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Home , Dusky dolphin, Lagenorhynchus, Narwhal, Right whale, Right whale dolphin, Sagmatias

Aquatic 2002, 28.2, 211–217

A possible between the dusky ( obscurus) and the southern right dolphin (Lissodelphis peronii)

Parissa Yazdi

Institut für Meereskunde, Abt. Meereszoologie, Düsternbrooker Weg 20, 24105 Kiel, Germany

Abstract Hemisphere (Jefferson et al., 1993; Carwardine, 1995). In , dusky occasion- In Golfo Nuevo, Península Valdés, an ally are seen in mixed groups with southern unusual dolphin was sighted several times, always dolphins (Yin, 1999). Off Southwest associated with dusky dolphins (Lagenorhynchus , mixed groups of both species were observed obscurus). Photographic evidence showed that the by Rose & Payne (1991) and Cruickshank & Brown anomalous dolphin shared characteristics of a (1981). In 1990, a large group of dusky dolphins southern (Lissodelphis peronii) (700–800) together with approximately 50 southern and the . The ’s features were a right whale dolphins was observed along the coast slender body of approximately 2.0–2.2 m in length. of southern (Van Waerebeek, 1992). Like dolphins, a sharp divid- On 6 December 1998, an unusual dolphin was ing line separated the black dorsal part from the sighted for the first time in Golfo Nuevo, Península white ventral part of the body, but the line in Valdés, Argentina, within a group of dusky the area of the head did not extend below the eyes. dolphins (R. Benegas, pers. comm.). The peduncle showed a patch of pale grey, similar to the lateral colour pattern of a dusky dolphin. Contrary to the southern right whale dolphin, the Materials and Methods anomalous dolphin had a dorsal fin, which was smaller and more triangular than that of the dusky Resightings of the animal were attempted between dolphin and located around two-thirds of the way 22 November 1999 and 16 March 2000, using a along the back. Colour patterns of the dorsal fin tourist vessel (11 m; Diesel Volvo Penta). During were very similar to that of a dusky dolphin with its each dolphin sighting, I recorded time, position typical half-moon shape and pale grey colouration (Garmin GPS MAP 175), surface water tempera- in the posterior part. Aerial behaviour of the ture (Digital maximum-minimum thermometer) unusual dolphin was very similar to previous obser- group size, and behaviour (Digital voice recorder vations of L. peronii. Based on the intermediate DS-150, Olympus). Dolphins with conspicuous morphological features between L. obscurus and features were photographed (Nikon F601, AF; L. peronii, I proposed that the anomalous dolphin is Sigma Zoom 28–200 mm D; Kodak-Elitechrome a hybrid of these two dolphin species. 200).

Key words: Lagenorhynchus obscurus, dusky Results dolphin, Lissodelphis peronii, southern right whale dolphin, anomaly, hybrid, aerial behaviour, inter- The anomalous dolphin was always associated with specific interaction dusky dolphins and was sighted 10 times (6% of the sightings) during the entire observation period Introduction (n=45.9 h at 32 days; Table 1). The specimen could not be identified via any of the available dolphin The waters of the Patagonian of classification keys (e.g., Carwardine, 1995; Jefferson Argentina are the habitat for a high diversity of et al., 1993). cetaceans, such as dusky dolphins (Lagenorhynchus Photographic data showed that it shared obscurus) and southern right whale dolphins characteristics of a southern right whale dolphin (Lissodelphis peronii). The association between (Lissodelphis peronii) and the dusky dolphin dusky dolphins and southern right whale dolphins (Figs. 1–2, Table 2). The animal’s features were a appears to be common in the whole Southern slender body of approximately 2.0–2.2 m in length.

 2001 EAAM 212 Parissa Yazdi

Table 1. Sightings of the anomalous dolphin associated with the dusky dolphins in Golfo Nuevo, Argentina between 29 November and 16 March 2000; surface water temperature between 17.6 and 19.0)C.

Group size of Date Time Location the dusky dolphins Behaviour of the group

29 November 1999 1111 42)36.19*S/64)17.21*W 50-100 feeding 29 November 1999 1155 42)36.18*S/64)18.35*W 50 feeding 28 January 2000 1310 42)43.30*S/64)58.04*W >100 socializing, aerial behaviour 8 February 2000 1335 42)43.03*S/64)57.15*W 50-100 socializing, aerial behaviour 10 February 2000 1245 42)43.26*S/64)56.84*W 50 social travel, aerial behaviour 15 February 2000 0958 42)44.58*S/64)58.58*W 8 socializing 15 February 2000 1034 42)44.46*S/64)58.48*W 20-30 socializing 15 February 2000 1100–1126 42)44.40*S/64)57.15*W- 10 following the boat, bow-wave riding, 42)44.84*S/64)57.92*W aerial behaviour, socializing 20 February 2000 1358 42)43.41*S/64)58.37*W >100 socializing, feeding, aerial behaviour 16 March 2000 1238 42)40.26*S/64)49.87*W >100 feeding, social travel

Like in southern right whale dolphins, a sharp dolphin and located around two-thirds of the way dividing line separated the black dorsal part from along the back. Colour patterns of the dorsal fin the white ventral part of the body, but the line in were very similar to that of a dusky dolphin with its the area of the head did not extend below the eyes. typical half-moon shape and pale grey colouration The peduncle showed a patch of pale grey, similar in the posterior part (Fig. 2 A). to the lateral colour pattern of a dusky dolphin. It can not be excluded that there was more than Contrary to the southern right whale dolphin, the one unusual dolphin among the dusky dolphins in anomalous dolphin had a dorsal fin, which was Golfo Nuevo, Argentina. However, based on smaller and more triangular than that of the dusky 10 sightings on seven different days (between 22 November 1999 and 16 March 2000; Table 1), available photographs (at 15 February 2000 and 16 March, 2000) and video tape recordings (in December 1999 and at 15 February 2000) the observed anomalous dolphin had the same individually-distinctive features (Figs. 1–2).

Discussion Colour pattern Geograhic variations of colour fields and anomalous pigmentation were previously reported for L. obscurus (Van Waerebeek, 1992; Gallardo, 1912). Dusky dolphins from the Península Valdés area greatly vary in their degree of melanization (Van Waerebeek, 1992). Van Waerebeek (1992) distinguished a heavily melanized and a light- coloured phenotype. However, most specimens were intermediates between the two extreme forms (Fig. 1). Relatively pronounced colour variations also occurred in the body, fluke, and flippers pigmen- tation of L. peronii (D’Orbigny & Gervais, 1847; Philippi, 1893; Lillie, 1915; Fraser, 1955; Figure 1. Morphological characteristics of (A) the dusky Aguayo, 1975, Torres & Aguayo, 1979; Baker, dolphin (Lagenorhynchus obscurus); drawing according 1981; Cruickshank & Brown, 1981; Rose & Payne, to the most common phenotype, observed in Golfo 1991) and pure white also have been Nuevo, Argentina; (B) the southern right whale dolphin (Lissodelphis peronii) according to Cawardine 1995, recorded (Brown, 1973). Juveniles have colour Torres & Aguayo 1979, Aguayo 1975; and (C) an anoma- patterns identical to those of the adults, but some lous dolphin, based on my photographs, recorded in submerged smaller calves appeared to be grey Golfo Nuevo, Argentina. dorsally (Cruickshank & Brown, 1981). As opposed Hybrid between the dusky dolphin and the southern right whale 213

Figure 2. The anomalous dolphin observed in the Golfo Nuevo, Argentina (A) associated with dusky dolphin, (B) during a wide- and low-angled leap with head re-entry, (C) exposing belly and ventral part of the flippers during back-slapping, and (D) exposing dorsal part of the body: All photographs were recorded on 15 February 2000 between 1000 and 1100 h. to these previous observations on known species, dolphin and approximately 10 dusky dolphins fol- the presence of the small dorsal fin strongly suggests lowed the boat for one half hour at a mean speed of that the unusual dolphin does not represent a approximately 10 km/h. During this time, the colour variant of a southern right whale dolphin. anomalous dolphin was videotaped (by L. Pettite, Features of the anomalous dolphin bear same camera: Panasonic M 9000). Based on these resemblance to the spectacled (Phocoaena recordings, the following behavioural elements were dioptrica). This species is known primarily from the analysed: southern coast of eastern (Jefferson et al., 1993). Adults are 1.3–2.2 m long and a (a) bow-wave riding, sharp demarcation exists between the black dorsal (b) fast exit out of the water until the body stands and the white ventral part. Female spectacled vertically above the water surface, falling down have low and triangular-shaped dorsal head first. This behaviour was observed while the fins (Cawardine, 1995). However, further character- animal kept its head in the water or during low istics of P. dioptrica, (typical porpoise body shape, leaps of approximately 50 cm height, absence of a beak, a black patch around the eyes, (c) low leap approximately 1 m high, with 180) spin surrounded by a fine white line) (Cawardine to the right; head re-entry with belly up, 1995; Jefferson et al., 1993) do not apply to the (d) back-slaps without or with 180) spin (Fig. 2 C) anomalous dolphin. to right and left, (e) side-slaps with 90) spin to left and right, Behaviour (f) belly-slap with 180) spin to right, In most of the sightings, this specimen was observed (g) tail-slaps, and in groups of dusky dolphins greater than 20 animals (h) rapid acceleration during swimming on the (Table 1). On 15 February 2000, the unusual side just below the surface, and three wide- and 214

Table 2. Distinctive features of dusky dolphins (Lagenorhynchus obscurus), southern right whale dolphins (Lissodelphis peronii), and the anomalous dolphin observed in Golfo Nuevo, Argentina.

Morphological parameters Lagenorhynchus obscurus Lissodelphis peronii Anomalous dolphin

Bodylength Adult: 1.6–2.1 m1 Adult: 1.8–2.9 m1 2.0–2.2 m (estimated)

Bodyshape Body small and moderately robust Long and slender, narrow tail stock2 Moderately long and slender Colour pattern Sides marked with blazes and patches of A sharp line demarcating black above A sharp line demarcating black above pale grey; front of the flank patch splits into and white below runs from the tail stock and white below runs from the flank 2 blazes, a shorter ventral and a longer forward, dips down to the flipper forward to the head; peduncle patch dorsal one (this latter narrows and insertion, and then sweeps back-up to splits into two blazes, shorter ventral and stretches-up onto the back, almost to the cross the between the longer dorsal one, that forms a broad blowhole); a recurved stripe from the and snout crease; the white colouration dorsal grey line; a dorsal grey line insert Parissa beak to the flippers and forms a broad, of the ventral area extends well up to the approximately 20 cm in front of the continuous grey band; the eye is set in a sides2, younger animals can be grey dorsal fin and leads-up to snout; a small patch of grey-black dorsally1,3 recurved stripe leads from the beak to the flippers and forms a broad, Yazdi continuous grey band Dorsal fin Conspicuous, moderately falcate and Absent1,2 Small, slightly falcate dorsal fin; located pointed (variable); frontal dark grey, fading about two-thirds of the way along the to pale grey in the posterior part back; anterior dark grey, fading to pale grey in the posterior part Fluke Grey above and below, sometimes fading to White below; above dark grey, fading to Pale grey below, but dark around the pale grey on the leading edge white on the leading edge1,2 trailing edge; above grey, fading to pale grey on the leading edge Flippers Moderately curved, grey (variable), Recurved; white; trailing edge with black Recurved; pale grey, but dark around sometimes darkened around the edges band1,2 the edges; a black patch at the shoulder Beak Short, grey-black around the tip, tapering Short; white; the tip of the lower jaw Short; white behind and dark grey in back to darken just the lips near the gape protudes a bit beyond the upper one4 front; the lower jaw protudes a bit (variable) beyond the upper one; white tip

According to 1Carwardine (1995), 2Jefferson et al. (1993), 3Cruickshank & Brown (1981), 4Aguayo (1975) Hybrid between the dusky dolphin and the southern right whale 215 low-angled leaps (height: 1 1.50 m; distance up to surface water temperatures of 9–16)C. However, 6 m) with head re-entry (Fig. 2 B), rapid up and this species is not restricted to these temperatures, down tail movements while breaking the water because sightings at temperatures of up to 20.1)C surface. have been confirmed (Cruickshank & Brown, 1981). Lissodelphis peronii occurs in cold waters off Santa In comparison to dusky dolphins, this rare speci- Cruz Province, Argentina and the Falklands men was capable of higher swimming speeds and Islands (Lesson, 1826), as well as off Tierra del almost exploding movements. Its behaviour was Fuego (Lahille, 1899; Goodall, 1978). The cold similar to southern right whale dolphin activities. Falkland Current leads along the Patagonian Rose & Payne (1991) reported L. peronii ‘exploding’ Continental Shelf to the north, whereby a small at high-speed action for 1–2 min, successive high separation flows to the coast, into Golfo Nuevo and jumps, and side-slaps. Its extremely attenuate body further along the shore of Península Valdés up to can allow it to take three or four rapid propulsive Mar de Plata (source: Satellite picture of National strokes with its flukes while its anterior body is in Metereologic Service, Argentina 13–14 February the air, thus reducing drag (Norris & Dohl, 1980). 1985). However, specimens of L. peronii were Cruickshank & Brown (1981) observed fast and recorded in coastal areas off Mar de Plata surface swimming accompanied by a series of low (Gallardo, 1912) and up to southeastern , off angle jumps, animals bouncing themselves with the coast of Sa˜o Paulo State (Martuscelli et al., well-timed flick of their tails as they broke the water 1996). This area receives both the influence of the surface (Cruickshank & Brown, 1981). This move- warm Brazilian Current and the cold Falkland ment pattern also was observed in the unusual Current, the latter prevailing during the austral dolphin. Due to its long and slender body shape, winter (Martuscelli et al., 1996). which is more Lissodelphis-like, it is evident that its Unfortunately, systematic data on dusky body movements are more similar to a southern dolphins in the Golfo Nuevo during the winter are right whale dolphin. not available. Some individuals of the local popu- Dusky dolphins are very acrobatic leapers, and lation may migrate out of the Gulf, similar to dusky show several types of aerial behaviour. Würsig & dolphins in Golfo San José (Würsig & Bastida, Würsig (1980) termed ‘clean’ leaps (headfirst 1986), probably to feed on southern re-entry leaps), ‘noisy’ leaps (dolphin’s headfirst exit (Engraulis anchoita), found off Mar de Plata from from the water, and falling back into water on its September through November (Brandhorst & side, back, or belly) and ‘acrobatic noisy’ leaps Castello, 1971). During the migration up to Mar de (head-over-tail and spin) on dusky dolphins. Plata (Würsig & Bastida, 1986), they could have During the study period, five types of ‘clean’ leaps, contact with groups of southern right whale nine ‘noisy’ leaps, and five different ‘acrobatic’ leaps dolphins, which follow the Falkland Current. Based were analysed (unpublished data). The unusual on stomach contents, epipelagic coastal food habits dolphin did not show any head-over-tail leaps (Torres & Aguayo, 1979), meso-pelagic (Baker, during the sightings. The total observation time 1981) or both, epi- and meso-pelagic feeding of dusky dolphins groups associated with the (Crovetto et al., 1992) were suggested for L. peronii. anomalous dolphin was relatively short (total observation time=5.1 h at 7 days). Reproduction Copulations between dolphins of different species Distribution and migration are not uncommon. The same dusky dolphins Lissodelphis peronii normally is considered to live in of Golfo Nuevo were acompanied frequently by offshore waters (Rose & Payne, 1991) and is rarely a male (Tursiops truncatus) sighted near shore. However, in Golfo Nuevo, and two female long-beaked common dolphins three southern right whale dolphins were observed (Delphinus capensis). Four times these were once during summer 1992, apparently associated observed in cross-species (cross-genera) sexual with dusky dolphins (R. D. Orri, pers. comm.). interactions and copulations. In the Bahamas, Lissodelphis peronii also has been observed close to interspecific mating interactions with penile intro- the coast of Chile (Aguayo, 1975), where deep mission were reported between Atlantic spotted waters occur in the immediate vicinity of the coast. dolphins ( frontalis) and bottlenose In Lüderitz, , L. peronii was observed in dolphins (Herzing & Johnson, 1997). inshore waters throughout the year (Rose & Payne, Testes of adult dusky dolphins off reach 1991), possibly related to the strong upwelling in their maximum size in September and October, in this area (Rose & Payne, 1991). synchrony with the peak period of conception (Van Gaskin (1968) reported that southern right whale Waerebeek & Read, 1994). Small calves (about dolphins prefer waters between the Subtropical equal to or less than one-third adult size) were seen Convergence and the Antarctic Convergence and in the Golfo San José from November through 216 Parissa Yazdi

February (Würsig & Würsig 1980) and several L. cruciger, L. australis), are closely related to calves were sighted during aerial surveys in Golfo Lissodelphis (L. peonii, L. borealis) and Cephalo- Nuevo in November and December (Dans et al., rhynchus (C. commersonii, C. eutropia, C. heavisidii 1997). Dans et al. (1997) suggested that the calving C. hectori) and placed all these named species in the season of northern Patagonian dusky dolphins . According to the classification of extends from spring to autumn. Assuming a gesta- Le Duc et al. (1999) the anomalous dolphin that I tion period of 11 months (Dans, 1999), most con- reported here is a hybrid between two closely ceptions should occur from September to February. related species. This sheds new light on the taxo- Unfortunately, there are no published reports on nomic classification of Lagenorhynchus obscurus the reproductive cycle of L. peronii. Since associ- and Lissodelphis peronii. ations between dusky and southern right whale dolphins were observed in the Golfo Nuevo in Acknowledgments summer 1992 (R. Orri, pers. comm.), the copu- lations and conceptions could have occured inside This investigation was supported by a grant or outside the Golfo Nuevo. from Deutscher Akademischer Austauschdienst Hybrids of different cetacean species have been (DAAD), Bonn. The Marine Laboratory recorded in captivity and in the field. A hybrid of a of Centro Nacional Patagónico (CONICET), female rough-toothed dolphin (Steno bredanensis) provided logistical support. I am and male bottlenose dolphin was born at Sea Life indebted to ASAHI PENTAX, Hamburg and Park in Hawaii, showing intermediate features SURVEYERS-EXPRESS for providing surveying between the two parental species (Dohl et al., 1974). equipment and to OLYMPUS for a digital voice Sylvestre & Tasaka (1985) recorded thirteen recorder. I thank Rafael Benegas for the oppor- of hybrids between bottlenose dolphins and tunity to carry-out research onboard of his vessel Risso’s dolphins (Grampus griseus) in Enoshima ‘Nanaia’ and for his interesting stories. R. Marineland, and four hybrids between (‘Penino’) Orri supplied helpful information about bottlenose dolphin and false (Pseudorca dolphin sightings. I thank Luis Pettite for his excel- crassidens) in Kamogawa Sea World, Japan. A lent videotape of the rare dolphin. I am very near-term foetus of a bottlenose dolphin and long- grateful to Prof. Dr. B. Culik for his valuable finned pilot dolphin (Globicephala macrorhynchus) support during all stages of this investigation exhibiting a combination of intermediate character- and his comments on this paper. I thank Dr. G. istics was recorded in Sea World of San Diego, Luna-Jorquera, Dr. M. Thiel and two anonymous California (Antrim & Cornell, 1981). Three referees for their constructive critism of the manu- anomalous dolphins stranded together in Blacksod script. I thank Javier Alvarez for scanning the Bay, Ireland were probably hybrids between T. photographs. Personal thanks go to Sebastian truncatus and Risso’s dolphins (Fraser, 1940), sug- Pavone-Cao for help in the field and his brilliant gesting that these three dolphins were the calves of ideas. the same cow (Sylvestre & Tasaka 1985). Reyes (1996) reported a stranding of a strange dolphin together with dusky dolphins. The animal showed Literature Cited intermediate characters between the common and Aguayo, L. A. (1975) Progress report on small cetacean dusky dolphin. Heide-Jørgensen & Reeves (1993) research in Chile. Journal of the Fisheries Research examined an anomalous whale’s skull, found in Board of 32, 1123–1143. West , suggesting a (Monodon Antrim, J. E. & Cornell, L. H. (1981) Globicephala- monoceros) and beluga (Delphinapterus leucas)- Tursiops hybrid (Abstract). 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