Incorporating thermal niche to benefit understanding climate‐induced biological variability in small pelagic fishes in the Kuroshio ecosystem

SummaryLength–length relationships and length–weight relationships were estimated for four small pelagic fishes (Japanese sardine Sardinops melanostictus, Japanese anchovy Engraulis japonicus, chub mackerel Scomber japonicus, and spotted mackerel Scomber australasicus) in the Kuroshio–Oyashio current system. Fish samples were collected from surface–midwater trawl surveys and commercial purse-seine fisheries between September and October of 2020 in the western North Pacific. Total length (TL), fork length (FL), and standard length (SL) were measured to 0.01 cm, and whole body weight (W) was measured to the nearest 0.01 g for each individual. All length–length relationships (TL–FL, TL–SL, and FL–SL) were highly significant (p < 0.0001), with r2 > 0.98 in all species. Length–weight relationships (W–TL, W–FL, and W–SL) were also highly significant (p < 0.0001), with r2 > 0.98 in all species. This study provides a useful reference for biological studies and stock assessments of these small pelagic fishes.

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Length–length and Length–weight Relationships for Four Dominant Small Pelagic Fishes in the Kuroshio–Oyashio Current System

Thalassas An International Journal of Marine Sciences ◽

10.1007/s41208-021-00300-9 ◽

2021 ◽

Author(s):

Sho Furuichi ◽

Yasuhiro Kamimura ◽

Ryuji Yukami

Keyword(s):

Current System ◽

Pelagic Fishes ◽

Oyashio Current ◽

The Kuroshio

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Long-Term and Short-Term Fluctuations in the Catches of Coastal Pelagic Fisheries Around Japan

Journal of the Fisheries Research Board of Canada ◽

10.1139/f73-370 ◽

1973 ◽

Vol 30 (12) ◽

pp. 2361-2367 ◽

Cited By ~ 2

Author(s):

F. Nagasaki

Keyword(s):

Large Scale ◽

Kuroshio Current ◽

Individual Species ◽

Short Term ◽

Intermediate Period ◽

Pelagic Fishes ◽

Consistent Trend ◽

Scale Fluctuation ◽

The Kuroshio

Although the total landings of coastal pelagic fishes around Japan have been fairly stable for 10 years, the catch of individual species has shown violent fluctuations. The catch of Hokkaido herring and the sardine is decreasing and shows no signs of recovery. The catch of saury has also decreased sharply since 1960, but that of mackerel has increased substantially. There are big yearly fluctuations in the landings of squid, horse-mackerel, and anchovy, but no consistent trend either way has been shown. Apparently the great variations in stock abundance relate to the hydrographic complex in the waters around Japan. As most of the important coastal pelagic fishes spawn and spend their early life in the area of the continental shelf of the southern half of the Japanese islands, the location and the strength of the Kuroshio current play an important role in the ever-changing environmental conditions. Although the causes of these fluctuations are largely unknown, they can be classified as long, intermediate and short-term. The large-scale fluctuation over a long term, as in the case of the Hokkaido herring and the sardine, may possibly be due to evacuation of the main spawning grounds. The intermediate period of fluctuation is caused by the degree of survival of the young. A variety of causes must be responsible for the short-term fluctuation, including survival, for which there is no consistent trend, and the effect of the Kuroshio current on the distribution of the young fish.

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