Estimating sea lice infestation pressure on salmon farms: Comparing different methods using multivariate state-space...

Area of Science:

• Aquaculture
• Parasitology
• Ecology

Background:

• Sea lice are significant ectoparasites impacting Atlantic salmon farming.
• Infestation originates from internal and external sources, necessitating effective quantification methods.

Purpose of the Study:

• To review and compare five methods for quantifying sea lice infestation pressure.
• To model the effects of internal infestation pressure (IIP) and external infestation pressure (EIP) on salmon farms.

Main Methods:

• Utilized sea lice data from 20 farms in the Bay of Fundy, New Brunswick.
• Employed a multivariate state-space model to estimate IIP and EIP, considering unique or common parameters across production cycles.
• Included predictive variables like water temperature and sea lice treatments.

Main Results:

• Models incorporating only EIP demonstrated superior explanatory power compared to those with only IIP.
• Models with unique IIP and EIP parameters across all cycles generally yielded the best model fit.
• The fixed lag method for calculating infestation pressure exhibited the highest predictive performance among the evaluated methods.

Conclusions:

• External infestation pressure is a more significant driver of sea lice dynamics than internal pressure in this context.
• A simplified, fixed lag approach offers robust predictive capabilities for sea lice management.
• Findings support improved management strategies for sea lice in Atlantic salmon aquaculture.