Integrating life-history and reproductive success data to examine potential relationships with organochlorine compounds for bottlenose dolphins (Tursiops truncatus) in Sarasota Bay, Florida

For the current study, 47 blubber samples collected during June 2000 and 2001 were analyzed for PCB concentrations of 22 congeners relative to life-history factors and reproductive success. Prior to sexual maturity, males and females exhibited similar concentrations of about 15-50 ppm. Classical patterns of accumulation with age were identified in males, but not in females. Subsequently, males accumulated higher concentrations of PCBs through their lives (>100 ppm), whereas females begin to depurate with their first calf, reaching a balance between contaminant intake and lactational loss (<15 ppm). In primiparous females, PCB concentrations in blubber and plasma and the rates of first-born calf mortality were both high. First-born calves had higher concentrations than subsequent calves of similar age (>25 vs.<25 ppm). Maternal burdens were lower early in lactation and increased as calves approached nutritional independence. Empirical data were generally consistent with a published theoretical risk assessment and supported the need for incorporation of threats from indirect anthropogenic impacts such as environmental pollutants into species management plans. Long-term observational monitoring and periodic biological sampling provide a powerful, non-lethal approach to understanding relationships between organochlorine residue concentrations in tissues and reproductive parameters for coastal dolphins.