being taken incidentally in commercial fisheries in the Gulf of 

 Mexico raise serious questions about the validity of the assump- 

 tions upon which live-capture quotas presently are based. In the 

 Commission's opinion, if the uncertainties cannot be resolved, 

 the Service will not be able to justify authorizing any live- 

 captures and removals in or near management units where inci- 

 dental take may be occurring. In this regard, the Commission 

 suggested that the Service should provide: (1) an assessment of 

 the types and levels of commercial fisheries in and near each of 

 the bottlenose dolphin management units currently in place; 

 (2) an assessment of the best available information concerning 

 the levels of incidental take in each area; (3) descriptions of 

 steps being taken or planned to obtain more reliable information 

 on the incidental take of bottlenose dolphins by fisheries in the 

 Gulf of Mexico; and (4) the estimated costs of the assessments 

 described in items 1 and 2 above. 



Gulf of California Harbor Porpoise (Phocoena sinus) 



The Gulf of California harbor porpoise is one of the 

 smallest and perhaps the rarest of all cetaceans. Its range 

 appears to be limited to the northern Gulf of California where 

 the estimated population may be as few as 50 to 100 animals. In 

 1985, the species was designated as endangered under the U.S. 

 Endangered Species Act. Major threats to its survival include 

 incidental take in various net fisheries and degradation of 

 habitat as a result agricultural run-off and sewage flow into the 

 northern Gulf of California and reduction in the flow of the 

 Colorado River. 



Since 1986, researchers from the University of California, 

 Santa Cruz, have conducted annual spring surveys (February-May) 

 in the northern Gulf of California. From 1986 to 1988, a total 

 of 99 animals were sighted — 30 in 1986, 46 in 1987, and 23 in 

 1988. In September 1989, University researchers carried out an 

 aerial survey of the northern Gulf during which 13 animals were 

 sighted. Gulf harbor porpoise were found in the same areas where 

 they had been sighted during the spring surveys, indicating that 

 animals are present in the northern Gulf in the fall as well as 

 the spring even though water temperatures may be 3 degrees F 

 warmer in the fall. 



As noted above, incidental take in fisheries is a major 

 threat to the species. The fishery of greatest concern is the 

 gillnet fishery for totoaba ( Totoaba macdonaldi ) , which operated 

 from the late 1940s until 1975 when it was closed by the Mexican 

 Government to allow recovery of the fish stock. In the spring of 

 1985, the Mexican Government conducted experimental fishing oper- 

 ations to assess the status of the totoaba stock in the upper 

 Gulf. During this experimental fishery, at least 13 harbor 

 porpoise were caught and killed. Illegal and limited experi- 



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