Whale Mortality Research Articles

Bilateral Action for Right Whales

In their Policy Forum “North Atlantic right whales in crisis” (22 July, p. [561][1]), S. D. Kraus et al. make clear the plight of the North Atlantic right whale, Eubalaena glacialis , and note that whale deaths from ship strikes and fishing gear entanglements have not been diminishing. Kraus et al. call for changes to U.S. National Oceanic and Atmospheric Administration (NOAA) management policy to put strong and immediate emphasis on reducing human-induced mortality of right whales. The species, though, is not restricted to U.S. waters; it ranges from Florida to the Canadian Maritimes. It is listed as Endangered under both the U.S. Endangered Species Act and the Canadian Species at Risk Act. ![Figure][2] CREDIT: NOAA U.S. and Canadian protection and recovery policies for North Atlantic right whales, administered respectively by NOAA and Fisheries and Oceans Canada (DFO), are not precisely the same. Although the current U.S. and Canadian plans both make reducing mortality due to ship strike and net entrapment a higher priority than reducing habitat degradation, the Canadian plan does not address direct human lethal take ([1][3], [2][4]). Bilaterally agreed-upon management policy is essential for the protection of globally endangered migratory species that cross political boundaries. A precedent was set by the bilateral recovery efforts in aid of the whooping crane. Some level of cooperation between the two countries has been achieved regarding the right whale, but it is insufficient to call only for changes to NOAA management policy when coordinated, bilateral management; regular joint meetings; and cooperative actions are needed. The new U.S. recovery plan calls for bilateral cooperative efforts to maximize protection for right whales. Canadian recovery planning should follow suit and both jurisdictions should work together. 1. 1.[↵][5] National Marine Fisheries Service, Recovery Plan for the Northern Right Whale ( Eubalaena glacialis ) (National Marine Fisheries Service, Silver Spring, MD, 2005). 2. 2.[↵][6] North Atlantic Right Whale Recovery Team, Canadian North Atlantic Right Whale Recovery Plan (Department of Fisheries and Oceans, Ottawa, 2000). # Response {#article-title-2} We agree with Sayles and Green. Migratory transboundary species like the right whale require bilateral efforts at many levels. For example, the U.S. National Marine Fisheries Services' Advanced Notice of Proposed Rulemaking ([1][7]) does require the U.S. government to work with Canada to develop bilateral agreements related to shipping. Further, most co-authors on the Policy Forum have benefited from close working relationships with both researchers and managers within Fisheries and Oceans Canada (DFO). Several breakthroughs in right whale conservation have already been made in Canada, including relocation of the internationally adopted shipping lanes in the Bay of Fundy to reduce ship kills, as well as the official recognition of two Conservation Areas where right whales aggregate. The Bay of Fundy shipping lane changes resulted from efforts by Irving Oil, Transport Canada, DFO, the International Maritime Organization, fishing organizations, whale watching groups, and right whale conservationists. Such multilateral partnerships are especially important in conserving transboundary species. However, we are aware that DFO's ability to really make a difference to right whale conservation is dependent on funding for their initiatives, and support for recovery plan implementation has been limited. We encourage both the Canadian government and nongovernmental organizations to support increased funding for right whale conservation in Canada and welcome additional collaboration with our Canadian colleagues, particularly in the development of bilateral measures to ensure the protection of right whales throughout their range. 1. 1.[↵][8] Department of Commerce, National Oceanic and Atmospheric Administration, 50 CFR Part 224 [040506143-4143-01; I.D. 052504C] RIN 0648-AS36 Endangered Fish and Wildlife; Advance Notice of Proposed Rulemaking (ANPR) for Right Whale Ship Strike Reduction, U.S. Fed. Reg. 69 (No. 105), 30857 (2004). [1]: /lookup/doi/10.1126/science.1111200 [2]: pending:yes [3]: #ref-1 [4]: #ref-2 [5]: #xref-ref-1-1 View reference 1. in text [6]: #xref-ref-2-1 View reference 2. in text [7]: #ref-3 [8]: #xref-ref-3-1 View reference 1. in text

Killer whales and whaling: the scavenging hypothesis

Killer whales (Orcinus orca) frequently scavenged from the carcasses produced by whalers. This practice became especially prominent with large-scale mechanical whaling in the twentieth century, which provided temporally and spatially clustered floating carcasses associated with loud acoustic signals. The carcasses were often of species of large whale preferred by killer whales but that normally sink beyond their diving range. In the middle years of the twentieth century floating whaled carcasses were much more abundant than those resulting from natural mortality of whales, and we propose that scavenging killer whales multiplied through diet shifts and reproduction. During the 1970s the numbers of available carcasses fell dramatically with the cessation of most whaling (in contrast to a reasonably stable abundance of living whales), and the scavenging killer whales needed an alternative source of nutrition. Diet shifts may have triggered declines in other prey species, potentially affecting ecosystems, as well as increasing direct predation on living whales.

Whale mortality from ship strikes in Ecuador and West Africa

We document two unusual cases of a Bryde's and a sei whale struck by container cargo vessels and draped over the bow bulb, respectively in the Southeast Pacific and the Eastern Tropical Atlantic. The 207m-length P&O Nedlloyd Pantanal collided with an adult Bryde's whale Balaenoptera edeni in the southern Gulf of Guayaquil, Ecuador, on 10 December 2004. The whale showed massive dermal hematoma indicating that it was alive when struck. Similarly, the container ship OSNA Bruck arrived at Dakar port, Senegal, on 19 March 1998 with the fresh carcass of a juvenile sei whale B. borealis on its bow bulb. The collision occurred between Las Palmas, Gran Canaria and Dakar, Senegal. Freshly dead balaenopterids can hardly be picked up by ships since they sink at death and do not float until decomposition and bloating sets in. A review of previous cases show that ship strikes are rarely recorded in these regions, partly due to the lack of regulations, including no reporting obligation. However, the case studies reveal that another factor may severely augment under-reporting of ship strike mortality. In both instances the crew became aware of the collision only upon arrival at port, suggesting that whales which are hit and killed or wounded, but do not become draped over the bow bulb (if the vessel has one), go unnoticed. The probability of bow draping may be low, and modelling should be attempted. National authorities are encouraged to improve data collection and introduce regulations such as mandatory reporting. These are the first fully documented, fatal whale collisions in Ecuador and West Africa (south of the Canary Islands), and the first struck and killed Bryde's whale in the Southeast Pacific.

CONSEQUENCES OF ALTERNATIVE FUNCTIONAL RESPONSE FORMULATIONS IN MODELS EXPLORING WHALE‐FISHERY INTERACTIONS

AbstractWe evaluated the utility of Ecosim for exploring interactions between cetacean predators, their prey, and fisheries. We formulated six Ecosim parameterizations, representing alternative hypotheses of feeding interactions (functional response) between cetaceans and their main fish prey, and examined differences in the predicted responses to simulated harvesting regimes for minke whales and their prey. Regardless of the type of function response formulated, intense fishing on the main fish prey of minke whales had a longer‐lasting negative impact on minke whales than when minke whale biomass was removed directly by harvesting. Consumption rate, biomass, feeding time and mortality of minke whales were all sensitive to the type of functional response specified. Inclusion of “handling time” limited minke whales consumption at high prey densities and predicted higher consumption at low prey densities; features characteristic of a type II functional response. Predicted decline and recovery rates of minke whales were slower than when consumption rates were not limited. Addition of “foraging time” adjustments resulted in more conservative estimates of decline and recovery. However, when “other mortality” was linked to time spent foraging, exposure to higher mortality at low prey densities, and reduced mortality at high prey densities resulted in dramatic differences in predicted biomass trajectory. Sensitivity to the “other mortality” assumption is important for cetaceans whose predation mortality is only a small proportion of total mortality. Differences in the feeding and biomass dynamics were also observed when prey availability to predators was represented by changes in prey vulnerability, confirming earlier reports that Ecosim predictions are sensitive to this parameter.

Abundance and mortality of gray whales at Laguna San Ignacio, Mexico, during the 1997-98 El Niño and the 1998-99 La Niña

Este trabajo presenta los cambios observados en la abundancia y mortalidad de las ballenas grises en la Laguna San Ignacio durante 1998 y 1999. En estos años se realizaron 28 censos semanales (febrero 8 a marzo 28) y se consideraron los registros de ballenas muertas de 1996-99. La abundancia de las ballenas sin crías (solitarias) fue similar en estos dos años; sin embargo, para las ballenas con cría se observó una disminución significativa en su abundancia además de un retraso en su pico de abundancia. El número de crías muertas fue similar al observado en estudios previos, pero la proporción de la mortalidad de ballenas adultas fue mucho más alta (60%). La tasa mínima de mortalidad de crías en 1998 y 1999 ha sido la más alta registrada en estudios previos en esta laguna, 1977-82 y 1996-97. Se plantea la hipótesis de que los eventos de El Niño y La Niña tuvieron un efecto en la mortalidad y en las condiciones nutricionales de las ballenas, así como en su área de distribución invernal.doi: sin doi

Demography of the endangered North Atlantic right whale.

Northern right whales (Eubalaena glacialis) were formerly abundant in the northwestern Atlantic, but by 1900 they had been hunted to near extinction. After the end of commercial whaling the population was thought to be recovering slowly; however, evidence indicates that it has been declining since about 1990 (ref. 1). There are now fewer than 300 individuals, and the species may already be functionally extinct owing to demographic stochasticity or the difficulty of females locating mates in the vast Atlantic Ocean (Allee effect). Using a data set containing over 10,000 sightings of photographically identified individuals we estimated trends in right whale demographic parameters since 1980. Here we construct, using these estimates, matrix population models allowing us to analyse the causes of right whale imperilment. Mortality has increased, especially among mother whales, causing declines in population growth rate, life expectancy and the mean lifetime number of reproductive events between the period 1980-1995. Increased mortality of mother whales can explain the declining population size, suggesting that the population is not doomed to extinction as a result of the Allee effect. An analysis of extinction time shows that demographic stochasticity has only a small effect, but preventing the deaths of only two female right whales per year would increase the population growth rate to replacement level.

COLLISIONS BETWEEN SHIPS AND WHALES

AbstractAlthough collisions with motorized ships are a recognized source of whale mortality, little has been done to compile information on the frequency of their occurrence or contributing factors. We searched historical records and computerized stranding databases for evidence of ship strikes involving great whales (i. e., baleen whales and the sperm whale). Historical records suggest that ship strikes fatal to whales first occurred late in the 1800s as ships began to reach speeds of 13‐15 kn, remained infrequent until about 1950, and then increased during the 1950s‐1970s as the number and speed of ships increased. Of 11 species known to be hit by ships, fin whales (Balaenoptera physalus) are struck most frequently; right whales (Eubalaena glacialis and E. australis), humpback whales (Megaptera novaeangliae), sperm whales (Physeter catodon), and gray whales (Escbricbtius robustus) are hit commonly. In some areas, one‐third of all fin whale and right whale strandings appear to involve ship strikes. To assess contributing factors, we compiled descriptions of 58 collisions. They indicate that all sizes and types of vessels can hit whales; most lethal or severe injuries are caused by ships 80 m or longer; whales usually are not seen beforehand or are seen too late to be avoided; and most lethal or severe injuries involve ships travelling 14 kn or faster. Ship strikes can significantly affect small populations of whales, such as northern right whales in the western North Atlantic. In areas where special caution is needed to avoid such events, measures to reduce the vessel speed below 14 kn may be beneficial.

High gray whale mortality and low recruitment in 1999: potential causes and implications

This paper documents the high incidence of gray whale deaths in 1999 and presents the hypothesis that some of the whales were starving. Predictions from this hypothesis are tested using data on the frequency and distribution of strandings, the sex and age composition of strandings, estimates of recruitment and physiological condition, and observations of foraging during migration. The data come from multiple sources. The mortality count of 274 gray whales in 1999 was twice as high as in any previous year dating back to 1985. Dead whales were widely distributed along the migratory route, with the majority observed on the northward migration from the Mexican breeding lagoons to Alaska. Most mortalities in Mexico and California were adults and immatures, rather than the usual calves and yearlings. The majority of dead adults in Mexico, California and the Oregon/Washington region were females. Many dead whales were emaciated. Calf production was lower than in the previous six years. Aberrancies in timing and location of migration, as well as foraging on pelagic prey, were observed. These results, and an even higher stranding rate in the Mexican breeding lagoons in 2000, are consistent with the hypothesis that the whales were undernourished. It is argued that the most likely cause of this condition was a decline in the biomass of their principal prey, the benthic amphipods in the Bering and Chukchi Seas over the last decade, due in part to the combined effects of increasing sea surface temperatures and increased predation from the growing population of gray whales themselves. A significant decline in amphipod density could have long-term effects on the future growth and stability of the gray whale population because amphipods recover slowly given their low fecundity and long generation times. Annual monitoring of the status of the amphipods in the Bering and Chukchi Seas, and the effect of inter alia sea surface temperature on their biomass, is vital for understanding fluctuations in gray whale mortality and numbers, and the extent to which they are dependent on this food resource.

Chemical contaminants in gray whales ( Eschrichtius robustus) stranded along the west coast of North America

The concentrations of selected chlorinated hydrocarbons (e.g. PCBs, DDTs, DDEs, chlordanes) and essential (e.g. zinc, selenium, copper) and toxic (e.g. mercury, lead, arsenic) elements were measured in tissues and stomach contents from 22 gray whales ( Eschrichtius robustus) stranded between 1988 and 1991 at sites from the relatively pristine areas of Kodiak Island, AK, to more urbanized areas in Puget Sound, WA, and San Francisco Bay, CA. The majority of animals were stranded at sites on the Washington outer coast and in Puget Sound. The gray whale has the unique feeding strategy among Mysticeti of filtering sediments to feed on benthic (bottom dwelling) invertebrates. Thus, the wide geographical distribution of the stranded whales allowed (1) an initial assessment of whether concentrations of chemical contaminants in these whales exhibited region specific differences and (2) whether toxic chemicals that accumulate in sediments may have contributed to the mortality and stranding of gray whales near the more polluted urban areas. Analyses for chlorinated hydrocarbons in blubber from 22 animals showed no apparent significant differences among stranding sites. The concentrations of ΣPCBs and ΣDDEs in blubber, for example, ranged from 120 to 10000 and 9 to 2100 p.p.b. (ng/g) wet weight, respectively. Additionally, analyses of chlorinated hydrocarbons and selected elements in liver ( n = 10) also showed no apparent significant differences between whales stranded in Puget Sound and whales stranded at more pristine sites (Alaska, Washington outer coast and Strait of Juan de Fuca and Strait of Georgia). For example, the concentrations of ΣPCBs and ΣDDEs in liver ranged from 79 to 1600 and 7 to 280 p.p.b., respectively, and the concentrations of the toxic elements, mercury and lead ranged from 9 to 120 and 20 to 270 p.p.b., respectively. Analyses of stomach contents revealed low concentrations of chlorinated hydrocarbons, but high concentrations (wet weight) of aluminum (1700 000 ± 450 000 p.p.b.), iron (320000 ± 250 000 p.p.b.), manganese (23 000 ± 15 000 p.p.b.), and chromium (3400 ± 1300 p.p.b.), but no significant differences were observed between whales stranded in Puget Sound compared to whales stranded at the more pristine sites. The relative proportions of these elements in stomach contents of stranded whales were similar to the relative proportions in sediments, which is consistent with a geological source of these elements from the ingestion of sediment during feeding. Thus, overall, the concentrations of anthropogenic chemicals in stranded gray whales showed little relation to the levels of chemical contaminants at the stranding sites. Further, the results showed that the concentrations of potentially toxic chemicals in tissues were relatively low when compared with the concentrations in tissues of marine mammals feeding on higher trophic level species, such as fish. The lack of data from apparently healthy gray whales, however, limits the assessment of whether the levels of anthropogenic contaminants found in tissues may have deleterious effects on the health of gray whales.

Ice entrapments of narwhals (Monodon monoceros) and white whales (Delphinapterus leucas) in Greenland

Information on historical and recent ice entrapments of narwhals (Monodon monoceros) and white whales (Delphinapterus leucas) in Greenland is presented. Most entrapments occur in the inner parts of Disko Bugt where both narwhals and white whales are caught. In this area entrapments happened under particular weather conditions and at certain sites at intervals of two to three years during the 197Os and 198Os.
 In the Uummannaq and Upernavik areas entrapments occurred less frequently and usually involved only narwhals. No entrapments were documented in East Greenland.
 The data suggest that whales sometimes die in entrapments that are not discovered by hunters and that ice entrapments may be regarded as contributing to the natural mortality of narwhals and white whales. These large-scale, periodic die-off events probably affect long-term population trends and represent a concern for the management of arctic whale stocks.

Scientific Correspondence Right Whale Mortality—A Correction and An Update

Marine Mammal ScienceVolume 9, Issue 4 p. 445-446 Scientific Correspondence Right Whale Mortality—A Correction and An Update Robert D. Kenney, Robert D. Kenney Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882-1197; Edgerton Research Laboratory, New England Aquarium, Boston, Massachusetts 02110-3309.Search for more papers by this authorScorr D. Klaus, Scorr D. Klaus Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882-1197; Edgerton Research Laboratory, New England Aquarium, Boston, Massachusetts 02110-3309.Search for more papers by this author Robert D. Kenney, Robert D. Kenney Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882-1197; Edgerton Research Laboratory, New England Aquarium, Boston, Massachusetts 02110-3309.Search for more papers by this authorScorr D. Klaus, Scorr D. Klaus Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882-1197; Edgerton Research Laboratory, New England Aquarium, Boston, Massachusetts 02110-3309.Search for more papers by this author First published: October 1993 https://doi.org/10.1111/j.1748-7692.1993.tb00480.xCitations: 12AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume9, Issue4October 1993Pages 445-446 RelatedInformation

RATES AND POTENTIAL CAUSES OF MORTALITY IN NORTH ATLANTIC RIGHT WHALES (EUBALAENA GLACIALIS)

AbstractNorth Atlantic right whale mortality rates range from 2% to 17% over the first four years of life. Sources of mortality in this population include ship collisions, entanglements, and natural causes. A combined analysis of stranding data, entanglement records, and photographic information indicates that approximately one third of all right whale mortality is caused by human activities. Anthropogenic sources of right whale mortality may be a significant factor inhibiting growth in the North Atlantic population.

Growth, physical maturity, and mortality of fin whales (Balaenoptera physalus) inhabiting the temperate waters of the northeast Atlantic

Data obtained from the examination of the ear plugs of 665 specimens were used to estimate age-related parameters for the fin whale population inhabiting the temperate waters of the northeastern Atlantic. Samples were collected from 1979 to 1984 at the Spanish whaling stations. The length of the ear plug core strongly correlated with the number of growth layers in whales younger than 25 years of age but showed no correlation in older whales. Readability of ear plug growth layers decreased with age in females but showed no clear trends in males. Minimum size limits of the fishery produced a selective fishing mortality rate in whales up to 5 years of age. Hence, only age-classes older than 5 years have been included in the fitting of the growth curves. Fully grown females are 1.47 m longer than males, but their growth rate is slower. Thus, males reach 95% of asymptotic length at age 9 years, while females reach it at age 13. Fin whales of both sexes attain physical maturity when they are between 20 and 30 years old. Despite growing relatively slower, females are always larger than males and recruitment to the fishery occurs at an age of 5 years in females and 6 years in males. Apparent mortality rates are similar in young whales of both sexes, but are higher in adult females than in adult males; the most plausible explanation for this difference is an increase in mortality associated with reproduction in sexually mature females.