Fish culling reduces tapeworm burden in Arctic charr by increasing parasite mortality rather than by reducing density‐dependent transmission

1. Two common Dibothriocephalus (formerly Diphyllobothrium) tapeworm species were significantly reduced by experimental culling of their fish host Arctic charr (Salvelinus alpinus) in a subarctic lake.
2. Between 1984 and 1991, funnel traps were used to cull ~ 35 metric tons of Arctic charr, reducing charr density by ~ 80%. As charr densities decreased, tapeworm prevalence and then intensity also declined over the following three decades, with D. dendriticus (formerly dendriticum) responding faster than D. ditremus (formerly ditremum). The two main hypotheses for how culling a host can decrease parasitism are reductions in parasite transmission due to reduced host density and reductions in parasite survival through increases in host mortality rates.
3. We found little evidence that charr density was the main driver for reduced parasite transmission. Instead, decreased survivorship in charr, initially, through fishing-induced changes in charr age structure, and later through increased ...

1. 通过在一处亚寒带湖泊中对其鱼类宿主北极红点鲑（Salvelinus alpinus）实施实验性种群剔除，两种常见的双叶槽绦虫属（Dibothriocephalus，旧称裂头绦虫属Diphyllobothrium）绦虫的种群丰度得到了显著降低。
2. 1984年至1991年间，研究人员使用漏斗陷阱共计捕获剔除约35公吨的北极红点鲑，使该种群密度下降约80%。随着红点鲑种群密度降低，绦虫的感染率与感染强度在后续三十年中逐步下降；其中树突双叶槽绦虫（D. dendriticus，旧称dendriticum）的响应速度快于双头双叶槽绦虫（D. ditremus，旧称ditremum）。关于宿主剔除可降低寄生水平的机制，目前存在两类主流假说：一是宿主密度降低导致寄生虫传播效率下降，二是宿主死亡率升高使得寄生虫存活概率降低。
3. 我们未发现足够证据表明红点鲑种群密度是寄生虫传播能力下降的主要驱动因素。与之相反，红点鲑的存活率降低最初源于捕捞活动引发的种群年龄结构改变，后续则因……