Reproductive sterility in aquaculture: A review of induction methods and an emerging approach with application to Pacific Northwest finfish species

Aquaculture is the fastest-growing food-production sector and is striving to become a long-term sustainable approach to meet the rising global demand for seafood. During the expansion and advancement of aquaculture, minimizing ecological impacts should occur concomitantly with maximizing production. Farmed fish, often genetically distinct from their natural conspecifics, may pose significant risks of genetic contamination and ecological imbalance to wild populations if they escape from aquaculture confinement. Growing reproductively sterile fish is the most effective way to genetically contain farmed fish. Atlantic salmon (Salmo salar) escape events in the ‘Pacific Northwest’ region of the United States and Canada have raised alarms over potential ecological impacts and led to legislation in Washington State phasing out the culture of non-native finfish species. Farming sterile native species such as coho salmon (Oncorhynchus kisutch) and sablefish (Anoplopoma fimbria) in the Pacific Northwest would ease public concerns and promote environmentally and economically sustainable aquaculture. Sterile fish also can mitigate the challenge of precocious maturation, a prominent issue associated with culture of salmonids and many other species, to improve somatic growth, flesh quality and fish health and welfare. Here, we review methods having potential applications for producing sterile fish and introduce our novel immersion-based technology that temporarily silences the dead end (dnd) gene using Morpholino oligonucleotides to produce sterile coho salmon and sablefish for the first time. The successful induction of sterility in these two iconic Pacific Northwest species without introducing genetic modifications would promote the use of this immersion-based sterilization technology for more aquaculture finfish worldwide.