... whales are estimated Statistical methods used by Whitehead (1979), Eber-hardt et a1 1979) and... more ... whales are estimated Statistical methods used by Whitehead (1979), Eber-hardt et a1 1979) and Burnham et a1 (1980) yield 781 Page 3. population estimates that may be up to 50% higher than those yielded by Method #4. On 13 ...
Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduce... more Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduced prey availability as a risk to the population. In order to better assess this risk, we studied prey selection from 2004 to 2008 in 2 regions of the whales' summer range: San Juan Islands, Washington and the western Strait of Juan de Fuca, British Columbia. Following the whales in a small boat, we collected fish scales and tissue remains from predation events, and feces, using a fine mesh net. Visual fish scale analysis and molecular genetic methods were used to identify the species consumed. Chinook salmon, a relatively rare species, was by far the most frequent prey item, confirming previous studies. For Chinook salmon prey, we used genetic identification methods to estimate the spawning region of origin. Of the Chinook salmon sampled, 80 to 90% were inferred to have originated from the Fraser River, and only 6 to 14% were inferred to have originated from Puget Sound area rivers. Within the Fraser River, the Upper Fraser, Middle Fraser, South Thompson River and Lower Fraser stocks were inferred to currently be sequentially important sources of Chinook salmon prey through the summer. This information will be of significant value in guiding management actions to recover the southern resident killer whale population.
Managing endangered species often involves evaluating the relative impacts of multiple anthropoge... more Managing endangered species often involves evaluating the relative impacts of multiple anthropogenic and ecological pressures. This challenge is particularly formidable for cetaceans, which spend the majority of their time underwater. Noninvasive physiological approaches can be especially informative in this regard. We used a combination of fecal thyroid (T3) and glucocorticoid (GC) hormone measures to assess two threats influencing the endangered southern resident killer whales (SRKW; Orcinus orca) that frequent the inland waters of British Columbia, Canada and Washington, U.S.A. Glucocorticoids increase in response to nutritional and psychological stress, whereas thyroid hormone declines in response to nutritional stress but is unaffected by psychological stress. The inadequate prey hypothesis argues that the killer whales have become prey limited due to reductions of their dominant prey, Chinook salmon (Oncorhynchus tshawytscha). The vessel impact hypothesis argues that high numbers of vessels in close proximity to the whales cause disturbance via psychological stress and/or impaired foraging ability. The GC and T3 measures supported the inadequate prey hypothesis. In particular, GC concentrations were negatively correlated with short-term changes in prey availability. Whereas, T3 concentrations varied by date and year in a manner that corresponded with more long-term prey availability. Physiological correlations with prey overshadowed any impacts of vessels since GCs were lowest during the peak in vessel abundance, which also coincided with the peak in salmon availability. Our results suggest that identification and recovery of strategic salmon populations in the SRKW diet are important to effectively promote SRKW recovery.
We used data from 78 individuals at 26 microsatellite loci to infer parental and sibling relation... more We used data from 78 individuals at 26 microsatellite loci to infer parental and sibling relationships within a community of fish-eating (''resident'') eastern North Pacific killer whales (Orcinus orca). Paternity analysis involving 15 mother/calf pairs and 8 potential fathers and whole-pedigree analysis of the entire sample produced consistent results. The variance in male reproductive success was greater than expected by chance and similar to that of other aquatic mammals. Although the number of confirmed paternities was small, reproductive success appeared to increase with male age and size. We found no evidence that males from outside this small population sired any of the sampled individuals. In contrast to previous results in a different population, many offspring were the result of matings within the same ''pod'' (long-term social group). Despite this pattern of breeding within social groups, we found no evidence of offspring produced by matings between close relatives, and the average internal relatedness of individuals was significantly less than expected if mating were random. The population's estimated effective size was ,30 or about 1/3 of the current census size. Patterns of allele frequency variation were consistent with a population bottleneck.
Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduce... more Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduced prey availability as a risk to the population. In order to better assess this risk, we studied prey selection from 2004 to 2008 in 2 regions of the whales' summer range: San Juan Islands, Washington and the western Strait of Juan de Fuca, British Columbia. Following the whales in a small boat, we collected fish scales and tissue remains from predation events, and feces, using a fine mesh net. Visual fish scale analysis and molecular genetic methods were used to identify the species consumed. Chinook salmon, a relatively rare species, was by far the most frequent prey item, confirming previous studies. For Chinook salmon prey, we used genetic identification methods to estimate the spawning region of origin. Of the Chinook salmon sampled, 80 to 90% were inferred to have originated from the Fraser River, and only 6 to 14% were inferred to have originated from Puget Sound area rivers. Within the Fraser River, the Upper Fraser, Middle Fraser, South Thompson River and Lower Fraser stocks were inferred to currently be sequentially important sources of Chinook salmon prey through the summer. This information will be of significant value in guiding management actions to recover the southern resident killer whale population.
This review considers the effect of anthropogenic sound on beaked whales 2 . Two major conclusion... more This review considers the effect of anthropogenic sound on beaked whales 2 . Two major conclusions are presented: (1) gas-bubble disease, induced in supersaturated tissue by a behavioural response to acoustic exposure, is a plausible pathologic mechanism for the morbidity and mortality seen in cetaceans associated with sonar exposure and merits further investigation; and (2) current monitoring and mitigation methods for beaked whales are ineffective for detecting these animals and protecting them from adverse sound exposure. In addition, four major research priorities, needed to address information gaps on the impacts of sound on beaked whales, are identified: (1) controlled exposure experiments to assess beaked whale responses to known sound stimuli; (2) investigation of physiology, anatomy, pathobiology and behaviour of beaked whales; (3) assessment of baseline diving behaviour and physiology of beaked whales; and (4) a retrospective review of beaked whale strandings. Diverse fields (marine mammal ecology, medicine, behaviour, physiology, pathobiology and anatomy, human diving physiology and acoustics) were represented at the 2004 workshop and were brought together for an interdisciplinary discussion of various topics related to interactions between beaked whales and anthropogenic sound. These included sound propagation and acoustic exposure during specific stranding events, behaviour and ecology of beaked whales, beaked whale distribution, abundance and habitat, beaked whale anatomy and physiology and the efficacy of existing monitoring and mitigation efforts.
... whales are estimated Statistical methods used by Whitehead (1979), Eber-hardt et a1 1979) and... more ... whales are estimated Statistical methods used by Whitehead (1979), Eber-hardt et a1 1979) and Burnham et a1 (1980) yield 781 Page 3. population estimates that may be up to 50% higher than those yielded by Method #4. On 13 ...
Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduce... more Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduced prey availability as a risk to the population. In order to better assess this risk, we studied prey selection from 2004 to 2008 in 2 regions of the whales' summer range: San Juan Islands, Washington and the western Strait of Juan de Fuca, British Columbia. Following the whales in a small boat, we collected fish scales and tissue remains from predation events, and feces, using a fine mesh net. Visual fish scale analysis and molecular genetic methods were used to identify the species consumed. Chinook salmon, a relatively rare species, was by far the most frequent prey item, confirming previous studies. For Chinook salmon prey, we used genetic identification methods to estimate the spawning region of origin. Of the Chinook salmon sampled, 80 to 90% were inferred to have originated from the Fraser River, and only 6 to 14% were inferred to have originated from Puget Sound area rivers. Within the Fraser River, the Upper Fraser, Middle Fraser, South Thompson River and Lower Fraser stocks were inferred to currently be sequentially important sources of Chinook salmon prey through the summer. This information will be of significant value in guiding management actions to recover the southern resident killer whale population.
Managing endangered species often involves evaluating the relative impacts of multiple anthropoge... more Managing endangered species often involves evaluating the relative impacts of multiple anthropogenic and ecological pressures. This challenge is particularly formidable for cetaceans, which spend the majority of their time underwater. Noninvasive physiological approaches can be especially informative in this regard. We used a combination of fecal thyroid (T3) and glucocorticoid (GC) hormone measures to assess two threats influencing the endangered southern resident killer whales (SRKW; Orcinus orca) that frequent the inland waters of British Columbia, Canada and Washington, U.S.A. Glucocorticoids increase in response to nutritional and psychological stress, whereas thyroid hormone declines in response to nutritional stress but is unaffected by psychological stress. The inadequate prey hypothesis argues that the killer whales have become prey limited due to reductions of their dominant prey, Chinook salmon (Oncorhynchus tshawytscha). The vessel impact hypothesis argues that high numbers of vessels in close proximity to the whales cause disturbance via psychological stress and/or impaired foraging ability. The GC and T3 measures supported the inadequate prey hypothesis. In particular, GC concentrations were negatively correlated with short-term changes in prey availability. Whereas, T3 concentrations varied by date and year in a manner that corresponded with more long-term prey availability. Physiological correlations with prey overshadowed any impacts of vessels since GCs were lowest during the peak in vessel abundance, which also coincided with the peak in salmon availability. Our results suggest that identification and recovery of strategic salmon populations in the SRKW diet are important to effectively promote SRKW recovery.
We used data from 78 individuals at 26 microsatellite loci to infer parental and sibling relation... more We used data from 78 individuals at 26 microsatellite loci to infer parental and sibling relationships within a community of fish-eating (''resident'') eastern North Pacific killer whales (Orcinus orca). Paternity analysis involving 15 mother/calf pairs and 8 potential fathers and whole-pedigree analysis of the entire sample produced consistent results. The variance in male reproductive success was greater than expected by chance and similar to that of other aquatic mammals. Although the number of confirmed paternities was small, reproductive success appeared to increase with male age and size. We found no evidence that males from outside this small population sired any of the sampled individuals. In contrast to previous results in a different population, many offspring were the result of matings within the same ''pod'' (long-term social group). Despite this pattern of breeding within social groups, we found no evidence of offspring produced by matings between close relatives, and the average internal relatedness of individuals was significantly less than expected if mating were random. The population's estimated effective size was ,30 or about 1/3 of the current census size. Patterns of allele frequency variation were consistent with a population bottleneck.
Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduce... more Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduced prey availability as a risk to the population. In order to better assess this risk, we studied prey selection from 2004 to 2008 in 2 regions of the whales' summer range: San Juan Islands, Washington and the western Strait of Juan de Fuca, British Columbia. Following the whales in a small boat, we collected fish scales and tissue remains from predation events, and feces, using a fine mesh net. Visual fish scale analysis and molecular genetic methods were used to identify the species consumed. Chinook salmon, a relatively rare species, was by far the most frequent prey item, confirming previous studies. For Chinook salmon prey, we used genetic identification methods to estimate the spawning region of origin. Of the Chinook salmon sampled, 80 to 90% were inferred to have originated from the Fraser River, and only 6 to 14% were inferred to have originated from Puget Sound area rivers. Within the Fraser River, the Upper Fraser, Middle Fraser, South Thompson River and Lower Fraser stocks were inferred to currently be sequentially important sources of Chinook salmon prey through the summer. This information will be of significant value in guiding management actions to recover the southern resident killer whale population.
This review considers the effect of anthropogenic sound on beaked whales 2 . Two major conclusion... more This review considers the effect of anthropogenic sound on beaked whales 2 . Two major conclusions are presented: (1) gas-bubble disease, induced in supersaturated tissue by a behavioural response to acoustic exposure, is a plausible pathologic mechanism for the morbidity and mortality seen in cetaceans associated with sonar exposure and merits further investigation; and (2) current monitoring and mitigation methods for beaked whales are ineffective for detecting these animals and protecting them from adverse sound exposure. In addition, four major research priorities, needed to address information gaps on the impacts of sound on beaked whales, are identified: (1) controlled exposure experiments to assess beaked whale responses to known sound stimuli; (2) investigation of physiology, anatomy, pathobiology and behaviour of beaked whales; (3) assessment of baseline diving behaviour and physiology of beaked whales; and (4) a retrospective review of beaked whale strandings. Diverse fields (marine mammal ecology, medicine, behaviour, physiology, pathobiology and anatomy, human diving physiology and acoustics) were represented at the 2004 workshop and were brought together for an interdisciplinary discussion of various topics related to interactions between beaked whales and anthropogenic sound. These included sound propagation and acoustic exposure during specific stranding events, behaviour and ecology of beaked whales, beaked whale distribution, abundance and habitat, beaked whale anatomy and physiology and the efficacy of existing monitoring and mitigation efforts.
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Papers by K. Balcomb