Faster growth during their first year leads to increased oxidative damage in wild European sardines

Despite major advantages associated with rapid growth, the variation in body size among individuals within a population remains remarkably large. Indeed, fast growth in itself might come at a cost in terms of oxidative stress. In the Bay of Biscay, sardines (Sardina pilchardus) face growth-related issues: body size at age 1 has declined substantially during the last decades, and sardines with higher growth during their first year have lower survival rates. We therefore tested the hypothesis that 1-yr-old sardines with larger body size exhibit higher levels of oxidative damage than their smaller conspecifics. To this end, we measured protein (protein carbonyl) and lipid (malondialdehyde) oxidative damage in dorsal muscle samples of sardines caught during five surveys conducted in the Bay of Biscay in spring and in autumn. We categorized “large” and “small” 1-yr-old sardines within each survey based on their length distribution, balancing their spatial coverage. As larger 1-yr-old sardines are more likely to be mature, which might influence the relationship between growth and oxidative damage, we included sardines’ maturity stage in our analyses. While there was no relationship between sardine body size and malondialdehyde levels, we found that larger sardines had greater protein carbonyl content compared with smaller ones. Furthermore, we found no evidence for the effect of maturity stage on either protein carbonyl or malondialdehyde levels. Overall, the greater accumulation of protein oxidative damage in larger sardines, regardless of their maturity stage, supports the hypothesis that faster growth might indeed lead to an oxidative cost in this wild fish species.