Wednesday, April 19, 2017

AFSC Study Examines Bering Sea Fish Populations Over 34 Years

A new study by the Alaska Fisheries Science Center examines how fish populations have changed over the past 34 years of varying climate conditions, and researchers say their work may provide clues to how future changes will affect fisheries.

According to fisheries biologist Steve Barbeaux, lead author of the study, climate variability has increased in recent years in the Bering Sea and the science center will use that information to study how ecosystems respond to change.

Summer bottom trawl surveys provide information fisheries managers need to set quotas for sustainable fishing. Data collected include where fish are, how many and what species are found, sex, size and age, as well as environmental data such as ocean temperature.

Barbeaux analyzed survey data from 1986 through 2015 to explore patterns of fish distribution by species, size and sex in relation to environmental conditions. He mapped that data to create visualizations that show fish life histories unfolding over space and time.

Sufficient data was available for in-depth analyses of 22 groundfish species, from arrowtooth flounder to yellowfin sole. While changes in Bering Sea fish distributions in relation to climate variability have been widely reported, no other study has specifically examined ontogenetic differences in how fish respond to climate variability, Barbeaux said. Ontogeny relates to the origination and development of an organism, usually from the time of fertilization of the egg to the organism’s mature form.

Barbeaux said the studies show that some species prefer relatively cold or warm, shallow or deep waters and this knowledge could help predict where they will go as conditions change. Climate affected middle life stages the most, he said. For species that shifted distribution between warm and cold years, mid-size fish were most affected, he said.

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