A recent article by scientists from the School of Aquatic and Fishery Sciences at the University of Washington in the open access online journal PLOS ONE helps to illustrate, at least in a general way, how little we know about maintenance of sustainable fisheries.

The research reviewed groundfish stocks in three fisheries: Alaska, British Columbia, and the U.S. West Coast. Groundfish are fish that live on or near the bottom of the water body which they inhabit. On the Pacific coast of North America they include such species as pacific cod, lingcod, halibut, and many more. In each of the studied fisheries fishers are, in most years, taking significantly less than the Total Allowable Catch, meaning that stocks are exploited at levels below their maximum sustainable yield. Potentially this means a loss of economic benefit and food resources that the fishery could provide.

Fish stocks that rarely exceed TACs and that are often fished at well below TACs provide a useful environment for evaluating the impact of potential conservation measures. The researchers studied various tools for limiting catches:

• individual quotas;
• the use of harvest control rules ;
• marine reserves;
• seasonal closures;
• bycatch constraints; and
• gear type.

The first three of these fishery management tools were found to have little effect on the status of stocks. Overall the researchers found that there is no single effective management measure for meeting conservation objectives. If scientifically established quotas are set and enforced, a variety of means can be used to ensure that exploitation rates and biomass levels are near to or more conservative than management targets.

As GallonDaily views it, the implication to be drawn from this research is that there is probably no one right answer for maintenance of sustainable stocks in fisheries. A number of tools are available and it may well be most appropriate for local decisions to be applied in selection of methods to keep a particular fishery in sustainable management.  Critics who promote a single tool as the answer for sustainable fisheries may not be promoting the best path for a sustainable fishery.

Effects of Management Tactics on Meeting Conservation Objectives for Western North American Groundfish Fisheries. Michael C. Melnychuk, Jeannette A. Banobi, Ray Hilborn. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0056684#ack