UW Aquatic & Fishery Sciences Quantitative Seminar

Suresh A. Sethi

UW Aquatic & Fishery Sciences

The interactions between poaching and management policy choice affect marine reserves as conservation tools

Abstract:

The existing body of marine reserve study largely ignores some realities of noncompliant resource-user behavior: poaching within reserve boundaries.  Non-compliance is almost universal property of fisheries management and it is probable that poaching within reserve boundaries may have a significant effect on the success of marine reserves as fishery management tools.  This analysis uses a simple age-structured reserve model with Black rockfish biology to explore the effects of poaching within reserve boundaries under three different management policies based on yield maximization or reproductive thresholds.  Departures from the traditional assumptions of full compliance to reserve boundaries alter the conclusions of prior modeling work that demonstrate yield equivalence to no-reserve effort control management and augmented reproductive benefits when small reserves are implemented.  By degrading the recruitment subsidization effect to nonreserve areas from protected reserve populations, poaching resulted in negative externalities for compliant fishermen in open areas in terms of yield and degraded the reproductive output and age-structure of the system.  All three policies required effort reduction in open areas as a response to poaching in reserves.  The strength of the impacts from poaching varied with policy choice and harvest intensity in the reserve, where at the highest level of poaching presented here (15% annual exploitation rate of the vulnerable reserve population) biological and fishery benefits of implementing reserves were totally negated.  Under the assumptions of this model, a policy managing for a reproductive threshold that excludes the reserve population is preferred if poaching is likely.  The results of this exercise emphasize the importance of garnering compliance to reserve boundaries from resource-users for spatial closures to be successful ocean management tools.