suggest that the species' range is limited to the northern 

 third of the Gulf. 



Researchers from the University of California, Santa 

 Cruz, conducted boat surveys in the northern Gulf of California 

 in the spring of 1986, 1987, and 1988. During these surveys, 

 a total of 99 Gulf of California harbor porpoise were seen -- 

 30 in 1986, 46 in 1987, and 23 in 1988. These surveys covered 

 much of the known range of the species and, based upon the 

 1986 sighting data, the National Marine Fisheries Service 

 estimated that the minimum population could number as few as 

 50 to 100 individuals. 



The major threat to the species appears to be incidental 

 take in the gill net fishery for totoaba (Totoaba macdonaldi ) . 

 This fishery operated in the Gulf of California from the late 

 1940s to 1975 when it was closed by the Mexican Government to 

 protect the fish. In the spring of 1985, the Mexican Government 

 conducted experimental fishing operations to assess the status 

 of the totoaba stock in the upper Gulf. During this experi- 

 mental fishery, at least 13 harbor porpoise were caught and 

 killed. Illegal and limited experimental fishing continued 

 in the spring of 1986 and 1987, and at least a few porpoise were 

 taken. The fishery remains closed, but the closure is difficult 

 to enforce and some illegal fishing and incidental take of 

 harbor porpoise continue to occur. 



Habitat degradation and destruction also may be affecting 

 the Gulf of California harbor porpoise. Dams and water projects 

 on the Colorado River in the southwestern United States have 

 reduced the outflow of the river into the Gulf of California. 

 This may have reduced nutrient input and biological productivity 

 in the Gulf, including reduction of species upon which harbor 

 porpoise depend for food. Also, exploratory drilling for oil 

 and gas has begun in the northern Gulf, raising the possibility 

 of future development, disturbance, oil spills, and other 

 types of environmental contamination. 



In addition, run-off from farms and roads in the northern 

 Gulf of California drainage system may be introducing 

 significant guantities of pesticides and other chlorinated 

 hydrocarbon contaminants. Commission- funded analysis of 

 blubber samples from 8 of the 13 porpoise recovered from gill 

 nets in 1985, however, revealed generally lower levels of 

 these contaminants than have been found in cetaceans in many 

 other areas. This suggests that at least chlorinated 

 hydrocarbons presently may not pose a significant threat to 

 the species. 



Because of its limited distribution, small numbers, and 

 vulnerability to gill net fisheries and other human activities, 

 the National Marine Fisheries Service, in January 1985, 



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