Download or read book The Relationship of the Foraging Ecology of Steller Sea Lions Eumetopias Jubatus to Their Population Decline in Alaska written by Richard Merrick and published by . This book was released on 1995 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Decline of the Steller Sea Lion in Alaskan Waters written by National Research Council and published by National Academies Press. This book was released on 2003-05-04 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: For an unknown reason, the Steller sea lion population in Alaska has declined by 80% over the past three decades. In 2001, the National Research Council began a study to assess the many hypotheses proposed to explain the sea lion decline including insufficient food due to fishing or the late 1970s climate/regime shift, a disease epidemic, pollution, illegal shooting, subsistence harvest, and predation by killer whales or sharks. The report's analysis indicates that the population decline cannot be explained only by a decreased availability of food; hence other factors, such as predation and illegal shooting, deserve further study. The report recommends a management strategy that could help determine the impact of fisheries on sea lion survival-establishing open and closed fishing areas around sea lion rookeries. This strategy would allow researchers to study sea lions in relatively controlled, contrasting environments. Experimental area closures will help fill some short-term data gaps, but long-term monitoring will be required to understand why sea lions are at a fraction of their former abundance.

Download or read book A Review of Proposed Fishery Management Actions and the Decline of Steller Sea Lions Eumetopias Jubatus in Alaska written by Morgen Crow and published by . This book was released on 2001 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Winter Ecology of Steller Sea Lions Eumetopias Jubatus in Alaska written by Boyd Porter and published by . This book was released on 1997 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Decline of the Steller Sea Lion in Alaskan Waters written by National Research Council and published by National Academies Press. This book was released on 2003-04-04 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: For an unknown reason, the Steller sea lion population in Alaska has declined by 80% over the past three decades. In 2001, the National Research Council began a study to assess the many hypotheses proposed to explain the sea lion decline including insufficient food due to fishing or the late 1970s climate/regime shift, a disease epidemic, pollution, illegal shooting, subsistence harvest, and predation by killer whales or sharks. The report's analysis indicates that the population decline cannot be explained only by a decreased availability of food; hence other factors, such as predation and illegal shooting, deserve further study. The report recommends a management strategy that could help determine the impact of fisheries on sea lion survival-establishing open and closed fishing areas around sea lion rookeries. This strategy would allow researchers to study sea lions in relatively controlled, contrasting environments. Experimental area closures will help fill some short-term data gaps, but long-term monitoring will be required to understand why sea lions are at a fraction of their former abundance.

Download or read book Steller Sea Lion and Northern Fur Seal Research written by and published by . This book was released on 2007 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimal Foraging Theory as a Model to Examine the Relationship Between Relative Prey Accessibility and Foraging Energetics in Stellar Sea Lions Eumetopias Jubatus in the Gulf of Alaska and Bering Sea written by Leslie Anne Cornick and published by . This book was released on 2001 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The western stock of the Steller sea lion (Eumetopias jubatus) (SSL) along the Aleutian Islands and in the Gulf of Alaska (GOA) has continuously declined over the past three decades, and is now listed as endangered. While the causes of this decline are not well understood, nutritional stress, resulting in excessive juvenile mortality, is the leading hypothesis. Optimal foraging theory predicts that predators should change their dive behavior (foraging strategy) as prey availability changes. Relative prey accessibility (RPA, the ability of an individual SSL to access prey during a dive cycle) is likely a crucial causal link between hypothesized reduced prey biomass resulting from commercial fishing activity and depressed foraging efficiency of SSL, but cannot be controlled in the wild, and is impossible to accurately quantify at the individual level. This study, for the first time, experimentally validates prey availability-foraging behavior relationships previously hypothesized by optimality and foraging theory, but never before experimentally tested for a diving mammal. I employed a combined approach of predictive model development and controlled experiments. Testable predictions were determined by developing a bioenergetics-based model of individual dive behavior for aerobic dives of otariids. To determine the relationship between RPA and dive behavior, I examined how dive duration, foraging time, surface interval, percent time foraging, submerged, surface time, dive efficiency, and foraging efficiency varied with changes in simulated RPA in optimal foraging experiments performed with three seven, year-old SSL (two females, one male) held captive at the Alaska Sea life Center in Seward, AK. RPA had a significant positive effect on dive duration, foraging time, percent time foraging, and relative foraging efficiency. The dive model accurately predicted the observed effect of changing RPA on dive behavior and foraging efficiency. A population-based model was also developed in order to predict the effects of varying regimes of commercial fisheries activity on SSL population trends, based upon an estimate of annual SSL energetic requirements. The model accurately portrayed SSL abundance trends predicted by published projections, but failed to implicate competition with the commercial groundfish fishery in Alaska as a cause of the decline of SSL"--Leaves iii-iv.

Download or read book Field Studies of Steller Sea Lions Eumetopias Jubatus at Marmot Island Alaska 1979 Through 1994 written by and published by . This book was released on 1997 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Steller Sea Lion Protection Measures written by and published by . This book was released on 2001 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Endangered Species Act Section 7 Consultation written by and published by . This book was released on 2000 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Regulatory Impact initial Flexibility Analysis of Proposed Inshore offshore Allocation Alternatives Amendment 18 23 to Groundfish Bering Sea and Aleutian Islands Fisheries Management Plan FMP and Gulf of Alaska Groundfish Fisheries Management Plan FMP written by and published by . This book was released on 1992 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fishery Bulletin written by and published by . This book was released on 1999 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Steller Sea Lion Decline written by Douglas P. DeMaster and published by . This book was released on 2002 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most likely cause of the moderate decline of western Alaska Steller sea lions, in the 1990s, is poor recruitment (reproduction and survival of young). Also implicated are nutritional stress, predation, and disease. In contrast, nutritional stress alone was the leading hypothesis for a steep decline in sea lions the 1980s. This book has 13 extended abstracts presented at a May 2001 workshop. Attendees included the nation's leading authorities on Alaska's Steller sea lions.

Download or read book Long term Ecological Change in the Northern Gulf of Alaska written by R.B. Spies and published by Elsevier. This book was released on 2006-12-12 with total page 609 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive text is a major synthesis on ecological change in the Gulf of Alaska. It encompasses the structural and annual changes, forces of change, long-ecological changes in the atmosphere and ocean, plankton, fish, birds and mammals, and the effects of the 1989 Exxon Valdez Oil Spill. With 5 major sections, Long-term Ecological Change in the Northern Gulf of Alaska first describes the physical features, the atmosphere and physical oceanography, the annual production cycle, the forage base for higher animals and trophic transfer, and the adaptations for survival in this changing environment for 9 portal species. Then, the major forces of change are introduced: climate, geophysics, fisheries and harvesting, species interactions, disease and contaminants. Next, the long-term records of change in physical factors and biological populations are presented, as well as the potential reasons for the biological changes. Following is the history of the Exxon Valdez oil spill and its long-term effects. And, finally, the emergent properties of the ecosystem are discussed and an attempt is made to weigh the importance of the major forcing factors in terms of their temporal and spatial scales of influence. * Examines important data on long-term change in the ecosystem and the forcing factors that are responsible for it * Provides an account of the 1989 Exxon Valdez oil spill with emphasis on the long-term effects * Describes the effects of climate change, geophysical change, species interactions, harvesting, disease, the 1989 oil spill, and marine contaminants on key populations of marine organisms

Download or read book Testing Conceptual Models of Marine Mammal Trophic Dynamics Using Carbon and Nitrogen Stable Isotope Ratios written by Donald M. Schell and published by . This book was released on 1998 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Encyclopedia of Marine Mammals written by William F. Perrin and published by Academic Press. This book was released on 2009-02-26 with total page 1355 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thorough revision of the classic Encyclopedia of Marine Mammals brings this authoritative book right up-to-date. Articles describe every species in detail, based on the very latest taxonomy, and a host of biological, ecological and sociological aspects relating to marine mammals. The latest information on the biology, ecology, anatomy, behavior and interactions with man is provided by a cast of expert authors – all presented in such detail and clarity to support both marine mammal specialists and the serious naturalist. Fully referenced throughout and with a fresh selection of the best color photographs available, the long-awaited second edition remains at the forefront as the go-to reference on marine mammals. More than 20% NEW MATERIAL includes articles on Climate Change, Pacific White-sided Dolphins, Sociobiology, Habitat Use, Feeding Morphology and more Over 260 articles on the individual species with topics ranging from anatomy and behavior, to conservation, exploitation and the impact of global climate change on marine mammals New color illustrations show every species and document topical articles FROM THE FIRST EDITION “This book is so good...a bargain, full of riches...packed with fascinating up to date information. I recommend it unreservedly it to individuals, students, and researchers, as well as libraries." --Richard M. Laws, MARINE MAMMALS SCIENCE "...establishes a solid and satisfying foundation for current study and future exploration" --Ronald J. Shusterman, SCIENCE

Download or read book Population Dynamics of Steller Sea Lions Eumetopias Jubatus in the Eastern Gulf of Alaska written by John Michael Maniscalco and published by . This book was released on 2015 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Steller sea lions (Eumetopias jubatus) were listed as endangered following a collapse of the western population beginning in the late 1970s. Low juvenile survival and reduced reproductive rates (natality) have been implicated as important factors in the decline. I conducted separate mark-recapture analyses to estimate juvenile survival and natality in an area of the western population where Steller sea lions have begun to show signs of recovery since the early 2000s. I then used these vital-rate estimates in a population matrix to estimate the strength of the recovery and assess which rates pose the greatest threats to recovery. First year survival was estimated at 80% for both males and females, but second-year survival dropped to a low of 40.6% for males and 64.2 % for females that were weaned at age 1. In contrast, survival was greatly improved (88.2%) for males and females that continued to suckle between ages 1 and 2. Cumulative survival to age 4 was double (35.7%) that estimated during the population decline. Natality was also higher in recent years (70%) than during the height of the decline in the 1980s (55%). The mean rate of population growth, based on matrix modeling of vital rates estimated in this study, was 4.1% per year between 2003 and 2013. By projecting these trends into the future, I estimated that the population in the study area may be fully recovered within 14 years, if density independent growth is to be expected in the near future. If density dependent factors come into play, the population will need another 37 years to fully recover. As would be expected from a long-lived, K-selected species, population growth rate was most sensitive to variation in adult survival, less sensitive to juvenile survival, and least sensitivity to natality. The findings of this study have important implications for Steller sea lion population management and suggest research priorities should be shifted from an emphasis on natality to an emphasis on survival rates and causes of mortality.