The study in Canada's British Columbia waters compared so-called individual transferable quotas with a previously used system of trip limits where vessels are only allowed to land a certain quantity of each species every two months.
The findings come at a time when individual transferable quotas are being considered for the west coast of the United States.
"Economic models have assumed all along that individual transferable quotas increase discards," says Trevor Branch, who earned his doctorate in aquatic and fishery sciences at the University of Washington and is lead author of an article published online this week by the journal Marine Policy.
But discards did not increase they declined for most species, report Trevor and co-authors Kate Rutherford, biologist with Fisheries and Oceans Canada in British Columbia, and Ray Hilborn, UW professor of aquatic and fishery sciences.
The study, "Replacing Trip Limits with Individual Transferable Quotas: Implications for Discarding," is the first to look at 35 species instead of only a handful, or even just a single species, before and after quotas were implemented.
With individual transferable quotas, the total allowable catch is divided among a limited number of boats with each quota holder receiving a specific proportion of the total catch. Quota holders then decide how and when to fish, and whether to buy additional quotas or lease or sell their quotas.
Such a system was implemented in British Columbia waters in 1997, after a one-year transition from individual trip limits and overall caps on the fleet. After a period of adjustment, rates have remained generally similar or even less than the 15 percent of fish discarded in 1996.
Discarding occurs when, for example, unmarketable fish are caught or where trip limits are imposed and
Contact: Sandra Hines
University of Washington