Finding fish: grouping and catch-per-unit-effort in the Pacific hake (Merluccius productus) fishery

摘要

Numerous papers have documented the problems in estimating stock abundance using only catch-per-unit-effort (CPUE) data. In this paper, logbook data from the onshore processing sector of the Pacific hake (Merluccius productus) fishery in Oregon from 1992 to 1996 are used to analyze the effect of grouping on CPUE and on search time. Two groups are investigated: (i) simple daily aggregations of vessels on fishing grounds and (ii) yearly information- sharing groups. It is found that both groups are positively associated with CPUE; however, in 1995, this result may be the spurious result of more vessels being drawn into the fishery by good conditions. It is argued that in other years, fishers benefit from grouping by being able to find high-quality patches. Fishers in larger groups also experienced lower search times from 1993 to 1995. However, a pattern of declining effect of information-sharing groups from 1993 to 1996 suggests that fishers who were relatively new to this fishery became less reliant on information-sharing networks for finding patches of fish, although fishers in larger groups still may have benefitted by being able to find higher quality patches.