MARINE MAMMAL COMMISSION — Annual Report for 1991 



A variety of techniques have since been tried to 

 eliminate such interactions. Fishermen have tried 

 acoustic harassment (fi.g., "bang pipes" and seal 

 bombs) and working in teams with vessels alternately 

 retrieving lines. None of the approaches, however, 

 has been effective. 



Fishermen also tried large explosive charges and 

 shooting whales. Until the mid-1980s, such measures 

 were permissible under the Marine Mammal Protec- 

 tion Act's incidental take permits for commercial 

 fishermen to allow them to protect gear, catch, or 

 human safety. The results were apparently mixed, 

 providing fishermen only temporary relief at best. In 

 this regard, studies of killer whaJe pods in Prince 

 William Sound between 1985 and 1986 documented at 

 least eight gunshot wounds and a high annual mortali- 

 ty (more than seven percent) in one pod known to 

 interact with fishing operations. In response, in July 

 1986, the National Marine Fisheries Service amended 

 incidental take permits to prohibit the use of explo- 

 sives on or the shooting of any cetacean as a way to 

 prevent interactions with fishing gear or catch. 



Interactions between whales and longline fishing in 

 Prince William Sound and along the Aleutian Islands 

 have continued, and recent reports indicate that whales 

 sometimes take halibut and Pacific cod from longlines 

 in Alaska waters. 



As noted in Chapter VII, killer whales also may 

 have been affected by die Exxon Valdez oil spill. In 

 one Prince William Sound pod, six animals, known to 

 have been in the pod a few months before the spill, 

 had disappeared when observers documented pod 

 composition a few weeks after the spill. Another 

 seven animals disappeared from the pod the following 

 year. 



Also, as noted in Chapter VII, populations of some 

 marine mammals that serve as prey for killer whales 

 have declined greatly in parts of Alaska. It is uncer- 

 tain what effect this may be having on killer whale 

 predator-prey relationships or population dynamics. 

 However, recent shifts in killer whale distribution and 

 behavior in some regions, such as Bristol Bay, have 

 been noted and may be due, at least partially, to these 

 changes. 



In view of these issues and the need to consider 

 what further actions, if any, should be taken to 

 address research and management needs regarding 

 killer whales in Alaska, the Commission contracted in 

 1991 for a study to develop a species account with 

 research and management recommendations on killer 

 whales. The report will be added to the series of 

 Commission-sponsored species reports on Alaska 

 marine mammals (see Appendix B, Lentfer 1988). 

 The report on killer whales is expected to be complet- 

 ed in the spring of 1992, at which time the Commis- 

 sion, in consultation with its Committee of Scientific 

 Advisors, will consider a range of recommendations 

 that may be appropriate to make to the National 

 Marine Fisheries Service or other Federal agencies. 



Gulf of California Harbor Porpoise 

 {Phocoena sinus) 



The endangered Gulf of California harbor por- 

 poise, or vaquita, is found only in the northern Gulf 

 of California in northwest Mexico. It is one of the 

 smallest, rarest, and least known of all cetaceans. 

 The species was first described taxonomically in 1958. 

 Prior to 1984, it was known from only 20 confirmed 

 reports. Between 1986 and 1989, aerial and boat 

 surveys by researchers from the University of Califor- 

 nia at Santa Cruz sighted 110 animals (although a 

 number of these may have been resightings). To date, 

 no reliable population estimates exist. Given so few 

 sightings, the species may number no more than a few 

 hundred individuals. 



As noted in previous Annual Reports, the Com- 

 mission has encouraged and supported vaquita re- 

 search and conservation efforts. In 1976 and again in 

 1979, the Conraiission provided funding for surveys 

 to determine the distribution of the species (see 

 Appendix B, Wells et al. 1981). In the mid-1980s, 

 the Commission provided support to locate the re- 

 mains of dead animals along the shores of the north- 

 em Gulf of California and to train Mexican students 

 to identify, collect, and prepare museum specimens of 

 the species. In 1987, the Commission supported a 

 smdy of environmental contaminants present in 

 blubber samples of vaquitas incidentally caught and 

 killed in fishing gear. The results of this study 



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