Selection response in fish and shellfish: a review

Abstract

The aquaculture sector is significantly behind plant and farm animal production in applying selective breeding, in spite of the fact that it has been suggested that the world aquaculture production could be doubled in 13 years if breeding programmes were supplying stocks for the farmed species. It is estimated that as late as in 2010, only 8.2% of the world's total aquaculture production was based on material developed in selective breeding programmes. Reported estimates of genetic gain per generation for a key trait like growth rate average 13%, implying that the animal's potential for growth can be doubled in a time span of only six generations of selection, as demonstrated for major farmed species like Atlantic salmon and Nile tilapia. Likewise are reported genetic gains for improved disease resistance generally very high. This study offers an updated review of published estimates on genetic gains for a range of traits in aquaculture species. Results are highly encouraging and demonstrate a substantial potential for genetic improvement in aquatic productions, in particular for traits such as growth rate and resistance to diseases.

Behaviour in the toolbox to outsmart parasites and improve fish welfare in aquaculture

“…As behavioural competence reduces transmission risk (Barron et al . ), coping styles or beneficial personalities could be selectively bred to enhance resistance traits (Gjedrem & Rye ). Similar goals have previously been achieved in cattle, where tick infections were reduced through selective breeding to enhance grooming behaviours (Norval ).…”

“…In addition, personality and skin pigmentation are related in salmon (Kittilsen et al 2009), and both factors have been correlated with susceptibility to sea lice, whereby fish with fewer skin spots were more prone to stress and more likely to acquire parasites (Kittilsen et al 2012;Øverli et al 2014). As behavioural competence reduces transmission risk (Barron et al 2015), coping styles or beneficial personalities could be selectively bred to enhance resistance traits (Gjedrem & Rye 2016). Similar goals have previously been achieved in cattle, where tick infections were reduced through selective breeding to enhance grooming behaviours (Norval 1992).…”

Defining Dermo resistance phenotypes in an eastern oyster breeding population

“…Breeding for resistance is an effective tool for managing the negative impacts of disease in several aquaculture species (Gjedrem & Rye, ). Yet, before selection for resistance can be implemented in genetic improvement programmes, disease resistance phenotypes must be defined clearly and the potential for genetic variation underlying those phenotypes documented.…”

Future directions in breeding for disease resistance in aquaculture species

“…Currently, less than 10% of aquaculture production derives from selectively bred stocks (Gjedrem et al, 2012), lagging significantly behind the terrestrial animal and plant farming industries (Gjedrem et al, 2012;Yáñez et al, 2015;Robledo et al, 2017). Encouragingly, genetic gains for aquatic species are generally higher than that of terrestrial farm animals (Gjedrem et al, 2012;Nguyen, 2016;Gjedrem and Rye, 2016). However, the status of breeding programmes and the level of technology used for aquatic species production are wide-ranging, from use of wild seed stocks through to family-based selection incorporating genomic tools (Yáñez et al, 2015).…”