Abstract

(…) On 11 September 1997, a harbour porpoise was found dead on a beach near Pictou, Nova Scotia, Canada (45° 41′N, 62° 42′W), bordering Northumberland Strait in the Gulf of Saint Lawrence. The animal was buried on the beach where it was found, and then uncovered on 14 September and transported to Halifax, Nova Scotia, where it was frozen intact for later post-mortem. While the animal had been dead for at least four days prior to freezing, because it had been buried, relatively little external damage from gulls or other scavengers was apparent. Upon external examination, it was noted that the porpoise, a 95.2 cm long male, was visibly emaciated, with a distinct concavity of the dorsal surface on both sides of the body, indicating atrophy of the epaxial muscles. The leading edge of the flippers, flukes, and dorsal fin, as well as the area around the snout, were all examined for net marking, but showed no signs of incidental entanglement in fishing gear. All thoracic and abdominal organ systems were examined, and no obvious gross pathology was noted. The stomach and intestines were empty, other than small amounts of bile stained liquid throughout the intestine. Upon examination of the esophagus, a balled up piece of black plastic (measuring when stretched out about 5 by 7 cm, weighing 0.36 g) was found adjacent to the junction with the stomach. Immediately cranial to this plastic was a mass of fish bones, partially digested fish, and three intact fish (a total of 2.7 g), all occluding the esophagus. The lining of esophagus immediately adjacent to the mass of fish peeled off easily, while the lining further cranial, as well as the stomach lining, remained firmly attached. However, histological examination of the esophageal lining showed no obvious necrosis (P.-Y. Daoust, pers. comm.). The fish remains recovered were identified as three-spined stickleback, Gasterosteus aculeatus (W.A. Walker, pers. comm.). A total of 18 individuals were represented, ranging in size from 22 to 28 mm standard length, and all had been recently ingested. (…)