Withdrawn article

The Institute of Marine Research has identified an error in the statistical analysis that affects the main results of a peer-reviewed article published in Aquaculture. The article is therefore being withdrawn.

The article, entitled “Long term effects of smolt production strategy and early seawater phase rearing environment on mortality, growth, sexual maturation, and vertebra deformities in farmed Atlantic salmon (Salmo salar L.)” (Aquaculture 569), examined the effects of different smoltification strategies and early seawater phases on growth, mortality, deformities, and sexual maturation in salmon.

In the original analysis, a higher proportion of sexual maturation was reported in one of the treatment groups. A new statistical review of the same data shows that this difference is not statistically significant. This means that the study’s main finding regarding differences in sexual maturation cannot be upheld, and conclusions based on this effect are therefore not valid.

The study compared the use of photoperiod regulation with a feed-based strategy (SuperSmolt FeedOnly), combined with different timings for transfer to seawater. The fish were subsequently kept in sea cages under natural light and temperature conditions. The published article also discussed differences in fish welfare between the treatment groups. These welfare assessments were largely linked to observed differences in sexual maturation. As there are no statistically significant differences between the groups, there is no basis for concluding that there are systematic differences in fish welfare related to sexual maturation between the strategies studied.

The study has been used as a reference in other publications assessing the effects of smolt strategies. The Institute of Marine Research will follow up relevant work to ensure that interpretations and conclusions are consistent with the updated results.

The Institute of Marine Research has submitted a formal request to the journal to withdraw the article.