Understanding the behaviour of fishermen is a key ingredient to successful fisheries management. The aggregate behaviour of fishing fleets can be predicted and managed with appropriate incentives. To ...determine appropriate incentives, we should look to successes to learn what works and what does not. In different fisheries incentive systems have been found to reduce the race-for-fish and make fisheries profitable, to stimulate stock rebuilding, to reduce bycatch, and to provide for reductions in illegal fishing. Yet, success can be evaluated in many dimensions, but is, in fact, rarely done - per cent overfished seems to be the dominant measure of performance. I evaluate the yield lost due to overfishing in several ecosystems and contrast the situation of North Atlantic cod where considerable yield is lost, to fisheries in New Zealand and the west coast of the USA where lost yield due to overfishing is very small. Much more systematic evaluation of the other aspects of fisheries performance is greatly needed. From examples explored in this paper I conclude that prevention of overfishing can be achieved with strong central governments enforcing conservative catch regulations, but economic success appears to require an appropriate incentive structure.
The traditional fisheries management objectives of maximizing yield and employment lead to heavily exploited stocks. Many current high-profile disputes arise from conflicting objectives, and the ...proposed solutions to “the fisheries problem” are primarily particular stakeholders’ efforts to have managers implement their own objectives. I suggest many “failures” are in fact successes for other objectives. Fisheries objectives, as reflected in management actions, are changing. Two current trends are the acceptance of objectives that value less disturbed ecosystems and acceptance of fisheries allocation through dedicated access to improve the fisheries’ economic efficiency. I suggest that increased use of dedicated access will result in more congruent objectives and less conflict.
Abstract
The argument persists that the continued overexploitation by many fisheries around the world is evidence that current approaches to fisheries management are failing, and that more ...precautionary management approaches are needed. We review the available estimates of the status of fish stocks from three sources: the FAO's “State of Marine Resources”, a database on scientific stock assessments, and recent estimates from statistical models designed to determine the status of unassessed fish stocks. The two key results are (i) that stocks that are scientifically assessed are in better shape and indeed are not typically declining but rebuilding, and (ii) that large stocks appear to be in better shape than small stocks. These results support the view that stocks that are managed are improving, while stocks that are not managed are not. Large stocks receive far more management attention than small stocks in jurisdictions that have active fisheries management systems, and most unassessed stocks are simply not managed. We assert that fisheries management as currently practised can (and often does) lead to sustainable fisheries, and what is needed is to actively manage the unassessed fisheries of the world. More precautionary management is not necessarily needed to ensure the sustainability of managed fisheries.
Efforts to understand how to manage aquatic ecosystems often rely on correlations between human actions and impacts in the ecosystem. We are often warned that correlation does not imply causation and ...that the gold standard for identifying cause and effect relationships is manipulative experiments. History shows us that correlations are often not causal and that managers should not design policies based on the assumption of causality. However, in the absence of manipulation, correlative evidence may be all that is available. Correlative evidence is strongest when (1) correlation is high, (2) it is found consistently across multiple situations, (3) there are not competing explanations, and (4) the correlation is consistent with mechanistic explanations that can be supported by experimental evidence. Where possible, manipulative experiments and formal adaptive management should be employed, but in large-scale aquatic ecosystems these opportunities are limited. More commonly, we should emphasize identifying the range of possible causal mechanisms and identify policies that are robust to the alternative mechanisms.
Status and Solutions for the World's Unassessed Fisheries Costello, Christopher; Ovando, Daniel; Hilborn, Ray ...
Science (American Association for the Advancement of Science),
10/2012, Letnik:
338, Številka:
6106
Journal Article
Recenzirano
Recent reports suggest that many well-assessed fisheries in developed countries are moving toward sustainability. We examined whether the same conclusion holds for fisheries lacking formal assessment ...which comprise >80% of global catch. We developed a method using species' life-history, catch, and fishery development data to estimate the status of thousands of unassessed fisheries worldwide. We found that small unassessed fisheries are in substantially worse condition than assessed fisheries, but that large unassessed fisheries may be performing nearly as well as their assessed counterparts. Both small and large stocks, however, continue to decline; 64% of unassessed stocks could provide increased sustainable harvest if rebuilt. Our results suggest that global fishery recovery would simultaneously create increases in abundance (56%) and fishery yields (8 to 40%).
Abrupt shifts in natural resources and their markets are a ubiquitous challenge to human communities. Building resilient social-ecological systems requires approaches that are robust to uncertainty ...and to regime shifts. Harvesting diverse portfolios of natural resources and adapting portfolios in response to change could stabilize economies reliant on natural resources and their markets, both of which are prone to unpredictable shifts. Here we use fisheries catch and revenue data from Alaskan fishing communities over 34 years to test whether diversification and turnover in the composition of fishing opportunities increased economic stability during major ocean and market regime shifts in 1989. More than 85% of communities show reduced fishing revenues following these regime shifts. However, communities with the highest portfolio diversity and those that could opportunistically shift the composition of resources they harvest, experienced negligible or even positive changes in revenue. Maintaining diversity in economic opportunities and enabling turnover facilitates sustainability of communities reliant on renewable resources facing uncertain futures.
The oceans provide food, employment and income for billions of people. Using data from scientific stock assessments and a statistical model for other fish stocks the past and present status, and the ...potential catch, abundance and profit for 4713 fish stocks constituting 78% of global fisheries are estimated. Three major scenarios of future trends are considered; business as usual (BAU) in which largely unmanaged fisheries move towards bioeconomic equilibrium but where well-managed fisheries maintain their management, maximum sustainable yield (MSY) in which fisheries are managed to maximize yield, and fisheries reform (REF) where the competitive race to fish is eliminated and fisheries are managed to maximize profit. The future prospects differ greatly based on region of the world and product type. This analysis forecasts that yield in major tuna and forage fish species will remain roughly the same as current levels under all three scenarios, while there does appear to be potential for increased yield of whitefish. There is considerable room for increased profit in most of these fisheries from better management. Increased yield will come from rebuilding overexploited stocks, reducing fishing mortality on stocks that are still abundant but fished at high rates, and surprisingly from fishing some stocks harder. Indeed in Europe and North America the primary potential for increased yield comes from fully exploiting stocks that are now lightly exploited. Asia provides the greatest opportunity for increased fish abundance and increased profit by fisheries reform that would lead to reduced fishing pressure.
•There is potential to increase global fish yield by 14% with current fishing methods.•There is potential to increase profit from fishing by 79%.•Two thirds of the increase in fish yield comes from increasing exploitation rates on specific stocks.•Most of the potential increase in profit comes from fisheries that have little effective management.
Marine fish stocks are an important part of the world food system and are particularly important for many of the poorest people of the world. Most existing analyses suggest overfishing is increasing, ...and there is widespread concern that fish stocks are decreasing throughout most of the world. We assembled trends in abundance and harvest rate of stocks that are scientifically assessed, constituting half of the reported global marine fish catch. For these stocks, on average, abundance is increasing and is at proposed target levels. Compared with regions that are intensively managed, regions with less-developed fisheries management have, on average, 3-fold greater harvest rates and half the abundance as assessed stocks. Available evidence suggests that the regions without assessments of abundance have little fisheries management, and stocks are in poor shape. Increased application of area-appropriate fisheries science recommendations and management tools are still needed for sustaining fisheries in places where they are lacking.
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