Dalhousie Repository

Ecology And Evolution Of Heavily Exploited Fish Populations

DalSpace/Manakin Repository

Show simple item record

dc.contributor.author Ricard, Daniel
dc.date.accessioned 2012-07-10T17:32:07Z
dc.date.available 2012-07-10T17:32:07Z
dc.date.issued 2012-07-10
dc.identifier.uri http://hdl.handle.net/10222/15069
dc.description.abstract Commercial harvest of fish stocks and their appropriate management requires an understanding of their population dynamics and of their ability to sustain exploitation. Here, some ecological and evolutionary consequences of excessive exploitation are examined. In Chapter 2 I evaluate the knowledge base and status of commercially exploited marine populations that undergo formal stock assessment. Despite a bias towards industrialised countries and stocks of commercial importance, I show the pervasiveness of overexploitation and, by using reference points of stock status, identify important regional differences in the effectiveness of fisheries management. In Chapter 3 I develop a data format suitable for ecological analyses to best disseminate the valuable information contained in scientific trawl surveys. This data format is suitable for inclusion into the public Ocean Biogeographic Information System (OBIS) and provides detailed observations that are suitable to the reconstruction of important fisheries-independent stock indices. In Chapter 4 I examine the spatiotemporal dynamics of groundfish populations. A positive abundance-occupancy relationship was estimated for the majority of groundfish populations examined suggesting that this well-described terrestrial pattern is also pervasive in the marine environment. Spatial hysteresis was exhibited by numerous populations, indicating that the spatial distribution of individuals failed to recover despite recoveries in abundance. In Chapter 5 I estimate the demographic consequences of changes in growth and maturation characteristics. The ability of a population to sustain harvest, and its ability to recover from previous depletions can be overestimated because of trends towards earlier maturation and slower growth. In Chapter 6 I conclude the thesis by discussing the implications of my research to fisheries science and management. I argue that trends in the spatial distribution and the overall productivity of populations must be accounted for when determining sustainable fishing levels and when predicting recovery trajectories under various catch abatement scenarios. While successful management measures have been implemented in a number of marine ecosystems, this thesis highlights the importance of improving our capacity to understand the dynamics of exploited populations and to fully use the wealth of available monitoring and assessment data. en_US
dc.language.iso en en_US
dc.subject fisheries ecology en_US
dc.subject population dynamics en_US
dc.subject Northwest Atlantic Ocean en_US
dc.title Ecology And Evolution Of Heavily Exploited Fish Populations en_US
dc.date.defence 2012-05-25
dc.contributor.department Department of Biology en_US
dc.contributor.degree Doctor of Philosophy en_US
dc.contributor.external-examiner Dr. Steve Cadrin en_US
dc.contributor.graduate-coordinator Dr. Hal Whitehead en_US
dc.contributor.thesis-reader Stephen J. Smith en_US
dc.contributor.thesis-reader Dr. Mike Dowd en_US
dc.contributor.thesis-supervisor Dr. Boris Worm and Dr. Jeff Hutchings en_US
dc.contributor.ethics-approval Not Applicable en_US
dc.contributor.manuscripts Not Applicable en_US
dc.contributor.copyright-release Not Applicable en_US


Files in this item

This item appears in the following Collection(s)

Show simple item record