Chlorinated hydrocarbon concentrations in the Gulf of California harbor porpoise (Phocoena sinus)

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Citation

Calambokidis, J. 1988. Chlorinated hydrocarbon concentrations in the Gulf of California harbor porpoise (Phocoena sinus). Final report for contract MM4465846-3 from the Marine Mammal Commission, Wash. D.C. 29pp.

Introduction

High concentrations of chlorinated hydrocarbon contaminants have been noted in coastal odontocetes from a number of areas (Gaskin et al. 1971, 1974, 1982, 1983, Calambokidis et al. 1984, O'Shea et al. 1980, Taruski et al. 1975). Many of these contaminant are stable, tend to concentrate up food chains, and are lipophillic accumulating in fatty tissues such as blubber. Coastal odontocetes occurring in nearshore waters near industrial or agricultural areas are particularly susceptible to accumulation of these contaminants. Impacts of chlorinated hydrocarbons on wild marine mammal populations have been hard to demonstrate conclusively because of the complexity of proving such a relationship in an uncontrolled environment. A number of studies have documented apparent relationships between chlorinated hydrocarbons (PCBs or DDE) and reproductive difficulties in pinnipeds (Helle et al 1976a, 1976b, Gilmartin et al. 1976, Reijnders 1982a, 1982b). A recent study with captive seals has demonstrated a cause and effect relationship between reproductive failure in harbor seals and consumption of fish from a contaminated area (Reijnders 1986).

The Gulf of California harbor porpoise (Phocena sinus) also known as cochito and vaquita is restricted to the northern waters of the Gulf of California (Brownell 1983, 1986, Brownell et al. 1987). The limited range of this species and low population size underscores the importance of research on this species. A series of tissues recently became available from 13 fresh animals examined in 1985 and described in Brownell et al. (1987).

This report summarizes results of analysis for chlorinated hydrocarbon concentrations in the blubber of eight vaquita. These results will be incorporated into a publication authored by the individuals involved in the collection and analyses of these samples.

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