The influence of warp length on trawl dimension and catch of walleye pollock Theragra chalcogramma in a bottom trawl survey
نویسندگان
چکیده
منابع مشابه
Classification of Ovarian Stages of Walleye Pollock (Theragra chalcogramma)
Walleye pollock, Theragra chalcogramma, is the most commercially important species in the eastern Bering Sea. Estimates of maturity are critical for setting an appropriate harvest rate for pollock spawning biomass, and correct classification of ovaries into a maturity condition is necessary for accurate estimation of maturity. Data on length, weight, and ovary weight and condition were collecte...
متن کاملThe influence of ontogeny, physiology, and behaviour on the target strength of walleye pollock (Theragra chalcogramma)
Variability in echo intensities from aquatic organisms is caused by physical factors associated with the transmission of sound through water, and by biological factors associated with the ontogeny, physiology, and behaviour of targets. Acoustic-based density estimates depend on accurately characterizing reflected or backscattered sound from any species of interest. Digitized lateral and dorsal ...
متن کاملClimate change causing phase transitions of walleye pollock (Theragra chalcogramma) recruitment dynamics.
In 1976 the North Pacific climate shifted, resulting in an average increase of the water temperature. In the Gulf of Alaska the climate shift was followed (i.e. early 1980s) by a gradual but dramatic increase in the abundance of groundfish species that typically prey on pre-recruitment stages of walleye pollock. In the present study we used a previously parameterized model to investigate the ef...
متن کاملBiogeographic evidence for selection on mitochondrial DNA in North Pacific walleye pollock Theragra chalcogramma.
Three major mitochondrial DNA (mtDNA) haplogroups were identified in 5 data sets for North Pacific and Bering Sea walleye pollock. The common haplogroup A showed mirror-image clines on both sides of the North Pacific with high frequencies in southern areas (P(A) > 0.84) and low frequencies in the Bering Sea (P(A) < 0.36). Two additional haplogroups showed complimentary, but weaker, clines in th...
متن کاملEffects of size and light on respiration and activity of walleye pollock (Theragra chalcogramma) larvae.
The respiration rate and swimming activity of walleye pollock (Theragra chalcogramma) larvae were measured in the laboratory to determine how these were affected by body size (measured as dry weight), and amount of light. Size influenced respiration rates, but not activity. Activity increased with increased light, and as walleye pollock larvae developed, light had an increasingly important effe...
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ژورنال
عنوان ژورنال: Fisheries Science
سال: 2005
ISSN: 0919-9268,1444-2906
DOI: 10.1111/j.1444-2906.2005.01023.x