ABSTRACT

Life history and demographic parameters of a species are critical factors in understanding population vulnerability, predicting the impact of exploitation and decline, and predicting the potential for recovery (Lewison et al. 2004). As large mammals, cetaceans have long life spans, lengthy generation times, high survival rates, and extended parental investment (Evans and Stirling 2001). These traits buffer the populations against short-term impacts but also limit their ability to recover when population levels are low (Stearns 1992). The primary cause of reductions in cetacean populations has been directed fisheries or incidental bycatch. Other anthropogenic factors may contribute to reductions in population size that lead to instability and sub-optimal recovery. These include the chronic and still unknown effects of chemical and physical pollutants. For cetaceans, data on sub-clinical or sub-lethal effects on reproductive parameters are limited. Nonetheless, there is information that population density and other factors affect reproductive parameters in ways that contribute to or inhibit potential conservation and recovery of populations.