Keskiviikko 8.7.2020 klo 14:27 - Mikko Nikinmaa
In an effort to introduce some physiological realism to stock assessments, Hänsel et al. (Ocean warming and acidification may drag down the commercial Arctic cod fishery by 2100; PLOS ONE, https://doi.org/10.1371/journal.pone.0231589 April 22, 2020) have modelled how some factors caused by temperature increase and ocean acidification affect traditional stock modelling of cod. Although at crude level (e.g. not taking into account any effects of aquatic pollution), the study gives sobering views. While up to the present an increase in temperature has been beneficial for recruitment, the future looks gloomier. Because of the improved recruitment until the bottom temperature reaches +5oC, cod stocks have actually increased with temperature increase. However, now the bottom temperature in most cod fisheries areas is beginning to be above that temperature, whereby further temperature increase causes reduced recruitment. Also, ocean acidification reduces recruitment. The modelling suggests that because of temperature increase and ocean acidification, cod catches, which could at present be sustainable, lead to rapid loss of cod populations by 2100.
The predictions by Hänsel et al give a very strong reason, why understanding the physiology of fisheries species is imperative for planning sustainable fisheries.