U.S. Pacific Marine Mammal Stock Assessments

Under the 1994 amendments to the Marine Mammal Protection Act, the National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (USFWS) were required to produce stock assessment reports for all marine mammal stocks in waters within the U.S. Exclusive Economic Zone. This document contains the stock assessment reports for the U.S. Pacific marine mammal stocks under NMFS jurisdiction. Marine mammal species which are under the management jurisdiction of the USFWS are not included in this report. A separate report containing background, guidelines for preparation, and .a summary of all stock assessment reports is available from the NMFS Office of Protected Resources. This report was prepared by staff of the Southwest Fisheries Science Center, NMFS and the Alaska Fisheries Science Center, NMFS. The information presented here was compiled primarily from published sources, but additional unpublished information was included where it contributed to the assessments. The authors wish to thanks the members of the Pacific Scientific Review Group for their valuable contributions and constructive criticism: Hannah Bernard, Robin Brown, Mark Fraker, Doyle Hanan, John Heyning, Steve Jeffries, Katherine Ralls, Michael Scott, and Terry Wright. Their comments greatly improved the quality of these reports, We also thanks the Marine Mammal Commission, The Humane Society of the United States, The Marine Mammal Center, The Center for Marine Conservation, and Friends of the Sea Otter for their careful reviews and thoughtful comments. Special thanks to Paul Wade of the Office of Protected Resources for his exhaustive review and comments, which greatly enhanced the consistency and technical quality of the reports. Any ommissions or errors are the sole responsibility of the authors. This is a working document and individual stock assessment reports will be updated as new information becomes available and as changes to marine mammal stocks and fisheries occur; therefore, each stock assessment report is intended to be a stand alone document. The authors solicit any new information or comments which would improve future stock assessment reports. This is Southwest Fisheries Science Center Technical Memorandum NOAA-TM-NMFS-SWFSC- 219, July 1995. 11

The Estimation of Theoretical Population Levels for Natural Populations

The focus of this dissertation was the estimation of theoretical reference levels such as K, the environmental carrying capacity, and MNPL, the maximum net productivity level, for three fishes off Southern California and for the northern fur seal (Callorhinus ursinus) population of St. Paul Island, Alaska. The estimation techniques were based on computer modeling of historical population trends. The assessment of these theoretical reference levels for natural populations is fundamentally important to the development and testing of concepts in theoretical ecology and population dynamics.In the first study, maximum-likelihood estimates of pre­-exploitation biomass were made for the white seabass (Atractoscion nobilis) and the yellowtail (Seriola Lalandei) by assuming that development of corresponding commercial fisheries led to a shift in size distributions of these fishes, as indicated by records of the Avalon Tuna Club, Santa Catalina Island, California. Pre­-exploitation biomass for Southern California populations of both these fishes was estimated to be about 20,000 tons. The pre­-exploitation biomass of the giant sea bass (Stereolepis gigas) was estimated to be 1300 tons. Due to insufficient natural history information, this estimate was based on commercial catch records only.In the second study, estimates of theoretical reference levels for the northern fur seal population of St. Paul Island were based on computer simulations of pup production from 1912 to 1970. Repetitive simulations were used to construct frequency distributions of estimates for MNPL, K, the number of pups born at MNPL and K, and the ratio MNPL/K. These distributions serve as a measure of the confidence that can be placed in single estimates of reference levels, and thereby provide a general context within which these reference levels can be evaluated.The final study of this dissertation investigated the pelagic migration of northern fur seal pups. Results indicated that initial migration paths for these pups are more widely dispersed that previously assumed. This information contributes to the understanding of northern fur seal life histories. A fuller understanding of life history information will eventually facilitate more accurate modeling of northern fur seal population dynamics

The Estimation of Theoretical Population Levels for Natural Populations

The focus of this dissertation was the estimation of theoretical reference levels such as K, the environmental carrying capacity, and MNPL, the maximum net productivity level, for three fishes off Southern California and for the northern fur seal (Callorhinus ursinus) population of St. Paul Island, Alaska. The estimation techniques were based on computer modeling of historical population trends. The assessment of these theoretical reference levels for natural populations is fundamentally important to the development and testing of concepts in theoretical ecology and population dynamics.In the first study, maximum-likelihood estimates of pre­-exploitation biomass were made for the white seabass (Atractoscion nobilis) and the yellowtail (Seriola Lalandei) by assuming that development of corresponding commercial fisheries led to a shift in size distributions of these fishes, as indicated by records of the Avalon Tuna Club, Santa Catalina Island, California. Pre­-exploitation biomass for Southern California populations of both these fishes was estimated to be about 20,000 tons. The pre­-exploitation biomass of the giant sea bass (Stereolepis gigas) was estimated to be 1300 tons. Due to insufficient natural history information, this estimate was based on commercial catch records only.In the second study, estimates of theoretical reference levels for the northern fur seal population of St. Paul Island were based on computer simulations of pup production from 1912 to 1970. Repetitive simulations were used to construct frequency distributions of estimates for MNPL, K, the number of pups born at MNPL and K, and the ratio MNPL/K. These distributions serve as a measure of the confidence that can be placed in single estimates of reference levels, and thereby provide a general context within which these reference levels can be evaluated.The final study of this dissertation investigated the pelagic migration of northern fur seal pups. Results indicated that initial migration paths for these pups are more widely dispersed that previously assumed. This information contributes to the understanding of northern fur seal life histories. A fuller understanding of life history information will eventually facilitate more accurate modeling of northern fur seal population dynamics

National Oceanic and Atmospheric Administration Report 241

The following report is based on findings from the observational studies on the Hawaiian monk seal in the Northwestern Hawaiian Islands during 1995. The objectives of this research were to conduct beach counts (censuses), tag weaned pups and immature seals for permanent identification, identify other seals by previously applied tags and by natural or applied markings, monitor reproduction, survival, injuries, entanglements, interatoll movements, disappearances, and deaths, perform necropsies, collect tissue samples for DNA analysis, and inventory, sample, and destroy debris capable of entangling wildlife

National Oceanic and Atmospheric Administration Report 172

The following document is meant to facilitate an analysis and review of historical counts of the Hawaiian monk seal. Provided here are tables ordered on an island-by-island or atoll-by-atoll basis, beginning in the early 1800s and on through the 1980s

National Oceanic and Atmospheric Administration Report 229

The following report is a summary of observational studies on the Hawaiian monk seal in the Northern Hawaiian Islands during 1994. The information provided is meant to evaluate the status and trends of monk seal populations, natural history traits such as survival, reproduction, growth, behavior, and feeding habits, and the success of various activities designed to facilitate population growth

National Oceanic and Atmospheric Administration Report 259

This document describes field studies of the endangered Hawaiian monk seal in the Northwestern Hawaiian Islands in 1996. The studies provide information on the status and trends of monk seal populations, natural history traits (survival, reproduction, growth, behavior, and feeding habits), and the success of various activities designed to facilitate population growth

National Oceanic and Atmospheric Administration Report 262

The following document provides the findings on the field studies over the endangered Hawaiian monk seal in the Northwestern Hawaiian Islands during 1997. The information covered evaluates the status and trends of monk seal populations, natural history traits (survival, reproduction, growth, behavior, and feeding habits), and the success of various activities designed to facilitate population growths

Marine mammal conservation

Marine mammals face an uncertain fate in our rapidly changing world. Despite human fascination with these species and protective legislation in many countries, conservation efforts for marine mammals have achieved mixed results to date: some species have experienced a degree of recovery following centuries of exploitation, whereas others have perished or are on the brink of extinction. To avoid or at least to minimize further losses, human societies must be willing to assess and alter their values and activities that compete with, or otherwise contribute to, the demise of marine mammals and marine ecosystems. The value of conservation must be elevated from an aesthetically pleasing concept championed when convenient to a fundamental construct of our lives and futures. This new paradigm will require a clear vision of future conservation goals and the roles of societies in achieving them, long-term planning and commitment of funding/resources, rigorous science to resolve critical uncertainties, precautionary protection of habitats and ecosystems in the face of such uncertainty, and an interdisciplinary, comprehensive approach to conservation that engages the social sciences and humanities to elevate the value of conservation over short-term economic gain and many other competing values. Without the social will to make such changes, the future for marine mammals looks bleak