environment (78%) and have no negative impacts on their fishing (73%).

We argue that recreational fishers, much like other Australians, support no-take marine sanctuaries because of the perceived environmental benefits they provide. This is perhaps not surprising, considering that appreciating nature is one of the primary reasons many people go fishing in the first place.

Exploring marine life within an established marine park.
Tim Langlois

In the past opposition from recreational fishing groups has been cited in the decision to scrap proposed no-take sanctuaries around Sydney, to open up established no-take sanctuaries to fishing and to reduce sanctuaries within the Australia Marine Parks (formerly the Commonwealth Marine Reserve network).

Our findings suggest that these policy decisions do not reflect the beliefs of the wider recreational fishing community, but instead represent the loud voices of a minority.

We suggest that recreational fishing groups and policy makers should survey grass roots recreational fishing communities (and other people who use marine parks) to gauge the true level of support for no-take marine sanctuaries, before any decisions are made.




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The backflip over Sydney’s marine park is a defiance of science


Despite what headlines may say, no-take marine sanctuaries are unlikely to face long lasting opposition from recreational fishers. Instead, our research suggests no-take marine sanctuaries provide a win-win: protecting marine life whilst fostering long term support within the recreational fishing community.The Conversation

Matt Navarro, Post-doctoral Fellow, University of Western Australia; Marit E. Kragt, Senior Lecture in Agricultural and Resource Economics, and Tim Langlois, Research Fellow, University of Western Australia

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

The backflip over Sydney’s marine park is a defiance of science



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Sydney’s iconic beaches are not yet part of a marine park.
John Turnbull

David Booth, University of Technology Sydney and John Turnbull, UNSW

The New South Wales government’s decision to back away from establishing no-fishing zones in waters around Sydney leaves significant question marks over the plan, which is open for public consultation until September 27.

Fisheries Minister Niall Blair explained the apparent backflip by saying he was “confident that fishing is not the key threat to the sustainability of our marine environment”, after receiving what he described as “robust” feedback from local communities and anglers.

The original plans for Sydney’s marine park. Click image to enlarge.
NSW government

The originally proposed Sydney Marine Park comprised 17 “sanctuary zones” (totalling 2.4% of the area, including estuaries), 3 “conservation zones” totalling 2.6%, and 21 “special purpose zones”, which would allow (and in some cases protect) fishing.

Sanctuary zones allow no fishing; conservation zones allow taking of lobster and abalone (see below); and special purpose zones have a range of restrictions or allowances, not necessarily of any conservation benefit. For instance, four offshore artificial reefs are classed as special purpose zones.

The plans cover the waters around Sydney, stretching from Newcastle in the north to Wollongong in the south. Formally known as the Hawkesbury Shelf marine bioregion, it is the only bioregion wholly in NSW that does not have a marine park. This is despite Sydney’s magnificent array of underwater and coastal habitats, which are home to more fish species than the entire British Isles.




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New zones and ranked threats

The original marine park proposal was far from ideal. A good marine park should have a string of closely connected sanctuary zones, but there was a large gap from southern Sydney to Wollongong where no sanctuary zones were proposed.

Instead, there was a new “conservation zone” to allow fishing for lobster and abalone. Yet lobster in particular are important to this ecosystem, because they protect kelp by preying on sea urchins.

Threats to the marine region around Sydney, as ranked in a NSW government report. Click image to enlarge.
NSW government

The NSW government based its earlier proposal on a principle called TARA, short for “threat and risk assessment”, in which all perceived factors are ranked according to their environmental, social and economic outcomes.

While other major threats such as climate change and pollution are ranked highly, fishing doesn’t appear until number 18 on the government’s list (see page 8 here. One reason for this is that fishing is split into eight categories (such as “recreational fishing by boat – line and trap”), masking its overall impact. Even 4WDs on beaches are ranked as a greater threat to the environment than many types of fishing.

Premier Gladys Berejiklian’s press release about the marine park public consultation didn’t mention the environmental threat posed by fishing at all. Yet there is clear evidence that fishing directly harms fish stocks.

One recent study shows that stocks of inshore fish species have declined in Australia by 30% in a decade, except in sanctuary zones. Worldwide, sanctuary zones (also called no-take zones) have been shown to help fish grow larger and more abundant. And recent studies in NSW coastal waters have reiterated the benefits of no-take zones for species such as morwong, bream, and snapper.

Partial protection doesn’t work

The latest proposals, which would allow recreational but not commercial fishing, would be much less effective than full protection. One recent study suggested that partial protection is no better than no protection at all.

According to a NSW government estimate, recreational fishing removes more than 3 million fish, crustaceans and molluscs from NSW coastal waters every year. But marine parks are primarily about conservation, and this requires us to face some stark realities. With more than 8 million people likely to call Sydney home in the next 40 years, pressures on our coasts will only increase.

Sanctuary zones are one of the best available conservation tools to guard against these impacts. These zones have also been shown to make wildlife more resilient to climate change.

Even before the government’s decision to rescind the proposed sanctuary zones, the original plan for no-take zones to cover just 2.4% of the region was a severe compromise. By comparison, the Great Barrier Reef Marine Park has 30% sanctuary zone coverage, and the rest of NSW has 7-8%. International best practice recommends at least 20%, and even the Commonwealth Marine Reserves Management Plan offers 6% no-take coverage.

But now, with no sanctuary zones, Sydney’s proposed “marine park” is not worthy of the name.

Wrong priorities

A peculiar contradiction is that despite one-quarter of the listed threats being fishing-related, the NSW government’s marine estate management strategy includes an initiative to encourage fishing. Pollution is also a high-priority threat, and fishing is the largest source of subtidal debris.

Kelp and a tangle of discarded fishing line.
John Turnbull

If local-level threats such as fishing and litter are not dealt with, resilience to climate change suffers as a result. We must tackle all threats – overfishing, pollution, climate change – and not shy away from one because it’s politically unpalatable.




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It is frustrating that the NSW government has opted to abolish these marine sanctuaries before the public consultation was complete. The wider public understands the value of sanctuary zones, as indicated in recent opinion polls showing clear support for the original plans among Sydneysiders – even many of those who fish.

Some fishers are now calling for sanctuary zones to be scrapped or wound back in other iconic NSW marine parks, such as Lord Howe Island and Solitary Islands. This move would be a defiance of the science. The evidence shows that sanctuary zones are essential for restoring and preserving our marine estate for future generations.The Conversation

David Booth, Professor of Marine Ecology, University of Technology Sydney and John Turnbull, , UNSW

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