Matching catches to quotas in a multispecies trawl fishery: targeting and avoidance behavior under individual transferable quotas

Optimizing yield in multispecies fisheries is only possible when fishers have a high degree of control over the species mixture in their catches, although incentives to encourage this kind of behavior are rarely in place. One exception is the British Columbia, Canada, groundfish trawl fishery, where individual transferable quotas govern total allowable catches (TACs) for 22 species, combined with 100% observer coverage and the deduction of discard mortality from quota. Despite the number of species covered, when TACs were increased for some species and reduced for others, fishers were able to adjust the species mixture in their catches. The top 34 vessels frequented a wide range (mean 38, range 20-69) of fishing opportunities (repeated trawls along the same track line) containing predictable species mixtures. When TACs for rougheye (Sebastes aleutianus), shortraker (Sebastes borealis), and yelloweye rockfish (Sebastes ruberrimus) were sharply cut, fishers avoided fishing opportunities where these species were more abundant. More generally, their choice of fishing opportunities depended on the expected multispecies composition, although other factors were probably also important.