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- Robards, M.D. and Reeves, R.R. The global extent and character of marine mammal consumption by humans: 1970–2009. Biological Conservation 144(12): 2770-2786, 2011.
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The killing and consumption of marine mammals fuels tense global struggles between advocates of sustainable use and advocates of complete protection for these animals. However, reporting on the extent and character of marine mammal consumption by people is uneven and often anecdotal. We developed a consistent approach to summarize information from approximately 900 sources. It is now clear that human consumption of marine mammals is geographically widespread, taxonomically diverse, and often of uncertain sustainability. Since 1990, people in at least 114 countries have consumed one or more of at least 87 marine mammal species. Although changing social, ecological, or political circumstances are leading to reduced killing and consumption of marine mammals in some regions, in other regions the prevailing socio-economic conditions and new technologies are leading to increased killing and consumption, particularly of small cetaceans. Consumption of marine mammals is considered a significant aspect of food security and cultural well being in many regions, and provides some economic (including cash) benefits to people in at least 54 countries. Our review highlights an escalation in utilization of small cetaceans caught in conjunction with fishing activities since 1970, a form of fishing-up-the-food-chain. Where consumption relates to food security and poverty, we found evidence of deliberate killing of animals caught both deliberately and accidentally in fishing gear. Constraints on government agencies responsible for implementing regulations, often due to the geographic remoteness of catches, mean that greater understanding is needed of the motivations that underlie consumption of marine mammals so that more effective conservation measures can be designed and implemented.
- Rotander, A., Kärrman, A., Van Bavel, B., Polder, A., Rigét, F., Auðnsson, G.A., Víkingsson, G., Gabrielsen, G.W., Bloch, D., and Dam, M. Increasing levels of long-chain perfluorocarboxylic acids (PFCAs) in Arctic and North Atlantic marine mammals, 1984–2009. Chemosphere 86(3): 278-285, 2012.
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Temporal variations in concentrations of perfluorinated carboxylic acids (PFCAs) and sulfonic acids (PFSAs), including perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) structural isomers, were examined in livers of pilot whale (Globicephala melas), ringed seal (Phoca hisida), minke whale (Balaenoptera acutorostrata), harbor porpoise (Phocoena phocoena), hooded seal (Cystophora cristata), Atlantic white-sided dolphin (Lagenorhynchus acutus) and in muscle tissue of fin whales (Balaenoptera physalus). The sampling spanned over 20 years (1984–2009) and covered a large geographical area of the North Atlantic and West Greenland. Liver and muscle samples were homogenized, extracted with acetonitrile, cleaned up using hexane and solid phase extraction (SPE), and analyzed by liquid chromatography with negative electrospray tandem mass spectrometry (LC-MS/MS). In general, the levels of the long-chained PFCAs (C9–C12) increased whereas the levels of PFOS remained steady over the studied period. The PFOS isomer pattern in pilot whale liver was relatively constant over the sampling years. However, in ringed seals there seemed to be a decrease in linear PFOS (L-PFOS) with time, going from 91% in 1984 to 83% in 2006.
- Davidson, A.D., Boyer, A.G., Kim, H., Pompa-Mansilla, S., Hamilton, M.J., Costa, D.P., Ceballos, G., and Brown, J.H. Drivers and hotspots of extinction risk in marine mammals. Proceedings of the National Academy of Sciences [USA] 109(9): 3395-3400, 2012.
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The world's oceans are undergoing profound changes as a result of human activities. However, the consequences of escalating human impacts on marine mammal biodiversity remain poorly understood. The International Union for the Conservation of Nature (IUCN) identifies 25% of marine mammals as at risk of extinction, but the conservation status of nearly 40% of marine mammals remains unknown due to insufficient data. Predictive models of extinction risk are crucial to informing present and future conservation needs, yet such models have not been developed for marine mammals. In this paper, we: (i) used powerful machine-learning and spatial-modeling approaches to understand the intrinsic and extrinsic drivers of marine mammal extinction risk; (ii) used this information to predict risk across all marine mammals, including IUCN 'Data Deficient' species; and (iii) conducted a spatially explicit assessment of these results to understand how risk is distributed across the world's oceans. Rate of offspring production was the most important predictor of risk. Additional predictors included taxonomic group, small geographic range area, and small social group size. Although the interaction of both intrinsic and extrinsic variables was important in predicting risk, overall, intrinsic traits were more important than extrinsic variables. In addition to the 32 species already on the IUCN Red List, our model identified 15 more species, suggesting that 37% of all marine mammals are at risk of extinction. Most at-risk species occur in coastal areas and in productive regions of the high seas. We identify 13 global hotspots of risk and show how they overlap with human impacts and Marine Protected Areas.
- Valqui, J. The marine otter Lontra felina: A review of its present status and implications for future conservation. Mammalian Biology 77(2): 75-83, 2012.
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The marine otter Lontra felina is an endangered and little known species living in a fragmented habitat: the coast of Peru and Chile. The smallest marine mammal's presence is unclear in Argentina and southern Tierra del Fuego and the current limits of the distribution are still under discussion. Recent population genetic studies suggest certain levels of gene flow despite a disjunct population. In the 20th century intensive hunting was the major threat to L. felina. This top predator still faces an uncertain future due to the impact of human activities (urbanization, pollution, and intensive fisheries). There is a need of further studies deepening the knowledge on population genetics, population numbers and migration behavior. Environmental education work, law enforcement and monitoring of protected areas are suggested to secure the survival of the species.
- Bodkin, J.L. et al. Long-term effects of the 'Exxon Valdez' oil spill: sea otter foraging in the intertidal as a pathway of exposure to lingering oil. Marine Ecology Progress Series 447: 273-287, 2012.
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The protracted recovery of some bird and mammal populations in western Prince William Sound (WPWS), Alaska, and the persistence of spilled 'Exxon Valdez' oil in intertidal sediments, suggests a pathway of exposure to consumers that occupy nearshore habitats. To evaluate the hypothesis that sea otter (Enhydra lutris) foraging allows access to lingering oil, we contrast spatial relations between foraging behavior and documented oil distribution. We recovered archival time-depth recorders implanted in 19 sea otters in WPWS, where lingering oil and delayed ecosystem recovery are well documented. Sea otter foraging dives ranged from +2.7 to -92 m below sea level (MLLW), with intertidal accounting for 5 to 38% of all foraging. On average, female sea otters made 16050 intertidal dives per year and 18% of these dives were at depths above the +0.80 m tidal elevation. Males made 4100 intertidal dives per year and 26% of intertidal foraging took place at depths above the +0.80 m tidal elevation. Estimated annual oil encounter rates ranged from 2 to 24 times yr-1 for females, and 2 to 4 times yr-1 for males. Exposure rates increased in spring when intertidal foraging doubled and females were with small pups. In summer 2008, we found sea otter foraging pits on 13.5 of 24.8 km of intertidal shoreline surveyed. Most pits (82%) were within 0.5 m of the zero tidal elevation and 15% were above 0.5 m, the level above which most (65%) lingering oil remains. In August 2008, we detected oil above background concentrations in 18 of 41 (44%) pits excavated by sea otters on beaches with prior evidence of oiling, with total PAH concentrations up to 56000 ng g-1 dry weight. Our estimates of intertidal foraging, the widespread presence of foraging pits in the intertidal, and the presence of oil in and near sea otter foraging pits documents a pathway of exposure from lingering intertidal oil to sea otters foraging in WPWS.
- Monson, D.H., Doak, D.F., Ballachey, B.E., and Bodkin, J.L. Could residual oil from the Exxon Valdez spill create a long-term population 'sink' for sea otters in Alaska? Ecological Applications 21(8): 2917-2932, 2011.
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Over 20 years ago, the Exxon Valdez oil tanker spilled 42 million L of crude oil into the waters of Prince William Sound, Alaska, USA. At the time of the spill, the sea otter (Enhydra lutris) population inhabiting the spill area suffered substantial acute injuries and loss. Subsequent research has resulted in one of the best-studied species responses to an oil spill in history. However, the question remains: Is the spill still influencing the Prince William Sound sea otter population? Here we fit time-varying population models to data for the sea otter population of western Prince William Sound to quantify the duration and extent of mortality effects from the spill. We hypothesize that the patchy nature of residual oil left in the environment has created a source-sink population dynamic. We fit models using the age distributions of both living and dying animals and estimates of sea otter population size to predict the number of sea otters in the hypothesized sink population and the number lost to this sink due to chronic exposure to residual oil. Our results suggest that the sink population has remained at just over 900 individuals (95% CI: 606–960) between 1990 and 2009, during which time prime-age survival remained 2–6% below pre-spill levels. This reduced survival led to chronic losses of ~900 animals over the past two decades, which is similar in magnitude to the number of sea otter deaths documented in western Prince William Sound during the acute phase of the spill. However, the unaffected source population appears to be counterbalancing these losses, with the model indicating that the sea otter population increased from ~2150 individuals in 1990 to nearly 3000 in 2009. The most optimistic interpretation of our results suggests that mortality effects dissipated between 2005 and 2007. Our results suggest that residual oil can affect wildlife populations on time scales much longer than previously believed and that cumulative chronic effects can be as significant as acute effects. Further, source-sink population dynamics can explain the slow recovery observed in the spill-affected western Prince William Sound sea otter population and are consistent with available data.
- Stirling, A. and Ross, J.E. Observations of cannibalism by polar bears (Ursus maritimus) on summer and autumn sea ice at Svalbard, Norway. Arctic 64(4): 478-482, 2011.
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We report three instances of intraspecific killing and cannibalism of young polar bears by adult males on the sea ice in Svalbard in summer and autumn. During breakup and melting in summer, the area of sea ice around the Svalbard Archipelago declines to a fraction of the winter total, and in many areas it disappears completely. As the area of sea ice that polar bears can use for hunting declines, progressively fewer seals are accessible to the bears, and therefore the bears' hunting success likely declines as well. Thus, at this time of year, young polar bears may represent a possible food source for adult males. As the climate continues to warm in the Arctic and the sea ice melts earlier in the summer, the frequency of such intraspecific predation may increase.
- Klein, D.R. and Sowls, A. History of polar bears as summer residents on the St. Matthew Islands, Bering Sea. Arctic 64(4): 429-436, 2011.
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Polar bears were found as summer residents on the St. Matthew Islands in the northern Bering Sea from the time of their discovery in the mid-18th century until the late 19th century, when the last bears were presumably shot by crews from Canadian and American sealers and a U.S. revenue cutter. Historical documents suggest that the killing of the last summer-resident polar bears on the St. Matthew Islands was an indirect consequence of the controversy between the United States and Great Britain over management of the fur seal harvest and the associated pelagic hunting of these seals. Although polar bears have continued to be present near the St. Matthew Islands in winter, when sea ice is present, a metapopulation of summer-resident bears has not reestablished on these islands. In 1972, the State of Alaska considered a proposal to reestablish a summer-resident polar bear population on the St. Matthew Islands, and since 2008, when the United States listed the polar bear as a threatened species, such reestablishment has been suggested as a conservation strategy. However, given the observed changes in local Bering Sea ice conditions in recent decades, the lack of detailed information on the population ecology and habitat dependencies of the historical St. Matthew bears, and the unavailability of an analogous extant metapopulation of polar bears for comparison, it is highly unlikely that reestablishment of summer-resident polar bears on the St. Matthew Islands could be realized.
- Knott, K.K., Boyd, D., Ylitalo, G.M., and O'Hara, T.M. Concentrations of mercury and polychlorinated biphenyls in blood of Southern Beaufort Sea polar bears (Ursus maritimus) during spring: variations with lipids and stable isotope (δ15N, δ13C) values. Canadian Journal of Zoology 89(11): 999-1012, 2011.
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Polar bears (Ursus maritimus Phipps, 1774) are exposed to heavy metal and lipophilic contaminants that are known to bioaccumulate and biomagnify. Few studies concurrently report both chemical classes in the same individuals and are thus unable to assess drivers of observed tissue concentrations, and the potential adverse biological responses to combined exposures. We examined blood concentrations of mercury (Hg) and the sum of seven polychlorinated biphenyls (Σ7PCB) from free-ranging Southern Beaufort Sea polar bears to assess which factors contributed to variations among cohorts (adult males, adult females, young) during spring. Concentrations of Hg ranged from 10.3 to 228.0 ng/g wet mass, but mean concentrations were similar between males and females independent of age. Concentrations of Σ7PCB (range 2.0-132.8 ng/g wet mass) were greater among females and young than among males. Toxicant concentrations were related to packed cell δ15N, an estimate of trophic position, after the inclusion of packed cell δ13C. Concentrations of Σ7PCB were also positively correlated with concentrations of neutral lipids (triglycerides and free fatty acids) and inversely correlated to body condition indices. Elevated concentrations of toxicants and lower body condition indices in females and young compared with males may be a sentinel to a changing arctic environment. Further assessment of the potential adverse health impacts of contaminants and nutritional stress in these cohorts is warranted.
- Rode, K.D., Peacock, E., Taylor, M., Stirling, I., Born, E.W., Laidre, K.L., and Wiig, Ø. A tale of two polar bear populations: ice habitat, harvest, and body condition. Population Ecology 54(1): 3-18, 2012.
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One of the primary mechanisms by which sea ice loss is expected to affect polar bears is via reduced body condition and growth resulting from reduced access to prey. To date, negative effects of sea ice loss have been documented for two of 19 recognized populations. Effects of sea ice loss on other polar bear populations that differ in harvest rate, population density, and/or feeding ecology have been assumed, but empirical support, especially quantitative data on population size, demography, and/or body condition spanning two or more decades, have been lacking. We examined trends in body condition metrics of captured bears and relationships with summertime ice concentration between 1977 and 2010 for the Baffin Bay (BB) and Davis Strait (DS) polar bear populations. Polar bears in these regions occupy areas with annual sea ice that has decreased markedly starting in the 1990s. Despite differences in harvest rate, population density, sea ice concentration, and prey base, polar bears in both populations exhibited positive relationships between body condition and summertime sea ice cover during the recent period of sea ice decline. Furthermore, females and cubs exhibited relationships with sea ice that were not apparent during the earlier period (1977–1990s) when sea ice loss did not occur. We suggest that declining body condition in BB may be a result of recent declines in sea ice habitat. In DS, high population density and/or sea ice loss, may be responsible for the declines in body condition.
- Freitas, C., Kovacs, K.M., Andersen, M., Aars, J., Sandven, S., Skern-Mauritzen, M., Pavlova, O., and Lydersen, C. Importance of fast ice and glacier fronts for female polar bears and their cubs during spring in Svalbard, Norway. Marine Ecology Progress Series 447: 289-304, 2012.
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Arctic sea ice is declining rapidly, making it vital to understand the importance of different types of sea ice for ice-dependent species such as polar bears Ursus maritimus. In this study we used GPS telemetry (25 polar bear tracks obtained in Svalbard, Norway, during spring) and high-resolution synthetic aperture radar (SAR) sea-ice data to investigate fine-scale space use by female polar bears. Space use patterns differed according to reproductive state; females with cubs of the year (COYs) had smaller home ranges and used fast-ice areas more frequently than lone females. First-passage time (FPT) analysis revealed that females with COYs displayed significantly longer FPTs near (<10 km) glacier fronts than in other fast-ice areas; lone females also increased their FPTs in such areas, but they also frequently used drifting pack ice. These results clearly demonstrate the importance of fast-ice areas, in particular close to glacier fronts, especially for females with COYs. Access to abundant and predictable prey (ringed seal pups), energy conservation and reluctance to cross large open water areas are possible reasons for the observed patterns. However, glacier fronts are retracting in Svalbard, and declines in land-fast ice have been notable over the past decade. The eventual disappearance of these important habitats might become critical for the survival of polar bear cubs in Svalbard and other regions with similar habitat characteristics. Given the relatively small size of many fast-ice areas in Svalbard, the results observed in this study would not have been revealed using less accurate location data or lower-resolution sea-ice data.
- Aubail, A., Dietz, R., Riget, F., Sonne, C., Wiig, O., and Caurant, F. Temporal trend of mercury in polar bears (Ursus maritimus) from Svalbard using teeth as a biomonitoring tissue. Journal of Environmental Monitoring 14(1): 56-63, 2012.
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We examined the use of mercury (Hg) and nitrogen and carbon stable isotopes in teeth of polar bear (Ursus maritimus) from Svalbard as biotracers of temporal changes in Hg pollution exposure between 1964 and 2003. Teeth were regarded as a good matrix of the Hg exposure, and in total 87 teeth of polar bears were analysed. Dental Hg levels ranged from 0.6 to 72.3 ng g-1 dry weight and increased with age during the first 10 years of life. A decreasing time trend in Hg concentrations was observed over the recent four decades while no temporal changes were found in the stable isotope ratios of nitrogen δ15N) and carbon (δ13C). This suggests that the decrease of Hg concentrations over time was more likely due to a lower environmental Hg exposure in this region rather than a shift in the feeding habits of Svalbard polar bears.
- Baker, J.D., Becker, B.L., Wurth, T.A., Johanos, T.C., Littnan, C.L., and Henderson, J.R. Translocation as a tool for conservation of the Hawaiian monk seal. Biological Conservation 144(11): 2692-2701, 2011.
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The deteriorating demographic status of the endangered Hawaiian monk seal has motivated renewed and expanded proposals for conservation action, including translocation of seals to improve survival. Over the past three decades, numerous monk seal translocations have been conducted with a variety of objectives, including mitigating shark predation and conspecific male aggression, reducing human-seal interactions, and taking advantage of favorable foraging habitats to improve survival. Here, we analyze our cumulative experience with translocation of Hawaiian monk seals. We found a strong correlation between the time seals remained in the vicinity of the release site and their age. Recently weaned pups (with little or no at-sea foraging experience) exhibited high fidelity to release sites commensurate with that shown by untranslocated pups to their birth location. In contrast, juvenile and adult seals tended to stray from their release locations farther and sooner. Nevertheless, when 21 adult male seals were moved more than 1000 km from Laysan Island in the Northwestern Hawaiian Islands (NWHI), to the main Hawaiian Islands (MHI), they subsequently dispersed among the MHI; however, only one was observed to return to the NWHI. Translocated seals appeared to survive at rates comparable to seals native to the release site. Outcomes suggest that in most cases the intended objectives of translocations were achieved. Except for one notable case, translocations within the MHI to arrest human-seal interactions were mostly unsuccessful. These findings will be essential for informing successful large-scale translocation plans in the future.
- Bajzak, C.E., Hammill, M.O., Stenson, G.B., and Prinsenberg, S. Drifting away: implications of changes in ice conditions for a pack-ice-breeding phocid, the harp seal (Pagophilus groenlandicus). Canadian Journal of Zoology 89(11): 1050-1062, 2011.
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Harp seals (Pagophilus groenlandicus (Erxleben, 1777)) required drifting pack-ice for birth, nursing, and as a resting platform for neonates after weaning. Data on the yearly location of whelping patches in the Gulf of St. Lawrence collected between 1977 and 2011 were combined with ice cover data (thickness and duration) to examine whether female harp seals actively select particular ice features as a breeding platform and to describe how these ice features have varied over the last 40 years at three spatial scales: the entire Gulf of St. Lawrence, the southern gulf, and the "traditional whelping area" within the southern Gulf. From our analyses, harp seals prefer the thickest ice stages available in the Gulf: grey-white and first-year ice. Lower than normal ice coverage years were more frequent for the required grey-white and first-year ice than for the total ice cover and less frequent at the "traditional whelping area" scale close to the northwestern coast of the Magdalen Islands than at the Gulf of St. Lawrence scale. The frequency of light ice years increased and the duration of the ice season decreased throughout the last decade. Our study showed that the temporal availability and the spatial distribution of the suitable ice are important when evaluating the effect of changes in ice conditions rather than overall ice extent.
- Horning, M. and Mellish, J.-A.E. Predation on an upper trophic marine predator, the Steller sea lion: Evaluating high juvenile mortality in a density dependent conceptual framework. PLoS ONE 7(1): art. e30173, 2012.
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The endangered western stock of the Steller sea lion (Eumetopias jubatus) - the largest of the eared seals - has declined by 80% from population levels encountered four decades ago. Current overall trends from the Gulf of Alaska to the Aleutian Islands appear neutral with strong regional heterogeneities. A published inferential model has been used to hypothesize a continuous decline in natality and depressed juvenile survival during the height of the decline in the mid-late 1980's, followed by the recent recovery of juvenile survival to pre-decline rates. However, these hypotheses have not been tested by direct means, and causes underlying past and present population trajectories remain unresolved and controversial. We determined post-weaning juvenile survival and causes of mortality using data received post-mortem via satellite from telemetry transmitters implanted into 36 juvenile Steller sea lions from 2005 through 2011. Data show high post-weaning mortality by predation in the eastern Gulf of Alaska region. To evaluate the impact of such high levels of predation, we developed a conceptual framework to integrate density dependent with density independent effects on vital rates and population trajectories. Our data and model do not support the hypothesized recent recovery of juvenile survival rates and reduced natality. Instead, our data demonstrate continued low juvenile survival in the Prince William Sound and Kenai Fjords region of the Gulf of Alaska. Our results on contemporary predation rates combined with the density dependent conceptual framework suggest predation on juvenile sea lions as the largest impediment to recovery of the species in the eastern Gulf of Alaska region. The framework also highlights the necessity for demographic models based on age-structured census data to incorporate the differential impact of predation on multiple vital rates.
- Johnston, D.W., Bowers, M.T., Friedlaender, A.S., and Lavigne, D.M. The effects of climate change on harp seals (Pagophilus groenlandicus). PLoS ONE 7(1): art. e29158, 2012.
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Harp seals (Pagophilus groenlandicus) have evolved life history strategies to exploit seasonal sea ice as a breeding platform. As such, individuals are prepared to deal with fluctuations in the quantity and quality of ice in their breeding areas. It remains unclear, however, how shifts in climate may affect seal populations. The present study assesses the effects of climate change on harp seals through three linked analyses. First, we tested the effects of short-term climate variability on young-of-the year harp seal mortality using a linear regression of sea ice cover in the Gulf of St. Lawrence against stranding rates of dead harp seals in the region during 1992 to 2010. A similar regression of stranding rates and North Atlantic Oscillation (NAO) index values was also conducted. These analyses revealed negative correlations between both ice cover and NAO conditions and seal mortality, indicating that lighter ice cover and lower NAO values result in higher mortality. A retrospective cross-correlation analysis of NAO conditions and sea ice cover from 1978 to 2011 revealed that NAO-related changes in sea ice may have contributed to the depletion of seals on the east coast of Canada during 1950 to 1972, and to their recovery during 1973 to 2000. This historical retrospective also reveals opposite links between neonatal mortality in harp seals in the Northeast Atlantic and NAO phase. Finally, an assessment of the long-term trends in sea ice cover in the breeding regions of harp seals across the entire North Atlantic during 1979 through 2011 using multiple linear regression models and mixed effects linear regression models revealed that sea ice cover in all harp seal breeding regions has been declining by as much as 6 percent per decade over the time series of available satellite data.
- Phillips, C.D., Gelatt, T.S., Patton, J.C., and Bickham, J.W. Phylogeography of Steller sea lions: relationships among climate change, effective population size, and genetic diversity. Journal of Mammalogy 92(5): 1091-1104, 2011.
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The biology of the Steller sea lion (Eumetopias jubatus) has been the subject of intense scientific investigation. This is primarily due to the rapid decline of population size in the western part of the species' range since the 1970s and the subsequent Threatened and Endangered species listings that had direct impact on the management of one of the world's largest fisheries. The Steller sea lion has emerged as an indicator species representing the environmental health of the North Pacific Ocean and Bering Sea. In this study, to better understand the historical processes that have culminated in the extant populations of E. jubatus, a large genetic data set consisting of 3 mitochondrial regions for >1,000 individuals was analyzed from multiple phylogeographic and demographic perspectives. The results describe the role of climate change in shaping the population structure of E. jubatus. Climatically associated historical processes apparently involved differential demographic responses to ice ages (and putative glacial vicariance) dependent on population size. Ice ages during times of small effective population size promoted restricted gene flow and fragmentation, and ice ages occurring during times of large population size promoted gene flow and dispersal. These results illustrate that effective population size has a profound effect on how species respond to climate change, an observation with obvious implications for large mammals and endangered species under the present conditions of imminent anthropogenically caused climate change. In addition, the results confirm previous observations of strongly biased historic and contemporary gene flow involving dispersal from west to east. Furthermore, phylogenetic patterns in combination with available fossil data suggest the potential of an Asian origin of E. jubatus. The results of this study provide a detailed scenario for the history that has shaped contemporary populations of E. jubatus.
- Popov, V.V., Klishin, V.O., Nechaev, D.I., Pletenko, M.G., Rozhnov, V.V., Supin, A.Ya., Sysueva, E.V., and Tarakanov, M.B. Influence of acoustic noises on the white whale hearing thresholds. Doklady Biological Sciences 440: 332-334, 2011.
- McQuinn, I.H. et al. A threatened beluga (Delphinapterus leucas) population in the traffic lane: Vessel-generated noise characteristics of the Saguenay-St. Lawrence Marine Park, Canada. Journal of the Acoustical Society of America 130(6): 3661-3673, 2011.
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The threatened resident beluga population of the St. Lawrence Estuary shares the Saguenay-St. Lawrence Marine Park with significant anthropogenic noise sources, including marine commercial traffic and a well-established, vessel-based whale-watching industry. Frequency-dependent (FD) weighting was used to approximate beluga hearing sensitivity to determine how noise exposure varied in time and space at six sites of high beluga summer residency. The relative contribution of each source to acoustic habitat degradation was estimated by measuring noise levels throughout the summer and noise signatures of typical vessel classes with respect to traffic volume and sound propagation characteristics. Rigid-hulled inflatable boats were the dominant noise source with respect to estimated beluga hearing sensitivity in the studied habitats due to their high occurrence and proximity, high correlation with site-specific FD-weighted sound levels, and the dominance of mid-frequencies (0.3-23 kHz) in their noise signatures. Median C-weighted sound pressure level (SPLRMS) had a range of 19 dB re 1 lPa between the noisiest and quietest sites. Broadband SPLRMS exceeded 120 dB re 1 lPa 8-32% of the time depending on the site. Impacts of these noise levels on St. Lawrence beluga will depend on exposure recurrence and individual responsiveness.
- Cassoff, R.M., Moore, K.M., McLellan, W.A., Barco, S.G., Rotstein, D.S., and Moore, M.J. Lethal entanglement in baleen whales. Diseases of Aquatic Organisms 96(3): 175-185, 2011.
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Understanding the scenarios whereby fishing gear entanglement of large whales induces mortality is important for the development of mitigation strategies. Here we present a series of 21 cases involving 4 species of baleen whales in the NW Atlantic, describing the available sighting history, necropsy observations, and subsequent data analyses that enabled the compilation of the manners in which entanglement can be lethal. The single acute cause of entanglement mortality identified was drowning from entanglement involving multiple body parts, with the animal's inability to surface. More protracted causes of death included impaired foraging during entanglement, resulting in starvation after many months; systemic infection arising from open, unresolved entanglement wounds; and hemorrhage or debilitation due to severe gear-related damage to tissues. Serious gear-induced injury can include laceration of large vessels, occlusion of the nares, embedding of line in growing bone, and massive periosteal proliferation of new bone in an attempt to wall off constricting, encircling lines. These data show that baleen whale entanglement is not only a major issue for the conservation of some baleen whale populations, but is also a major concern for the welfare of each affected individual.
- Risch, D., Corkeron, P.J., Ellison, W.T., and Van Parijs, S.M. Changes in humpback whale song occurrence in response to an acoustic source 200 km away. PLoS ONE 7(1): art. e29741, 2012.
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The effect of underwater anthropogenic sound on marine mammals is of increasing concern. Here we show that humpback whale (Megaptera novaeangliae) song in the Stellwagen Bank National Marine Sanctuary (SBNMS) was reduced, concurrent with transmissions of an Ocean Acoustic Waveguide Remote Sensing (OAWRS) experiment approximately 200 km away. We detected the OAWRS experiment in SBNMS during an 11 day period in autumn 2006. We compared the occurrence of song for 11 days before, during and after the experiment with song over the same 33 calendar days in two later years. Using a quasi-Poisson generalized linear model (GLM), we demonstrate a significant difference in the number of minutes with detected song between periods and years. The lack of humpback whale song during the OAWRS experiment was the most substantial signal in the data. Our findings demonstrate the greatest published distance over which anthropogenic sound has been shown to affect vocalizing baleen whales, and the first time that active acoustic fisheries technology has been shown to have this effect. The suitability of Ocean Acoustic Waveguide Remote Sensing technology for in-situ, long term monitoring of marine ecosystems should be considered, bearing in mind its possible effects on non-target species, in particular protected species.
- Ivashchenko, Y.V., Clapham, P.J., and Brownell, R.L. Soviet illegal whaling: The devil and the details. Marine Fisheries Review 73(3): 1-18, 2011.
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In 1948, the U.S.S.R. began a global campaign of illegal whaling that lasted for three decades and, together with the poorly managed "legal" whaling of other nations, seriously depleted whale populations. Although the general story of this whaling has been told and the catch record largely corrected for the Southern Hemisphere, major gaps remain in the North Pacific. Furthermore, little attention has been paid to the details of this system or its economic context. Using interviews with former Soviet whalers and biologists as well as previously unavailable reports and other material in Russian, our objective is to describe how the Soviet whaling industry was structured and how it worked, from the largest scale of state industrial planning down to the daily details of the ways in which whales were caught and processed, and how data sent to the Bureau of International Whaling Statistics were falsified. Soviet whaling began with the factory ship Aleut in 1933, but by 1963 the industry had a truly global reach, with seven factory fleets (some very large). Catches were driven by a state planning system that set annual production targets. The system gave bonuses and honors only when these were met or exceeded, and it frequently increased the following year's targets to match the previous year's production; scientific estimates of the sustainability of the resource were largely ignored. Inevitably, this system led to whale populations being rapidly reduced. Furthermore, productivity was measured in gross output (weights of whales caught), regardless of whether carcasses were sound or rotten, or whether much of the animal was unutilized. Whaling fleets employed numerous people, including women (in one case as the captain of a catcher boat). Because of relatively high salaries and the potential for bonuses, positions in the whaling industry were much sought-after. Catching and processing of whales was highly mechanized and became increasingly efficient as the industry gained more experience. In a single day, the largest factory ships could process up to 200 small sperm whales, Physeter macrocephalus; 100 humpback whales, Megaptera novaeangliae; or 30–35 pygmy blue whales, Balaenoptera musculus brevicauda. However, processing of many animals involved nothing more than stripping the carcass of blubber and then discarding the rest. Until 1952, the main product was whale oil; only later was baleen whale meat regularly utilized. Falsified data on catches were routinely submitted to the Bureau of International Whaling Statistics, but the true catch and biological data were preserved for research and administrative purposes. National inspectors were present at most times, but, with occasional exceptions, they worked primarily to assist fulfillment of plan targets and routinely ignored the illegal nature of many catches. In all, during 40 years of whaling in the Antarctic, the U.S.S.R. reported 185,778 whales taken but at least 338,336 were actually killed. Data for the North Pacific are currently incomplete, but from provisional data we estimate that at least 30,000 whales were killed illegally in this ocean. Overall, we judge that, worldwide, the U.S.S.R. killed approximately 180,000 whales illegally and caused a number of population crashes. Finally, we note that Soviet illegal catches continued after 1972 despite the presence of international observers on factory fleets.
- Heide-Jørgensen, M.P., Iversen, M., Nielsen, N.H., Lockyer, C., Stern, H., and Ribergaard, M.H. Harbour porpoises respond to climate change. Ecology and Evolution 1(4): 579-585, 2011.
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The effects of climate change on marine ecosystems and in particular on marine top predators are difficult to assess due to, among other things, spatial variability, and lack of clear delineation of marine habitats. The banks of West Greenland are located in a climate sensitive area and are likely to elicit pronounced responses to oceanographic changes in the North Atlantic. The recent increase in sea temperatures on the banks of West Greenland has had cascading effects on sea ice coverage, residency of top predators, and abundance of important prey species like Atlantic cod (Gadus morhua). Here, we report on the response of one of the top predators in West Greenland; the harbour porpoise (Phocoena phocoena). The porpoises depend on locating high densities of prey species with high nutritive value and they have apparently responded to the general warming on the banks of West Greenland by longer residence times, increased consumption of Atlantic cod resulting in improved body condition in the form of larger fat deposits in blubber, compared to the situation during a cold period in the 1990s. This is one of the few examples of a measurable effect of climate change on a marine mammal population.
- Gray, H. and Van Waerebeek, K. Postural instability and akinesia in a pantropical spotted dolphin, Stenella attenuata, in proximity to operating airguns of a geophysical seismic vessel. Journal for Nature Conservation 19(6): 363-367, 2011.
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Aberrant behaviour including erratic locomotion was observed in a pantropical spotted dolphin 600 m ahead of an airgun array during 3D seismic explorations off Liberia in March 2009. The dolphin, presumably in acoustic distress, lifted its head and cervical region above the surface in an oblique, strikingly rigid posture during 5 min. Turbulent white-water evidenced a major propulsory thrust. Incremental postural instability and apparent exhaustion progressed to a catatonic-like state of akinesia as the dolphin rolled over onto one side, then its back before sinking virtually motionless close to the airgun array. Unless it recovered full locomotory control, asphyxiation was inevitable. Potential internal injury is discussed, both acoustic-mediated and from extreme exertion (exertional myopathy, rhabdomyolysis and myoglobinuric nephrosis). As behaviour was spatially and temporally closely associated with firing seismic airguns, we suggest a cause-effect relationship. Differential diagnoses of pre-existing morbidity, senescence, or intoxication are considered possible but unlikely.
- Brito, C. Medieval and early modern whaling in Portugal. Anthrozoös 24(3): 287-300, 2011.
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Mainland Portugal is not renowned for having been a whaling nation of significance. However, preliminary studies have brought to light enough historical references to suggest that whaling occurred from at least the 13th century, and the present work identifies 38 historical sources documenting whale use or whaling on the Portuguese coast between 1201 and 1728. A peak of whale-related sources occurred during the 13th and 14th centuries, and almost all Portuguese accounts are contemporary to those found from the French and Spanish Basque countries, such that the beginning of the whaling activity seems to be coeval. No geographical cluster of whaling activities can be established – they seem to have been unevenly scattered along the entire coastline. Nor can a chronological north-south movement of coastal whaling activities be discerned. The geographical and chronological patterns give support to the assumption that whaling was not introduced to Portugal by the Basques, who are known to have spread westward from the French Labourd (11th century), via Golf of Biscay, to Asturias, and southward to Galicia (14th century). Rather, Portuguese whale use seems to have originated independently of Basque influence. Several of the sources specify "black whales" as the target species. This is consistent with modern knowledge about the distribution and migration patterns of North Atlantic right whales during Basque medieval and early modern whaling. The Portuguese sources are not clear as to numbers of whales taken, nor to the whaling technology used, but the activity was sufficiently well organized and developed to warrant the levying of tithes in the feudal system of 13th-century Portugal.
- Frouin, H., Loseto, L.L., Stern, G.A., Haulena, M., and Ross, P.S. Mercury toxicity in beluga whale lymphocytes: Limited effects of selenium protection. Aquatic Toxicology 109: 185-193, 2012.
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Increasing emissions of anthropogenic mercury represents a growing concern to the health of high trophic level marine mammals. In its organic form, this metal bioaccumulates, and can be toxic to several physiological endpoints, including the immune system. In this study, we (1) evaluated the effects of inorganic mercury (mercuric chloride, HgCl2) and organic mercury (methylmercuric chloride, MeHgCl) on the in vitro function of lymphocytes isolated from the peripheral blood of beluga whales (Delphinapterus leucas); (2) characterized the potential protective effects of sodium selenite (Na2SeO3) on cell proliferation of HgCl2 or MeHgCl-treated beluga whale lymphocytes; and (3) compared these dose-dependent effects to measurements of blood Hg in samples collected from traditionally harvested beluga whales in the western Canadian Arctic. Lymphocyte proliferative responses were reduced following exposure to 1 μM of HgCl2 and 0.33 μM of MeHgCl. Decreased intracellular thiol levels were observed at 10 μM of HgCl2 and 0.33 μM of MeHgCl. Metallothionein induction was noted at 0.33 μM of MeHgCl. Concurrent exposure of Se provided a degree of protection against the highest concentrations of inorganic Hg (3.33 and 10 μM) or organic Hg (10 μM) for T-lymphocytes. This in vitro protection of Se against Hg toxicity to lymphocytes may contribute to the in vivo protection in beluga whales exposed to high Hg concentrations. Current Hg levels in free-ranging beluga whales from the Arctic fall into the range of exposures which elicited effects on lymphocytes in our study, highlighting the potential for effects on host resistance to disease. The implications of a changing Arctic climate on Hg fate in beluga food webs and the consequences for the health of beluga whales remain pressing research needs.
- Doucette, G.J., Mikulski, C.M., King, K.L., Roth, P.B., Wang, Z., Leandro, L.F., DeGrasse, S.L., White, K.D., De Biase, D., Gillett, R.M., and Rolland, R.M. Endangered North Atlantic right whales (Eubalaena glacialis) experience repeated, concurrent exposure to multiple environmental neurotoxins produced by marine algae. Environmental Research 112: 67-76, 2012.
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The western North Atlantic population of right whales (Eubalaena glacialis) is one of the most critically endangered of any whale population in the world. Among the factors considered to have potentially adverse effects on the health and reproduction of E. glacialis are biotoxins produced by certain microalgae responsible for causing harmful algal blooms. The worldwide incidence of these events has continued to increase dramatically over the past several decades and is expected to remain problematic under predicted climate change scenarios. Previous investigations have demonstrated that N. Atlantic right whales are being exposed to at least two classes of algal-produced environmental neurotoxins—paralytic shellfish toxins (PSTs) and domoic acid (DA). Our primary aims during this six-year study (2001–2006) were to assess whether the whales' exposure to these algal biotoxins occurred annually over multiple years, and to what extent individual whales were exposed repeatedly and/or concurrently to one or both toxin classes. Approximately 140 right whale fecal samples obtained across multiple habitats in the western N. Atlantic were analyzed for PSTs and DA. About 40% of these samples were attributed to individual whales in the North Atlantic Right Whale Catalog, permitting analysis of biotoxin exposure according to sex, age class, and reproductive status/history. Our findings demonstrate clearly that right whales are being exposed to both of these algal biotoxins on virtually an annual basis in multiple habitats for periods of up to six months (April through September), with similar exposure rates for females and males (PSTs: ~70–80%; DA: ~25–30%). Notably, only one of 14 lactating females sampled did not contain either PSTs or DA, suggesting the potential for maternal toxin transfer and possible effects on neonatal animals. Moreover, 22% of the fecal samples tested for PSTs and DA showed concurrent exposure to both neurotoxins, leading to questions of interactive effects. Targeted studies employing both in vivo and in vitro model systems represent the next logical step in assessing how and to what extent these algal biotoxins might compromise the health and reproduction of this endangered population.
- Buckman, A.H., Veldhoen, N., Ellis, G., Ford, J.K.B., Helbing, C.C., and Ross, P.S. PCB-associated changes in mRNA expression in killer whales (Orcinus orca) from the NE Pacific Ocean. Environmental Science and Technology 45(23): 10194-10202, 2011.
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Killer whales in the NE Pacific Ocean are among the world's most PCB-contaminated marine mammals, raising concerns about implications for their health. Sixteen health-related killer whale mRNA transcripts were analyzed in blubber biopsies collected from 35 free-ranging killer whales in British Columbia using real-time quantitative polymerase chain reaction. We observed PCB-related increases in the expression of five gene targets, including the aryl hydrocarbon receptor (AhR; r2 = 0.83; p < 0.001), thyroid hormone α receptor (TRα; r2 = 0.64; p < 0.001), estrogen α receptor (ERα; r2 = 0.70; p < 0.001), interleukin 10 (IL-10; r2 = 0.74 and 0.68, males and females, respectively; p < 0.001), and metallothionein 1 (MT1; r2 = 0.58; p < 0.001). Best-fit models indicated that population (dietary preference), age, and sex were not confounding factors, except for IL-10, where males differed from females. While the population-level consequences are unclear, the PCB-associated alterations in mRNA abundance of such pivotal end points provide compelling evidence of adverse physiological effects of persistent environmental contaminants in these endangered killer whales.
- Higdon, J.W. and Ferguson, S.H. Reports of humpback and minke whales in the Hudson Bay region, eastern Canadian Arctic. Northeastern Naturalist 18(3): 370-377, 2011.
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We summarize recently reported sightings of Megaptera novaeangliae (Humpback Whales) and Balaenoptera acuturostrata (Minke Whales) in the Hudson Bay region, in the eastern Canadian Arctic. Balaena mysticetus (Bowhead Whale) is the only baleen whale historically known from Hudson Bay, and during the commercial whaling era (1860–1915), no other large whale was reported to occur there. We note recent (ca. last 10 years) Humpback observations reported by local Inuit hunters in Hudson Bay and northern Foxe Basin. One Humpback was also observed by cetacean biologists in Ungava Bay during an aerial survey for Delphinapterus leucas (Beluga Whales). Minke Whales have previously been reported in southern Hudson Bay and James Bay, and recent discussions with Inuit hunters have indicated possible sightings in Foxe Basin and western Hudson Bay. They are commonly observed by Inuit in eastern Hudson Strait, where there have also been recent detections by biologists. Observations of these species in Hudson Bay and Foxe Basin may be related to reduced ice cover and increased open water, changes in prey species distributions, population recovery and growth following commercial whaling, or some combination of factors. More efficient reporting of observations is needed, and improved community-level monitoring would assist with documentation of temperate-region species in high-latitude areas.
- Parks, S.E., Warren, J.D., Stamieszkin, K., Mayo, C.A., and Wiley, D. Dangerous dining: surface foraging of North Atlantic right whales increases risk of vessel collisions. Biology Letters 8(1): 57-60, 2012.
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North Atlantic right whales are critically endangered and, despite international protection from whaling, significant numbers die from collisions with ships. Large groups of right whales migrate to the coastal waters of New England during the late winter and early spring to feed in an area with large numbers of vessels. North Atlantic right whales have the largest per capita record of vessel strikes of any large whale population in the world. Right whale feeding behaviour in Cape Cod Bay (CCB) probably contributes to risk of collisions with ships. In this study, feeding right whales tagged with archival suction cup tags spent the majority of their time just below the water's surface where they cannot be seen but are shallow enough to be vulnerable to ship strike. Habitat surveys show that large patches of right whale prey are common in the upper 5 m of the water column in CCB during spring. These results indicate that the typical spring-time foraging ecology of right whales may contribute to their high level of mortality from vessel collisions. The results of this study suggest that remote acoustic detection of prey aggregations may be a useful supplement to the management and conservation of right whales.
- Alava, J.J., Barragán, M.J., and Denkinger, J. Assessing the impact of bycatch on Ecuadorian humpback whale breeding stock: A review with management recommendations. Ocean and Coastal Management 57: 34-43, 2012.
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The Southeastern Pacific Humpback whale Megaptera novaeangliae reproduces from June to September off the coast of Ecuador where a large artisanal fisheries fleet consisting of more than 15,000 vessels operates year round. The bycatch impact on this humpback population has been overlooked. Based on the annual bycatch mortality documented in this study, about 0.53% (95% CI 0.2–1.5%) of the population might be potentially bycaught in gillnets annually. Depending on the total population numbers estimated and reported elsewhere for this stock (2917 or 6277 whales), the bycatch mortality is equivalent to 15 or 33 whales per year. A significant correlation was found between the annual bycatch rate and fishing effort for the period 2000–2009 (r = 0.68, p < 0.05). An increase in artisanal fisheries may cause drastic consequences since humpback whales as K-strategists have low birth and survival rates. Calves are probably the most threatened age class due to gillnet entanglements in proximity to coastal waters where artisanal vessels operate. The Ecuadorian breeding grounds for humpback whales migrating from Antarctica might become a hot spot for bycatch in the Southeastern Tropical Pacific, if the bycatch rate continues to increase. Urgent mitigation strategies coupled with precautionary management and conservation measures are required to protect this vulnerable stock of whales in the long term. The consequences of humpback whale bycatch off coastal Ecuador and possible solutions to mitigate the bycatch are analyzed.
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