A new report says creating conditions for global fish stocks to recover is a win-win for environmentalists, and for commercial fisheries.
However, the report co-authored by Dalhousie University biologist Jeff Hutchings, says that many of the world’s fish stocks have not recovered in spite of efforts by several nations to limit or restrict fishing. For example, Canada’s Atlantic cod stocks, once bountiful, have never recovered in spite of some 20 years of moratorium. Even today some remain at only about 2-3% of the numbers in the 1960’s. Listen
Recognizing the global importance of recovery, the United Nations (UN) 2002 World Summit on Sustainable Development proposed that global fisheries be rebuilt to maximum sustainable yield (MSY) levels by 2015
The report, called the “Resilience and Recovery of Overexploited Marine Populations” was published this week in the online journal Science. It says that by 2010 only about 1% of the global commercial stocks requiring rebuilding had achieved that goal, and suggests that it is highly unlikely the UN 2015 targets will be met.
Professor Hutchings said their study also found that ¾ of the fish stocks globally for which they have information, and which are known to be depleted, are still being overfished, that is, fished too heavily to allow recovery.
The report studied 153 marine stocks worldwide, while modelling recovery times for 184 recorded depletion events.
Dr Hutchings says on the one hand, it would appear species are more resilient than previously thought, however any such recovery is dependent on taking immediate action to limit fishing pressure at the first sign of overfishing.
Recovery times for a species are dependent upon a number of factors including the rate or degree of overfishing, and for how long, how far the population has dwindled as a result of overfishing, and the intrinsic rate of increase of the species, with slow reproducing species at particular risk. Another factor is its place in the food chain (trophic interaction). Modelling shows that species and situations requiring longer recovery times result in increased uncertainty of recovery. Continued fishing once a depletion of stock has been identified, makes the recovery of the stock even more uncertain.
He notes that in the case of Canada’s northern cod, action was not taken until well after a crisis was known, and then by allowing a limited fishery a few years after the initial moratorium, it further hindered any recovery that was taking place. Ocean warming and environmental change was not explicitly included in this study due to a lack of information on a global basis, although it is known that conditions are changing and that Professor Hutchings says that does affect a reduced population’s ability to adapt to changing conditions and so reduces the stock’s ability to recover.
One of the problems is that politicians and regulators face pressure for short term solutions, whereas recovery is usually a long multi-year, even multi-decade process.
Dr Hutchings hope the study provides the information and incentive for politicians and regulators to act immediately and decisively the moment overfishing is determined.
SCIENCE- abstract of Resilience and Recovery of Overexploited Marine Populations
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