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Diana E. Barshaw 



Boston University Marine Program 



Marine Biological Laboratory 



Woods Hole. MA 025iS 



present address: Center for Marine Studies 



University of Haifa 



Ml. Carmel. Haifa 31999, Israel 



BEHAVIORAL OBSERVATIONS ON 



FIN WHALE, BALAENOPTERA PHYSALUS, 



IN THE PRESENCE OF 



KILLER WHALE, ORCINUS ORCA 



Detailed observations of baleen whales attacked by 

 killer whales, Orcinus orca, are scarce. Most of these 

 records involve attacks on gray whales, Eschrich- 

 tius rohustus (e.g., Scammon 1874; Gilmore 1961; 

 Morejohn 1968; Pike and MacAskie 1969; Rice and 

 Wolman 1971; Baldridge 1972). Although reports 

 exist of killer whale tooth marks on different body 

 parts of fin whales, Balaenoptera physalus, sei 

 whales, B. borealis (Hoyt 1981), minke whales, B. 

 acutarostrata (Jonsgard 1968), and bowhead whales, 

 Balaena mysticetus (Tomilin 1967); and although re- 

 mains of some of these species (fin, sei, and minke 

 whales) have been found in stomachs of killer whales 

 (Nishiwaki and Handa 1958; Tomilin 1967; Rice 

 1968; Hoyt 1981; International Whaling Commis- 

 sion 1982), we know of only a few reports of direct 

 observations of killer whales attacking mysticetes 

 besides gray whales. These include attacks on 1) 

 southern right whales, Euhalaena australis [ = 

 glacialis] (Cummings et al. 1972); 2) a humpback 

 whaJe, Megaptera novaeangliae (Martinez and Kling- 

 hammer 1970); 3) a minke whale (Hancock 1965); 



4) a female sei whale with a calf (Gaskin 1982); 5) 

 a fin whale (Pike and MacAskie 1969); and 6) an 

 immature blue whale, Balaenoptera musculus 

 (Tarpy 1979). Of these authors, only Hancock (1965) 

 and Cummings et al. (1972) provided some detailed 

 behavioral observations. 



In this paper, we describe the behavior of a group 

 of fin whales in the presence of three killer whales 

 and discuss these observations with regard to the 

 available literature. 



Field Observations 



While searching for gray whales on 2 March 1982 

 (0850 h), we headed offshore from Tojahui (lat. 

 26°37'N, long, 109°23'W), a small fishing camp ap- 

 proximately 9 km SE of Yavaros, Sonora, in the Gulf 

 of California, Mexico, in a 5 m dory powered by a 

 75 hp outboard motor. Sea conditions were excel- 

 lent with a calm and glassy water surface, no wind, 

 and visibility about 6 km. Twelve km from shore, 

 over a water depth of 50 m, we encountered a large 

 group of 20 fin whales, judged to be adults (esti- 

 mated total lengths ca. 18-20 m). We stopped the 

 boat and motor within 40-300 m of the whales, and 

 began observing their behavior. The whales formed 

 closely spaced pairs or triplets within <5 m of each 

 other and were lunge-feeding at the surface on 

 dense patches of fish larvae and other macroplank- 

 ton. The whales continued in this activity for 20 

 minutes, while forming a large semicircle off the 

 stern of the boat at distances ranging from ca. 50 

 to 500 m (Fig, 1). None of the whales appeared to 

 be moving in any definite direction. 



While we were photographing a pair of fin whales 

 swimming slowly north, 50 m from the boat and 

 parallel to it, we sighted several killer whales ca. 

 200 m from us and heading in the direction of the 

 pair. The killer whales were moving extremely fast 

 and disturbing the water surface. The pair of fin 

 whales continued swimming in their original direc- 

 tion for 30 m and then abruptly changed direction, 

 by about 65°, increased their speed notably, and 

 moved towards the boat (Fig. 1). At that time the 

 killer whales were 60 m behind the fin whales, and 

 the two sets of whales and the boat were all in 

 straight line. As the killer whales moved to 20 m 

 from the boat, the fin whales disappeared just below 

 the surface, and at that instant, a killer whale's head 

 protruded above the water with its mouth open and 

 teeth visible. There were two other killer whales 

 slightly behind the first one. Judging by the size and 

 shape of their dorsal fins, all three individuals were 

 females or immature males. The pair of fin whales 



370 



