scholarly journals Do Pacific cod (Gadus macrocephalus) and walleye pollock (Theregra chalcogramma) lack a herding response to the doors, bridles, and mudclouds of survey trawls?

2004 ◽  
Vol 61 (7) ◽  
pp. 1186-1189 ◽  
Author(s):  
David A. Somerton
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Walleye Pollock ◽  
Pacific Cod ◽  
The North ◽  
Pacific Cod Gadus Macrocephalus ◽  
Gadus Macrocephalus ◽  
The North Pacific ◽  
Trawl Surveys

Abstract Pacific cod and walleye pollock were subjected to herding experiments in which trawl hauls are conducted repeatedly in an area with the bridles varied among three distinct lengths. For the flatfishes in these studies, catch per unit of area swept (cpue) by the trawls increased greatly with increasing bridle length, indicating that flatfish are stimulated to herd into the path of the net by the action of the bridles. In contrast, the cpue of Pacific cod and walleye pollock did not increase significantly with increasing bridle length. This lack of significance indicates that these two species respond only weakly to any herding stimuli produced by the 83–112 Eastern and Poly Nor'eastern trawls used to conduct groundfish trawl surveys in the North Pacific Ocean.

Lack of Genetic Stock Discretion in Pacific Cod (Gadus macrocephalus)

1987 ◽  
Vol 44 (3) ◽  
pp. 490-498 ◽  
Author(s):  
W. Stewart Grant ◽  
Chang Ik Zhang ◽  
Tokimasa Kobayashi ◽  
Gunnar Ståhl
Keyword(s):  
Pacific Ocean ◽  
Bering Sea ◽  
Yellow Sea ◽  
North Pacific ◽  
Gene Diversity ◽  
North Pacific Ocean ◽  
The Yellow Sea ◽  
Pacific Cod ◽  
Pacific Cod Gadus Macrocephalus ◽  
Gadus Macrocephalus

We examined the ocean-wide genetic population structure of Pacific cod (Gadus macrocephalus) using electrophoretically detectable population markers at 41 protein loci. Samples were collected at 11 locations extending over most of the species's range from the Yellow Sea, Korea, to Puget Sound, Washington. Seven loci (17%) were polymorphic using the 0.05 criterion of polymorphism. Sample heterozygosities ranged from 0.018 to 0.041 and averaged 0.025 (±0.013). Two major genetic groups were detected: a western North Pacific Ocean (Asian) group and an eastern North Pacific group (including Bering Sea stocks). The UPGMA Nei genetic distance, D, (based on 41 loci) between samples from these two groups was 0.025, and this subdivision accounted for 18.9% of the total gene diversity. Genetic differentiation between these two groups appears to reflect the barrier effects of coastal Pleistocene glaciation. Morphological and tagging data from other studies suggest that Pacific cod are subdivided into several independent stocks. In this study, significant allele-frequency differences were detected between samples within the eastern North Pacific Ocean, the Bering Sea, and the western North Pacific Ocean, but not between stocks on a larger geographic scale. The average Nei genetic distance (based on 41 loci) between samples was only 0.0007, and a gene diversity analysis indicated that within-region differences represented only 3.1% of the total gene diversity. There was a slightly greater amount of differentiation between the Yellow Sea and the Sea of Japan (D = 0.0041), which reflects geographic isolation of the Yellow Sea stock not found in other areas. From theoretical considerations, little genetic divergence between stocks of Pacific Cod is expected because random genetic drift in large population sizes is insignificant and because migration between areas prevents genetic differentiation.

Levels and profiles of long-chain perfluoroalkyl carboxylic acids in Pacific cod from 14 sites in the North Pacific Ocean

2019 ◽  
Vol 247 ◽  
pp. 312-318 ◽  
Author(s):  
Yukiko Fujii ◽  
Hayato Tuda ◽  
Yoshihisa Kato ◽  
Osamu Kimura ◽  
Tetsuya Endo ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Carboxylic Acids ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Pacific Cod ◽  
The North ◽  
The North Pacific ◽  
Long Chain

scholarly journals Neural Network Approach to Retrieving Ocean Subsurface Temperatures from Surface Parameters Observed by Satellites

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 388
Author(s):  
Hao Cheng ◽  
Liang Sun ◽  
Jiagen Li
Keyword(s):  
Neural Network ◽  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Sea Surface ◽  
Satellite Measurements ◽  
Surface Parameters ◽  
The North ◽  
The North Pacific ◽  
Bpnn Model

The extraction of physical information about the subsurface ocean from surface information obtained from satellite measurements is both important and challenging. We introduce a back-propagation neural network (BPNN) method to determine the subsurface temperature of the North Pacific Ocean by selecting the optimum input combination of sea surface parameters obtained from satellite measurements. In addition to sea surface height (SSH), sea surface temperature (SST), sea surface salinity (SSS) and sea surface wind (SSW), we also included the sea surface velocity (SSV) as a new component in our study. This allowed us to partially resolve the non-linear subsurface dynamics associated with advection, which improved the estimated results, especially in regions with strong currents. The accuracy of the estimated results was verified with reprocessed observational datasets. Our results show that the BPNN model can accurately estimate the subsurface (upper 1000 m) temperature of the North Pacific Ocean. The corresponding mean square errors were 0.868 and 0.802 using four (SSH, SST, SSS and SSW) and five (SSH, SST, SSS, SSW and SSV) input parameters and the average coefficients of determination were 0.952 and 0.967, respectively. The input of the SSV in addition to the SSH, SST, SSS and SSW therefore has a positive impact on the BPNN model and helps to improve the accuracy of the estimation. This study provides important technical support for retrieving thermal information about the ocean interior from surface satellite remote sensing observations, which will help to expand the scope of satellite measurements of the ocean.

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