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With growing demand for seafood, and many scientists advocating “balanced harvesting” that would involve fishing more on lower levels of the marine food chain, a new project on the impact of such fisheries is being initiated at University of Washington. Low trophic levels, often called “forage fish” are currently some of the largest fisheries in the world, but ecological studies suggest that the potential for increased fish yield from the ocean come primarily from fishing new forage species and in many cases fishing existing species harder. At the same time there is concern that fishing more at low trophic levels will have adverse impacts on higher trophic level predators, including marine birds, mammals and other fishes.

While there have been several recent studies of the impacts of fishing forage fish on higher predators, many of these used very simple ecosystem models that ignored the great natural variability in forage fish abundance, the importance of spatial distribution of forage fish in relation to their predators, especially at the time of breeding, and often simplified the composition of the forage fish community and the size composition of both forage fish, their predators, and the human harvest. The new study will explore the implications of each of these issues by using a range of different kinds of ecosystem models and more explicit analysis of the relationship between natural variability of forage fish in space and time, the size distribution of forage fish, predators and the harvest, and the factors affecting predator abundance other than food.

This project will be complementary to two ongoing projects at the School of Aquatic and Fishery Sciences. Tim Essington and his laboratory have been working on forage fish impacts and evaluating alternative harvest control rules. Andre Punt is co-chairing the “Ocean Modelling Forum” whose objective is group to improve the use and usefulness of models in informing the management of Pacific sardines on the west coast of North America.

The overall goal of this work will be to evaluate the trade-offs between fisheries yield and impact on higher trophic levels of the ecosystem for the larger forage fisheries of the world and specifically to evaluate the impact of alternative harvest control rules. Analysis of these trade-offs will allow decision makers to use scientific analysis for their ecosystems to make the decision that best meet the national fisheries objectives. Our work will also provide a framework that could be used for other fisheries that we do not explicitly consider.

The forage fish project will involve a team of collaborators from a range of institutions and will hold a first meeting of this team in early 2016. We are currently soliciting funding for this project at a level of $300,000 from governments, foundations, industry and NGOs.

Interested parties should contact Ray Hilborn at rayh@uw.edu.

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