منابع مشابه
Midwater Fish Surveys at the AFSC
chalcogramma) stocks in the Bering Sea and Gulf of Alaska since 1979. As fisheries acoustic methodology has matured, acoustic research at the APSC has involved refinements in equipment and techniques. Whereas early echosounders and echo integrators were subject to the drifts associated with the use of analogue electronic circuitry and were limited by system dynamic range, modern units utilized ...
متن کاملModeling of the Part Dynamics of the Midwater Trawl Based on R Language
In this study, the part dynamics of the midwater trawl were modeled and simulated using mechanical equations and R language. A lumped mass method was used to model the dynamical behavior of a net in steady flow. And the implicit algorithm was developed to solve the stiff differential equations. The programming, simulation and visualization of the modeling were based on the R platform. The part ...
متن کاملReliability of trawl surveys on cod in Norwegian fjords
According to ICES, the International Council for the Exploration of the Sea, populations of coastal cod (CC) in Norway north of 628N have been declining since 1994. The estimates are based on analytical assessment in which the most recent estimates are tuned with survey information. We evaluate the quality of bottom-trawl surveys conducted in four North Norwegian fjords during autumn of the yea...
متن کاملGeostatistical Assessment of Sampling Designs for Portuguese Bottom Trawl Surveys
New sampling designs for the Autumn Portuguese bottom trawl survey (ptBTS) were investigated to explore alternative spatial configurations and possible increments on sample size. The currently used stratified random design and five proposals of systematic based designs were assessed by a simulation study, adopting a geostatistical approach based on likelihood methods of inference. The construct...
متن کاملTwo Demersal Trawl Surveys in the Gulf of Alaska: Implications of Survey Design and Methods
In 1984 and 1987, demersal trawl surveys of fish stocks in the western and central Gulf of Alaska were executed by the National Marine Fisheries Service in cooperation with the Fisheries Agency of Japan. Details of the survey design and sampling methods are presented. Fishing power differences resulted from differences among vessels, gears, and trawling procedures. Chartered fishing vessels fro...
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ژورنال
عنوان ژورنال: Limnology and Oceanography
سال: 1962
ISSN: 0024-3590
DOI: 10.4319/lo.1962.7.suppl.xxxix