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

Length-length and length-weight relationships in various length measurement standards were estimated for dominant small pelagic fishes in the Kuroshio-Oyashio current system (Japanese sardine Sardinops melanostictus, Japanese anchovy Engraulis japonicus, chub mackerel Scomber japonicus, and spotted mackerel Scomber australasicus). 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 total 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 r(2) > 0.98 in all species. Length-weight relationships (W-TL, W-FL, and W-SL) were also highly significant (p < 0.0001), with r(2) > 0.98 in all species. This study provides new comprehensive information on length-length and length-weight relationships in various length measurement standards for the four small pelagic fish species. These data will be useful references for biological studies and stock assessments of these small pelagic fishes.

Automated summary

The study estimated length-length and length-weight relationships for dominant small pelagic fishes in the Kuroshio-Oyashio current system, providing comprehensive information for biological studies and stock assessments of these fish species.