Status of Stocks & Multispecies Assessment Program
First Cooperative Aleutian Islands Atka Mackerel Tagging Cruise with the North Pacific Fisheries Foundation a Success!
Top: Scientists and vessel crew with the Fisheries Interaction Team tagging cruise transferring live Atka mackerel from the trawl net into holding tanks. Bottom: John Hargrove (NPFF scientist), Rob Freyer (UW intern) and Dan Cooper preparing to tag an Atka mackerel. Photos by Teresa A’mar.
The Fisheries Interaction Team (FIT) conducted an Atka mackerel tagging cruise aboard the charted fishing vessel Pacific Explorer in the Aleutian Islands at Seguam Pass and near Kiska Island 5-21 July 2006.
The objective of our ongoing tag release-recovery study is to determine the efficacy of trawl exclusion zones as a management tool to maintain prey abundance/availability for Steller sea lions at local scales. Tagging experiments are being used to estimate abundance and movement between areas open and closed to the Atka mackerel fishery.
This was our first cruise in collaboration with the North Pacific Fisheries Foundation (NPFF), a nonprofit organization formed by members of the fishing industry to support research essential to the conservation and management of North Pacific Atka mackerel and other fishery resources. Kimberly Rand (FIT/University of Washington Joint Institute for the Study of the Atmosphere and Ocean) and John Hargrove (former FIT intern) were hired as scientists by the NPFF.
Atka mackerel were collected by short duration trawl hauls, placed in live tanks, and then measured, tagged, and released. Approximately 8,000 Atka mackerel were tagged and released during this cruise at Kiska Island, and 7,200 fish were tagged and released near Seguam Island. Atka mackerel sex ratio and length frequency were also estimated for each haul, along with gonads, stomachs, and otoliths from 10 fish per haul. Temperature, salinity, and fluorescence were recorded continuously, and chlorophyll samples were also collected.
Left: Teresa A’mar (UW graduate student) placing an Atka mackerel into the cradle used to hold fish while a tag is inserted. Right: An Atka mackerel fitted with a spaghetti tag. The fish was released immediately through the white tube shown in the background. Photos by Dan Cooper.
Several additional projects were completed during the cruise. Rob Freyer (UW intern) deployed a plankton net as part of his undergraduate capstone research project studying Atka mackerel prey and diet. Measurements were taken for a sexual dimorphism study by Jared Guthridge (University of Alaska graduate student) which may provide a non-lethal method of sex determination. Three yellow Irish lords (Hemilepidotus jordani) were collected for comparative fish skeletons to use in studies of fish bones from coastal archaeological sites in the Aleutian Islands. Twenty-one Pacific cod stomachs were collected and preserved for food habits analysis.
Future Atka mackerel fisheries will recover fish tagged during this cruise. Dedicated tag recovery cruises will provide recovery effort inside areas closed to the Atka mackerel fleet. A recovery cruise aboard the fishing trawler Seafisher is planned for October of this year.
