Assessing heritable variation in biological control of the salmon louse by two species of cleaner fish and co-operative behaviour by their client, Atlantic salmon

现在，加拿大人消费的所有大西洋鲑鱼都是由水产养殖生产的，而且大量出口。鲑鱼虱是桡足类的一种海洋寄生物种，它通过皮肤和鳃损伤造成的库存损失对农场收入产生直接影响，这也可能增加疾病风险。历史上，通过包括区域管理和降低放养密度在内的畜牧业措施控制海虱侵扰水平。已批准使用数量有限的化学疗法，但完全依赖这些杀寄生虫剂可能导致海虱产生抗药性。该行业现在采用了一种综合有害生物管理方法来管理海虱，该方法使用了几种替代治疗方案。在欧洲，一些清洁鱼类，如圆头鱼和欧洲濑鱼，被引入海笼中，吃大西洋鲑鱼身上的虱子。在加拿大东部，块状鱼和北美濑鱼（cunner）已经被证明可以显著减少生活在海洋笼子里的鲑鱼身上的成年虱子密度。此外，一些肿块鱼家族比其他家族更有效地清除虱子，这表明清除虱子的倾向是遗传的。目前尚不清楚鲑鱼的合作行为（例如，保持静止）是否在海笼中发生过，以促进虱子的清洁，如果有，这种行为是否可遗传。用高密度SNP（单核苷酸多态性）芯片对大西洋鲑鱼进行基因分型发现，在没有清洁鱼的情况下，SNP与虱子数量减少有关。我们的提案有以下目标：1)确定用于清洗商业海笼中大西洋鲑鱼的最佳尺寸级别的容器；2)确定种群结构，检验不同种群的鱼和鱼体除虱效果的差异；3)评估鱼科和鱼科食虱行为的遗传变异；4)在有无虱清洁鱼存在的情况下进行虱挑战，看看在有无生物防治剂存在的情况下，鲑鱼科的虱数排名是否有变化。我们的工作将降低加拿大大西洋鲑鱼产业控制海虱的经济成本，并提高其可持续性。

Aquaculture now produces all the Atlantic salmon consumed by Canadians as well as a significant amount for export. The salmon louse is a marine parasitic species of copepod that has a direct impact on farm income through inventory losses caused by skin and gill damage which can also increase disease risks. Levels of sea lice infestation were historically controlled using husbandry practices including area management and lower stocking densities. A limited number of chemical therapeutants have been authorized for use but sole reliance on these parasiticides can lead to sea lice resistance. The industry has now adopted an Integrated Pest Management approach to sea lice management, which uses several alternate treatment options. In Europe, cleaner fishes such as the lumpfish and European wrasses are introduced into sea cages to eat the lice off the Atlantic salmon. In eastern Canada, the lumpfish and a North American wrasse, the cunner, have been shownto significantly reduce adult lice densities on salmon living in marine sea cages. Further some families of lumpfish are more effective lice cleaners than others suggesting lice cleaning propensity is heritable. It is unknown whether co-operative behaviour by salmon (e.g., remaining stationary) to facilitate lice cleaning ever occurs in sea cages, and if so whether the behaviour is heritable. Genotyping Atlantic salmon with high density SNP (Single Nucleotide Polymorphisms) chips has revealed SNPs associated with lower lice counts in the absence of cleaner fish. Our proposal has the following objectives: 1) determine the best size-class of cunners to use to clean Atlantic salmon in commercial sea cages; 2) determine the stock structure and examine variation in lice-cleaning performance among cunners and among lumpfish from different stocks; 3) assess heritable variation in lice eating behaviour among families of cunners and of lumpfish; 4) Conduct lice challenges with and without the lice cleaner fish present to see if there is a change in the ranking of salmon families with respect to lice counts with and without the biological control agent present. Our work will reduce the economic costs of sea lice control by the Canadian Atlantic salmon industry and increase its sustainability.