title: Effects of host migration, diversity and aquaculture on sea lice threats to Pacific salmon populations.
abstract: Animal migrations can affect disease dynamics. One consequence of migration common to marine fish and invertebrates is migratory allopatry-a period of spatial separation between adult and juvenile hosts, which is caused by host migration and which prevents parasite transmission from adult to juvenile hosts. We studied this characteristic for sea lice (Lepeophtheirus salmonis and Caligus clemensi) and pink salmon (Oncorhynchus gorbuscha) from one of the Canada's largest salmon stocks. Migratory allopatry protects juvenile salmon from L. salmonis for two to three months of early marine life (2-3% prevalence). In contrast, host diversity facilitates access for C. clemensi to juvenile salmon (8-20% prevalence) but infections appear ephemeral. Aquaculture can augment host abundance and diversity and increase parasite exposure of wild juvenile fish. An empirically parametrized model shows high sensitivity of salmon populations to increased L. salmonis exposure, predicting population collapse at one to five motile L. salmonis per juvenile pink salmon. These results characterize parasite threats of salmon aquaculture to wild salmon populations and show how host migration and diversity are important factors affecting parasite transmission in the oceans.
authors.affiliation: Centre for Mathematical Biology, Department of Mathematical, University of Alberta, Edmonton, Alberta, Canada T6G 2G1. mkrkosek@ualberta.ca
authors.forename: Martin
authors.initials: M
authors.lastname: Krkosek
authors.forename: Allen
authors.initials: A
authors.lastname: Gottesfeld
authors.forename: Bart
authors.initials: B
authors.lastname: Proctor
authors.forename: Dave
authors.initials: D
authors.lastname: Rolston
authors.forename: Charmaine
authors.initials: C
authors.lastname: Carr-Harris
authors.forename: Mark A
authors.initials: MA
authors.lastname: Lewis
mesh_terms: D025041:Animal Migration; D000818:Animals; D000835:Animals, Wild; D017756:Aquaculture; D033342:Copepoda / Q000502:physiology*; D017753:Ecosystem; D005393:Fish Diseases / Q000469:parasitology*; D005398:Fisheries; D008954:Models, Biological; D010140:Pacific Ocean; D010273:Parasitic Diseases, Animal / Q000469:parasitology*; D011157:Population Dynamics; D012474:Salmon / Q000469:parasitology*