UNIT 23 



PACIFIC MARINE MAMMALS 



102 



INTRODUCTION 



Marine mammals are managed under the 

 Marine Mammal Protection Act (MMPA) of 

 1972 and the Endangered Species Act 

 (ESA) of 1973. Other responsibilities are 

 addressed in the Magnuson Fishery Con- 

 servation and Management Act (MFCMA) 



of 1976, which extends the jurisdiction of 

 the MMPA throughout the U.S. EEZ, and 

 the Whale Conservation Act of 1 976, which 

 was intended to further aid the recovery of 

 whales. 



SPECIES AND STATUS 



Forty-two species of marine mammals 

 occur in U.S. Pacific waters (31 whales, 

 dolphins, and porpoises, and 1 1 species of 

 seals and sea lions). Fourteen are com- 

 monly seen along the coast (gray whale, 

 bottlenose dolphin, harbor seal, and oth- 

 ers), whereas the 28 others frequent off- 

 shore or remote island waters (beaked 

 whales, ribbon seal, Hawaiian monk seal, 

 and others), or are severely reduced in 



numbers and thus seldom seen (blue 

 whale, right whale, Guadalupe fur seal, for 

 example). 



Table 23-1 shows what is (and is not) 

 known about the status and trends of sev- 

 eral Pacific marine mammals. Brief 

 summaries below for selected species give 

 additional data on distribution, current and 

 historical abundance, and population 

 trends. 



Table 23-1— Stock assessments 

 of selected marine mammals in 

 U.S. North Pacific Ocean waters. 



Species 

 and area 



Abundance Status 



Trends 



Status in U.S. 

 waters 



Bowhead whale 

 (W. Arctic) 



Gray whale 

 (N.E. Pacific) 



7,500 

 (6,400-9.200)' 



21,113 

 (19.737-22.489) 1 



Humpback whale 1,398-2,040 



(E. Pacific) 



Harbor porpoise 35,000' 



(Washington/Oregon) 



Hawaiian monk seal 1,500 



Northern fur seal 

 (Pribilof Islands) 



Steller sea lion 

 (N. Pacific) 



871,000 



42,000 



California sea lion 87,000 



(California-Washington) 



Current population size 

 is 40.9% (38.0-42.0%) 

 of the 1848 population size. 



Fully recovered and now equal 

 or more abundant than 

 known since 1846. 



Probably less than 1 5% of 

 abundance prior to 1850. 



Unknown 



Unknown. Small remnant, 

 monotypic species. 



Current level is <40% of the 

 population in the mid-1950's. 



Currently 22% of size 

 in the late 1950's. 



Unknown, but believed to 

 be at or above the level of 

 maximum net production. 



Increasing at 3.1% 



(0.1-6.2%)/year, 



1978-88 



Increasing at 3.2% 

 (2.3-4.2%)/year 

 since 1 968 



Unknown 



Unknown 



Unknown. Pup 

 counts declining. 



No significant trend 

 since 1983 on St. Paul; 

 declining at 6%/year 

 on St. George. 



Declining at 4.2%/year, 

 1960-90. 



Increasing at 6%/year, 

 1975-86 



Increasing 7 



Declining (1986-90) 

 based on preliminary 

 analyses of observer data. 

 Unknown 



Stable (1986-90) based 



on analysis of observer 



data. 



Unknown 



Unknown 



Unknown 



Unknown 



Unknown 



Unknown 



95% confidence interval. 



! E = listed under the Endangered Species Act as endangered 

 3 D = listed under the Marine Mammal Protection Act as depleted 

 "T = listed under the Endangered Species Art as threatened 



