摘要:

Abstract:A new method, the “dynamic response method,” was developed (DeMaster et al. 1982) in an attempt to use time series data on relative population sizes to satisfy the requirements of the Marine Mammal Protection Act of 1972 for maintaining an “optimum sustainable population” of marine mammals. Three methods of implementing this approach were studied, using a computer simulation of stochastic population growth with density‐dependence operating on first‐year survival in the form of a generalized‐logistic function. Methods developed by Gerrodette (1988) and Boveng et al. (1988) appeared to be less sensitive than desirable when used with the simulated population data. The third method, developed in this study, offers better protection against “Type II error” (failing to identify populations in the optimum sustainable population range), particularly when combined with Gerrodette'

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00404.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:This is the first report of recordings of sounds from the pygmy right whale,Caperea marginata. The recordings were obtained in the presence of a juvenile in the harbor at Portland, on the southeastern corner of the Australian continent. Only one type of sound was heard‐a short thump‐like pulse or tone burst with a downsweep in frequency and decaying amplitude, with most energy between 60 and 120 Hz. The pulses occurred predominantly in pairs and once in a trio. The sounds are simpler than those of most baleen whales, but they show some similarity in characteristics. Source levels are in the lower end of the range determined for other species. There was no evidence to indicate the purpose of these sou

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00405.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:The first range‐wide survey of Steller (northern) sea lions (Eumetopias jubatus) was completed in 1989 with a total of 68,094 adult and juvenile (nonpup) Steller sea lions counted. This total count includes 10,000 in Russia (15% of the range‐wide count), 47,960 in Alaska (70%), 6,109 in British Columbia (9%), 2,261 in Oregon (3%), and 1,764 in California (3%). A range‐wide pup count was not obtained. We estimated the 1989 world population based on a calculation for total pups and obtained a range‐wide estimate of 116,000 total animals, or about 39–48% of the 240,000‐300,000 estimate

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00406.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Two hundred and eighty‐nine skulls of Dall's porpoises from the North Pacific Ocean, Sea of Japan, Sea of Okhotsk, and Bering Sea were investigated morphometrically. A clear pattern of geographic variation was found in overall size of the skull. In the North Pacific, overall skull size became gradually smaller eastward from the coast of Japan to the offshore eastern Pacific, and it became larger again off the coast of California. Specimens from the Sea of Japan‐Okhotsk and Bering Sea had larger skulls than those from the central North Pacific. The distribution of primary productivity corresponds well with this pattern of geographic variation, suggesting that quantity of food might affect the overall size of Dall's porpoise skulls. By canonical discriminant analyses, about 70% (male) and 90% (female) of specimens of the Sea of Japan‐Okhotsk population were distinguished from those of other populations. This agrees with the results of genetic st

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00407.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:I studied behavior and range patterns of individual bottlenose dolphins during 1984 in the mid‐eastern Gulf of California, Mexico. Dolphin sighting rate was significantly higher in areas close to estuary mouths, 0.306 sightings per hour compared with 0.155 sightings per hour in areas distant from estuary mouths. Dolphins used these estuarine areas to feed; 61% of all behavior observed near estuaries was feeding as compared with 23% elsewhere. Traveling comprised 61% of all behavior observed in areas distant from estuary mouths. Estuaries are sites of large concentrations of nutrients which support great numbers of filter‐feeding zooplankton and fish. Bottlenose dolphins may specialize on esmarine prey, or they may feed in estuarine areas simply because of the abundance of potential prey that these systems support. In either case, data on relative numbers, distribution patterns, behavior and diet indicate that this is a general trend in habitat use for many coastal populations of this species in the Pacific and Atlantic.Ranges of a few individuals spanned a minimum of 65 km of coastline, and animals were not permanent residents of a monitored bay. In contrast, dolphins off the coast of Sarasota, Florida, have been reported to be year‐round residents with smaller ranges. This difference in degree of site fidelity may be related to habitat differences. The west coast of Florida is dotted with numerous and large estuarine systems which may host permanent prey populations and support resident groups of dolphins. The Gulf of California coastline contains few estuaries; most are small and perhaps support prey resources which are ephemeral, requiring dolphins to range over larger distances in search of

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00408.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Several species of cetaceans naturally slough visible quantities of skin. We have investigated the prospect of using this material as a viable alternative to the use of biopsy darts for the collection of samples for molecular analysis. Pieces of skin were collected from free‐ranging individuals of three different species—the humpback (Megaptera novaeangliae), sperm (Physeter macrocephalus) and right whales (Eubalaena glacialis). DNA was extracted from 11 pieces of sloughed skin and DNA “fingerprint” profiles prepared. All samples contained DNA of both sufficient quality and quantity for genetic analysis. The applicability of this approach is discussed generally in relation to answering problems about the population structure and breeding systems of ce

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00409.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00410.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00411.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00412.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1992.tb00413.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY