Examining recruitment paradigms under projected climate change with a global fish model

Recruitment of adults to a fishery determines the fishable population biomass and is noted for its high variability. Capturing recruitment extremes and understanding the dominant mechanisms responsible for them are important for managing fisheries in the face of climate change. Many recruitment paradigms have been postulated, such as the Match-Mismatch, Member-Vagrant, and Stage Duration hypotheses, which hold for many regional studies of specific stocks. These biophysical relationships with recruitment, however, often break down over time (e.g. with regime shifts) and/or in other systems. In addition to being regional, these studies often examine climate-mediated bottom-up processes while maintaining rather static top-down drivers like predation. It is our objective to develop a global fish model that resolves bottom-up and top-down forcings for simulating the projected effects of recruitment and population biomass from climate change scenarios. As a first approach, we develop “fish recruitment types” using a suite of life history traits that emerged from statistical analyses between individual species’ traits and stock recruitment time series metrics. We then test how recruitment of each of these fish types responds to individual recruitment paradigm drivers using both hindcasts and forecasts of the GFDL Earth System Model.