Papers by Kenneth Balcomb
The migratory destinations of humpback whales that feed off California. Oregon and Washington wer... more The migratory destinations of humpback whales that feed off California. Oregon and Washington were determined using photo-identification. Fluke photographs of 594 individuals were taken between 1981 and 1992 and compared to collections from 9 wintering regions in the North Pacific: Ogasawara (162) and Okinawa (17) islands of Japan; the Big Island and Maui (634 for both) and Kauai (384) of Hawaii; the Revillagigedo Archipelago (450), the mainland coast (383) and Baja Peninsula (471) of Mexico; and Central America (31). A total of 160 matches were found to 6 central and eastern North Paclfic wintering regions, with most from Central America, Baja, and mainland Mexico. Of whales identified off Central America, 84 % were resighted off California-Washington, this high rate of interchange suggests that whales in these tropical waters appear to be comprised entirely of animals from the California-Washington feeding aggregation. Humpback whales seen off Central America were reslghted disproportionately off southern California while those from mainland ~Vexico tended to be seen off northern California-Washington. From 157 same-season migratory transits documented, the shortest were 29 d to Baja and 56 d to Costa Rica and the longest distance was 5322 km. Of the Cal-ifornia-Washington whales with known sex, the proportion of males identified at a wintering region was significantly higher than females (2.2:1, p < 0.05).
Northwestern Naturalist, 2007
... We thank R Emmett, B Hanson, J Estes, and three anon-ymous reviewers for providing critiques ... more ... We thank R Emmett, B Hanson, J Estes, and three anon-ymous reviewers for providing critiques of the man-uscript. C Wilson at the Northwest Fisheries Science Center provided critical library services to our re-mote field site. ...
Marine Mammal Science, 2006
Population substructure has important implications for a species' ecology and evolution. As such,... more Population substructure has important implications for a species' ecology and evolution. As such, knowledge of this structuring is critical for the conservation and management of natural populations. Among marine mammals, many examples exist of species that enjoy a broad geographical distribution, yet are characterized by fine-scale population subdivisions. Coastal bottlenose dolphins have been studied extensively in a few regions globally, and these studies have highlighted a great diversity in both social strategies and demographic isolation. Here we use molecular genetic markers to examine the degree of population subdivision among three study sites separated by less than 250 km on Little Bahama Bank in the northern Bahamas. Mitochondrial DNA (mtDNA) sequence variation and microsatellite 276 PARSONS ET AL.: BAHAMAS DOLPHIN POPULATION STRUCTURE 277 genotypes were used to assess partitioning of genetic variance among 56 individually recognized coastal ecotype bottlenose dolphins. Although resolved levels of genetic differentiation suggest gene flow among the three study sites, both nuclear and mitochondrial data indicate a significant degree of subdivision within the Little Bahama Bank population, and sex-based analyses suggest that patterns of dispersal may not be strictly biased toward males. These results corroborate the site fidelity documented through long-term photo-identification studies in the NE Bahamas, and highlight the need to consider independent subpopulation units for the conservation and management of coastal bottlenose dolphins in the Bahamas.
Marine Mammal Science, 1996
Marine Mammal Science, 1999
Marine Mammal Science, 1996
Contract report to National …, 2009
Summary The endangered southern resident population of killer whales has been shown to be food li... more Summary The endangered southern resident population of killer whales has been shown to be food limited, and the reduced availability of their primary prey, chinook salmon, has been identified as a key threat to population viability. Our study aimed to collect aerial ...
The humpback whale (Megaptera novaeangliae) is a cosmo- politan species whose stocks were dras- t... more The humpback whale (Megaptera novaeangliae) is a cosmo- politan species whose stocks were dras- tically decreased by commercial whal- ing practices prior to 1967. The North Pacific population was estimated to be between 15,000 and 20,000 animals before the practice of whaling. At the time of the commencement of its inter- national protection in 1967, this popu- lation may have
Marine Mammal Science, 2000
Marine Mammal Science, 2006
Population substructure has important implications for a species' ecology and evolution. As such,... more Population substructure has important implications for a species' ecology and evolution. As such, knowledge of this structuring is critical for the conservation and management of natural populations. Among marine mammals, many examples exist of species that enjoy a broad geographical distribution, yet are characterized by fine-scale population subdivisions. Coastal bottlenose dolphins have been studied extensively in a few regions globally, and these studies have highlighted a great diversity in both social strategies and demographic isolation. Here we use molecular genetic markers to examine the degree of population subdivision among three study sites separated by less than 250 km on Little Bahama Bank in the northern Bahamas. Mitochondrial DNA (mtDNA) sequence variation and microsatellite 276 PARSONS ET AL.: BAHAMAS DOLPHIN POPULATION STRUCTURE 277 genotypes were used to assess partitioning of genetic variance among 56 individually recognized coastal ecotype bottlenose dolphins. Although resolved levels of genetic differentiation suggest gene flow among the three study sites, both nuclear and mitochondrial data indicate a significant degree of subdivision within the Little Bahama Bank population, and sex-based analyses suggest that patterns of dispersal may not be strictly biased toward males. These results corroborate the site fidelity documented through long-term photo-identification studies in the NE Bahamas, and highlight the need to consider independent subpopulation units for the conservation and management of coastal bottlenose dolphins in the Bahamas.
Marine Mammal Science, 2005
Marine Mammal Science, 1996
Marine Mammal Science, 2008
Marine Mammal Science, 2001
Despite the extensive use of photographic identification methods to investigate humpback whales i... more Despite the extensive use of photographic identification methods to investigate humpback whales in the North Pacific, few quantitative analyses have been conducted. We report on a comprehensive analysis of interchange in the North Pacific among three wintering regions (Mexico, Hawaii, and Japan)
Marine Mammal Science, 1991
Marine Ecology Progress Series, 2000
Journal of Applied Ecology, 2009
1. Management decisions for threatened and endangered species require risks to be identified and ... more 1. Management decisions for threatened and endangered species require risks to be identified and prioritized, based on the degree to which they influence population dynamics. The potential for recovery of small populations at risk may be determined by multiple factors, including intrinsic population characteristics (inbreeding, sex ratios) and extrinsic variables (prey availability, disease, human disturbance). Using Bayesian statistical methods, the impact of each of these risk factors on demographic rates can be quantified and assigned probabilities to express uncertainty.
Frontiers in Zoology, 2009
Background: Menopause is a seemingly maladaptive life-history trait that is found in many longliv... more Background: Menopause is a seemingly maladaptive life-history trait that is found in many longlived mammals. There are two competing evolutionary hypotheses for this phenomenon; in the adaptive view of menopause, the cessation of reproduction may increase the fitness of older females; in the non-adaptive view, menopause may be explained by physiological deterioration with age. The decline and eventual cessation of reproduction has been documented in a number of mammalian species, however the evolutionary cause of this trait is unknown.
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Papers by Kenneth Balcomb