DSTs collect and store information on water temperature, depth, and time that will be used to investigate the vertical movement patterns of Atka mackerel within the water column. Also, two current meters were deployed in the vicinity of the tag release sites in the closed area, one of which was recovered. The basic biology of Atka mackerel has been poorly studied despite its commercial value and importance as a key forage species for the endangered Steller sea lion and other marine piscivores. A peculiar aspect of Atka mackerel s life history is that the adults switch from a predominantly pelagic to mostly demersal existence during spawning in summer and early fall. Adults migrate to shallower water where females deposit their eggs onto rocky substrate.
Males fertilize the demersal egg clusters and remain over the nests to guard and aerate the eggs.
The seasonality, spatial extent, and physical characteristics of Atka mackerel nesting areas within the Aleutian Islands are in need of further study. The primary objective of the second leg of the cruise was to estimate and more fully describe the spawning area near Finch Cove, Seguam Island. The Morning Star served as a support platform for near-shore dives and underwater camera work. Thirty-four scuba dives and numerous drop camera sets were made in the near shore areas surrounding Seguam and Amlia Islands. The first deployment was done prior to spawning on 14 June during a previous, separately funded Aleutian Island groundfish bottom trawl survey.