Summer Is Coming! Tackling Ocean Warming in Atlantic Salmon Cage Farming.

Ricardo Calado,Miguel C Leal,Diana Madeira,Vasco C Mota

doi:10.3390/ani11061800

Ricardo Calado, Miguel C Leal + Show 2 more

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https://doi.org/10.3390/ani11061800

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Abstract

Simple SummaryAtlantic salmon (Salmo salar) has become a commodity worldwide. The culture of Atlantic salmon is by far the most well-developed branch of marine finfish aquaculture, with this species ranking among the top ten most highly produced in global aquaculture. While Atlantic salmon has been commonly farmed in sea cages located in colder waters (e.g., in Norway, Chile and Tasmania), these regions can experience the negative impacts of heat waves that push seawater temperature above values tolerated by this species. These climate-change-driven shifts in water temperature can be associated with mass mortality events and urgent actions are needed to cope with a changing ocean. This paper reviews the thermal limits of adult Atlantic salmon and lists the negative effects driven by heat stress. We highlight how biotechnology and the genetic diversity of wild populations may help producers to tackle this challenge. Selective breeding programs and other more advanced biotechnological solutions (e.g., gene editing) may play a key role in this quest to produce new strains of Atlantic salmon that more readily tolerate higher water temperatures, without compromising productivity and profitability.Atlantic salmon (Salmo salar) cage farming has traditionally been located at higher latitudes where cold seawater temperatures favor this practice. However, these regions can be impacted by ocean warming and heat waves that push seawater temperature beyond the thermo-tolerance limits of this species. As more mass mortality events are reported every year due to abnormal sea temperatures, the Atlantic salmon cage aquaculture industry acknowledges the need to adapt to a changing ocean. This paper reviews adult Atlantic salmon thermal tolerance limits, as well as the deleterious eco-physiological consequences of heat stress, with emphasis on how it negatively affects sea cage aquaculture production cycles. Biotechnological solutions targeting the phenotypic plasticity of Atlantic salmon and its genetic diversity, particularly that of its southernmost populations at the limit of its natural zoogeographic distribution, are discussed. Some of these solutions include selective breeding programs, which may play a key role in this quest for a more thermo-tolerant strain of Atlantic salmon that may help the cage aquaculture industry to adapt to climate uncertainties more rapidly, without compromising profitability. Omics technologies and precision breeding, along with cryopreservation breakthroughs, are also part of the available toolbox that includes other solutions that can allow cage farmers to continue to produce Atlantic salmon in the warmer waters of the oceans of tomorrow.

Highlights

Atlantic salmon (Salmo salar) ranks in the top 10 of the most produced and most valuable marine fish species in world aquaculture [1]
Another factor that threatens cage farming operations of Atlantic salmon is the occurrence of unsuitable seawater temperature, likely a consequence of ongoing climate change
While losses promoted by cold are certainly of concern and may have even been somehow neglected by the scientific community [5], the present work will only focus on the impact of warming seawater temperature

Summary

Introduction

Atlantic salmon (Salmo salar) ranks in the top 10 of the most produced and most valuable marine fish species in world aquaculture [1]. The threat posed by sea lice (Lepeophtheirus salmonis and Caligus elongatus) has long been recognized [4] and continues to be of particular concern, as these parasitic copepods continue to induce high levels of mortality that result in serious production shortfalls [3] Another factor that threatens cage farming operations of Atlantic salmon is the occurrence of unsuitable seawater temperature, likely a consequence of ongoing climate change. Cold-water regions are being increasingly impacted by climate change, with ocean warming and recurrent heat wave events being recorded in recent years [12] This scenario has been reported at farming sites in Newfoundland (Canada), resulting in major mass mortality events in salmon cage farming operations, and has raised a global awareness among multiple stakeholders to address this issue [13,14].

Adult Atlantic Salmon Thermal Tolerance and Physiological Responses to

Impacts of Heat Stress on Atlantic Salmon Cage Farming

Accessing Local Adaptation and Phenotypic Plasticity to Foster

The Role of the Salmon Breeding Industry

Findings

The Way Forward