Marine ecosystem models predict a decline in fish production with anthropogenic ocean warming, but how fish production equilibrates to warming on longer timescales is unclear. We report a positive nonlinear correlation between ocean temperature and pelagic fish production during the extreme global warmth of the Early Paleogene Period (62-46 million years ago [Ma]). Using data-constrained modeling, we find that temperature-driven increases in trophic transfer efficiency (the fraction of production passed up trophic levels) and primary production can account for the observed increase in fish production, while changes in predator-prey interactions cannot. These data provide new insight into upper-trophic-level processes constrained from the geological record, suggesting that long-term warming may support more productive food webs in subtropical pelagic ecosystems.
Fish production is predicted to decrease with anthropogenic global warming. Here the authors analyse fish fossil assemblages from 62–46 My old deep-sea sediments and instead find a positive correlation between fish production and ocean temperature over geological timescales, which a data-constrained model explains in terms of trophic transfer efficiency and primary production.