Quantifying predator consumption of mid-trophic level prey species to inform ecosystem-based fisheries management decisions in the California Current ecosystem
Summary
PRBO Conservation Science is investigating the feasibility of gathering existing and new data and information necessary to assess and describe predator consumption of mid-trophic level prey species in the California Current ecosystem. As we begin, we are reaching out to scientists, stakeholders, and resource managers who are interested in the subject and may wish to provide input on the project design, and/or may wish to contribute data and information.
Background
Long-term, sustainable management of mid-trophic level prey species (or forage species) is essential to the ecological health of the California Current food web, and to the wildlife and human communities that depend upon its productivity. Ecosystem-based management of marine resources is particularly important for forage species in the highly variable California Current ecosystem.
An ecosystem-based approach to forage species management should utilize information about regional predator dietary needs1. Quantification of these needs is challenging, but essential, and much work has already been done.
Project Concept
PRBO and partners will evaluate existing, available research on predator populations and diet in order to compile and translate the available information into a user-friendly format. We will also identify and prioritize gaps in data that need to be filled to provide quantitative information to fishery managers. We will then design a research protocol to collect and analyze new data necessary to meet resource management needs.
Results of this work will be tailored for use in ecosystem models, fishery management plans, and other decision-making tools. Web-based programs are also an intended destination for information in order to increase accessibility of information to members of the scientific community, fishery managers, stakeholders, and the general public.
1PRBO’s report Ecosystem-based Management of West Coast Forage Species identified the need to better understand and quantify predator requirements for forage species, such as diversity, density, and spatial-temporal availability, in the California Current ecosystem. The report recommends formation of a west coast food habits working group to project regional predator dietary needs, and effects of predation on forage species populations, and to identify priority predator-prey linkages for monitoring. Species Definitions
Forage species are defined as a suite of species that provide a critical link between lower and upper trophic levels. These species generally exhibit one or more of the following characteristics:
Important prey for upper trophic levels (e.g., small schooling pelagic fish);
Prey throughout much of their life-cycle;
Abundance highly influences productivity of predators;
Key forage species at the juvenile stage.
Species managed in the California Current include: anchovy, sardine, euphausiids, mackerel, market squid, shortbelly rockfish, sandlance, eulachon, and Pacific herring.
Predator species include upper trophic level species that regularly reside in or migrate through the California Current in sufficient numbers to impact prey population dynamics. These species include:
Cetacean
Pinnipeds
Seabirds
Large predatory fishes
Sharks and squid
Information Needs
Quantifying information of this kind is a large undertaking, and one that we cannot do alone. We invite you to participate by providing information, expertise, ideas, or analyses that will help answer the following questions:
What are the population abundance estimates of predator species (for residents and migrants)?
What is the diet composition of each predator species and at which predator and prey life stages?
What are the predator energy demands and what are their assimilation efficiencies?
What are the prey energy densities (i.e., how much energy does an individual provide)?
When during the year does predation take place?
Where does predation take place?
What prey density is needed for successful foraging?
PRBO Conservation Science is dedicated to conserving birds, other wildlife and ecosystems through innovative scientific research and outreach. For more information or to get involved, please contact the Marine Director at marinedirector@prbo.org or visit our web site at http://www.prbo.org/forage.
