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 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 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.

估算了黑潮—大矢流系统中的优势小中上层鱼类（日本沙丁鱼Sardinops melanostictus，日本an鱼Engraulis japonicus，鲭鱼Scomber japonicus和斑点鲭鱼Scomber australasicus）在各种长度测量标准中的长度-长度和长度-重量关系）。2020年9月至10月之间，从北太平洋西部的地表-水下拖网调查和商业性围网渔业中收集了鱼类样品。测量每个人的总长度（TL），叉子长度（FL）和标准长度（SL），并将其总体重（W）精确至0.01 g。所有的长度-长度关系（TL-FL，TL-SL和FL-SL）都非常显着（p  <0.0001）， 在所有物种中r ² > 0.98。长度与体重的关系（W–TL，W–FL和W–SL）也非常显着（p  <0.0001），r ² 在所有物种中> 0.98。这项研究为四种中上层鱼类提供了有关各种长度测量标准中长度-长度和长度-重量关系的新的综合信息。这些数据将为这些小型远洋鱼类的生物学研究和种群评估提供有用的参考。