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Articles 1 - 4 of 4
Full-Text Articles in Physical Sciences and Mathematics
A Whale Of A New Species, Katherine Ralls, Robert L. Brownell Jr.
A Whale Of A New Species, Katherine Ralls, Robert L. Brownell Jr.
United States Department of Commerce: Staff Publications
Although four new species of whale have been identified since 1937, the absence of new ones for the past 28 years might be taken to mean that they had finally all been dis- covered. Not so - a new species of beaked whale, Mesoplodonperuvianus, is described by J. C. Reyes and colleagues in the latest issue of Marine Mammal Science.
Geographic Variation In Sea Otters, Enhydra Lutris, Don E. Wilson, Michael A. Bogan, Robert L. Brownell Jr., A. M. Burdin, M. K. Maminov
Geographic Variation In Sea Otters, Enhydra Lutris, Don E. Wilson, Michael A. Bogan, Robert L. Brownell Jr., A. M. Burdin, M. K. Maminov
United States Department of Commerce: Staff Publications
Univariate and multivariate analyses of 20 skull characters of 304 adult sea otters from throughout the geographic range strongly suggest that three subspecies should be recognized. The nominate form, Enhydra lutris lutris, occurs from the Kuril Islands north to the Commander Islands in the western Pacific Ocean. Individuals of E. l. lutris are characterized by large size and wide skulls with short nasal bones. E. 1. nereis is found along the California coast and off San Nicolas Island, where the species recently has been reintroduced from coastal California. Specimens of E. 1. nereis have narrow skulls with a long …
Modeling Age-Specific Mortality For Marine Mammal Populations, Jay Barlow, Peter Boveng
Modeling Age-Specific Mortality For Marine Mammal Populations, Jay Barlow, Peter Boveng
United States Department of Commerce: Staff Publications
A method is presented for estimating age-specific mortality based on minimal information: a model life table and an estimate of longevity. This approach uses expected patterns of mammalian survivorship to define a general model of age-specific mortality rates. One such model life table is based on data for northern fur seals (Callorhinus ursinus) using Siler’s (1979) 5-parameter competing risk model. Alternative model life tables are based on historical data for human females and on a published model for Old World monkeys. Survival rates for a marine mammal species are then calculated by scaling these models by the longevity …
Long-Term Decline In Freshwater Mussels (Bivalvia: Unionidae) Of The Western Basin Of Lake Erie, Thomas F. Nalepa, Bruce A. Manny, James C. Roth, Samuel C. Mozley, Donald W. Schloesser
Long-Term Decline In Freshwater Mussels (Bivalvia: Unionidae) Of The Western Basin Of Lake Erie, Thomas F. Nalepa, Bruce A. Manny, James C. Roth, Samuel C. Mozley, Donald W. Schloesser
United States Department of Commerce: Staff Publications
Long-term trends in the abundance of unionids in the western basin of Lake Erie were examined from data collected at 17 stations in 1961, 1972, and 1982. The mean number of unionids at these stations declined over this time period, decreasing from 10 m-2 in 1961, to 6 m-2 in 1972, down to 4 m-2 in 1982. This decline in abundance was reflected in the decrease in the number of stations where mussels were found; unionids were found at 16 of the 17 stations in 1961, but at only 6 stations in 1982. Reasons for the decrease …