3 resultados para preposition-stranding

em DigitalCommons@University of Nebraska - Lincoln


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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.

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I. Gunter and Christmas (1973) described the events leading to the stranding of a baleen whale on Ship Island, Mississippi, in 1968, giving the species as Balaenopteru physalus, the Rorqual. Unfortunately the identification was in error, but fortunately good photographs were shown. The underside of the tail was a splotched white, but there was no black margin. The specimen also had fewer throat and belly grooves than the Rorqual, as a comparison with True’s (1904) photograph shows. Dr. James Mead (in litt.) pointed out that the animal was a Sei Whale, Balaenoptera borealis. This remains a new Mississippi record and according to Lowery’s (1974) count, it is the fifth specimen reported from the Gulf of Mexico. The stranding of a sixth Sei Whale on Anclote Keys in the Gulf, west of Tarpon Springs, Florida on 30 May 1974, was reported in the newspapers and by the Smithsonian Institution (1974). II. Gunter, Hubbs and Beal (1955) gave measurements on a Pygmy Sperm Whale, Kogia breviceps, which stranded on Mustang Island on the Texas coast and commented upon the recorded variations of proportional measurements in this species. Then according to Raun, Hoese and Moseley (1970) these questions were resolved by Handley (1966), who showed that a second species, Kogia simus, the Dwarf Sperm Whale, is also present in the western North Atlantic. Handley’s argument is based on skull comparisons and it seems to be rather indubitable. According to Raun et al. (op. cit.), the stranding of a species of Kogia on Galveston Island recorded by Caldwell, Ingles and Siebenaler (1960) was K. simus. They also say that Caldwell (in litt.) had previously come to the same conclusion. Caldwell et al. also recorded another specimen from Destin, Florida, which is now considered to have been a specimen of simus. The known status of these two little sperm whales in the Gulf is summarized by Lowery (op. cit.).

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Killer whale predation on belugas in Cook Inlet, Alaska, has become a concern since the decline of these belugas was documented during the 1990s. Accordingly, killer whale sightings were compiled from systematic surveys, observer databases, and anecdotal accounts. Killer whales have been relatively common in lower Cook Inlet (at least 100 sightings from 1975 to 2002), but in the upper Inlet, north of Kalgin Island, sightings were infrequent (18 in 27 yr), especially prior to the 1990s. Beach cast beluga carcasses with teeth marks and missing flesh also provided evidence of killer whale predation. Most observed killer whale/beluga interactions were in the upper Inlet. During 11 of 15 observed interactions, belugas were obviously injured or killed, either through direct attacks or indirectly as a result of stranding. Assuming at least one beluga mortality occurred during the other four encounters, we can account for 21 belugas killed between 1985 and 2002. This would suggest a minimum estimate of roughly l/yr and does not include at least three instances where beluga calves accompanied an adult that was attacked.