Estimating Trawl Catchability

Somerton, David

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Estimating Trawl Catchability

1996
By Somerton, David
Series: AFSC quarterly report Jan, Feb, March 1994

Details

Alternative Title:

Alaska Fisheries Science Center Quarterly Report : January, Febuary, March, 1996 [feature article]
Personal Author:

Somerton, David
Corporate Authors:

Alaska Fisheries Science Center (U.S.)
NOAA Program & Office:

NMFS (National Marine Fisheries Service) ; AFSC (Alaska Fisheries Science Center)
Description:

Swept-area estimates of groundfish biomass, the primary product of Alaska Fisheries Science Center (AFSC) bottom trawl surveys, require knowledge of the proportion offish captured within the swept area of a trawl (Q). Until recently, Q, also known as catchability, had never been estimated for any species sampled by bottom trawl surveys and was assumed to equal Q in the calculation of biomass. Recent studies by both Norwegian and Canadian investigators, however, have shown that the processes of fish herding and escapement often lead to values of Q that are quite different from unity. Because departures of Q from unity can result in biased estimates of biomass and possibly faulty advice for fishery management, the Groundfish Assessment Task of the AFSC Resource Assessment and Conservation Engineering (RACE) Division initiated a study designed to experimentally estimate the value of Q for several species sampled with the 83-112 bottom trawl (Fig. 1) used on the annual National Marine Fisheries Service (NMFS) surveys of the eastern Bering Sea
Keywords:

Biomass Catch Effort Groundfishes Herding Surveying Trawls And Trawling United States. Endangered Species Act Of 1973 Catch Effort Trawls And Trawling United States. Endangered Species Act Of 1973
Series:

AFSC quarterly report Jan, Feb, March 1994
Document Type:

Technical Report
Place as Subject:

Bering Sea
Rights Information:

Public Domain
Compliance:

Submitted
Main Document Checksum:

urn:sha-512:8a3705875375714ebc2b78a7d80fd0e3214925a812e19e28338e68fd312aff12f96d4b2a81d01ef58c557bcfce60ebd2376aad7209a3c9e229ded286fac911b6
Download URL:

https://repository.library.noaa.gov/view/noaa/19954/noaa_19954_DS1.pdf
File Type:

[PDF - 325.39 KB ]

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