Potential Welfare Impacts of Chase and Capture of Small Cetaceans during Drive Hunts in Japan.

Drive hunts are a method to herd, capture and kill small cetaceans (whales and dolphins) in coastal waters of some countries including Japan and the Faroe Islands. In Japan, these methods are often associated with the acquisition of live dolphins for international marine parks and aquaria. During the hunts, dolphins are herded by a flotilla of fishing vessels and loud underwater noise created by fishermen banging hammers on metal poles. The prolonged and strenuous chase and use of sound barriers to herd, capture, and restrain the dolphins can result in acute stress and injury. The authors review physiological and behavioral data pertaining to chase, encirclement, and live capture of dolphins and draw comparisons between chase and capture data for marine and terrestrial species. This analysis raises substantial welfare concerns associated with the hunts and acquisition of dolphins from such capture operations. The authors assert that this data detailing the negative impacts of chase, herding and handling (capture) of small cetaceans renders these hunts inherently inhumane and should inform policy relating to the collection and management of dolphins in the wild.

Epidermal Lesions and Injuries of Coastal Dolphins as Indicators of Ecological Health.

Humpback dolphins (genus Sousa), obligatory inshore delphinids, are frequently exposed to adverse effects of many human activities. In Hong Kong, one of the world's most urbanised coastal regions, ~ 50% of the dolphins suffer from at least one type of epidermal lesions, likely related to anthropogenically degraded habitat. Furthermore, one in every ten dolphins has physical injuries indicative of vessel collisions, propeller cuts and fishing-gear entanglements. As top predators with long lifespan, dolphins are good "barometers" of marine environment and their compromised health conditions are symptomatic of increasingly degraded ecological conditions of coastal seas, especially in rapidly developing regions of fast-growing economies.

Unsustainable human-induced injuries to the Critically Endangered Taiwanese humpback dolphins (Sousa chinensis taiwanensis).

The Critically Endangered Taiwanese humpback dolphin (Sousa chinensis taiwanensis) is endemic to inshore and estuarine waters of central western Taiwan. It numbers fewer than 75 individuals, is declining and faces a myriad of human threats. Data from a long-term photo-identification program on these dolphins allowed major injuries to be examined quantitatively. A large proportion (57.7%) of individuals had suffered major human-induced injuries that likely compromised their health, survivorship or reproductive potential and thus, the future of this subspecies. Considering major injuries as "takes", the injury rate (1.13 dolphins/year) for the population was 8-8.5 times higher than its Potential Biological Removal rate. Observations of new injuries and fishing gear entanglements on several dolphins showed that fisheries continue to be the predominant cause of these major injuries. Unless immediate action is taken to reduce harmful fisheries, extinction is imminent for Taiwan's only endemic dolphin.

Conservation Status of the Indo-Pacific Humpback Dolphin (Sousa chinensis) in the Northern Beibu Gulf, China.

There has been very little previous research on Indo-Pacific humpback dolphins (Sousa chinensis) in the Beibu Gulf of southern China. Here, we report on the population size, habitat and ecology, threats, and overall conservation status of this putative population. 'Population size' was estimated based on photo-identification mark/recapture analysis. It was estimated to number a total of 398-444 individuals (95% CI: 393-506), with two apparently distinct groups in the Dafengjiang-Nanliujiang Estuary and at Shatian-Caotan. Movements of dolphins in the Beibu Gulf appear to be limited, with high site fidelity. These dolphins were found to occur mainly in shallow coastal waters near estuaries. The main threats are fisheries interactions (including by-catch), vessel traffic, mariculture operations, dolphin-watching tourism, and habitat degradation (including marine construction activities and large-scale land reclamation). Although the conservation status of this putative population has been considered to be better than that of other populations of the species in more northern areas of China, there is still reason for strong concern about its future, and several management recommendations are made.

Prevalence of external injuries in small cetaceans in Aruban waters, southern Caribbean.

Aruba, located close to the coasts of Colombia and Venezuela, is one of the most densely populated islands in the Caribbean and supports a wide range of marine-related socio-economic activities. However, little is known about the impacts of human activities on the marine environment. Injuries in marine mammals can be used to examine interactions with human activities and identify potential threats to the survival of populations. The prevalence of external injuries and tooth rake marks were examined in Atlantic spotted dolphin (Stenella frontalis) (n = 179), bottlenose dolphin (Tursiops truncatus) (n = 76) and false killer whale (Pseudorca crassidens) (n = 71) in Aruban waters using photo identification techniques. Eleven injury categories were defined and linked to either human-related activities or natural causes. All injury categories were observed. In total, 18.7% of all individuals had at least one injury. Almost half (41.7%) of the injuries could be attributed to human interactions, of which fishing gear was the most common cause (53.3%) followed by propeller hits (13.3%). Major disfigurements were observed in all three species and could be attributed to interactions with fishing gear. The results of this study indicate that fishing gear and propeller hits may pose threats to small and medium-sized cetaceans in Aruban waters. Thus, long-term monitoring of population trends is warranted. Shark-inflicted bite wounds were observed in Atlantic spotted dolphin and bottlenose dolphin. Bite wounds of cookie cutter sharks (Isistius sp.) were recorded in all three species, and include the first documented record of a cookie cutter shark bite in Atlantic spotted dolphin. This is one of the few studies which investigates the prevalence of injuries in cetaceans in the Caribbean. Further study is necessary to determine to which extent the injuries observed in Aruba affect the health and survival of local populations.

Histopathological muscle findings may be essential for a definitive diagnosis of suspected sharp trauma associated with ship strikes in stranded cetaceans.

Ship strikes are a major issue for the conservation of may cetacean species. Certain gross and microscopic criteria have been previously reported for establishing a diagnosis of death due to ship strikes in these animals. However, some ship-strike injuries may be masked by advanced carcass decomposition and may be undetectable due to restricted access to the animals. In this report we describe histopathological muscular findings in 13 cetaceans with sharp trauma from ship strikes as the cause of death. Skeletal muscle samples were taken from the incision site and from the main locomotor muscle, the longissimus dorsi, in areas not directly affected by the sharp injury. The microscopic findings in tissues from both sites mainly consisted of haemorrhages; oedema; flocculent, granular or/and hyalinised segmentary degeneration; contraction band necrosis; and discoid degeneration or fragmentation of myofibres. We propose that skeletal muscle histopathology provides evidence of ante-mortem injuries even if the sample was taken elsewhere in the carcass and not only within or adjacent to the sharp trauma site and despite the advanced decomposition of some of the carcasses. This method helps to establish the diagnosis of ship strike as the cause of death.

First confirmed record of Feresa attenuata (Delphinidae) for the Northern Brazilian Coast / Primeiro registro confirmado de Feresa attenuata (Delphinidae) para o litoral norte do Brasil

In Brazil only one confirmed stranding is known from an emaciated specimen collected along the southeastern coast. The aim of this work is to report a recent record of a pygmy killer whale from the coast of Maranhão State, northern Brazil. On 22 October 2005, through regular surveys conducted by Projeto Cetáceos do Maranhão team, a beach-worn skull of a pygmy killer whale was found on the Mangue Seco beach, at Caju Island, Maranhão State. The specimen was identified through peculiar features, such as a short beak, 11 teeth per row in the maxile and the distance between the anterorbital notch and the end of the toothrow. This stranding suggests that pygmy killer whales may use oceanic waters close to Maranhão continental shelf. This is the second confirmed stranding of F. attenuata for the Brazilian Coast and the first along the northern coast. The present record increases our poor knowledge on the cetacean fauna of the northern Brazilian coast.

No Brasil somente um exemplar de Feresa attenuata foi coletado ao longo da costa sudeste. O objetivo deste trabalho é registrar o recente encalhe da orca-pigméia para a costa do Maranhão, litoral norte do Brasil. Em 22 de outubro de 2005, através de monitoramentos regulares conduzidos pelo Projeto Cetáceos do Maranhão, um crânio do exemplar de F. attenuata foi encontrado na praia do Mangue Seco, na Ilha do Caju, Estado do Maranhão, Brasil. O espécime foi identificado através de características peculiares, como o rostro curto, 11 pares de dentes na maxila e pela distancia entre o anterorbital e o término dos alvéolos dentares. Este encalhe sugere que a orca-pigméia pode usar águas oceânicas próximas à plataforma continental do Maranhão. Este é o segundo registro de encalhe confirmado para F. attenuata para a costa brasileira e o primeiro para a costa norte. O presente estudo contribui com o pouco conhecimento sobre os cetáceos na costa norte do Brasil.

Evidence for infanticide in bottlenose dolphins of the western North Atlantic.

Nine bottlenose dolphin (Tursiops truncatus) calves that stranded in Virginia in 1996 and 1997 died of severe blunt-force trauma. Injuries were concentrated on the head and chest and multiple rib fractures, lung lacerations, and soft tissue contusions were prominent. Skeletal and/or soft tissue trauma occurred bilaterally in all of the calves. One had a bite wound across the left mandible that exhibited deep punctures consistent with the tooth placement in an adult bottlenose dolphin. The lesions were not compatible with predation, boat strike, fisheries interactions, rough-surf injury, or blast injury. However, they were similar to traumatic injuries described in stranded bottlenose dolphin calves and harbor porpoises (Phocoena phocoena) in Great Britain attributed to violent dolphin interactions. The evidence suggests that violent dolphin behavior was the cause of the trauma in the nine calves reported here and that infanticide occurs in bottlenose dolphins of the western North Atlantic.

Post-mortem investigations on stranded dolphins and porpoises from Hong Kong waters.

Stranded cetaceans reported from the territorial waters of Hong Kong during the period May 1993 to March 1998 were examined to establish factors that may have contributed to their death. During the current study, 28 Indo-Pacific hump-backed dolphins (Sousa chinensis), 32 finless porpoises (Neophocaena phocaenoides), and four bottlenose dolphins (Tursiops truncatus) were necropsied. Bacteria (15 species) were isolated from nine animals. Of these bacteria, 47% were of possible fecal origin reflecting the high level of sewage contamination in Hong Kong's waters. One finless porpoise displayed wounds caused by a shark attack, and two female finless porpoises presented prolapsed uteri. At least 10 finless porpoises showed evidence of moderate to heavy lungworm infections (Halocercus pingi), and this appears to have been a factor contributing to death in at least six animals. Evidence suggesting blunt traumatic injury (probably caused by boat collisions) was found in six cetaceans (three finless porpoises and three hump-backed dolphins). Signs of fishery-related mortality were detected in at least nine animals (six hump-backed dolphins, two finless porpoises, and one bottlenose dolphin). Of these two human-caused mortality types, pre-existing disease or bacterial infection were detected in 29% of cases. Results indicate that human factors may have played a significant role in the death of at least 15 animals (32% of hump-backed dolphins, 15% of finless porpoises, and 25% of bottlenose dolphins).

Mass mortality of common dolphins (Delphinus delphis) in south west England due to incidental capture in fishing gear.

In the first quarter of 1992, 118 dolphin carcases, of which 54 were positively identified as common dolphins (Delphinus delphis), were found stranded on the coast of Cornwall and Devon. To determine the cause, detailed post mortem examinations were carried out on 38 of the carcases, and the results were compared with those from 20 common dolphins that stranded on the coast of Cornwall and Devon in the previous 15 months. There was no evidence that the deaths were due to an infectious or parasitic disease, or acute intoxication by any of the algal toxins, trace metals or chlorinated hydrocarbons measured. However, 30 of the 38 dolphins showed signs associated with incidental capture in fishing gear. Skin lesions characteristic of capture in a small-meshed net and the predominance of recently ingested Atlantic mackerel (Scomber scombrus) and pilchard (Sardina pilchardus) in the stomachs of the dolphins suggested that they had been caught in the trawl or purse seine nets used for these fish. There is insufficient information to explain why this high mortality occurred in 1992 and not in other years.

Mass stranding of striped dolphin, Stenella coeruleoalba, at Augusta, Western Australia: notes on clinical pathology and general observations.

Seventeen striped dolphins, Stenella coeruleoalba, were found stranded on a West Australian beach. Three animals died before a rescue attempt was made and a further three died during the rescue. The remaining dolphins were released 24 km offshore and were not seen again. One dolphin was noted to have a broken mandible. Evidence of physical trauma to the other dolphins was minimal; one adult female was observed with some peeling skin. Blood was collected for analysis. All dolphins were slightly dehydrated and had a leukogram typical of a stressed animal. Plasma biochemistry reflected primary muscle trauma. There were no clues to the cause of the stranding; observed pathology reflected damage that occurred as a direct consequence of stranding.