The ecosystem approach to managing fisheries: achieving conservation objectives for predators of fished species

Managing fisheries to achieve ecosystem objectives is in its infancy. A general approach for maintaining ecological relationships and providing for the recovery of depleted populations in food webs supporting fisheries is proposed. This paper addresses the following general questions for taking the ecosystem approach in managing fisheries: (i) how might fisheries impact incidentally on an ecosystem, (ii) what should be the conservation objectives for predators of fished species, and (iii) what approaches could be considered for achieving the conservation objectives?  The approach proposed here takes account of uncertainties in knowledge of the structure of ecosystems.  Estimates of production arising from fished species (encapsulated in proposed indices P and W) potentially provide useful indicators for management purposes because they integrate across a range of “ecosystem” effects and, as formulated here, can also be related directly to the effects of fishing.  These features are currently unavailable in ecosystem approaches to managing fisheries.  The paper elaborates the steps required to establish management procedures based on these indices.