{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/28636"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/28636","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"The Evolutionary Effects of Fishing: Implications for Stock Management and Rebuilding","abstract":"Recent empirical studies have demonstrated inter-generational morphological and life-history changes in fish stocks that have been impacted by size-selective harvest. Evolutionary processes in biological populations occur through differential survival and reproductive success based, in part, upon individual phenotypic variability. Fishing is a source of directional selection resulting in the directed removal of some phenotypes; however, many aspects of the evolutionary effects of fishing remain have yet to be described. In order to better understand the life-history and morphological changes that occur as a result of size-selective fishing, and their effect on fishery dynamics, I first determined the suitability of Japanese medaka (Oryzias latipes) for selection experiments. I performed selection experiments using Japanese medaka and report how morphology and life-history characteristics changed over multiple generations of selection. I then used these patterns of change in life-history and morphology to validate individual-based simulation candidate models to test general mechanisms of life-history relationships. Finally, I applied the individual-based simulation modeling approach in order to describe how biological and fishery characteristics change in a large, age-structured population exposed to size-selective fishing over multiple generations. I found that the Japanese medaka has attractive characteristics for biological investigation. The selection experiments indicated large changes in the age-atmaturity, including a nearly 50% decrease over four generations in the most intense sizeselective removal regimes. However, I did not observe significant changes in length-at-age or weight-at-age over the course of the experiment. Candidate simulation models were poor at predicting some aspects of the life-history characteristics of Japanese medaka. The simulation model to determine fishery characteristics predicted large decreases in yield and egg production as a result of decreases in length-at-age. Understanding the relationships of life-history characteristics and their role in determining population resilience is a step toward understanding the importance of evolutionary processes in fishery management.","abstract_html":"Recent empirical studies have demonstrated inter-generational morphological and life-history changes in fish stocks that have been impacted by size-selective harvest. Evolutionary processes in biological populations occur through differential survival and reproductive success based, in part, upon individual phenotypic variability. Fishing is a source of directional selection resulting in the directed removal of some phenotypes; however, many aspects of the evolutionary effects of fishing remain have yet to be described. In order to better understand the life-history and morphological changes that occur as a result of size-selective fishing, and their effect on fishery dynamics, I first determined the suitability of Japanese medaka (Oryzias latipes) for selection experiments. I performed selection experiments using Japanese medaka and report how morphology and life-history characteristics changed over multiple generations of selection. I then used these patterns of change in life-history and morphology to validate individual-based simulation candidate models to test general mechanisms of life-history relationships. Finally, I applied the individual-based simulation modeling approach in order to describe how biological and fishery characteristics change in a large, age-structured population exposed to size-selective fishing over multiple generations. I found that the Japanese medaka has attractive characteristics for biological investigation. The selection experiments indicated large changes in the age-atmaturity, including a nearly 50% decrease over four generations in the most intense sizeselective removal regimes. However, I did not observe significant changes in length-at-age or weight-at-age over the course of the experiment. Candidate simulation models were poor at predicting some aspects of the life-history characteristics of Japanese medaka. The simulation model to determine fishery characteristics predicted large decreases in yield and egg production as a result of decreases in length-at-age. Understanding the relationships of life-history characteristics and their role in determining population resilience is a step toward understanding the importance of evolutionary processes in fishery management.","abstract_has_math":false,"creators":["Leaf, Robert Thomas"],"institution":"Virginia Tech","degree_name":"Ph. D.","degree_level":"doctoral","degree_discipline":"Fisheries and Wildlife Sciences","degree_department":"Fisheries and Wildlife Sciences","school":null,"contributors":[],"advisors":[],"committee_chairs":["Jiao, Yan"],"committee_members":["Hallerman, Eric M.","Murphy, Brian R.","Berkson, James M.","Prager, Michael H."],"year":2010,"date_issued":"2010-06-22","date_published":"2010-06-22","updated_at":"2026-07-22T22:19:37Z","subjects":["Japanese medaka","Oryzias latipes","aquaculture","life-history evolution","quantitative genetics","heritability","individual-based model","fishery-induced evolution"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-08122010-063252"],"render_values":[{"text":"etd-08122010-063252","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/28636","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Jiao, Yan"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Hallerman, Eric M.","Murphy, Brian R.","Berkson, James M.","Prager, Michael H."]},{"key":"dc:contributor.department","label":"Department","values":["Fisheries and Wildlife Sciences"]},{"key":"dc:creator","label":"Author","values":["Leaf, Robert Thomas"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:15:07Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:15:07Z","2010-08-25"]},{"key":"dc:date.issued","label":"Date","values":["2010-06-22"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Fisheries and Wildlife Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. 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Evolutionary processes in biological populations occur through differential survival and reproductive success based, in part, upon individual phenotypic variability. Fishing is a source of directional selection resulting in the directed removal of some phenotypes; however, many aspects of the evolutionary effects of fishing remain have yet to be described. In order to better understand the life-history and morphological changes that occur as a result of size-selective fishing, and their effect on fishery dynamics, I first determined the suitability of Japanese medaka (Oryzias latipes) for selection experiments. I performed selection experiments using Japanese medaka and report how morphology and life-history characteristics changed over multiple generations of selection. I then used these patterns of change in life-history and morphology to validate individual-based simulation candidate models to test general mechanisms of life-history relationships. Finally, I applied the individual-based simulation modeling approach in order to describe how biological and fishery characteristics change in a large, age-structured population exposed to size-selective fishing over multiple generations. I found that the Japanese medaka has attractive characteristics for biological investigation. The selection experiments indicated large changes in the age-atmaturity, including a nearly 50% decrease over four generations in the most intense sizeselective removal regimes. However, I did not observe significant changes in length-at-age or weight-at-age over the course of the experiment. Candidate simulation models were poor at predicting some aspects of the life-history characteristics of Japanese medaka. The simulation model to determine fishery characteristics predicted large decreases in yield and egg production as a result of decreases in length-at-age. Understanding the relationships of life-history characteristics and their role in determining population resilience is a step toward understanding the importance of evolutionary processes in fishery management."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph. D."]},{"key":"dc:title","label":"Title","values":["The Evolutionary Effects of Fishing: Implications for Stock Management and Rebuilding"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Jiao, Yan"],"dc:contributor.committeemember":["Hallerman, Eric M.","Murphy, Brian R.","Berkson, James M.","Prager, Michael H."],"dc:contributor.department":["Fisheries and Wildlife Sciences"],"dc:creator":["Leaf, Robert Thomas"],"dc:date.accessioned":["2014-03-14T20:15:07Z"],"dc:date.available":["2014-03-14T20:15:07Z","2010-08-25"],"dc:date.issued":["2010-06-22"],"dc:description.abstract":["Recent empirical studies have demonstrated inter-generational morphological and life-history changes in fish stocks that have been impacted by size-selective harvest. Evolutionary processes in biological populations occur through differential survival and reproductive success based, in part, upon individual phenotypic variability. Fishing is a source of directional selection resulting in the directed removal of some phenotypes; however, many aspects of the evolutionary effects of fishing remain have yet to be described. In order to better understand the life-history and morphological changes that occur as a result of size-selective fishing, and their effect on fishery dynamics, I first determined the suitability of Japanese medaka (Oryzias latipes) for selection experiments. I performed selection experiments using Japanese medaka and report how morphology and life-history characteristics changed over multiple generations of selection. I then used these patterns of change in life-history and morphology to validate individual-based simulation candidate models to test general mechanisms of life-history relationships. Finally, I applied the individual-based simulation modeling approach in order to describe how biological and fishery characteristics change in a large, age-structured population exposed to size-selective fishing over multiple generations. I found that the Japanese medaka has attractive characteristics for biological investigation. The selection experiments indicated large changes in the age-atmaturity, including a nearly 50% decrease over four generations in the most intense sizeselective removal regimes. However, I did not observe significant changes in length-at-age or weight-at-age over the course of the experiment. Candidate simulation models were poor at predicting some aspects of the life-history characteristics of Japanese medaka. The simulation model to determine fishery characteristics predicted large decreases in yield and egg production as a result of decreases in length-at-age. Understanding the relationships of life-history characteristics and their role in determining population resilience is a step toward understanding the importance of evolutionary processes in fishery management."],"dc:description.degree":["Ph. D."],"dc:identifier.other":["etd-08122010-063252"],"dc:identifier.uri":["http://hdl.handle.net/10919/28636"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Japanese medaka","Oryzias latipes","aquaculture","life-history evolution","quantitative genetics","heritability","individual-based model","fishery-induced evolution"],"dc:title":["The Evolutionary Effects of Fishing: Implications for Stock Management and Rebuilding"],"dc:type":["Dissertation"],"thesis:degree_discipline":["Fisheries and Wildlife Sciences"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Ph. D."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:37Z"}