Environment‐Recruitment Relationships May Be Shadows of Other Life‐History Processes

Abstract

Despite over a century of fisheries research focused on identifying environment‐recruitment relationships, robust and long‐standing relationships remain elusive, and the prevalence of ephemeral relationships has raised doubts about their utility for explaining recruitment. However, what if these relationships are shadows of other life‐history processes? To explore this question, we simulated populations where the environment affects natural mortality, a life‐history process often assumed to be constant, to determine whether spurious environment‐recruitment relationships arise. Specifically, we produced a series of simulations in which the environment affects only one life‐history process, while estimation models were misspecified with respect to which process was environmentally driven. Our simulations show that misspecified models consistently produce false detections of environmental effects on recruitment when the environment affects only natural mortality. These results indicate that previously identified environment‐recruitment relationships that later broke down may have been artifacts of environmental effects acting on other life‐history processes that were assumed to be constant. Focusing exclusively on recruitment may therefore obscure the true pathways through which environmental variability influences population dynamics. Ultimately, sound scientific advice in the face of marine ecosystem complexity requires hypothesis driven model comparisons and transparent model assumptions.