Physiology, climate change, and the ecosystem approach to fishery management in Northeastern Pacific ecosystems: improving the representation of functional group physiologies in end-to-end ecosystem models

Problem: Federal policy and the COCA Fisheries and Climate program support the development of ecosystem-based fisheries management and the tools that enable accurate evaluation of trade-offs between competing resource management and conservation objectives in a changing environment. End-to-end (physics-to-fisheries) ecosystem models describing interactions between multiple species and fishing fleets within dynamic physical environments provide a tool to evaluate consequences of alternate management actions and a changing climate. These models typically emphasize the impact of environmental variability in terms of effects upon plankton productivity, distribution, and taxonomic composition. But rearrangements in food web structure arising from differential physiological responses to temperature and prey quality conditions can have large consequences among economically important species. Accurate representation of the ecophysiologies of individual groups is necessary to correctly represent the effects of climate change upon fishery production and anticipate effects of management actions.

Objectives: 1. Expand capabilities of end-to-end models through improved representation of the ecophysiologies of individual groups in terms of allocation of consumed energy to growth in changing temperature and prey quality conditions. 2. Evaluate ecological and economic consequences of changing temperature, current, and prey quality regimes. 3. Improve policy exploration capabilities of end-to-end models to quantify trade-offs between competing resource management and conservation objectives arising out of management actions for individual stocks.

Approach: ECOTRAN is a high taxonomic complexity end-to-end model. Revised descriptions of how bioenergetic budgets of individual groups respond to changes in temperature and prey quality will be incorporated into ECOTRAN models representing two Large Marine Ecosystems (LME), the Northern California Current (NCC) and the coastal Gulf of Alaska (CGoA). Simulations will evaluate how changing environmental conditions and fishing effort in each LME affect ecosystem structure, yield among different fishing sectors, and the economic well-being of communities that depend upon access to LME resources. Simulations under a “business-as-usual” CO2 emissions scenario will estimate how NCC ecosystem structure and fishing sector yields will change with the climate in coming decades. Finally, ECOTRAN will be applied to estimate the collateral consequences of changing effort by the Pacific hake fleet within the NCC upon other commercially important stocks, conservation goals, and economic revenue of other fishing fleets within the context of a changing physical environment. Hake are the most important stock within the California Current in terms of landed tons and play an important ecological role as major consumers of forage species and prey for higher trophic level predators.