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Economics & Social Sciences Research Program

Management Institutions, Incentives, and the Margins of Selectivity in Fishing: Evidence from the Amendment 80 Trawl Fishery

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The ecological and economic ramifications of imperfect selectivity in fisheries are well-known and significant particularly with respect to bycatch. In both fisheries science and a sizable portion of the fisheries economics literature, it is commonplace to see the selectivity of gear across species assumed as static, with the particularities of gear modifications and the spatial and temporal decisions associated with gear use implicitly ignored. However, if variations in the spatial and temporal deployment of gear have important implications for catch composition at the individual gear-deployment level, this implies there may be a significant aspect of catch composition that is behavioral in nature rather than purely technical.

The extent to which the realized catch composition in a fishery is behaviorally rather than technologically determined is critical to resolving an important debate in multispecies management policy the applicability of catch shares to multispecies fisheries.

A number of critics, often relying upon inferences from pre-catch-share data, have asserted that fishermen may find it difficult or impossible to accommodate their catch composition to their portfolio of quota holdings with potential consequences including high prices for binding species' quota, a collapse in markets for "slack" species, rampant illegal discarding, data fouling and subverted quota markets. In stark contrast to these predictions, ex post evidence from multispecies catch share systems have often shown far greater malleability of catch composition than anticipated.

We address this disagreement in the literature in several ways. First, we utilize detailed data at the individual haul level on the Amendment 80 trawl fishery before and after the implementation of catch shares in 2008. In the initial phase, the catch of all species, including bycatch species, was regulated by the assignment of multiple total allowable catches (TACs) for each species to the entire fleet.

Under this common pool incentive system, bycatch species often closed the entire fishery prematurely. Under Amendment 80, individual vessels essentially operate under a multispecies catch share system, with individual accountability for their catch of target and bycatch species.

We find dramatic evidence of a shift in overall catch composition away from formerly binding bycatch species and toward valuable target species. We also note far less variability in the target/bycatch ratio than in the pre-catch share era.

Second, we conduct a detailed analysis of behaviors that fishermen employed to affect their catch composition. This analysis shows that fishermen were able to alter their catch composition substantially through their choices of when and where to fish on fine and coarse scales. We find evidence that large scale and durable shifts in fishing grounds, spatial avoidance behavior in response to high bycatch signals, and strategic shifts in the incidence of night-fishing have all contributed significantly to the observed changes.

Importantly, these margins of change were all available to fishermen before the institutional change, and yet were not adopted. This suggests that management systems which provide few incentives for selective fishing may obscure significant hidden short-run flexibilities of fishermen to alter their catch composition.

By Joshua K. Abbott, Alan C. Haynie, and Matthew N. Reimer

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