Mass mortality in marine mammals: Its implications for population dynamics and genetics

The death of tens of thousands of common seals (Phoca vitulina) around the coast of Europe in 1988 provoked wide interest in the popular press, but it also raised questions about the importance of mass mortality in the dynamics of marine mammal populations. Here, we summarize published information on the occurrence of mass mortalities among marine mammals and review the mathematical models that have been developed to investigate the role of such disasters in population dynamics. We conclude that mass mortalities may play a more important role than density-dependent factors in the dynamics of some marine mammal populations. This, in combination with recent improvements in our understanding of the structure of these populations, has important implications for their genetics and evolution.