Abiotic and biotic factors affecting recruitment variability of walleye pollock (Theragra chalcogramma) off the Pacific coast of Hokkaido, Japan

2013 ◽  
Vol 22 (3) ◽  
pp. 193-206 ◽  
Author(s):  
Tetsuichiro Funamoto ◽  
Orio Yamamura ◽  
Tokihiro Kono ◽  
Tomonori Hamatsu ◽  
Akira Nishimura
Keyword(s):  
Pacific Coast ◽  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Biotic Factors ◽  
Factors Affecting ◽  
Walleye Pollock Theragra Chalcogramma ◽  
The Pacific ◽  
Recruitment Variability ◽  
Abiotic And Biotic Factors

scholarly journals Distribution and habitat conditions of walleye pollock Theragra chalcogramma at southern Kuril Islands

2021 ◽  
Vol 201 (2) ◽  
pp. 340-358
Author(s):  
S. L. Ovsyannikova ◽  
E. E. Ovsyannikov ◽  
Yu. V. Novikov
Keyword(s):  
Walleye Pollock ◽  
Kuril Islands ◽  
Tidal Mixing ◽  
Theragra Chalcogramma ◽  
Intermediate Water ◽  
Habitat Conditions ◽  
Walleye Pollock Theragra Chalcogramma ◽  
The Pacific ◽  
Pacific Side ◽  
Benthic Front

Data on spatial distribution and habitat conditions are presented for walleye pollock Theragra chalcogramma at southern Kuril Islands in spawning season (spring 2015) and feeding season (summer 2016). In spring, walleye pollock are distributed over the entire shelf and continental slope down to 900 m depth and occupy the upper layer on the shelf and intermediate layer at the slope with water temperature 0.1–1.5 o C. In summer, they aggregate at the depth of 200–270 m beyond the shelf in the intermediate water at the Pacific slope of Iturup Island, under the temperature of 1.3–2.9 o C. Both spatial and bathymetric migrations of pollock are minimal at the Pacific side of Iturup, but they migrate for spawning westward and southwestward to the Okhotsk Sea and slope of Small Kuril Ridge where concentrate at the benthic front between the tidal mixing zone and the Intermediate water. Seasonal redistribution of walleye pollock is accompanied with changes of size-age structure in the main aggregations.

Evidence for interaction between the seagrasses Zostera marina and Zostera japonica on the Pacific coast of Canada

1991 ◽  
Vol 69 (9) ◽  
pp. 2004-2010 ◽  
Author(s):  
Kathy M. Nomme ◽  
Paul G. Harrison
Keyword(s):  
Zostera Marina ◽  
Pacific Coast ◽  
Morphological Characters ◽  
Zostera Japonica ◽  
Factors Affecting ◽  
The Pacific ◽  
Shallow Subtidal ◽  
Clear Plastic ◽  
Abiotic And Biotic Factors ◽  
Manipulation Experiment

Experiments were undertaken to differentiate between abiotic and biotic factors affecting seagrass growth. Monospecific patches of both Zostera marina and Zostera japonica were transplanted into one shallow subtidal and three intertidal sites at Roberts Bank, British Columbia. In transplanted patches, initiated in 1988, neither Z. marina nor Z. japonica showed any consistent differences in either population growth or mean shoot length among the sites. Abiotic environmental conditions could therefore not be considered responsible for the differences observed between the natural vegetation of the respective monospecific zones and the zone of naturally mixed seagrass vegetation. In a manipulation experiment, opaque and clear plastic seagrass canopies were imposed on Z. japonica vegetation and the resulting growth was compared with treatments of a natural Z. marina canopy and removal of the natural canopy. The artificial seagrasses combined with the patch layout of the experiment did not create the shade conditions intended and may have facilitated the loss of shoots. The results were not conclusive, but there were consistently higher densities of Z. japonica in the treatment where Z. marina had been removed. Interactions between these two seagrasses in their vegetative phase may contribute to the observed differences in population and morphological characters, but the dispersal and establishment phases remain to be studied. Key words: Zostera marina, Zostera japonica, seagrass, competition, transplants, artificial seagrass.

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