First Antarctic Record of a Killer Whale Stranding

FIRST ANTARCTIC RECORD OF A KILLER WHALE STRANDING

HUGO P. CASTELLO Centro Nacional Patag6nico de Geo-Helioffsica, Puerto Madryn, Pvcia. de Chubut, Argentina ALDO P. TOMO Instituto Antdrtico Argentina, Cap. Fed., Argentina JORGE S. PANIZZA Depto. Cs. Biol6gicas, Universidad de Buenos Aires, Cap. Fed., Argentina

On the afternoon (6 P.M.) of 16 January 1973, during a "Zodiac" out motor rub ber boat collecting trip from Palmer Station (64° 45' S, 64° 58' W), Antarctica, to Cormorant Island, looking for the blue-eyed shag (Phalacrocorax atriceps) we needed for neurophysiological research (Torno, Panizza and Castello, 1973) arriving to the shore of Cormorant Island through a short channel carved in the rocks, we were sur prised to find, during low-tide, a stranded killer whale (Orcinus orca), 5.2 meters long and approximately 1. 5 metric ton in weight (Fig. 1). We took color photo graphs immediately and also some notes. The stranded "orca" was of female sex; time since death was estimated on two weeks or more. Black and white colors of the tegument had been partially removed by floating ice debris abrasion, some of the 25 powerfull teeth were broken, possibly by crashing floating ice against the open mouth (Fig. 2). It was possible to observe, also, "tooth wear" as it has been previously described (Caldwell and Brown, 1964) and some blood clots on a rock just under the tongue. Even though 0°C water temperatures are common during austral summer, air temperatures, specially during sunny days, may reach l0°C or more, thus the sun had heated the body and visceral putrefaction had greatly progressed when we met the carcass. Some gas bubbles sporadically escaped from a 3 cm wide circular hole on the tegument of the middle back. No other wound was seen in the carcass. The body was full of gas and increased in width, so it probably floated. Floating and drifting dead whales like the Balaenoptera a.ff borealis (Fig. 3) are not common in the Antarctic. Scientific reports on stranded cetacea or bones collected in those latitudes are few, only one skull of the " cruciger dolphin " (Lagenorhynchus cruciger) has been found and recently described from Livingston Island (Islas Shetland del Sur) (Fraser and Noble, 1968) and one Phocoena dioptrica collected at South Georgia (Fraser, 1968). When five days latter we returned to Cormorant Island for obtaining measure ents and to examine it's stomach content we could not find the " orca " carcass along the coast of the tiny island. We realized then what had happened: in the same way as it probably reached the shore it went away, floating and drifting like

Sci. Rep. Whales Res. Inst., No. 26, 1974, 255-258 256 CASTE しし 0, TOl¥,fO 八i¥"D PA:¥J IZ ZA

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K I LLE HA E S TI AND l 1 '¥G ！ミ＼＼＇しミ 'l.57 258 CASTELLO, TOMO AND PANIZZA about its distribution is not available or whether it migrates or if stocks in the north are separate from those in the south. The second of us spent 1967 at Estacion Cientifica "Almirante Brown" (64° 50' S, 62° 50' W) and carried among other works, a record of cetacean sightings. Three different species were observed in 19 occasions with a total of 34 specimens observed in front of the main building of the Station in the period March-July. Only once, the 6 of April (08.50 A.M. ), 5 killer whales were observed at Bahia Para iso. As something unusual a whale (Balaenoptera spp.) was observed the 23 of July swimming between broken ice, while the last two were recorded the 15 of May. It is almost sure that during the austral winter, before thick ice covers coastal areas of the Antarctic Peninsula, killer whales move to open waters, probably swim ming to subantarctic areas. This hypothesis has to be proved and we must remark what has been previously stated: " research in the Antarctic so far has contributed but little to what is known of this creature " (Fraser, 1964 ). Hershkovitz (1966) gives 80 bibliographic mentions on Orcinus orca only 5 are referred to sightings in antarctic waters at different places (Hope Bay; between Powell and South Shetland Islands; 70° 23' S, 85° 57' W; 78° S, 170° E; 77° 46' S, 166° E). In the period December 1972-February 1973, killer whales were observed in eight occasions in the Gerlache Strait (Castello and Duguy, in press) and in our opinion this strait must be selected as an area for studying the behaviour and biology of this important and largely neglected species.

REFERENCES CASTELLO, H.P. and R. DuGuv, (In press). Observations sur Jes Cetaces de Patagonie, Subantarctique et Antarctique (novembre 1972-fevrier 1973). Mammalia. CALDWELL, D. K. and D. H. BROWN, 1964. Tooth wear as a correlate of described feeding behavior by the killer whale, with notes on a captive specimen. Bull. Soc. Calif. Acad. Sc., 63(3): 128-140. FRASER, F. C., 1964. Whales and whaling. In Antarctic Research (ed. R. Priestley and others) Butter worth, cap., XI: 191-205. FRASER, F. C., 1968. Notes on a specimen of Phocoena dioptrica from South Georgia. Brit. Ant. Surv. Bull., 16: 51-56. FRASER, F. C. and B. A. NoBLE, 1968. A skull of Lagenorhynchus cruciger from Livingston Island, South Shetland Islands. Brit. Ant. Surv. Bull., 15: 29-38. HERSKOVITZ, P., 1966. Catalog of living whales. Bull. Unit. Stal. Nat. Mus., 246: 1-259. RrcE, D. W. and V. B. SCHEFFER, 1968. A list of the marine mammals of the world. U.S. Fish Wild!. Ser. Spee. Scient. Rep. Bur. Comm. Fish., 579: 1-16. TAYLOR, R.J. F., 1957. An unusual record of three species of whale being restricted to pools in Antarctic sea-ice. Proc. Zoo!. Soc. London, 129: 325-331. ToMo, A. P., PANIZZA, J. S. and H.P. Y CASTELLO, 1973. Neurophysiological research in fishes and birds at Palmer Station. Ant.]. U. S., VIII, 4, 202-203. WILSON, E. A., 1907. Cetacea. Nat. Ant. Exp. Nat. Hist. Zoo!., II: 6-8.

Sci. Rep. Whales Res. Inst., No. 26, 1974