Warming temperatures and ectoparasitic sea lice impair internal organs in juvenile Atlantic salmon

Ke Medcalf,A Kuparinen,Ja Hutchings,Md Fast,Sc Godwin

doi:10.3354/meps13610

Abstract

Without insights into the threats affecting species across their distributions and throughout their annual cycles, effective conservation management cannot be applied. The Whenua Hou diving petrel Pelecanoides whenuahouensis (WHDP) is a Critically Endangered small seabird whose offshore habits and threats are poorly understood. We tracked WHDPs year-round in 2015/16, 2017/18, and 2018/19 using global location-sensing immersion loggers to identify offshore distribution, movements, behaviour, and overlap with commercial fishing effort. During the breeding period, WHDPs ranged from southern Aotearoa (New Zealand) to Maukahuka (Auckland Islands). After breeding, WHDPs migrated southwest towards the Polar Front south of Australia, exhibited clockwise movements, and returned to their breeding grounds via the Subantarctic Front. During the non-breeding period, WHDPs exhibited extreme aquatic behaviour and spent >95% of their time on, or under, water. The core areas used consistently during breeding and non-breeding periods warrant listing as Important Bird and Biodiversity Areas. Spatiotemporal overlap of commercial fishing effort with breeding distributions was considerable, in contrast with non-breeding distributions. Spatiotemporal management of anthropogenic activity around the breeding colony during the breeding period could help protect WHDPs, but such measures should be subjected to a structured decision-making framework. Our results illustrate the importance of year-round studies to inform conservation of marine species.

Highlights

The progression of climate change in the marine environment and the increasing global reliance on seafood-based protein necessitate assessment of their individual and combined implications for wild and farmed fish
Our top model predicted that relative to zero infestation, high louse infestation reduced %DWL by 5.7% and low infestation reduced %DWL by 2.6% (2.2−3.0%), on average (Table S3)
These findings suggest that liver energy stores and cardiac muscle performance are negatively impacted by elevated temperature and louse infestation

Summary

Introduction

The progression of climate change in the marine environment and the increasing global reliance on seafood-based protein necessitate assessment of their individual and combined implications for wild and farmed fish. Of the numerous varieties of finfish aquaculture, marine net-pen salmon farming is by far the most profitable (FAO 2018). Salmon farming is a major contributor to overall seafood production in coastal countries like Norway, the UK, Ireland, Chile, and Canada, with the sector’s global production exceeding 2.4 million t and US $17.1 billion annually (FAO 2020). Global sea surface temperatures (SSTs) have been increasing due to anthropogenic climate change, especially in the nearshore marine waters in which salmon-aquaculture facilities operate (Wong et al 2014). Since there is no barrier between the internal net-pen environment and the surrounding coastal marine ecosystem, salmon-aquaculture operations stand to be affected by ocean warming

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Conclusion