Field Activity Details for field activity M294EG

AKA: none

Other ID: M-2-94-EG

Status: Completed

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Principal Investigator(s): Gary Greene

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Information Specialist(s):

Data Type(s): Location-Elevation: Navigation, Sonar: Sidescan

Scientific Purpose/Goals: The object of the cruise was to map the seafloor morphology of rockfish habitats that had been observed on earlier submersible dives.

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Start Date: 1994-07-26

End Date: 1994-07-29

Equipment Used: navigation, sidescansonar

Information to be Derived:

Summary of Activity and Data Gathered: The survey successfully delineated the geometry and extent of the offshore lava field, a 30 X 20 sq. km. area, and also highlighted substrate habitats that are attractive to different rockfish. Two favorite fishing spots lie on partially eroded volcanic cones. Side-scan imagery indicated the shallowest cone has shear vertical walls that drop to a angular rubble apron on one side; this cone attracts high concentrations of rockfish and lingcod. The deeper cone had a more gentle morphology and significantly fewer rockfish and lingcod, probably because less habitat shelter exists on the smooth surface of the cone. NURP and Alaska Fish and Game anticipate that this type of surveying to define fish habitats will be needed in the future in many areas of Alaska and on fishing grounds in the lower 48 too].

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Notes: (modified from USGS bulletin dated Aug.12,1994 and August GD News) - ALASKA FISHERIES WORK. Gary Greene, John Gann and Mike Boyle spent 2 days side scan surveying near Sitka as part of a cooperative program with USGS, Moss Landing, NURP and Alaska Department of Fish and Game. Initially widely spaced swaths were run to determine the character and extent of the Mt. Edgecumbe lava field, which covers the shallow seafloor west of the Mt. Edgecumbe volcano. Then overlapping side-scan survey were run over the offshore extension of the southwest rift of the volcano; this survey will be mosaicked at USGS. On both the widely spaced and detailed swaths, a variety of volcanic features were seen including cones, vents, plugs, collapsed lava tubes, lava flow fronts, pressure ridges, and the like.

Staff information imported from InfoBank
Gary Greene (USGS Western Region) - Chief Scientist

Location:

Eastern Gulf of Alaska

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