Thesis (Ph. D.)--University of California, Davis, 2004. / Degree granted in Molecular, Cellular, and Integrative Physiology. Includes bibliographical references. Also available via the World Wide Web. (Restricted to UC campuses)

Ocular disease is one of the most common problems encountered in sea lions at various zoos and aquariums around the world.1 The California sea lion (Zalophus californianus) is one of the most common marine mammals maintained in zoos and is also the most commonly afflicted with ocular disease. Studies have shown that pinnipeds housed in captivity manifest an array of ocular lesions.2 Eye disease can range from a pinpoint corneal opacity to loss of vision due to keratopathy, cataracts and secondary glaucoma. Glaucoma is a disease that has not been extensively studied in the sea lion.3 Observation of clinical signs and determination of intraocular pressures (IOP) are critical for early diagnosis. IOP measurement may elucidate intraocular disease and provides information on the balance between aqueous humor production and outflow. The objective of this study is to measure IOP in California sea lions that have clinically normal eyes as well as those with varying degrees of ocular diseases, and to evaluate the incidence of secondary glaucoma in this species.

Thesis (Ph. D.)--Montana State University--Bozeman, 2004. / Title from PDF t.p. (viewed on June 12, 2006). Chairperson, Graduate Committee: Daniel Goodman. Includes bibliographical references (p. 189-207).

New Zealand sea lion (Phocarctos hookeri) is a pinniped endemic to New Zealand and is among the rarest of sea lion species. New Zealand sea lions are incidentally caught in the trawl fishery for squid around the Auckland Islands, and a sea lion catch-limit or Fishing Related Mortality Limit (FRML) is used to manage this interaction. Since 2003 such limits have been calculated using an age-structured Bayesian population model. One problem with this approach is that several key demographic parameters have had to be assumed, or are based on very few data. Archaeological and other historical records demonstrate that New Zealand sea lions were substantially more widespread before the arrival of humans to New Zealand than they are today (Chapter 2 published as Childerhouse & Gales 1998). The present population size is clearly reduced, with subsistence and commercial hunting the most likely cause of historical changes in distribution and abundance. Campbell Island, the only significant breeding site outside the Auckland Islands, was thoroughly surveyed for New Zealand sea lions for the first time in 2003. An estimated 385 pups were born there, comprising 13% of the total pup production for the species for 2003 (Chapter 3 published as Childerhouse et al. 2005). This thesis provides the first robust estimates of several demographic parameters for New Zealand sea lions. These data were gained via the capture, tagging and ageing of 865 individual females, which had come ashore to pup between 1999 and 2001. This research was underpinned by the development of a novel and robust ageing technique for live New Zealand sea lions (Chapter 5 published as Childerhouse et al. 2004). Chapters 6, 7 and 8 used analyses of the age structure of these females, and of subsequent resightings of them, and of known-age females between 1998 and 2005, provided the first estimates of individual growth, mean reproductive rate (0.67, SE = 0.01), mean adult survival (0.81, SE = 0.04), and maximum age (28 years) for females. These data show that New Zealand sea lions are among the slowest growing, slowest reproducing, and longest lived sea lion species. Significant differences in the age structure of the two largest breeding colonies highlight flawed assumptions of the current management approach. The application of this new demographic information has the potential to significantly alter the existing management advice relating to the setting of FRMLs and the impact of the squid fishery on the New Zealand sea lion population. Taken alone, these results suggest a dim outlook for an already threatened species. In the context that pup production is in significant decline (e.g. 32% since 1998 Chilvers et al. 2007), the species� foraging environment is thought to be marginal (Costa & Gales 2000), and that resource competition may also be impacting on the population (Chapter 4 published as Childerhouse et al. 2001a), the picture darkens further. Taken as a whole, these data suggest that current management is insufficient to ensure population stasis, let alone meet the Government�s statutory goal of recovery.

Sequence variation of a 238 bp segment of the mitochondrial control region was analyzed for 1,568 Steller sea lions (2.8% of the estimated species population) sampled from 50 rookeries representing nearly every locality at which Steller sea lions are known to breed in significant numbers. Haplotype diversity (H = 0.9164 ± 0.0035) was high and nucleotide diversity (π = 0.00967 ± 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Rookeries were grouped into regions and stocks to examine structure at different spatial scales. F- and Φ-statistics were computed for all pairwise comparisons of rookeries, regions and stocks. Significant (P<0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated using Φ-statistics at the regional level. The Commander Islands clearly associate with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the three stocks there is significant isolation by distance among rookeries. This relationship does not hold for inter-stock comparisons indicating that there are important barriers to gene flow among stocks. Mitochondrial DNA analysis supports the recognition of three stocks for appropriate conservation of the species. The currently recognized eastern stock is unaffected, but the western stock is now partitioned west of the Commander Islands yielding a western stock which ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhtosk.

Recent studies indicate a 70% decrease in the Alaskan Steller sea lion (SSL) population (ca. 5% per year) since the early 1980's. In accordance with a 1997 status classification of the Western Steller sea lion (WSSL) stock as endangered, the "critical habitat" for the species was to be defined. This habitat has now been designated to include 10-20 nautical mile buffer zones around most rookeries and haulouts in the Gulf of Alaska (GOA) and Aleutian Islands. However, these zones were based on limited, summer, foraging data. The primary objective of this study was to characterize juvenile SSL diving behavior and habitat use along the Kenai Peninsula and Prince William Sound (PWS) from winter to spring. Fifteen free ranging, subadult SSL of both sexes were captured and equipped with satellite telemeters at five haulout sites in PWS and Resurrection Bay, Alaska. Telemeters transmitted for an average of 122 days (range 38-181 days). A total of 11,692 locations were received and 217,419 dives recorded. All sea lions exhibited localized movements parallel or close to shore (3-15 km offshore). Young of the year (YOY) exhibited high site fidelity. Older juvenile sea lion lions were less restricted in their movements and traveled greater distances (200-400km) visiting a variety of islands, buoys, and other locations in PWS. Most dives were short (mean duration = 1.1 min) and shallow (mean depth = 10.8 m), with animals diving to an average maximum depth of 193 m. During winter (January and February), many dives (>40%) occurred during the daytime (0900-1500 LT). However, by April and May this pattern shifted and the animals made most of their dives (>40%) during the night (2100-0300 LT). This relationship was more pronounced for dives deeper than 20 m and coincided with the seasonal increase in photoperiod. Subadult SSL, especially YOY, remained within the 20 nautical mile coastal zone during winter and spring. Shallow, nearshore waters provide important habitat during this critical period of transition to nutritional independence. However, more conclusive data on SSL foraging ecology is necessary to better understand locations and depths preferred by the species.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 97-117).

Sequence variation of a 238 bp segment of the mitochondrial control region was analyzed for 1,568 Steller sea lions (2.8% of the estimated species population) sampled from 50 rookeries representing nearly every locality at which Steller sea lions are known to breed in significant numbers. Haplotype diversity (H = 0.9164 ± 0.0035) was high and nucleotide diversity (π = 0.00967 ± 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Rookeries were grouped into regions and stocks to examine structure at different spatial scales. F- and Φ-statistics were computed for all pairwise comparisons of rookeries, regions and stocks. Significant (P<0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated using Φ-statistics at the regional level. The Commander Islands clearly associate with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the three stocks there is significant isolation by distance among rookeries. This relationship does not hold for inter-stock comparisons indicating that there are important barriers to gene flow among stocks. Mitochondrial DNA analysis supports the recognition of three stocks for appropriate conservation of the species. The currently recognized eastern stock is unaffected, but the western stock is now partitioned west of the Commander Islands yielding a western stock which ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhtosk.

New Zealand sea lion (Phocarctos hookeri) is a pinniped endemic to New Zealand and is among the rarest of sea lion species. New Zealand sea lions are incidentally caught in the trawl fishery for squid around the Auckland Islands, and a sea lion catch-limit or Fishing Related Mortality Limit (FRML) is used to manage this interaction. Since 2003 such limits have been calculated using an age-structured Bayesian population model. One problem with this approach is that several key demographic parameters have had to be assumed, or are based on very few data. Archaeological and other historical records demonstrate that New Zealand sea lions were substantially more widespread before the arrival of humans to New Zealand than they are today (Chapter 2 published as Childerhouse & Gales 1998). The present population size is clearly reduced, with subsistence and commercial hunting the most likely cause of historical changes in distribution and abundance. Campbell Island, the only significant breeding site outside the Auckland Islands, was thoroughly surveyed for New Zealand sea lions for the first time in 2003. An estimated 385 pups were born there, comprising 13% of the total pup production for the species for 2003 (Chapter 3 published as Childerhouse et al. 2005). This thesis provides the first robust estimates of several demographic parameters for New Zealand sea lions. These data were gained via the capture, tagging and ageing of 865 individual females, which had come ashore to pup between 1999 and 2001. This research was underpinned by the development of a novel and robust ageing technique for live New Zealand sea lions (Chapter 5 published as Childerhouse et al. 2004). Chapters 6, 7 and 8 used analyses of the age structure of these females, and of subsequent resightings of them, and of known-age females between 1998 and 2005, provided the first estimates of individual growth, mean reproductive rate (0.67, SE = 0.01), mean adult survival (0.81, SE = 0.04), and maximum age (28 years) for females. These data show that New Zealand sea lions are among the slowest growing, slowest reproducing, and longest lived sea lion species. Significant differences in the age structure of the two largest breeding colonies highlight flawed assumptions of the current management approach. The application of this new demographic information has the potential to significantly alter the existing management advice relating to the setting of FRMLs and the impact of the squid fishery on the New Zealand sea lion population. Taken alone, these results suggest a dim outlook for an already threatened species. In the context that pup production is in significant decline (e.g. 32% since 1998 Chilvers et al. 2007), the species� foraging environment is thought to be marginal (Costa & Gales 2000), and that resource competition may also be impacting on the population (Chapter 4 published as Childerhouse et al. 2001a), the picture darkens further. Taken as a whole, these data suggest that current management is insufficient to ensure population stasis, let alone meet the Government�s statutory goal of recovery.

Thesis (Ph. D.)--University of Adelaide, 2005. / Title from PDF title page (viewed on Feb. 3, 2006). Includes bibliographical references.