Case 1: A dead adult male Indian Ocean bottlenose dolphin (Tursiops cf aduncus) was found floating off an Adelaide beach on 11 December 2000. An autopsy revealed a single, lethal stab wound to the ventral thorax between the flippers (Boxes 1 and 2). The stab had penetrated the heart and caused a left-sided haemothorax. Examination of the wound indicated that the weapon was likely to have been a single-edged blade with a maximum width of 18 mm at a distance of 85 mm from the tip. Although three wounds were present in the right ventricle (Box 3), these could have resulted from one thrust with the weapon, with movement of the weapon, the dolphin or the heart causing the three injuries. Given the right-to-left direction of the wound, it could have been inflicted from the left side of a boat if the dolphin had been swimming beside the boat and had angled over onto its left side, thus exposing the anterior thorax. The dolphin otherwise appeared to be in good health, with no evidence of significant trauma or underlying organic illnesses. The presence of regurgitated, partly digested food in the oesophagus may have indicated recent feeding, although stress is known to delay gastric emptying in a variety of species.^1,2

Case 2: On 19 May 2001, an immature male common bottlenose dolphin (Tursiops cf truncatus) was found dead on a beach in southeastern South Australia. An autopsy revealed a wound that was similar in appearance to the wound seen in Case 1. The wound was in the ventral thorax between the flippers (Box 4), overlying a cavity in muscle; however, no damage to underlying vital structures was found. Although death was not caused by trauma, we could not determine the precise cause. However, the presence of stomach contents and a small, partly digested squid in the oesophagus may have indicated recent feeding. Sealice activity around the wound suggested that death may have occurred before beaching.

Discussion

For the dolphin in Case 1, death was attributed to a stab wound inflicted to the heart, most likely by a knife or similar single-edged sharp weapon. This conclusion resulted in the launching of a coordinated search for the perpetrators, with media appeals to the public for help. Although the injury to the dolphin in Case 2 appeared superficially similar, it was not lethal. Thus, forensic examination could determine quite quickly that the injury in Case 2 had not been responsible for death, and may even have occurred post mortem.

The significance of the findings in these cases is far from academic, as the penalty in South Australia for killing a marine mammal may be a $30 000 fine and/or a jail term of up to two years.⁴ Given these penalties, it is likely that anyone charged with such an offence would employ an active legal defence that could easily terminate the case on technical grounds if the examination and subsequent handling of evidence did not follow established guidelines. For this reason, cases of sea-mammal deaths, including the two we describe, have been processed in a routine forensic manner. This means that the examination of each dead dolphin was undertaken in a similar fashion to a standard human autopsy in a suspicious case, including accurate documentation of times, personnel present and possible trauma. The measurement, assessment and recording of injuries was undertaken in the usual manner, with descriptions being recorded in original notes and subsequently transcribed into an official signed report. Specimens that were taken for histological examination, storage for possible future DNA matching and toxicological evaluation were also signed and sealed at documented times and submitted to the Forensic Science Centre so that a formal chain of evidence could be maintained. Biological information, including species verification, was lodged at the South Australian Museum. To date, however, no charges have been laid in the reported cases.

Involvement of forensic pathologists in such cases has resulted in the early determination of whether trauma was implicated in the death, and has also facilitated an understanding of the relationship between the mechanism of death and the external injuries. In addition, investigating officers have been given some idea of the type of weapon to look for, material has been secured for possible DNA cross-matching between possible weapons and a particular animal, and wounds have been recorded accurately for possible court presentation if required.

In reporting these cases we have demonstrated that a standard branch of medicine, forensic pathology, may be useful in areas other than the assessment of human medicolegal cases, and that pathologists may play an important role in investigating the deaths of marine or other mammals.

References

1. Byard RW, Gilbert JD, Brown K. Pathological features of fatal shark attacks. Am J Forensic Med Pathol 2000; 21: 225-229.
2. Knight B. Forensic pathology. 2nd ed. London: Arnold, 1996: 89-90.
3. Gilbert JD, Kemper CM, Hill M, Byard RW. Forensic studies of a stabbed infant bottlenose dolphin. J Forensic Med 2000; 7: 150-152.
4. Fisheries Act 1982 (South Australia). Reprint no. 8.

Authors' details

South Australian Museum, Adelaide, SA.
Catherine M Kemper, PhD, Senior Curator of Mammals.

Reprints will not be available from the authors.
Correspondence: Professor Roger W Byard, Forensic Science Centre, 21 Divett Place, Adelaide, SA 5000.
byard.rogerATsaugov.sa.gov.au

©MJA 2001
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