The Vaquita: Can It Survive?

The vaquita (Spanish for "little cow"), or Gulf of California harbor porpoise (Phocoena sinus), has the most limited range of any marine cetacean and is probably the rarest. It has been caught incidentally in gill nets set commercially for totoaba (Totoaba macdonaldi), large fish that were over-exploited in the upper Gulf of California until they, too, were endangered. In 1975. the Mexican Government announced a total indefinite closure on fishing for totoaba, Between the time this porpoise was described as new to science (1958) and its listing by the U.S. Fish and Wildlife Service as Endangered (early 1985), the vaquita was known from only 26 confirmed records (partial remains found on beaches) and a few sightings of live animals. (Note: the vernacular name "cochito" was cited when this animal was listed, but biologists have since learned that "vaquita" is the term used by most local fishermen.) The Endangered Species Technical Bulletin story about its listing (see BULLETIN Vol. X No. 2) said the species was on the brink of extinction "if it still exists."

Biological Background on Bottlenose Dolphins (Tursiops spp.) in the 'Live-Capture' Trade and Specifically on the Indo-Pacific Bottlenose Dolphin, T. Aduncus

The most significant cetacean trade items until commercial whaling all but ceased in the 1990s (aside from scientific exchanges of tissues etc.) were meat and blubber from baleen whales for human consumption. Since then, live dolphins and 'small' whales for display (and to some extent for research, military use, and 'therapy') have become the most significant cetacean 'products' in international trade. Trade in live cetaceans is presently dominated by bottlenose dolphins (Tursiops spp.), beluga whales (Debhinapterns leucas) and to a lesser extent killer whales (Orcinus orca) (Fisher and Reeves 2005). In the past, most of the dolphins in trade were common bottlenose dolphins (Tursiops truncatus) originating in the United States, Mexico and the Black Sea, but since the 1980s the United States has essentially stopped its capture-for-export activities and in 2001Mexico implemented a moratorium on live-captures. The source countries for dolphins in trade are now geographically diverse, but Cuba and Japan are currently major source nations for common bottlenose dolphins. Russia is the only current source for belugas. Russia and Japan have become the main potential sources for killer whales since Iceland ceased exporting them in the 1980s or early 1990s.

Saving the Vaquita: Immediate Action, Not More Data

The recent likely extinction of the baiji (Chinese river dolphin [Lipotes vexillifer]) (Turvey et al. 2007) makes the vaquita (Gulf of California porpoise [Phocoena sinus]) the most endangered cetacean. The vaquita has the smallest range of any porpoise, dolphin, or whale and, like the baiji, has long been threatened primarily by accidental deaths in fishing gear (bycatch) (Rojas-Bracho et al. 2006). Despite repeated recommendations from scientific bodies and conservation organizations, no effective actions have been taken to remove nets from the vaquita’s environment. Here, we address three questions that are important to vaquita conservation: (1) How many vaquitas remain? (2) How much time is left to find a solution to the bycatch problem? and (3) Are further abundance surveys or bycatch estimates needed to justify the immediate removal of all entangling nets from the range of the vaquita? Our answers are, in short: (1) there are about 150 vaquitas left, (2) there are at most 2 years within which to find a solution, and (3) further abundance surveys or bycatch estimates are not needed. The answers to the first two questions make clear that action is needed now, whereas the answer to the last question removes the excuse of uncertainty as a delay tactic. Herein we explain our reasoning.

A note on the unprecedented strandings of 56 deep-diving whales along the UK and Irish coast

In the first seven months of 2008, eighteen Cuvier’s beaked whales (Ziphius cavirostris), four Sowerby’s beaked whales (Mesoplodon bidens), five unidentified beaked whales and twenty-nine long-finned pilot whales (Globicephala melas) were reported stranded in the UK and Ireland. Decomposition of those animals investigated puts the predicted time of death at mid-January. Concerns that an unusual mortality event had taken place prompted further investigations. Most carcasses were too decomposed for necropsy. A summary of findings is presented here. Although the initial stranding of five Cuvier’s beaked whales in Scotland shared some similarities with atypical mass stranding events linked in time and space to mid-frequency naval sonars, there were two important differences with the remaining strandings during this period. First, the geographical range of the event was very wide and second, the strandings occurred over a prolonged period of several months. Both of these factors could be related to the fact that the mortalities occurred offshore and the carcasses drifted ashore. The cause(s) of this high number of strandings of mixed offshore cetacean species during this period remain undetermined.

Indo-Pacific Bottlenose Dolphin Assessment Workshop Report

A workshop on the assessment of Indo-Pacific bottlenose dolphins (Tursiops aduncus), with the Solomon Islands as a case study, took place from 21-23 August 2008 in Apia, Samoa. It was planned and organized under the auspices of the Cetacean Specialist Group and attended by 19 invited participants from eight countries. Financial support was provided by WWF (International), The Ocean Conservancy, Animal Welfare Institute, Humane Society of the United States, Whale and Dolphin Conservation Society, U.S. Marine Mammal Commission and U.S. National Oceanic and Atmospheric Administration. The workshop was hosted by the Secretariat of the Pacific Regional Environment Program (SPREP). Live-capture, holding in captivity and export of Indo-Pacific bottlenose dolphins from the Solomon Islands began in 2003. These activities stimulated global interest and generated concern about the potential conservation implications. The IUCN Global Plan of Action for the Conservation of Cetaceans had stated that as a general principle, small cetaceans should not be captured or removed from a wild population unless that specific population has been assessed and shown capable of sustaining the removals. A principal goal of the present workshop was to elaborate on the elements of an assessment that would meet this standard. Participants noted that an assessment involving delineation of stock boundaries, abundance, reproductive potential, mortality and trend cannot necessarily be achieved quickly or inexpensively.

Evolution of river dolphins

The world's river dolphins (Inia, Pontoporia, Lipotes and Platanista) are among the least known and most endangered of all cetaceans. The four extant genera inhabit geographically disjunct river systems and exhibit highly modified morphologies, leading many cetologists to regard river dolphins as an unnatural group. Numerous arrangements have been proposed for their phylogenetic relationships to one another and to other odontocete cetaceans. These alternative views strongly affect the biogeographical and evolu- tionary implications raised by the important, although limited, fossil record of river dolphins. We present a hypothesis of river dolphin relationships based on phylogenetic analysis of three mitochondrial genes for 29 cetacean species, concluding that the four genera represent three separate, ancient branches in odontocete evolution. Our molecular phylogeny corresponds well with the first fossil appearances of the primary lineages of modern odontocetes. Integrating relevant events in Tertiary palaeoceanography, we develop a scenario for river dolphin evolution during the globally high sea levels of the Middle Miocene. We suggest that ancestors of the four extant river dolphin lineages colonized the shallow epicontinental seas that inundated the Amazon, Parana, Yangtze and Indo-Gangetic river basins, subsequently remaining in these extensive waterways during their transition to freshwater with the Late Neogene trend of sea-level lowering.

Mandibular fractures in short-finned pilot whales, Globicephala macrorhynchus

This study’s objective was to investigate mandibular fractures in 50 short-finned pilot whales, Globicephala macrorhynchus, from two mass strandings. Based on current theories that this species is sexually dimorphic and polygynous, hypotheses were: (1) males should suffer more frequent or more substantial mandibular fractures than should females, and (2) fracture occurrence should increase with male reproductive maturity and potential correlates of maturity, such as age and length. Fractures were described and correlated with physical characteristics to infer possible explanations for injuries. Mandibular fractures were surprisingly common in males and females, being found in more than half of the animals examined (27/50, or 54% overall; 17/36 or 47% of females and 10/14 or 71% of males). Length was the only correlate of fracture presence; the proportion of animals showing evidence of fracture increased with length. These results offer some support to initial hypotheses, but there must be another set of consequences that contribute to mandibular fractures in females. A combination of intra- and interspecific interactions and life history characteristics may be responsible for fractures. Further research from a larger sample of this and other cetacean species are suggested to help elucidate both the causes and implications of mandibular fractures.

Cetaceans of Southeast Alaska: Distribution and Seasonal Occurrence

Aim To assess the distribution, group size, seasonal occurrence and annual trends of cetaceans. Location The study area included all major inland waters of Southeast Alaska. Methods Between 1991 and 2007, cetacean surveys were conducted by observers who kept a constant watch when the vessel was underway and recorded all cetaceans encountered. For each species, we examined distributional patterns, group size, seasonal occurrence and annual trends. Analysis of variance (anova F) was used to test for differences in group sizes between multiple means, and Student’s t-test was used to detect differences between pairwise means. Cetacean seasonal occurrence and annual trends were investigated using a generalized linear model framework. Results Humpback whales (Megaptera novaeangliae) were seen throughout the region, with numbers lowest in spring and highest in the fall. Fin whale (Balaenoptera physalus) and minke whale (Balaenoptera acutorostrata) distributions were more restricted than that reported for humpback whales, and the low number of sightings precluded evaluating seasonal trends. Three killer whale (Orcinus orca) eco-types were documented with distributions occurring throughout inland waters. Seasonal patterns were not detected or could not be evaluated for resident and offshore killer whales, respectively; however, the transient eco-type was more abundant in the summer. Dall’s porpoise (Phocoenoides dalli) were distributed throughout the region, with more sightings in spring and summer than in fall. Harbour porpoise (Phocoena phocoena) distribution was clumped, with concentrations occurring in the Icy Strait/Glacier Bay and Wrangell areas and with no evidence of seasonality. Pacific white-sided dolphins (Lagenorhynchus obliquidens) were observed only occasionally, with more sightings in the spring. For most species, group size varied on both an annual and seasonal basis. Main conclusions Seven cetacean species occupy the inland waters of Southeast Alaska, with distribution, group size, seasonal occurrence and annual trends varying by species. Future studies that compare spatial and temporal patterns with other features (e.g. oceanography, prey resources) may help in identifying the key factors that support the high density and biodiversity of cetaceans found in this region. An increased understanding of the region’s marine ecology is an essential step towards ensuring the long-term conservation of cetaceans in Southeast Alaska.

A Novel Behavior Observed in Humpback Whales on Wintering Grounds at Abrolhos Bank (Brazil)

We describe a novel behavior, termed “tail-up,” observed in humpback whales (Megaptera novaeangliae) on wintering grounds on Abrolhos Bank, Brazil. The behavior involves the whale positioned vertically in the water column with its tail in the air. Wirh the exception of calves, tail-up was observed in all social classes, and its frequency increased through the end of the season. Tail-ups were recorded in 144 (5.8%) of 2,465 groups of whales observed from a shore station, and in 297 (14.9%) of 1,996 groups observed from vessel surveys; biases in each method suggest that the true frequency lies between these sources. One hundred and fifty-two hours of continuous sampling showed that the duration of tail-up events lasted from a few seconds to 12 min and was longest in groups comprised of a single adult. The maximum duration of a recorded period that consistently included tail-up was 10 h; however, some individuals were observed to engage in the behavior at night and for four consecutive days. Tail-up movement speed did not vary by social class; however, it varied according to wind direction and speed. The characteristics of tail-up that we observed showed that it differed from the descriptions of similar behaviors in other cetacean species. The function of tail-up is unknown, but we suggest that it may be a multifunctional behavior.

Levels of persistent organic pollutants and residual pattern of DDTs in small cetaceans from the coast of Sao Paulo, Brazil

The State of Sao Paulo is the most developed area in Brazil and was impacted by persistent organic pollutants for several decades. This study investigated organochlorines in five species of small cetaceans (Pontoporia blainvillei, Stenella frontalis, Sotalia guianensis, Tursiops truncatus and Steno bredanensis) found dead along the coast of Sao Paulo between 1997 and 2003. DDTs (15.9 mu g g(-1) lipid: mean for all pooled individuals) and PCBs (8.08 mu g g(-1)) exhibited the highest concentrations in the animals, reflecting large amounts formerly used in Brazil. Lower levels of mirex (0.149 mu g g(-1)), HCB (0.051 mu g g(-1)), CHLs (0.008 mu g g(-1)) and HCHs (0.007 mu g g(-1)) were detected in all species. Residual pattern of DDTs in dolphins suggests that o,p`-DDT is more recalcitrant than p,p`-DDT in the body of the animals and/or the environment. In contrast to p,p`-DDT, residues of o,p`-DDT seem to be preferentially converted into o,p`-DDD rather than op-DDE. (C) 2010 Elsevier Ltd. All rights reserved.

Skeletal abnormalities in humpback whales Megaptera novaeangliae stranded in the Brazilian breeding ground

Skeletal tissues of 49 humpback whales Megaptera novaeangliae that stranded between 2002 and 2011 along the Abrolhos Bank seashore and its adjacent waters in Brazil were studied. Twelve (24.5%) animals presented pathological changes in one or more bones. Degenerative changes and developmental malformations were most frequent (10.2% each), followed by inflammatory/infectious and traumatic lesions (8.2% each). Infectious diseases led to severe lesions of the caudal vertebrae of 2 whales. In one of these individuals, the lesions involved 6 caudal vertebrae, leading to ankylosis of 3 vertebrae. Degenerative changes were observed in the vertebral columns of 3 animals, involving the joints of 13 ribs of 1 individual, and in the humerus of 1 whale. Traumatic lesions, such as osseous callus in the ribs, were observed in 4 animals. In 1 whale, the rib showed severe osteomyelitis, possibly resulting from the infection of multiple fractures. Developmental abnormalities such as spina bifida on 3 cervical vertebrae of 1 whale, fusion of spinal processes on thoracic vertebrae of 1 individual and fusion of the first 2 ribs unilaterally or bilaterally in 4 animals were found. Chronic infectious conditions found in the axial skeleton may have restrained spinal mobility and had detrimental effects on the general health of the animals, contributing to stranding and death. To our knowledge, this is the first systematic study on skeletal lesions in stranded humpback whales.

Disentangling social networks from spatiotemporal dynamics: the temporal structure of a dolphin society

Social networks are static illustrations of dynamic societies, within which social interactions are constantly changing. Fundamental sources of variation include ranging behaviour and temporal demographic changes. Spatiotemporal dynamics can favour or limit opportunities for individuals to interact, and then a network may not essentially represent social processes. We examined whether a social network can embed such nonsocial effects in its topology, whereby emerging modules depict spatially or temporally segregated individuals. To this end, we applied a combination of spatial, temporal and demographic analyses to a long-term study of the association patterns of Guiana dolphins, Sotalia guianensis. We found that association patterns are organized into a modular social network. Space use was unlikely to reflect these modules, since dolphins' ranging behaviour clearly overlapped. However, a temporal demographic turnover, caused by the exit/entrance of individuals (most likely emigration/immigration), defined three modules of associations occurring at different times. Although this factor could mask real social processes, we identified the temporal scale that allowed us to account for these demographic effects. By looking within this turnover period (32 months), we assessed fission-fusion dynamics of the poorly known social organization of Guiana dolphins. We highlight that spatiotemporal dynamics can strongly influence the structure of social networks. Our findings show that hypothetical social units can emerge due to the temporal opportunities for individuals to interact. Therefore, a thorough search for a satisfactory spatiotemporal scale that removes such nonsocial noise is critical when analysing a social system. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

An insight into the populations of blainville's and curvier's beaked whales off El Hierro (Canary Islands)

Trabajo realizado por: Reyes, C., Schiavi, A., Aguilar del Soto,

Habitat use of migrating dwarf minke whales (Balaenoptera acutorostrata subspecies) in Tasmanian waters

The Great Barrier Reef hosts the only known reliable aggregation of dwarf minke whale (Balaenoptera acutorostrata subspecies) in Australian waters. While this short seasonal aggregation is quite predictable, the distribution and movements of the whales during the rest of their annual cycle are poorly understood. In particular, feeding and resting areas on their southward migration which are likely to be important have not been described. Using satellite telemetry data, I modelled the habitat use of seven whales during their southward migration through waters surrounding Tasmania. The whales were tagged with LIMPET satellite tags in the GBR in July 2013 (2 individuals) and 2014 (5 individuals). The study area around Tasmania was divided into 10km² cells and the time spent by each individual in each cell was calculated and averaged based on the number of animals using the cell. Two areas of high residency time were highlighted: south-western Bass Strait and Storm Bay (SE Tasmania). Remotely sensed ocean data were extracted for each cell and averaged temporally during the entire period of residency. Using Generalised Additive Models I explored the influence of key environmental characteristics. Nine predictors (bathymetry, distance from coast, distance from shore, gradient of sea surface temperature, sea surface height (absolute and variance), gradient of current speed, wind speed and chlorophyll-a concentration) were retained in the final model which explained 68% of the total variance. Regions of higher time-spent values were characterised by shallow waters, proximity to the coast (but not to the shelf break), high winds and sea surface height but low gradient of sea surface temperature. Given that the two high residency areas corresponded with regions where other marine predators also forage in Bass Strait and Storm Bay, I suggest the whales were probably feeding, rather than resting in these areas.

(Table 1) Beluga (Delphinapterus leucas) density and abundance, and pod characteristics in west Greenland waters

An aerial survey was conducted to estimate the abundance of belugas (Delphinapterus leucas) on their wintering ground in West Greenland in March-April 2006 and 2008. The survey was conducted as a double platform aerial line transect survey, and sampled approximately 17% of the total survey area of ca. 125 000 km**2. The abundance of belugas was 10 595 (95% confidence interval 4904-24 650). The largest abundance was found at the northern part of Store Hellefiske Bank, at the eastern edge of the Baffin Bay pack ice, a pattern similar to that found in eight systematic surveys conducted since 1981. A clear relationship between decreasing sea-ice cover and increasing offshore distance of beluga sightings was established from all previous surveys, suggesting that belugas expand their distribution westward as new areas on the banks of West Greenland open up earlier in spring with reduced sea-ice coverage or early annual ice recession. This is in contrast to the relatively confined distribution of belugas near the coast in limited open areas in the early 1980s, when sea-ice cover was greater. However, the effects of the changes in coastal availability of belugas can also be observed with the correlation between catches from the local Inuit hunt and sea-ice cover, where the catches increased significantly with increasing sea-ice coverage during the period 1954-2006. These results, based on nearly 30 years of dedicated survey effort, are among the first available evidence showing a shift in distribution of an Arctic cetacean in response to changes in sea-ice coverage.