Assessing Fisheries: Marine Fish Diversity and Production
Historically, fishery management has generally been crisis-based rather than proactive. However, there is a growing national and international recognition of the need to develop an ecosystem-based approach to fisheries management (EBFM) in response to the challenges and shortcomings of traditional resource management approaches in sustaining marine ecosystems. While EBFM is a laudable goal for fishery management, the purpose of the cases illustrated here is ultimately to go beyond single objective or sector management (e.g., fisheries) to consider multiple objectives in a more holistic management context.
In setting the context for fisheries in the Pacific Northwest region we have provided some background on the Essential Fish Habitat (EFH) process.
We first assessed diversity and production by developing marine fish targets and including them within the spatial database. We designed multiple Marxan scenarios to examine the influence marine fish targets had on priority conservation site selection.
In order to better address fisheries and multiple trophic relationships, we have examined the use of Ecopath with Ecosim (EwE). EwE is a widely used fisheries modeling tool around the globe. EwE software analyzes exploited aquatic ecosystems, combining software components for ecosystem trophic mass balance analysis (Ecopath) with a dynamic modeling capacity (Ecosim) for exploring past and future impacts of fishing and environmental disturbances. Ecosim models can be replicated over a spatial map grid (Ecospace) to allow exploration of policies such as marine protected areas, while accounting for dispersal and migration of fishes. This toolkit provides a brief overview of the Ecopath with Ecosim model but focuses primarily on Ecospace.
An Ecopath model has been developed in the Northern California Current (NCC) ecosystem, extending from Cape Mendocino in California to Cape Flattery, Washington (Field 2005). This case study utilizes the NCC Ecopath model and extends its utility to include an Ecospace component.