Due to the difficulties and limitations associated with field sampling of marine mammals, quantitative surveys on their parasites are still scarce in Japan. We here report the infection statuses of intestinal parasites in harbor porpoises (n = 34) and Dall's porpoises (n = 10), bycaught between 2014 and 2018 by a bottom set-net fishery in the northern part of the Nemuro Strait, Japan. Necropsies of the harbor porpoises recovered one digenean, Synthesium nipponicum, and two acanthocephalans, Corynosoma sp. and Bolbosoma sp.; no infection was observed in the Dall's porpoises. The dominant parasites were Corynosoma sp. and S. nipponicum, with a prevalence of 73.53 and 64.71% and a mean abundance of 43.88 and 7.38 individuals, respectively. Although the two porpoise-species have a sympatric distribution in this narrow strait, the findings support the existence of trophic-link dependences, which can differentially affect vulnerability to these parasites.

由于与海洋哺乳动物的野外采样有关的困难和局限性，在日本仍缺乏对其寄生虫的定量调查。我们在此报告了 2014年至2018年之间在日本根室海峡北部的一个底部固定网捕捞所捕获的港口海豚（n  = 34）和达尔海豚（n = 10）中肠道寄生虫的感染状况。港口海豚的尸体解剖发现了一种双基因动物nipponicum和两种棘头动物Corynosoma sp。和Bolbosoma sp .；在Dall的海豚中未观察到感染。主要寄生虫是Corynosoma sp。和小号。忍冬，患病率分别为73.53％和64.71％，平均丰度分别为43.88和7.38个人。尽管这两种海豚物种在这个狭窄的海峡中具有同胞分布，但是这些发现支持了营养纽带依赖性的存在，这可以不同地影响对这些寄生虫的脆弱性。