Length-length and length-weight relationships for four small pelagic fishes in the Kuroshio-Oyashio current system

Length-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 0.98 in all species. Length-weight relationships (W-TL, W-FL, and W-SL) were also highly significant (p 0.98 in all species. This study provides a useful reference for biological studies and stock assessments of these small pelagic fishes.