Reconstructing historical abundances of exploited marine mammals at the global scale
department or school: Science, Faculty of
department or school: Resources, Environment and Sustainability (IRES), Institute for
data provider: DSpace
degree campus: UBCV
creator: Christensen, Line Bang
issued: 2010-01-09T00:26:57Z
issued: 2006
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The relationship between humans and marine mammals extends back for centuries and covers a multitude of facets; literature and spirituality, necessities (food) and luxuries (corsets). Their exploitation history changed from small-scale hunting for foodlfur, to large commercial ventures for oil, to limited hunting as marine mammals became the poster child for environmental movements. The International Whaling Commission, national and regional bodies assess the current status of marine mammals. Information on stock size relative to carrying capacities is, however, hard to come by. Assessments to date have been limited to a relatively small number of stocks/species because data quality, availability and politics. To address concerns over stock status, the analyses have to be expanded to all exploited populations. Employing a Bayesian approach to stochastic stock reduction analysis, I construct probability distributions over historical stock sizes. The method allows me to use historical catch time series to estimate a distribution over population parameters, the intrinsic rate of growth and carrying capacity, that give rise to extant populations. I tested this stock reconstruction approach on simulated data sets generated from a reference model, and then applied it to available catch and abundance data. Simulation tests indicate that parameter estimates were unbiased. Globally, I find that aggregated information on all marine mammal populations indicate a decline of 22% (0-62%) in numbers, and 76% (58-86%) in biomass. The decline has been greatest for the great whales, with a 64% (40-79%) decline in numbers, and an 81% (69-89%) decline in biomass. My estimates are consistent with published estimates of carrying capacity. These estimates are intended to provide a status overview, rather than direct management advice, affording us the ability to begin calculating how humans have impacted these large fauna in their marine ecosystems. The International Convention on the Reg…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/17967
note: RECONSTRUCTING HISTORICAL ABUNDANCES OF EXPLOITED MARINE M A M M A L S A T THE GLOBAL SCALE by LINE BANG CHRISTENSEN B.Sc, The University of British Columbia, 2004. A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE F A C U L T Y OF GRADUATE STUDIES (Resource Management and Environmental Studies) THE UNIVERSITY OF BRITISH COLUMBIA September 2006 © Line Bang Christensen, 2006 Abstract The relationship between humans and marine mammals extends back for centuries and covers a multitude of facets; literature and spirituality, necessities (food) and luxuries (corsets). Their exploitation history changed from small-scale hunting for food/fur, to large commercial ventures for oil, to limited hunting as marine mammals became the poster child for environmental movements. The International Whaling Commission, national and regional bodies assess the current status of marine mammals. Information on stock size relative to carrying capacities is, however, hard to come by. Assessments to date have been limited to a relatively small number of stocks/species because data quality, availability and politics. To address concerns over stock status, the analyses have to be expanded to all exploited populations. Employing a Bayesian approach to stochastic stock reduction analysis, I construct probability distributions over historical stock sizes. The method allows me to use historical catch time series to estimate a distribution over population parameters, the intrinsic rate of growth and carrying capacity, that give rise to extant populations. I tested this stock reconstruction approach on simulated data sets generated from a reference model, and then applied it to available catch and abundance data. Simulation tests indicate that parameter estimates were unbiased. Globally, I find that aggregated information on all marine mammal populations indicate a decline of 22% (0-62%) in numbers, and 76% (58-86%) in biomass. The decline has bee…
has type: Thesis/Dissertation
date issued: 2006-11
is shown at: 10.14288/1.0074892
language: eng
degree discipline: Resource Management and Environmental Studies
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/17967