Multiple-batch spawning : a risk-spreading strategy disarmed by highly intensive size-selective fishing rate

• Main Authors: Hočevar, Sara, Hutchings, Jeffrey A., Kuparinen, Anna
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 2022
• Subjects: Atlantic cod; bet-hedging; fitness; fisheries-induced evolution; multiple-batch spawning; size-selective fishing; turska; kalastus; evoluutioekologia; liikakalastus; elinkierto; lisääntymiskäyttäytyminen; atlantic cod; Gadus morhua
• Online Access: http://urn.fi/URN:NBN:fi:jyu-202209024453

Can the advantage of risk-managing life-history strategies become a disadvantage under human-induced evolution? Organisms have adapted to the variability and uncertainty of environmental conditions with a vast diversity of life-history strategies. One such evolved strategy is multiple-batch spawning, a spawning strategy common to long-lived fishes that ‘hedge their bets' by distributing the risk to their offspring on a temporal and spatial scale. The fitness benefits of this spawning strategy increase with female body size, the very trait that size-selective fishing targets. By applying an empirically and theoretically motivated eco-evolutionary mechanistic model that was parameterized for Atlantic cod (Gadus morhua), we explored how fishing intensity may alter the life-history traits and fitness of fishes that are multiple-batch spawners. Our main findings are twofold; first, the risk-spreading strategy of multiple-batch spawning is not effective against fisheries selection, because the fisheries selection favours smaller fish with a lower risk-spreading effect; and second, the ecological recovery in population size does not secure evolutionary recovery in the population size structure. The beneficial risk-spreading mechanism of the batch spawning strategy highlights the importance of recovery in the size structure of overfished stocks, from which a full recovery in the population size can follow. peerReviewed