Phase transitions in marine fish recruitment processes

There has been a recent resurgence of interest in fisheries recruitment as a dynamic and complex process that is integrated over several life stages, with a variety of factors acting across scales to initiate, modulate, and constrain population abundance and variability. In this paper, we review the theory of recruitment phase transitions using a marine fisheries perspective. We propose that transitions in recruitment are dependent upon the balance of activating and constraining processes of recruitment control, and we highlight fundamental differences in recruitment transitions precipitated by climate events, those related to community alterations, and those manifested by fishery practices (though each is not necessarily mutually exclusive). We maintain that the emergent properties of fisheries populations post-phase transition are contingent upon their histories, their differing initial states, the degree of food web complexity, interaction strengths among interspecifics, and contrasting external forcing, any or all of which may be dissimilar between one regime and another. We suggest that it may be challenging to forecast recruitment phase transitions, though we encourage efforts to determine whether there are unifying relationships that govern recruitment dynamics.