Population Structure And Behavior Of Pacific Halibut Item Type Thesis Authors Seitz, Andrew C. Download date 26/09/2021 01:51:59 Link to Item http://hdl.handle.net/11122/8917 POPULATION STRUCTURE AND BEHAVIOR OF PACIFIC HALIBUT A THESIS Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Andrew C. Seitz, B.S. Fairbanks, Alaska December 2006 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 3251429 INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. ® UMI UMI Microform 3251429 Copyright 2007 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. POPULATION STRUCTURE AND BEHAVIOR OF PACIFIC HALIBUT By Andrew C. Seitz RECOMMENDED: f\\ T; (LV rH g; Advisory Committee Chair • ' / t r ' > /^ iA ^ TZj ~r;c~■■ Head, Program in Maj^ne Science and Limnology APPROVED: Dean, School of Fisheries and OcemNSciences Jean of the Graduate School / ~7y Z<3&<c> Date Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Abstract Pacific halibut (Hippoglossus stenolepis) is not managed on regional scales with separate population dynamics, but rather as a single, fully mixed population extending from California through the Bering Sea. However, some of the evidence from which this paradigm was established is questionable and I hypothesize that there are separate spawning populations of Pacific halibut in three regions, the Gulf of Alaska, Bering Sea and Aleutian Islands, because these regions are geographically separated by land masses and/or deep water passes that may prevent movement by adults. Pop-up Archival Transmitting (PAT) tags were attached to Pacific halibut in each region to examine their movement and behavior. First, geolocation by ambient light was able to discern basin- scale movements of demersal fishes in high latitudes and therefore this technique provided a feasible method for providing scientific inference on large-scale population structure in Pacific halibut. Second, because seasonally low ambient light levels and inhabitation of deep water (>200 m) restricted geolocation by light during winter, an alternative method, a minimum distance dispersal model, was developed for identifying migration pathways of demersal fish in the Gulf of Alaska based on daily maximum depth. Third, the PAT tags provided no evidence that Pacific halibut in the southeastern Bering Sea and Aleutian Islands moved among regions during the mid-winter spawning season, supporting my hypothesis of separate populations. Fourth, geographic landforms and discontinuities in the continental shelf appeared to limit the interchange of Pacific halibut among areas and possibly delineate the boundaries of potential populations in the Gulf of Alaska and eastern Bering Sea, with apparent smaller, localized populations Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. IV along the Aleutian Islands. This possible population structure may be reinforced by regional behavioral variation in response to the environment. Future research should be directed at quantifying the exchange of individual fish among regions for possible local area management plans that more accurately reflect population structure. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table of Contents Page Signature Page............................................................................................................................i Title Page................................................................................................................................... ii Abstract ..................................................................................................................................... iii Table of Contents.......................................................................................................................v List of Figures.........................................................................................................................viii List of Tables.............................................................................................................................x List of Appendices................................................................................................................... xi Acknowledgements ................................................................................................................. xii Chapter 1: Introduction............................................................................................................. 1 Literature Cited .............................................................................................................4 Chapter 2: Evaluating light-based geolocation for estimating demersal fish movements in high latitudes ..........................................................................................................................6 Abstract ..........................................................................................................................6 Introduction................................................................................................................... 7 Materials and methods ..................................................................................................9 Results..........................................................................................................................13 Discussion....................................................................................................................16 Acknowledgements .....................................................................................................21 Literature Cited ...........................................................................................................26 Reproduced with permission of the copyright owner. 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VI Chapter 3: Minimum distance dispersal model of demersal fish in the Gulf of Alaska.. .29 Abstract ........................................................................................................................29 Introduction................................................................................................................. 30 Methods........................................................................................................................32 Results..........................................................................................................................36 Swimming speed ............................................................................................ 36 Dispersal distance ..........................................................................................37 Discussion................................................................................................................... 38 Acknowledgements .................................................................................................... 45 References................................................................................................................... 53 Chapter 4: Evidence of Pacific halibut Hippoglossus stenolepis population structure in the Bering Sea and Aleutian Islands .....................................................................................55 Abstract ........................................................................................................................55 Introduction................................................................................................................. 56 Materials and methods ............................................................................................... 59 Results..........................................................................................................................61 Behavior..........................................................................................................61 Attu Island Pacific halibut ............................................................................ 62 Atka Island Pacific halibut ............................................................................ 63 St. Paul Island Pacific halibut .......................................................................64 Discussion................................................................................................................... 66 Acknowledgements .................................................................................................... 73 Reproduced with permission of the copyright owner. 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