Size-selective harvesting impacts learning and decision-making in zebrafish, Danio rerio

• Published in: Behavioral ecology 2023-07, Vol.34 (4), p.682-694
• Main Authors: Roy, Tamal, Rohr, Tabea, Arlinghaus, Robert
• Format: Article
• Language: English
• ISSN: 1045-2249; 1465-7279
• DOI: 10.1093/beheco/arad037

Abstract Size-selective harvesting common to fisheries is known to evolutionarily alter life history and behavioral traits in exploited fish populations. Changes in these traits may, in turn, modify learning and decision-making abilities through energetic trade-offs with brain investment that can vary across development or via correlations with personality traits. We examined the hypothesis of size-selection induced alteration of learning performance in three selection lines of zebrafish (Danio rerio) generated through intensive harvesting for large, small and random body-size for five generations followed by no further selection for ten generations that allowed examining evolutionarily fixed outcomes. We tested associative learning ability throughout ontogeny in fish groups using a color-discrimination paradigm with a food reward, and the propensity to make group decisions in an associative task. All selection lines showed significant associative abilities that improved across ontogeny. The large-harvested line fish showed a significantly slower associative learning speed as subadults and adults than the controls. We found no evidence of memory decay as a function of size-selection. Decision-making speed did not vary across lines, but the large-harvested line made faster decisions during the probe trial. Collectively, our results show that large size-selective harvesting evolutionarily alters associative and decision-making abilities in zebrafish, which could affect resource acquisition and survival in exploited fish populations. Selective removal of large-sized fish generation after generation (like in fisheries) was found to reduce the associative performance and increased consensus decision-making in zebrafish. This is evidence that size-selective fisheries may change the cognitive performance of exploited fish stocks. Learning and decision-making enable animals to find resources, avoid threats and adapt to changing environments. Our findings indicate the possibility of long-term consequences of size-selective harvesting on resource acquisition, which could affect survival in exploited populations.