EVALUATING THE EFFECTIVENESS OF FISH STOCK REBUILDING PLANS IN THE UNITED STATES
Patrick J. Sullivan, Ph.D.
Department of Natural Resources
Co-Chair, Committee on Evaluating the Effectiveness of Stock Rebuilding Plans of the 2006 Fishery Conservation and Management Reauthorization Act
Ocean Studies Board
Division on Earth and Life Studies
National Research Council
The National Academies
Committee on Natural Resources
U.S. House of Representatives
September 11, 2013
Good morning, Mr. Chairman and members of the Committee. My name is Patrick Sullivan. I am an Associate Professor in the Department of Natural Resources at Cornell University. My colleague Dr. Ana Parma and I co-chaired the Committee on Evaluating the Effectiveness of Stock Rebuilding Plans of the 2006 Fishery Conservation and Management Reauthorization Act.
In 2010, U.S. Senator Olympia Snowe and U.S. Representative Barney Frank requested that NOAA fund a study by the National Academy of Sciences’ National Research Council regarding the Magnuson-Stevens Fishery Conservation and Management Act’s rebuilding requirements.
The committee reviewed the technical specifications that underlie the current set of federally-implemented rebuilding plans, the outcomes of those plans in terms of trends in fishing mortality and stock size, and changes in stock status with respect to fishery management reference points.
Fish stock rebuilding plans have proven successful in reducing fishing pressure on many overfished stocks and stock sizes have generally increased. However, in some cases fisheries have not rebuilt as quickly as the plans projected, due to factors such as overestimation of the size of stocks and incidental catch by fisheries targeting other species. Even when fishing is reduced appropriately for the actual stock size, the rate at which rebuilding occurs will depend on ecological and other environmental conditions. Because of all these factors, it is difficult to make accurate predictions of the time it will take stocks to rebuild. Therefore, rebuilding plans that focus more on meeting selected fishing mortality targets than on adhering to strict schedules for achieving rebuilding may be more robust to assessment uncertainties, environmental variability, and the effect of ecological interactions.
Well-managed, productive fisheries provide a livelihood, a nutritious source of food, and recreational activity for coastal communities around the country. However, if overfishing takes place and stocks experience serious declines, the lost productivity affects the fishing industry and communities that depend on fishing, and raises concerns about the overall health of the associated marine ecosystem. In the United States, the 1976 Magnuson-Stevens Fishery Conservation and Management Act was the first piece of major legislation to regulate federal fisheries. Although the Act contained language to “prevent overfishing,” it focused on developing the domestic fishing industry. Major declines in the productivity of several important fisheries led Congress to amend the Act in 1996. The amendment, the Sustainable Fisheries Act, more clearly defined overfishing and required rebuilding of overfished stocks within a specified time limit. In 2006, Congress made additional mandates for conserving and rebuilding fish stocks and strengthening the role of scientific advice in fisheries management. The Act now includes regulatory provisions such as ending overfishing immediately, annual catch limits and accountability measures.
To meet these provisions, rebuilding plans have required substantial reductions in catch for many fisheries, resulting in social and economic impacts to fishing communities and industry. This report reviews the technical specifications that underlie current federally-implemented rebuilding plans, and the outcomes of those plans.
Implementing Rebuilding Plans
The National Marine Fishery Service evaluates the status of US fish stocks to determine which stocks are overfished; that is, which stocks are too small in size to sustain continued productive fisheries. Once a stock is classified as overfished, the appropriate Regional Fishery Management Council selects and implements a rebuilding plan.
Rebuilding plans are simple in theory; annual catch limits are set to reduce fishing, which allows the stock to grow and recover. However, in order to design a rebuilding plan, fishery managers need to anticipate how the stock may respond to different levels of fishing pressure. Currently, rebuilding plans use a concept called Maximum Sustainable Yield (MSY) to determine when a stock is overfished, and to set annual catch limits and rebuilding targets for stock size.
The Challenges of Rebuilding Plans
The concept of Maximum Sustainable Yield can be useful in establishing population size and harvest rates that a population can sustain. Rebuilding plans based on MSY have proven successful for many stocks: of the 85 stocks declared overfished or approaching an overfished state between 1997 and 2012, 41 are no longer classified as overfished (of these, 11 are rebuilding and 30 are rebuilt). However, a further 41 stocks have not rebuilt yet, and are still classified as overfished. The committee identified several challenges associated with current rebuilding plans.
MSY Reference Points
A major challenge comes from the fact that current rebuilding plans use a static metric of MSY, which in theory represents average conditions. In reality, ecosystems are dynamic and as a consequence MSY varies with factors such as changes in environmental conditions and ecological interactions. Generating reliable estimates of MSY depends on having extensive information about the biology of the species and its abundance in the years before it was overfished. This wealth of information is only available for a relatively few stocks, hence there is considerable uncertainty in the MSY estimates for most stocks. Although the MSY approach has been successful for some fisheries, management based on MSY can fall short in addressing ecosystem complexity and variability and in accounting for uncertainty in the estimates of reference points.
Uncertainty in Stock Assessments
Because it is not possible to count every individual fish in a stock, scientists rely on a variety of sampling and statistical methods to estimate abundance. These estimates are used in models to project trends in future stock size. The accuracy of the population estimates and the projections depends on the quality and amount of data available and the ability of models to reproduce the primary determinants of the species’ population growth. The frequency of stock assessments can vary widely, both within and among regions, from stocks that are assessed annually to stocks that have never been assessed. As more data are collected and new models and assessment methods become available, past estimates of the status of fish stocks can change substantially. For example, some stocks that were previously classified as overfished (and put under rebuilding plans) would not have been considered overfished based on the most recent assessments. The inverse may also have occurred, with overfished stocks misclassified as not overfished.
Climate, environmental conditions, and ecosystem interactions can have significant effects on the rate at which a stock rebuilds. Although these factors affect the time it takes for a stock to rebuild, it is not currently possible to incorporate them into models to improve projections to a degree of accuracy that is useful for management.
Mixed Stock Fisheries
Fish do not live in isolation—each stock is part of a community of species that live in the same waters. For example, when a fishing net is cast into the ocean, it can capture several different fish species. This is called a mixed-stock fishery.
When one stock within a mixed-stock fishery is declared overfished, reductions in fishing required by the rebuilding plans affect all the stocks in the fishery, leading to a loss of yield and income. For example, juvenile red snapper in the Gulf of Mexico are incidentally caught during shrimp trawl fishing, driving the red snapper to overfished status. Devices were installed in shrimp nets to reduce bycatch, but were not sufficient to end overfishing. Subsequent rebuilding plans included a shrimp trawl fishing threshold, in addition to fishing limits for red snapper.
The management of mixed-stock fisheries is a complex and contentious issue, but the problem will need to be addressed to allow more practical guidance on the balance of fisheries harvest across stocks, subject to assurances that the less productive species are not driven to unacceptably low abundance.
Alternative Management Strategies
Current rebuilding plans rely on a prescriptive approach, which has had demonstrated successes in identifying and rebuilding some fish stocks. However, the plans’ focus on achieving rebuilding targets within set timeframes forces reliance on forecasts and estimates of MSY-based reference points, which often carry a high level of uncertainty. Rebuilding plans that focus on meeting selected fishing mortality targets may be more effective than a plan with an exact time period for rebuilding. The report makes several suggestions for alternative management strategies for rebuilding fish stocks.
Gradual Reductions in Annual Catch
Delaying reductions in annual catch until the stock biomass has declined to overfished status means that fishery managers must then make immediate and substantial decreases in fishing. Alternative management actions, such as harvest control rules that promptly but gradually reduce fishing as estimated stock size falls would result in a lower likelihood of a stock becoming overfished.
Fishing Mortality Reference Points
Fishing mortality reference points seem to be more robust to uncertainty than biomass reference points, both in the context of rebuilding and more generally. Estimates of biomass are expected to change, and hopefully improve, as stocks rebuild—but predicting these changes is difficult as it requires predicting average future recruitment of juvenile fish to the adult population. In contrast, setting reference points based on fishing mortality requires comparatively less information.
Most fisheries select for the largest fish, and by doing so, reduce the average age of the fished population. A rebuilding strategy based on maintaining reduced fishing mortality for an extended period—longer than the mean generation time of the stock—would help restore the stock’s age structure (i.e., increase the average age) and would be more robust to changing environmental conditions than strategies that require rebuilding to pre-specified biomass targets by a given time limit.
Setting Fishing Limits Below FMSY
The Magnuson-Stevens Act specifies that stocks designated as overfished must rebuild within a maximum time period (usually 10 years). This strategy means rebuilding usually occurs quickly once a stock is designated overfished. However, if rebuilding is slower on average than expected when the plan was adopted—for example, due to unfavorable environmental conditions that affect recruitment of juveniles—ever more severe controls on fishing must be applied to try to keep rebuilding “on schedule”. These reductions in fishing can have significant economic and social impacts to the fishing industry and community. Maintaining fishing at some constant level below FMSY may help achieve rebuilding goals on a schedule that accommodates natural variability in stock productivity.
Analytical assessments are not available for many of the stocks classified as overfished because there are not enough data and information to build the required models and to estimate MSY reference points. Without these data, catch limits are difficult to establish. In these cases, empirical rebuilding strategies that rely on input controls to reduce fishing—for example, reductions in fishing operations, or closing fishing areas—may be more effective and defensible than strategies based on annual catch limits and biomass (BMSY) targets.
Socio-Economic Impacts of Rebuilding Plans
It is clear that reducing fishing to meet rebuilding targets can have severe social and economic impacts on fishing communities and the fishing industry. However, socio-economic information is not readily available to evaluate the broader and long-term impacts of rebuilding plans. Retrospective reviews of the socio-economic impacts of rebuilding plans would help in refining rebuilding plans and objectives, thus improving the consequences of future plans.
Thank you, Mr. Chairman, for inviting me to testify before the Committee today. I am happy to answer any questions you may have.
An archived webcast of the hearing can be found on the House Natural Resources Committee's Web site.