In the United States, the Fishery Conservation and Management Act of 1976, now known as the Magnuson-Stevens Fishery Conservation and Management Act (MSFCMA), was the first major piece of legislation to regulate federal fisheries in the Fishery Conservation Zone (later designated as the U.S. Exclusive Economic Zone). Although the MSFCMA contained language to “prevent overfishing,” the emphasis was on developing the domestic fishery. Major declines in the productivity of several important fisheries led Congress to amend the MSFCMA in 1996, with the Sustainable Fisheries Act, which more clearly defined overfishing and required rebuilding of overfished stocks within a specified time limit. The reauthorization of the MSFCMA passed by Congress in 2006 included additional mandates for conserving and rebuilding fish stocks and strengthening the role of scientific advice in fisheries management.
The depleted status of many fish stocks continues to be a challenge for fishery managers and the fisheries that depend on these stocks. Approximately 20% of the fisheries that have been assessed are considered overfished according to the September 2012 stock status report to Congress prepared by the U.S. National Oceanic and Atmospheric Administration (NOAA). Overfished refers to a stock that is below the minimum stock size threshold, commonly set to half the stock size at which maximum sustainable yield (MSY) is achieved. Under the provisions of the MSFCMA, rebuilding plans for overfished stocks, covering both commercial and recreational fisheries, should take no more than 10 years, except when certain provisions apply. To meet these provisions, rebuilding plans have required substantial reductions in catch and effort for many fisheries, raising concerns about the consequent social and economic impacts to the fishing communities and the industry. Fishing restrictions not only have affected stocks under rebuilding plans, but also have impacted the utilization of stocks that are not overfished but are part of mixed-stock fisheries. In 2010, U.S. Senator Olympia Snowe and U.S. Representative Barney Frank requested that the NOAA Administrator fund a study by the National Academies’ National Research Council (NRC) regarding the MSFCMA’s rebuilding requirements.
The Committee on Evaluating the Effectiveness of Stock Rebuilding Plans of the 2006 Fishery Conservation and Management Reauthorization Act 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 the changes in stock status with respect to fishery management reference points.
Over the period 1997-2011, 85 stocks or stock complexes were declared overfished or approaching an overfished state. Rebuilding plans were implemented for 79 stocks, of which 25 were classified as rebuilt as of 2012. In addition, 5 stocks were declared rebuilt before a rebuilding plan was either developed or adopted. Based on the review of information for a subset of stocks that were assessed by analytical methods, the committee found that fishing mortality of stocks placed under rebuilding plans has generally been reduced and that stock biomass has generally increased following reductions in fishing mortality. Although some stocks have rebuilt, others are still below rebuilding targets, and of those, some continue to experience overfishing.
The committee attributes some of the variable or mixed performance of rebuilding plans to uncertainties inherent in specifying a rebuilding threshold and in assessing stock status relative to that threshold. Estimates of both the threshold and stock status are influenced by statistical variation associated with sampling and uncertainty inherent in modeling fish populations as well as the natural variation associated with the dynamic nature of ecosystems. As a
result, estimates of stock size and productivity may change dramatically between successive assessments, leading to changes in stock metrics and the biological reference points to which they are compared. Given these uncertainties, the current policy dependence on biomass thresholds often triggers abrupt changes, or discontinuities, in management. Although scientific uncertainty contributes to the variable results of rebuilding plans, this should not be interpreted as a criticism of the science. Rather, mixed performance of rebuilding plans often reflects a mismatch between policy makers’ expectations for scientific precision and the inherent limits of science because of data limitations and the complex dynamics of ecosystems.
The mixed outcomes of rebuilding plans add to concerns about the significant social and economic costs associated with implementation of time-constrained rebuilding plans. To address these rebuilding challenges, the committee highlights the following key findings for consideration by scientists, managers, and policy makers:
1. Harvest control rules that promptly but gradually reduce fishing mortality as estimated stock size falls below BMSY could result in a lower likelihood of a stock becoming overfished and could provide an approach for rebuilding if necessary.
2. Fishing mortality reference points seem to be more robust to uncertainty than are biomass reference points, both in the context of rebuilding and more generally.
3. Rebuilding plans that focus more on meeting selected fishing mortality targets than on exact schedules for attaining biomass targets may be more robust to assessment uncertainties, natural variability, and ecosystem considerations, and may have lower social and economic impact.
a. The rate at which a fish stock rebuilds depends on ecological and other environmental conditions such as climate change in addition to the fishing-induced mortality,
b. A rebuilding strategy that maintains reduced fishing mortality for an extended period (e.g., longer than the mean generation time) would rebuild the stock’s age structure and would be less dependent on environmental conditions than one that requires rebuilding to pre-specified biomass targets, and
c. When rebuilding is slower than expected, a rule to keep fishing mortality at a constant level below FMSY may forgo less yield and may have fewer social and economic impacts than a rule that requires ever more severe controls to meet a predetermined schedule for reaching a biomass target.
4. In the case of data-poor stocks for which analytical assessments are not available and catch limits are therefore difficult to establish, empirical rebuilding strategies that rely on input controls to reduce fishing mortality may be more effective and defensible than strategies based on annual catch limits and BMSY targets.
5. Retrospective reviews of the socioeconomic impacts of rebuilding plans are rare, in part because insufficient data are not available. Such reviews would help in refining rebuilding plans and objectives and alleviating the consequences of restrictions implemented under rebuilding plans.
These key findings are described in more detail below. The remainder of this summary is organized around the seven tasks that the committee was directed to address.
TASK 1
Evaluate methods and criteria used (1) to set target fishing mortality and biomass levels for rebuilding overfished stocks, and (2) to determine the probability that a particular stock will rebuild by a certain date. Consider the quantity and quality of information available for defining maximum sustainable yield (MSY)-based reference points or proxies for such reference points. Compare these methods and criteria to those used in major fishery management settings outside the U.S.
The committee reviewed the evolution of the MSFCMA from its origins in 1976, its subsequent amendments that introduced rebuilding requirements and accountability measures, and the guidelines for rebuilding U.S. fish stocks. Fisheries management has evolved substantially since 1977 when the United States extended its jurisdiction to 200 miles, becoming more prescriptive and precautionary in terms of preventing overfishing and rebuilding overfished fisheries. This evolution has been positive in making clear the objectives, resulting in fewer fisheries currently subject to overfishing. However, the tradeoffs among precaution, ecosystem impacts, and net benefits from fisheries have not been fully evaluated.
One of the central tenets of fisheries management is the concept of MSY, which represents the maximum, sustainable, long-term average yield that can be taken from a fish stock. The MSFCMA measures the success or failure of fisheries management on MSY and its associated population biomass (BMSY) and fishing mortality rate (FMSY), which are used as reference levels against which to compare stock status and harvest rate as they change over time.
MSY is not fixed but may be influenced by a variety of factors encompassing fishing practices, ecological interactions, and environmental conditions. In addition, management reference points based on MSY have a level of uncertainty that depends on the amount and quality of information available. Estimates of BMSY may be imprecise
even for stocks that are relatively “data-rich,” because of the complex and dynamic nature of ecosystems. The MSFCMA is virtually silent on the implications of uncertainty and variability of MSY. Guidelines for implementing the Act are primarily oriented to situations in which estimates of MSY reference points are reasonably precise and stable. Although it has been successful for some fisheries, in others the MSY approach falls short in addressing ecosystem complexity and variability and in accounting for uncertainty in the estimates of stock size and reference points.
The requirement to end overfishing for all stocks in mixed-stock fisheries has protected less productive species but with yield forgone for healthy stocks in the same complex. The “mixed-stock exception” in the MSFCMA provides an option for reducing the impact of rebuilding on the harvest of healthy stocks. However, the exception has not been invoked, in part because of the narrow range of situations to which it applies under the MSFCMA and also because of the complexity of the issue it is meant to address. The operational feasibility of the exception could be modified to expand the range of situations to which it can be applied, subject to assurances that the less productive species are not driven to unacceptably low abundance.
Rebuilding plans are designed using quantitative models to project likely future trends in stock size in response to alternative harvest control rules. This approach works best for data- and knowledge-rich fisheries, which generally involve stocks with a long history of exploitation and high economic value and that contribute to the bulk of U.S. landings. The main focus of this review was on the stocks for which quantitative assessments and estimates of MSY reference points are available. For many stocks, however, data and understanding are so limited that stock projections cannot be conducted and stock-by-stock application of MSY-based control rules is unrealistic. NOAA reports to Congress indicate that more than half of the stocks or stock complexes identified either have not been assessed or their status as overfished or experiencing overfishing is unknown.
In general, fishing mortality reference points appear more robust to scientific uncertainty than do biomass reference points. Fishing mortality reference points are often more reliably estimated at lower stock sizes than are biomass reference points, whose estimates rely more strongly on density-dependent processes that generally manifest only at higher stock sizes. Furthermore, proxy values for fishing mortality reference points can often be derived from other information sources, such as life history parameters of growth and natural mortality, which do not require estimates of future recruitment levels.
When data and understanding are too limited to design a rebuilding plan with a predetermined time limit for rebuilding, it may be practical to implement harvest control measures (either by adjusting catch limits or effort controls) that at a minimum would be expected to increase stock size. In the case of data-poor stocks for which analytical assessments are not available, and therefore catch limits are difficult to establish, empirical rebuilding strategies that rely on input controls to reduce fishing mortality may be more effective and defensible than strategies based on annual catch limits and BMSY targets as prescribed by the National Standard 1 Guidelines (NS1G).
TASK 2
Assess the effects of uncertainty in current stock abundance, population dynamics, and variability in recruitment in setting rebuilding targets. Identify criteria for adjusting rebuilding targets and schedules based on new information and updated stock assessments.
Scientific management advice is subject to several sources of uncertainty, including variability and bias in the data, sensitivity to model assumptions, implementation uncertainty (reflecting management effectiveness and fishermen responses), and unpredictable natural events. These sources act simultaneously, resulting in substantial uncertainty surrounding reference points, determination of stock status, and projected outcomes of management regulations. As required by law, rebuilding plans have target years for recovery to BMSY, but the rate at which stocks rebuild is probabilistic such that some stocks will rebuild before the target year, while others will rebuild after the target year or not rebuild until environmental conditions improve, even if the rebuilding plan is implemented as intended, fishing mortalities are close to the targets, and targets are based on robust stock assessments.
The MSFCMA requires review of progress of rebuilding plans at least every other year. However, reviews do not always include updated, quantitative stock assessments. The frequency of assessments varies widely, both within and among regions, from stocks that have never been assessed to stocks that are assessed annually. More frequent assessments might lead to more frequent, but less extreme, changes in rebuilding plans and closer adherence to fishing mortality targets.
Because of the uncertainty in stock assessments, the perceived status of fish stocks in any particular year can change substantially as more data become available and as assessment methods change over time. According to the most recent assessments available, there is a substantial probability of (1) classifying stocks as overfished and implementing rebuilding plans when subsequent assessments indicate that the stocks were not below the minimum stock-size threshold and (2) classifying stocks as rebuilt when the updated assessments indicate that the stocks were never overfished. By inference, the inverse may also occur so that overfished stocks may be misclassified as not overfished. How many and which stocks these are cannot be determined from the data available.
The MSFCMA, as operationalized by the NS1G, requires an end to overfishing and provides minimum standards for
stock rebuilding, namely that stocks designated as overfished must rebuild to BMSY within a maximum time period. Although NS1G has been effective in increasing the probability that rebuilding occurs quickly once a stock has fallen below the minimum stock-size threshold, taking preventative management actions before stocks are declared overfished could obviate the need for a rebuilding plan. Harvest control rules that promptly, but gradually, reduce fishing mortality as estimated stock size falls below BMSY could result in a lower likelihood of a stock becoming overfished as well as provide an approach for rebuilding if necessary.
Such rules may reduce the need for more severe restrictions to rebuild stocks that fall below the minimum stock-size threshold. Delaying reductions in fishing mortality until the stock falls below the threshold creates a discontinuity—managers are then required to take immediate and substantial action to decrease fishing mortality based on what may be only small changes in estimates of stock size from a previous assessment. Furthermore, the mandates to meet rebuilding targets with a certain minimum probability and to utilize the most current stock assessments may lead to marked adjustments to rebuilding plans based on new data or models as they become available. Such adjustments can cause economic and social impacts, either positive (e.g., increases in allowable catch when rebuilding is rapid) or negative (e.g., decreases in allowable catch when rebuilding is slower than expected). Although the adjustments may reflect the best available science, the perceived credibility of the science among stakeholders may be reduced when rebuilding plans are changed markedly.
Projections of population sizes used in rebuilding analyses have much higher uncertainties than do historical estimates of population sizes. Because of the uncertainty surrounding projections, the emphasis placed on achieving a biomass threshold in a defined time frame may require severe reductions in the target fishing mortality rate (well below FMSY) when rebuilding is slower than expected. In situations where recruitment is below expectations (e.g., because of unfavorable environmental conditions), a control rule aimed at maintaining fishing mortality at some constant level below FMSY may forgo less yield, especially in mixed-stock situations, and have fewer social and economic impacts than one that forces increasingly severe controls in an attempt to keep rebuilding on schedule.
In most regions, the prevailing approach to adjust catch limits involves the use of a single “best” estimate of current or projected stock size. In practice, several alternative models or different configurations of a standard stock-assessment model are considered, and the “best” of these models is selected using formal criteria or expert judgment. An alternative to this best-assessment approach is to describe the consequences of alternative decision rules under each of the models considered plausible. A general framework known as Management Strategy Evaluation (MSE) has been used internationally and by some Regional Fishery Management Councils (RFMCs) to evaluate alternative harvest control rules that specify in advance how catch limits will be adjusted in response to new data as they become available. Different candidate rules are tested across a broad range of simulated scenarios (e.g., different levels of stock productivity, different environmental regimes), a process that enables decision makers to select a decision rule based on robust performance under various scenarios.
TASK 3
Provide an overview of the success of rebuilding plans under the MSA and compare to success of approaches used outside the U.S. Using a few representative rebuilding plans, identify factors (such as fishing mortality rate, life histories, uncertainty in stock assessments, and others) that affect the timeframe over which a stock is rebuilt.
The committee reviewed the 85 stocks or stock complexes that were declared to be overfished or approaching an overfished state between 1997 and 2011. Rebuilding plans were implemented for 79 of these 85 stocks, employing target fishing mortality rates lower than 75% FMSY in most cases. In some regions, the rates were substantially lower, and rebuilding time frames were much shorter than the maximum time frame specified by the NS1G.
The committee focused on a subset of 55 stocks that were assessed using quantitative methods. The most recent assessments indicated that fishing mortality was reduced below FMSY (i.e., overfishing was halted) in 23 of the 36 stocks that were subject to overfishing at the time of overfished designation. According to these recent assessments, 20 of the 55 stocks were not overfished and 10 were actually above BMSY at the time of overfished designation. Of the 35 stocks that were below the minimum stock-size threshold:
- Forty-three percent of the stocks are no longer overfished: 10 have rebuilt and 5 are rebuilding.
- Of the 20 stocks estimated to still be overfished, 11 had fishing mortalities well below FMSY during the last year included in the assessment and are therefore expected to rebuild if low fishing mortalities are sustained.
Stocks that rebuilt or whose biomass increased appreciably were, in almost all cases, experiencing fishing mortalities below FMSY.
Some stocks (9 of the 35) continue to be subject to overfishing even though fishing mortality targets were set at or below 75% FMSY to allow for rebuilding within the maximum time frame. The failure of rebuilding plans to achieve the intended reductions in fishing mortality reflects implementation problems due to ineffective input controls and lack of accountability measures, difficulties in reducing fishing mortality of species caught as bycatch in other fisheries, or
errors in the estimates of stock size that led to catch limits that were too high. In particular, retrospective biases in the assessments revealed apparent overestimations of stock size that contributed to continued overfishing.
The U.S. approach to rebuilding overfished stocks is comparable to that used by several developed countries (such as Australia, Canada, and New Zealand), and the results are similar (in terms of the fraction of overfished stocks). The European Union has a higher proportion of stocks that are subject to overfishing than the United States, although in the European Union the proportion has decreased sharply in recent years.
TASK 4
Consider the effects of climate and environmental conditions, habitat loss and degradation, ecological effects of fishing on the food chain, and ecological interactions among multiple species, and identify ways to adjust rebuilding plans to take these factors into account.
Ecosystem variables related to climate, habitat, and food-web interactions can influence the population dynamics of stocks, and hence the rate of rebuilding. Because of these ecosystem influences, the spectrum of possible outcomes is broader than would typically be considered in single-species rebuilding projections. Also, stock biomass forecasts and projections can vary in response to alternative plausible assumptions (models) and parameter values used in simulations, because the underlying population dynamics are nonlinear. Reference points, such as BMSY, that are used throughout fisheries management, are based on single-species production functions that generally do not account for environmental and ecological interactions. The committee notes that reference points based on single-species assessments are likely to shift over time as a consequence of climate change and the complex and dynamic nature of ecosystems.
Fishing truncates the age structure of a population, especially when fisheries selectively harvest larger fish. Removing the more productive individuals from a population may amplify the effects of environmentally driven recruitment variability. Rebuilding plans that restore the demographic structure of the overfished population are more likely to improve recruitment and increase the likelihood of success of the rebuilding effort than are plans that restore spawning stock biomass without also restoring demographic structure. In nature, growth, maturity, and natural mortality are influenced by interactions with other species that may be competitors, predators, or prey. Fisheries management involves tradeoffs among harvested species that interact, even if these tradeoffs are not explicitly considered in management decisions. Our understanding of how ecosystems function is improving, in some cases enough to contribute to the models used in fisheries management. For example, stock assessments can be linked with multispecies models. Adopting rebuilding plans that place more emphasis on maintaining reduced fishing mortality for an extended period (e.g., longer than the mean generation time) may help to accommodate these ecosystem interactions. This approach rebuilds age structure and increases resilience to natural variability more than does an approach that focuses on biomass targets, which may be more or less attainable depending on environmental conditions.
TASK 5
Assess the types of information needed and current understanding of the economic and social impacts of rebuilding programs, particularly on fishing communities. Identify the economic, social, and ecological tradeoffs of rebuilding a fishery associated with shorter or longer rebuilding times. Evaluate available methods for integrating these social, economic and ecological factors when designing and evaluating rebuilding plans.
The relationships between socioeconomic factors and rebuilding programs that extend over multiple years are complex and dynamic, although knowledge and understanding of these relationships are improving. Causal relationships among rebuilding and socioeconomic outcomes are difficult to disentangle, because of the overall quantity and quality of data and resources available to fishery managers and scientists, the behavioral responses of people who are affected by the changes, and the multitude of confounding factors. It can also be difficult to establish what the status of a stock might have been in the absence of rebuilding or under alternative rebuilding plans. The estimated impacts of a rebuilding plan are conditional on these (assumed or estimated) counterfactual conditions. Hence, the ability to rigorously predict and measure the ex-post socioeconomic impacts and tradeoffs is limited.
Socioeconomic analyses and research are used to inform the evaluation of alternative rebuilding plans, but the role of these formal analyses in the decision-making process is less clear in a highly charged political setting. Furthermore, compliance with MSFCMA requires that socioeconomic considerations for rebuilding plans are contingent on biological mandates being met. Rebuilding plans that do not meet these mandates cannot be adopted, even if doing so would improve projected socioeconomic outcomes.
Fish stock rebuilding plans are designed to achieve rapid rebuilding of biomass and spawning stocks consistent with the biological characteristics of the resource. However, the requirement to rebuild within 10 years, if biologically possible, prevents consideration of alternative management actions that could lead to greater socioeconomic benefits while supporting stock recovery in the long term. Several alternative management strategies that could be considered in this context have been implemented successfully in venues outside of the United States (e.g., New Zealand).
At the same time, socioeconomic considerations do influence the management of overfished stocks through the public participation process (e.g., public testimony to Councils regarding the magnitude of socioeconomic impacts). Stakeholder participation and concerns regarding the impacts of rebuilding plans can also result in ad hoc mitigation measures (e.g., disaster relief assistance) that operate outside of the fishery management process. The implications of these measures on other fisheries and on the long-term social and economic viability of coastal communities are not fully known.
TASK 6
Summarize how the social, economic and ecological impacts of rebuilding plans are affected by the structure of fisheries management measures, e.g., limited entry, catch shares systems, and closed areas.
In the United States, many commercial and recreational fisheries are managed by allocating a portion of a species’ total allowable catch to different fishing sectors (defined, e.g., by gear type, recreational versus commercial, and size of fishing vessel) and linking this allocation with additional controls (e.g., restrictions on locations, seasons, technology, size and sex of catch, number of trips, and retained harvest per trip). These regulatory strategies create incentives and constraints that affect the economics of fishing, the structure of fishing communities, and the choices available to fishermen. The nature of the constraints and incentives may vary depending on the management regime (e.g., catch shares, limited entry, regulated open-access) but all reduce to some degree the ability of fishermen to adapt their fishing behaviors (e.g., changing where, how and for what species they fish) in response to the new harvest limits that accompany rebuilding plans. As a result, fishermen are less able to mitigate the losses associated with rebuilding plans.
Another factor limiting the adaptability of fishermen is the highly specialized fleets that evolved in response to the sector-by-sector allocation process institutionalized by the RFMCs. Although specialization can result in economic gains, it reduces the number and extent of possible behavioral responses to a rebuilding plan, such as switching fishing gears to improve quality (and obtain higher prices for the fish) or switching between species. Specialization of the fishing sector has ripple effects in the fish processing and fishing-related industries and results in local communities having less diverse economies to mitigate the economic impacts of rebuilding plans.
In summary, the nature of fisheries management can lead to situations that exacerbate the economic and social impacts of meeting rebuilding targets by institutionalizing the specialization of the fishing industry (including fishing fleets, processing, and related support businesses). These constraints reduce the ability of the fishermen and communities to absorb some of the costs associated with curtailing catches and have potential impacts on the resilience of fishing communities.
TASK 7
Identify the biological, ecological, social and economic knowledge gaps that impede the implementation and effectiveness of rebuilding programs, and determine what additional data and analyses are needed to address those gaps.
Gaps in knowledge exist at many different points in the management system because of the following limitations: (1) data and assessment methods, (2) human resources and expertise, and (3) analytical capabilities to integrate biological, economic, and social data. Some of these gaps could be filled with additional data collection and analysis, but others will likely remain unfilled because of finite resources and the limited predictability of coupled human-natural systems (e.g., the influence of climate change on fisheries). Current knowledge gaps and the resulting uncertainties require robust management strategies, as mentioned below.
When data are insufficient to perform analytical stock assessments to estimate biomass and fishing mortality reference points with sufficient confidence for the design and application of MSY-based control rules, alternative paradigms should be considered and evaluated. Strategies that combine spatial controls and habitat-based approaches with empirical rules to adjust harvest measures in response to demographic indicators or other proxies of stock status, as well as ecosystem-level indicators, could be designed for reasonable and precautionary fishing rates, and progress in rebuilding stocks.
The success of any formal approach to develop robust control rules requires clearly specified management objectives, so that quantitative performance measures and tradeoffs (e.g., between risks and yield) can be evaluated. Analyses generally consider uncertainties that affect population or ecosystem projections and future catch rates, but most do not consider the full suite of risks in these complex and dynamic systems. Currently, the treatment of uncertainty is not integrated across the ecological, economic, and social dimensions of rebuilding, and the cumulative risk tradeoffs are not well understood. Consequently, it is not clear whether the appropriate level of precaution is being applied.
In terms of assessing actual outcomes of rebuilding plans, the committee focused its review on biological metrics, consistent with current legal mandates. These metrics are available through regular stock assessments conducted for ongoing management. In contrast, information to evaluate the broader impact of rebuilding plans is not readily available. Retrospective reviews of the socioeconomic impacts of rebuilding plans are rare, at least partially because the necessary data are not available. These socioeconomic impacts include changes in the structure of the commercial
fishing sector, economic returns, recreational values, the fish processing industry, and the culture of fishing communities. Methods exist and innovations are emerging to characterize the breadth of economic and social impacts of rebuilding plans and the factors in a coupled human-natural system that contribute to the success of these plans, although they have not yet been broadly applied, tested, and refined to meet information needs.
CONCLUSIONS
The current implementation of the MSFCMA relies on a prescriptive approach that has demonstrated successes in identifying and rebuilding overfished stocks. For most stocks placed under a rebuilding plan, fishing mortality generally decreased, and stock biomass generally increased. Where they have been estimated, the long-term net economic benefits of rebuilding appear to be generally positive. Stocks that rebuilt or whose biomass increased appreciably were, in almost all cases reviewed, experiencing fishing mortalities below FMSY, and often lower than 75% of FMSY. Stocks for which rebuilding progress was slower than anticipated when the rebuilding plan was designed were subject to more extreme reductions in target fishing mortality as the target year for rebuilding approached. In some cases rebuilding plans failed to reduce fishing mortality as much as intended in the rebuilding plan, either because of overestimation of stock sizes or because of implementation issues, and in these cases rebuilding has been slow or has not occurred.
The legal and prescriptive nature of rebuilding mandates forces difficult management decisions, ensures a relatively high level of accountability, and can help to prevent protracted debate over whether and how stocks should be rebuilt. The rebuilding time frame provides a guide for setting target fishing mortality rates and creates an incentive to avoid delays in initiating rebuilding plans, which otherwise would require more severe management responses. However, the focus on achieving a rebuilding target by a given time places unrealistic demands on the science and forces reliance on forecasts and estimates of biomass-based reference points, which may be very uncertain. An emphasis on controlling fishing mortality rates rather than meeting a biomass target after a certain amount of time may result in strategies that are more resilient to assessment uncertainties, natural variability, and ecosystem factors and less likely to result in acute management adjustments, which can increase the severity of social and economic impacts. The choice between a rapid or gradual response involves tradeoffs between economic and social impacts and ecological/resource risks, all of which should be evaluated. The current approach is designed for the nations’ most valuable, high-volume stocks, but more than half of the nation’s stocks have not been assessed and their status is unknown, rendering application of MSY-based control rules unrealistic. Alternative paradigms should be considered for these data-poor stocks.
The Committee offers comments on the major issues surrounding rebuilding with a long-term view to improve the efficiency of the current approach to stock rebuilding. These issues directly or indirectly relate to the overarching issue of what is the appropriate balance between prescription and flexibility in stock rebuilding. Many of our comments could serve as suggestions for research and for future revisions of the National Standard Guidelines to improve the overall performance of stock rebuilding programs and thereby enhance the benefits derived from fisheries in the future.
