Effects of regional coordination of salmon louse control in reducing negative impacts of salmonid aquaculture on wild salmonids

Overview
TitleEffects of regional coordination of salmon louse control in reducing negative impacts of salmonid aquaculture on wild salmonids
AuthorsChristian Stige L, Jansen PA, Helgesen KO
TypeJournal Article
Journal NameInternational journal for parasitology
VolumeN/A
IssueN/A
Year2024
Page(s)N/A
CitationChristian Stige L, Jansen PA, Helgesen KO. Effects of regional coordination of salmon louse control in reducing negative impacts of salmonid aquaculture on wild salmonids. International journal for parasitology. 2024 Apr 10.

Abstract

Parasitic salmon lice (Lepeoptheirus salmonis) are a constraint to the sustainable growth of salmonids in open net pens, and this issue has caused production to level off in recent years in the most aquaculture-intensive areas of Norway. The maximum allowed biomass at a regional level is regulated by using the so-called "traffic light" system, where salmon louse-induced mortality of migrating wild salmon post-smolts is evaluated against set targets. As a case study, we have investigated how a specific aquaculture-intensive area can reduce its louse levels sufficiently to achieve a low impact on wild salmon. Analyses of the output from a virtual post-smolt model that uses data on the reported number of salmon lice in fish farms as key input data and estimates the salmon louse-induced mortality of wild out-migrating Atlantic salmon post-smolts, suggested that female louse abundance on the local farms must be halved in spring to reach the goal implied by the traffic light system. The outcome of a modelling scenario simulating a proposed new plan for coordinated production and fallowing proved beneficial, with an overall reduction in louse infestations and treatment efforts. The interannual variability in louse abundance in spring, however, increased for this scenario, implying unacceptably high louse abundance when many farms were in their second production year. We then combined the scenario with coordinated production with other louse control measures. Only measures that reduced the density of farmed salmonids in open cages in the study area resulted in reductions in salmon louse infestations to acceptable levels. This could be achieved either by stocking with larger fish to reduce exposure time or by reducing fish numbers, e.g. by producing in closed units.

Author Details
Additional information about authors:
Details
1Leif Christian Stige
2Peder A Jansen
3Kari O Helgesen
Properties
Additional details for this publication include:
Property NameValue
Journal CountryEngland
Publication TypeJournal Article
Language Abbreng
LanguageEnglish
CopyrightCopyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.
DOI10.1016/j.ijpara.2024.04.003
Elocation10.1016/j.ijpara.2024.04.003
PIIS0020-7519(24)00073-0
Journal AbbreviationInt J Parasitol
Publication Date2024 Apr 10
eISSN1879-0135
ISSN1879-0135
Publication ModelPrint-Electronic
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PMID: PMID:38609075