Breeding fish to better withstand climate change

Petuna Aquaculture is spearheading a ground-breaking research program designed to breed physically advanced Atlantic salmon and rainbow trout which have the ability to withstand the impact of climate change on sea temperature and oxygen levels.

Posted on October 23, 2019

The program is based on the principle of selective breeding, which is an age-old practice used by farmers down through the centuries. Today, however, we have the benefit of vastly improved breeding techniques, hi-tech equipment, sophisticated data software and team of specialists, including Dr Gianluca Amoroso and Rene Contreras, all of which enables us to be far more precise in the breeding process.

Dr Amoroso, who holds a PhD from the University of Tasmania, has been conducting this vital research for Petuna over the past two years.

What started as part of a Fisheries Research and Development Corporation project, now has been taken to a commercial level under the supervision of Rene Contreras, Petuna’s Manager Freshwater Operations, and one of the most experienced professionals in the area of aquaculture breeding and reproduction. During this time, massive amounts of data from carefully designed trials has been collected and evaluated. While progress has been very pleasing to date, the first eggs with genetic gain are due to arrive with the next spawning in 2020.

Petuna’s decision to embark on this breeding program was prompted by the environmental challenges we continue to face across our marine grow-out sites. These include low salinity, low oxygen and elevated summer temperatures. The aim is to breed fish that can happily thrive in our sea farms under a range of different conditions. This is an important objective as we venture further out to sea with our farms and as prevailing weather conditions continue to be affected by climate change.

This sort of challenge is not peculiar to the aquaculture industry. It affects all types of primary production from fruit growers and livestock producers to beekeepers and viticulturalists. And as weather patterns become increasingly extreme, the need to take counter measures becomes more urgent.

Of course, Atlantic salmon in Tasmania have always had a higher temperature tolerance than those in the northern hemisphere. Furthermore, recent analyses show that Petuna’s genetics are now not only different from those of fish from other parts of the world, but from those of other Tasmanian producers. This achievement is a major break-through given our sea farms are susceptible to elevated water temperatures in summer, which can be problematic for salmon despite their natural hardiness.

The process used in the selective breeding of Atlantic salmon and rainbow trout follows much the same basic rules as that used in breeding superior livestock such as sheep and cattle.

During spawning, we select the best performing fish with the most desirable traits. We then create 160 crosses which will produce different families of fish. From these families we gather genetic data, which is stored and analysed by UK firm, Xelect, which holds aquaculture DNA information from more than 20 countries.

An evaluation group, which fully represents all the afore mentioned families, is then chosen and sent out to the marine grow-out sites, while the rest of the fish remain in the hatchery to become brood stock.

Repeated evaluations are then undertaken in the marine grow-out sites as well as at our Devonport processing factory from which we identify the outstanding performers with the best traits. Armed with this information, we can produce fish with the genetic merits we are seeking by spawning from the fish held in the hatchery.

Based on an enormous store of data which has been assessed in great detail, we now realise that many families are already performing better than we had expected. Not surprisingly, the best performers are also those with higher thermal tolerance. This is good news for us as producers of fine salmon and trout. It is also very good for the welfare of the fish themselves as we are giving them the ability to better withstand uncomfortable variations in sea conditions, which at their worst, can cause mortalities.

Petuna is proud of this important research and development program, which holds enormous significance for the entire industry in Tasmania, especially as seasonal weather conditions continue to change and as the industry pushes further out to sea.

The program also provides a pathway to raising even further the quality of our produce. Tasmanian grown Atlantic salmon and ocean trout are already recognised internationally as amongst the very finest in the world. However, we must continue to strive for a level of excellence which will ensure we maintain our competitive edge.

Ruben Alvarez, who has held senior positions in aquaculture across three continents, is CEO of Petuna Aquaculture.

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