Getting More From Less: How to Set Catch Limits and Assess Stocks in Data-Poor Fisheries

Recent changes to federal law mandate that fishery managers must implement annual catch limits and accountability measures for all U.S. fish stocks by 2011. For fisheries with sparse data, this is a significant challenge as traditional stock assessments are costly and demand large quantities of time and information. 

British Columbia fisherman collecting data (measuring fish size).

Many fisheries in the U.S. and around the world suffer from inadequate data – in fact, this may be more the rule than the exception. Moreover, there are many serious constraints to the timely assessment of stocks and to the development of annual catch limits in addition to lack of data – including stock assessment and vetting processes that cannot process available data with available resources.  

Fortunately, there are new tools available to help assess data-poor fisheries using easily gathered data and/or data already on hand. Depending upon the method used, data-poor assessment models allow fisheries scientists working in agencies, in advisory panels, and in other relevant bodies to estimate current population biomass, sustainable yield, the risk of overfishing, or stock status relative to specific reference points (or proxies for any or all of these).  This information can then be used to determine appropriate catch limits for target populations.

Given the large number of unassessed stocks and the urgent need for initial assessments of data poor stocks, EDF’s Ocean Innovations team has summarized relevant scientific papers into a user-friendly guide to 11 data-poor methods (available from Rod Fujita at rfujita[at]edf.org).

We’re also currently working on a comparison of four data-poor methods to determine how closely they agree with results from traditional stock assessments. Preliminary results suggest that many of these methods perform well in simulation studies and in comparison with traditional stock assessment methodology (although in some cases they may result in sustainable yield estimates that are more conservative than Maximum Sustainable Yield).  Some have already been used to set Annual Catch Limits for some U.S. fisheries (see examples below).

Data-poor methods fall into four categories, depending upon the type of data each method requires and the information each method produces.  For more information on a specific method, please contact Rod Fujita at rfujita[at]edf.org.

Extrapolation Methods

  • Robin Hood Approach

Life-History Vulnerability Analysis

  • Productivity and Susceptibility Analysis (PSA)

Sequential Trend Analysis

  • In-Season Depletion Estimator
  • Depletion-Corrected Average Catch (DCAC)
  • Depletion-Based Stock Reduction Analysis (DB-SRA)
  • An-Index-Method (AIM)
  • Reserve-Based Spawning Potential Ratio (Dynamic SPR)
  • Fractional Change in Lifetime Egg Production (FLEP)
  • Multivariate El Niño Southern Oscillation (ENSO) Index (MEI)

Decision Trees

  • Length-Based Reference Point
  • MPA-Based Decision Tree

While these methods are relatively new, they have already been successfully used to assess several U.S. fish stocks, including Atlantic wolffish, New England red crab, and 50 groundfish species on the West Coast.  

These new methods, while subject to many caveats and qualifications, are generally much faster and less expensive than traditional stock assessments. Continuing to fish stocks that are not assessed due to a lack of data poses risks to the biological and economic sustainability of fisheries. While having long-term, continuous datasets for each species is the ultimate goal, data-poor methods can help managers extract more useful information from readily available data and reduce risks associated with fishing in ignorance.

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A Brief History of Fisheries

Rod Fujita, EDF Senior Scientist & Director of Oceans Innovations

Rod Fujita, EDF Senior Scientist & Director of Oceans Innovations

In the beginning, there were no controls at all on fishing.  This worked alright when there were not many of us around, but soon people started noticing that fish were disappearing in coral reefs, bays, and nearshore waters – in some places. This apparently started happening thousands of years ago. 

As with any other resource that is not owned by anybody in particular and is used by people who are not well organized, fish tend to get overexploited.  This is because individual fishermen know that any fish they leave in the water for noble purposes like conservation or future generations could just get caught by another fisherman.

Ancient peoples solved this problem by establishing exclusive fishing grounds.  However, such traditions were generally replaced (with a few notable exceptions in Hawaii, the Gulf of Maine, some South Pacific islands, parts of Africa, and other places) with policies and laws that encouraged access for all (“open access” or “fisheries modernization”) and the extraction of maximum sustainable yield.  Over the years, this led to an “arms race” in some fisheries as technology entered the picture. This “arms race” occurred not because of rampant greed or a desire to wreck the environment – it was an entirely reasonable response to the incentives created by open access. 

Fishermen tried to win the competition to maximize catch by catching as much fish as quickly as possible, leading to giant trawlers with enormous, powerful engines and sophisticated fish-finding equipment.  Again, these technological innovations were rational responses to the incentives created by open access. 

Managers tried to control fisheries first by limiting the efficiency of fishermen.  This, however, sets up a cat and mouse game between managers and fishermen who are still trying to win the competition, and guess who usually wins?  Innovation and ingenuity in industry almost always out-runs regulation (witness the fancy financial instruments that helped destroy the global economy recently; regulators could not even understand these innovations in the financial sector, let alone get ahead of them).

Managers next introduced catch limits, which successfully limited catches in many fisheries but in many cases wrought economic havoc, as suddenly there were way too many fishermen and way too much gear chasing fish around (“overcapitalization”).  Costs were high and revenues low due to low prices resulting from supply gluts, leading to strong political pressure to ease up on catch limits (e.g. the West Coast groundfish disaster) and attacks on the underlying science.  There was also pressure to forgo catch limits altogether and stick with effort controls (e.g. the New England groundfish collapse). 

The crazy economics of open access fisheries is one of the main reasons some countries (including the U.S.) subsidize fisheries – some analysts think that globally, subsidies might be as high as $30-34 billion a year  – in support of an industry that generates only $80-90 billion annually . While effort controls and catch limits are working well in some fisheries, generally speaking, such measures — divorced from measures to address incentives to compete for maximum catches — have not worked out too well for lots of fisheries.  Sometimes conservation goals are met, but the fishery fails economically – people lose their jobs, their vessels, and sometimes even communities because fishing costs are too high and revenues are too low due to restrictive regulations.  In other cases, the economics are good (for a while) but these gains are often achieved at the expense of conservation, resulting in population decline and collapse. 

The answer is to tackle the incentives straight on by strengthening the rights, privileges, and responsibilities of fishermen.  This can be done in many ways.  One way is to allocate or auction secure shares of a scientifically determined sustainable catch level for individual fishermen and communities, and then designing and enforcing rules to ensure that the program achieves its social and economic goals.  This kind of management is known as catch shares

Another way is to designate fishing territories (another form of catch share) that give fishermen a sense of ownership and stewardship over their local resources.  Yet another way is to create cooperatives that allow fishermen and other partners to pool assets, share skills, and cooperate rather than compete. 

These solutions – catch shares and cooperatives – have been shown to stop the competition to maximize catch and reduce the risk of fishery collapse substantially.  In fact, if the historical performance of catch share systems is a good guide, then many of the fishery collapses we’ve seen since the 1950s could have been avoided if all fisheries had been under catch share management.  Similarly, extensive research has shown that people can stop destructive races to extract natural resources – from forests to water to fish – by organizing themselves into cooperatives with certain rights, rules, and responsibilities. 

There are solutions to overfishing, bycatch, and habitat degradation due to fishing.  Designing them well and getting them implemented pose great challenges – but the potential to save fish, habitats, fishermen, and fishing communities makes it all worthwhile.

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Climate Change Threatens Chemical Composition of the Oceans

Rod FujitaThe recent U.N. Climate Change conference in Copenhagen highlighted the range of challenges associated with fighting climate change, from cutting energy use to financing clean technology in developing countries.  Why the global sense of urgency and focus?  Because the impacts of climate change are already being felt.  Most of our discussions center on the dangers of sea level rise, which is already inundating low-lying islands and valuable wetlands; on changes in precipitation and air temperature, which will affect everything from agriculture to asthma; and on the shift in seasons and habitat that will make life difficult for trees, butterflies, and the other wildlife we are familiar with.

Enormous threats indeed.  And it is perhaps inevitable that we are focused on the land and our fellow terrestrial inhabitants.  But let us not forget the fact that we are changing the ocean profoundly in many ways.  A recent study suggests that over a third of the entire ocean is heavily impacted by human activities, and that there is no longer a single patch of seawater anywhere that can be said to be pristine.  And incredibly, we are not just affecting patches of the ocean here or there – we are changing the very chemistry of the seas, chemistry that has remained stable for millennia and which defines the parameters for life in the sea and also for the habitability of the planet for us.

All living systems are buffered from extreme change by their chemistry.  If not for the carbonate/bicarbonate and other buffering chemicals in our blood, the pH (a measure of acidity) would fluctuate wildly and none of the myriad proteins or enzymes essential for life would function.  Because pH is a logarithmic scale, very small changes in pH can be disastrous for life – for example, a change of less than one pH unit is lethal to humans. Oceans along coast

The ocean is a gigantic living system, and is perhaps one of the best-buffered systems on the planet.  Enormous quantities of buffering chemicals have been entering the ocean each year for billions of years.  Remarkably, though, even the ocean is not impervious to the impacts of fossil fuel combustion and carbon dioxide emissions. 

As atmospheric carbon dioxide concentrations have risen, the ocean has steadfastly taken up about 2 billion tons of it every year, protecting us from an even more serious climate crisis than we have already.  However, carbon dioxide reacts with seawater to create carbonic acid.  As a result, while the pH of the ocean varies widely in response to local conditions, scientists have detected a noticeable drop in pH (an increase in average acidity) over the last 20 years and project a decrease in pH by 0.3-0.4 units – a huge change –  by 2100 if nothing is done to reduce carbon dioxide emissions. 

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New Study Supports Conservation Benefits of Catch Shares

RodFRod Fujita, Ph.D
Director, Ocean Innovations
Environmental Defense Fund

A new study released today (Essington, 2009) supports the results of other studies showing the benefits of catch share management in fisheries (Costello et al., 2008; Heal and Schlenker 2008).

The paper looks for a response in biomass, exploitation rate, discards, effort, compliance with catch targets and landings in 15 North American catch share fisheries.

The paper did not find that these catch share fisheries, on average, reduced overall landings or that they increased biomass.  That seems to be because most of these fisheries were not overfished–so the overall catch would not be expected to go down, and biomass would not be expected to increase, because these were not management goals.  To test the hypothesis that catch shares can rebuild depleted populations, it will be important to analyze depleted fisheries, over rebuilding time frames.  In this study, only one of the 8 fisheries that had explicit overfishing targets was substantially overfished.

The study did show that catch share fisheries moved landings, exploitation rates, and biomass levels closer to their targets, whether they were above or below the targets.  Since some of the fisheries were above and some were below, these changes averaged out, resulting in small net changes.  The exception was discard rate, which appears to have dropped by about 30% in the small number of fisheries examined. Read More »

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First Woman Recipient of Nobel Prize for Economics, A Key Player in Ending the Race for Fish

Elinor Ostrom, who shares this year’s Nobel Prize for Economics, laid much of the intellectual foundation for EDF’s current work with fishery cooperatives. Catch shares evolved from common property theory and empirical observations that, under certain conditions, resources such as fish, water, or pasture land tend to be overexploited when property rights are not clearly delineated. Ostrom’s research shows that resource users can develop cooperative methods to avoid overexploiting resources and dissipating wealth through competition. 

While some say that this idea “challenges” the conventional wisdom, research conducted by EDF’s Ocean Innovations suggests that competitive and cooperative dynamics depend on scale and the attributes of the communities themselves. Our results will soon be published in the Bulletin of Marine Science. This research and our experience with fishermen on the water motivates our work with the Cape Cod Commercial Hook Fishermen’s Association and the Morro Bay Community Based Fishing Association, two pioneering efforts to cooperatively manage fisheries. 

We believe that cooperative approaches can complement catch shares, which often apply at larger scales and to more industrial, less socially cohesive fishing communities. Such approaches are also broadly applicable in many developing countries, where social values are emphasized over individualism and economic gain, and where legal and political structures facilitate the delegation of resource use privileges to groups.

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