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Fatal Asphyxiation in Bottlenose Dolphins (Tursiops truncatus) from the Indian River Lagoon.

Stolen M, St Leger J, Durden WN, Mazza T, Nilson E - PLoS ONE (2013)

Bottom Line: Asphyxiated animals presented with a fish lodged in the cranial esophagus associated with a dislocated and obstructed or compressed larynx.Cetacean choking is related to selection of prey fish species with strong dorsal spines and may be secondarily associated with fish attached to fishing gear.Environmental alterations leading to changes in prey availability or increased interactions with fishing gear may change the significance of fatal choking in dolphin populations.

View Article: PubMed Central - PubMed

Affiliation: Hubbs-SeaWorld Research Institute, Melbourne Beach, Florida, United States of America.

ABSTRACT
Multiple single case reports of asphyxiation in dolphins caused by fish lodged in the esophagus exist. However, the significance of this cause of mortality in a single population has not been documented. We performed a retrospective evaluation of pathology records from stranded bottlenose dolphins (Tursiops truncatus) from the Indian River Lagoon to evaluate the impact of this cause of death on this population. From 1997 to 2011, asphyxiation due to choking was identified as the cause of death in 14 of 350 cases (4%). Sampling of an unrelated but adjacent population over this same period yielded 186 necropsy cases of bottlenose dolphins with no cases of asphyxiation. Asphyxiated animals presented with a fish lodged in the cranial esophagus associated with a dislocated and obstructed or compressed larynx. There was no clear sex predilection. Affected animals included 12 adults and two juveniles. The fish species involved included sheepshead, black chin tilapia and striped mojarra. In five cases, recreational fishing gear was also present. Cetacean choking is related to selection of prey fish species with strong dorsal spines and may be secondarily associated with fish attached to fishing gear. Prey abundance and dolphin behavior may influence these selections. Environmental alterations leading to changes in prey availability or increased interactions with fishing gear may change the significance of fatal choking in dolphin populations.

No MeSH data available.


Related in: MedlinePlus

Photograph of stranded dolphin with fish.Photograph of IRL dolphin (Hubbs-0723) with sheepshead lodged in the esophagus.
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pone-0066828-g002: Photograph of stranded dolphin with fish.Photograph of IRL dolphin (Hubbs-0723) with sheepshead lodged in the esophagus.

Mentions: Over the study period, 350 dolphin carcasses were examined in the IRL and examined for cause of death. Fatal asphyxia was diagnosed as the cause of death when laryngeal displacement, compression, or obstruction was indentified and no significant histologic changes were identified as the cause of death. Case review demonstrated 14 cases (4%, Table 1). In at least five cases, dolphins were found with the tail of the prey fish extending from the mouth. On gross examination, all of the dolphins demonstrated fish lodged in the esophagus displacing or compressing the larynx (Fig. 2 and 3). In seven cases, fish were firmly lodged and held into the area of the larynx by dorsal spines that were embedded in the esophageal wall. Eight cases involved males, five were females, and one animal could not be clearly identified. Twelve dolphins were adults and two of the animals were juveniles. Detailed examinations of the lodged fish resulted in identification of eight of the 14 fish. Positive identification of the remaining six was hindered by decomposition or missing portions of the fish. Identified fish included six cases with sheepshead (Archosargus probatocephalus), one black chin tilapia (Sarotherodon melanotheron) and one striped mojarra (Diapterus plumieri). Three other fish were tentative classified as a jack (Carangidae) and two tilapia (Cichlidae) but positive species identification could not be made. The fishes measured 19 cm to 40 cm.


Fatal Asphyxiation in Bottlenose Dolphins (Tursiops truncatus) from the Indian River Lagoon.

Stolen M, St Leger J, Durden WN, Mazza T, Nilson E - PLoS ONE (2013)

Photograph of stranded dolphin with fish.Photograph of IRL dolphin (Hubbs-0723) with sheepshead lodged in the esophagus.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3686726&req=5

pone-0066828-g002: Photograph of stranded dolphin with fish.Photograph of IRL dolphin (Hubbs-0723) with sheepshead lodged in the esophagus.
Mentions: Over the study period, 350 dolphin carcasses were examined in the IRL and examined for cause of death. Fatal asphyxia was diagnosed as the cause of death when laryngeal displacement, compression, or obstruction was indentified and no significant histologic changes were identified as the cause of death. Case review demonstrated 14 cases (4%, Table 1). In at least five cases, dolphins were found with the tail of the prey fish extending from the mouth. On gross examination, all of the dolphins demonstrated fish lodged in the esophagus displacing or compressing the larynx (Fig. 2 and 3). In seven cases, fish were firmly lodged and held into the area of the larynx by dorsal spines that were embedded in the esophageal wall. Eight cases involved males, five were females, and one animal could not be clearly identified. Twelve dolphins were adults and two of the animals were juveniles. Detailed examinations of the lodged fish resulted in identification of eight of the 14 fish. Positive identification of the remaining six was hindered by decomposition or missing portions of the fish. Identified fish included six cases with sheepshead (Archosargus probatocephalus), one black chin tilapia (Sarotherodon melanotheron) and one striped mojarra (Diapterus plumieri). Three other fish were tentative classified as a jack (Carangidae) and two tilapia (Cichlidae) but positive species identification could not be made. The fishes measured 19 cm to 40 cm.

Bottom Line: Asphyxiated animals presented with a fish lodged in the cranial esophagus associated with a dislocated and obstructed or compressed larynx.Cetacean choking is related to selection of prey fish species with strong dorsal spines and may be secondarily associated with fish attached to fishing gear.Environmental alterations leading to changes in prey availability or increased interactions with fishing gear may change the significance of fatal choking in dolphin populations.

View Article: PubMed Central - PubMed

Affiliation: Hubbs-SeaWorld Research Institute, Melbourne Beach, Florida, United States of America.

ABSTRACT
Multiple single case reports of asphyxiation in dolphins caused by fish lodged in the esophagus exist. However, the significance of this cause of mortality in a single population has not been documented. We performed a retrospective evaluation of pathology records from stranded bottlenose dolphins (Tursiops truncatus) from the Indian River Lagoon to evaluate the impact of this cause of death on this population. From 1997 to 2011, asphyxiation due to choking was identified as the cause of death in 14 of 350 cases (4%). Sampling of an unrelated but adjacent population over this same period yielded 186 necropsy cases of bottlenose dolphins with no cases of asphyxiation. Asphyxiated animals presented with a fish lodged in the cranial esophagus associated with a dislocated and obstructed or compressed larynx. There was no clear sex predilection. Affected animals included 12 adults and two juveniles. The fish species involved included sheepshead, black chin tilapia and striped mojarra. In five cases, recreational fishing gear was also present. Cetacean choking is related to selection of prey fish species with strong dorsal spines and may be secondarily associated with fish attached to fishing gear. Prey abundance and dolphin behavior may influence these selections. Environmental alterations leading to changes in prey availability or increased interactions with fishing gear may change the significance of fatal choking in dolphin populations.

No MeSH data available.


Related in: MedlinePlus