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An Estimate of Juvenile Fish Densities in Skilak and Kenai Lakes, Alaska, Through the Use of Dual Beam Hydroacoustic Techniques in 1987

出版	Alaska Department of Fish and Game, Division of Commercial Fisheries, 1988
URL	http://books.google.com.hk/books?id=VU_SzwEACAAJ&hl=&source=gbs_api

註釋In 1986 the State of Alaska, Department of Fish and Game (ADF&G) begin developing new methodologies (Tarbox and King 1987) to assess the rearing success of sockeye salmon (Oncorhynchus nerka) in the glacial lake systems of the Kenai River, Upper Cook Inlet, Alaska (Figure 1). The Kenai River drainage consist of a number of sockeye rearing lakes (Figure 2) and is the single largest producer of sockeye salmon in Upper Cook Inlet. Recent sockeye salmon adult returns to the Kenai River have ranged between 5 and 9 million fish and have contributed over 75% to the total Upper Cook Inlet harvest. Unfortunately, because of the glacial nature and size of the Kenai River system, historical investigations which attempted to establish production models for rearing sockeye salmon have been ineffective. Typical capture mechanisms (tow netting) and survey techniques have failed to adequately estimate rearing fish populations. Therefore, the ADF&G began a new approach in 1986 which used hydroacoustic equipment to survey rearing fish populations and continued that approach into 1987. The report presented herein is a presentation of the results of the 1987 efforts. Formation of production models will be initiated after suitable counting techniques are achieved. Specific objectives for the 1987 field investigation were: (1) to estimate the number and spatial distribution of sockeye salmon juveniles in Kenai and Skilak Lakes; and (2) to define the target strength distribution for fish targets in both lakes using dual beam hydroacoustic techniques.