(Jul Lniiit; Rcsdiiices — Manuiuils 



95 



available for 19 stocks. The recently reautho- 

 rized MMPA requires the NMFS to conduct 

 periodic assessments of marine mammal stocks 

 that occur in U.S. waters, For this reason, better 

 status and trends data are likely to become 

 available over the next few years. 



Abimdance and status data for selected 

 marine mammals are summarized in Table I 

 (Atlantic species) and Table 2 (Pacific species). 

 Trend data are mixed, but a number of conser- 

 vation success stories have come from marine 

 mammals. The bowhead and grey whales have 

 shown significant population increases, as have 

 California sea lions, the northem elephant seal, 

 harbor seals in California, Oregon, Washington, 

 and the Northeast, and the southern sea otter. 

 These increases are largely the result of prohi- 

 bition of commercial whaling by the 

 International Whaling Commission (IWCl and 

 by protection enacted under the MMPA and 

 ESA. Other marine mammal populations, such 

 as the Steller sea lion and the common dolphin 

 in the eastern tropical Pacific, are still declining. 

 Causes of decline in marine mammal popula- 

 tions include bycatch associated with commer- 

 cial fishing, illegal killings, strandings, entan- 

 glement, disease, ship strikes, altered food 

 sources, and possibly exposure to contaminants. 



Table 2. Status ol selected PacifiL ciiast species of iiianne mammals 



Population Trends 



Whales 



The eastern North Pacific stock of grey 

 whale (Eschrichtius robustus) is rising (Fig, 1 ) 

 and is one success story in species restoration. 

 The NMFS estimates that the historical popula- 

 tions of grev whales in 1896 were around 

 15,000-20"!^00b. While current population levels 

 are below the estimated carrying capacity of 

 24,000, they appear higher than historical levels 

 and represent a substantial gain. The population 

 growth rate between 1968 and 1988 was 3.3% 

 per year. After 3 years of review, on 15 June 

 1994. this species was removed from protection 

 (delisted) under the ESA, an indication of suc- 

 cessful management. 



8 20 



° rio da»a 



Species and area 



Abundance 



Status 



Trends 



Official status in des- 

 ignated U.S. waters 



Fin wliale 



Humpback whale. E 



Pacific 



Northern right wtiale 



Bowhead whale, W. 



Arctic 



Grey whale 



935 

 -1,400 



Unknown 

 7,500 



20,869(19,200- 

 22,700) 



Unknown 



Probably less than 1 5% of 



1850 population 



Unknown 



About 40% of 1848 



population size 



Recovered to tiislorical 1845 



abundance levels 



Unknown 

 Unknown 



Unknown 



Increasing at 3. 1%/yr, 



1978-88 



Increasing at 3 3%/yr, 



1968-88 



Endangered' 



Endangered" 



Endangered' 

 Endangered" 



Removed from ESA 

 listing June 1994 



Harbor porpoise 

 SE Alaska 

 W Gulf of Alaska 

 N California 

 Central California 

 Inland Washington 

 Oregon/Washington 



Hawaiian monk seal 



2,052 

 1,273 



10,000 

 3,806 

 3,298 



23,701 

 1,550 



Declined 50% since 1 950's 



Unknown, pup counts 

 declining to vanable 



Endangered' 



Fig. 1. Estimated population of grey whales, 1967-90 

 (NOAA 1994). 



'Endangered Species Act 

 "lylarine (Mammal Protection Act, 



The bowhead whale (Balaena mysiiceiiis) is 

 an endangered species that has shown a signifi- 

 cant increase since the IWC adopted new rules 

 in 1980 regulating its harvest for subsistence 

 puiposes by Native Americans (Fig. 2). The 

 total prewhaling (before the mid-1800"s) popu- 

 lation of the bowhead whale is believed to have 

 been 12,000-18,000; NMFS e.stimates that by 

 1900 it was pi'obably in the low thousands. The 

 current population of 7,500 is about 40% of its 

 estimated 1848 population level (Table 2), more 

 than 3 times the population low reached in 

 1980. The bowhead whale population has been 

 growing by about 3% per year since 1978. 



The endangered western North Atlantic pop- 

 ulation of right whales (Eiibalaemi glacialis) is 

 considered by NMFS to be the only northern 

 hemisphere right whale population with a sig- 

 nificant number of individuals, about 300-350 

 animals (Table 1). Other stocks are considered 

 virtually extinct: only five to seven sightings 

 have been made in the last 25 years. Estimates 

 of the pre- 1 8th century population are as high as 



