10 MARINE MAMMALS AND SEA TURTLES - Hebron Project

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Hebron Project Comprehensive Study Report Marine Mammals and Sea Turtles a second whale, associated with the one captured, remained free-swimming in the southern part of Trinity Bay for at least three additional days (Sergeant and Fisher 1957). There were no sightings of northern bottlenose whales reported in the DFO cetacean sightings database in the Nearshore Study Area (Table 10-6). Thus, it appears possible, but quite unlikely, that northern bottlenose whales will occur in the Nearshore Study Area. Long-finned Pilot Whale Long-finned pilot whales are widespread in the North Atlantic (Jefferson et al. 2008). There is an estimated 31,139 individuals in the Northwest Atlantic (although that number could also contain some short-finned pilot whales) (Waring et al. 2009), and they are abundant year-round residents of Newfoundland waters (Nelson and Lien 1996). Hay (1982) estimated a total of 13,167 individuals in eastern Newfoundland and southern Labrador waters. Pilot whales are sexually dimorphic, such that males are longer than females and have larger dorsal fins as well as more pronounced melons (Jefferson et al. 2008). Pilot whales studied in Nova Scotia seem to form long-term social groups of related individuals, with minimal dispersal from natal groups (Ottensmeyer and Whitehead 2003). Average group size was 20 individuals, but ranged from two to 135 (Ottensmeyer and Whitehead 2003). Pilot whales appear to associate with the continental shelf break, slope waters, and areas of high sub-surface relief, and often have inshore-offshore movements that coincide with their prey (Jefferson et al. 2008). Primary prey in nearshore Newfoundland has been identified as short-finned squid (Sergeant 1962), but they are also known to consume other species of cephalopod and fish (Nelson and Lien 1996). Pilot whales are regular inhabitants of eastern Newfoundland. In the Jeanne d‘Arc Basin, pilot whales were observed during all but the late fall 2005 seismic monitoring programs (Table 10-4), and were also frequently sighted in the Orphan Basin (Moulton et al. 2005, 2006b; Abgrall et al. 2008b). The long-finned pilot whale was the second most frequently sighted non-SAR species in the Offshore Study Area, according to the DFO cetacean sightings database (Table 10-6). Long-finned pilot whales are expected to be common year-round in the Offshore Study Area, particularly during summer months. Pilot whales also frequently occur in coastal Newfoundland. Prior to 1900, small harvests of pilot whales were taken in Newfoundland bays by whalers and fishermen driving groups ashore; commercial whaling began in 1947, centred on Trinity Bay, and continued until 1972 (Abend and Smith 1999). Hay (1982) estimated a density of 0.1115 pilot whales per square nautical mile in Trinity Bay, based on an August 1980 aerial survey, but it is unknown how many pilot whales currently use Trinity Bay. During the commercial whaling period, whales entered the bay in July and remained through October (Sergeant 1962). There were no long-finned pilot whales reported in the DFO cetacean sightings database in the Nearshore Study Area (Table 10-5). Long-finned pilot whales may occur in the Nearshore Study Area year-round, and are likely one of the most common odontocetes to be present during summer and fall. 10-20 June 2010
Hebron Project Comprehensive Study Report Marine Mammals and Sea Turtles Risso’s Dolphin Risso‘s dolphins are widely distributed in tropical and warm temperate oceans (Jefferson et al. 2008). In the Northwest Atlantic, 20,479 individuals are estimated to occur from Florida to eastern Newfoundland (Waring et al. 2009). Eastern Canada appears to be at the upper limit of the Risso‘s dolphin‘s range, where an unknown number occur, but are considered rare (Baird and Stacey 1991). Risso‘s dolphin group sizes generally range from 10 to 100 animals, but groups of up to 4,000 individuals have been reported (Jefferson et al. 2008). They are often sighted in association with other cetacean species, and are thought to be deep divers. Squid are presumed to be their primary prey, but Risso‘s dolphins also consume crustaceans and other cephalopods (Jefferson et al. 2008). Risso‘s dolphins are primarily associated with steep portions of the continental slope that may concentrate cephalopod prey (Baumgartner 1997). Off the northeast United States coast, they are distributed along the continental shelf edge during spring, summer, and autumn, but range into pelagic regions during winter (Waring et al. 2009). Risso‘s dolphins are relatively abundant in warm temperate and tropical waters, but rarely range as far north as eastern Canada waters (Baird and Stacey 1991). In the Jeanne d‘Arc Basin, there have been no sightings of Risso‘s dolphins during summer and fall monitoring programs (Table 10-4), nor have any been recorded in the deeper Orphan Basin (Moulton et al. 2005, 2006b; Abgrall et al. 2008b). Also, Risso‘s dolphins have not been recorded in the DFO cetacean sightings (Table 10-6). While Risso‘s dolphins may occur in the Offshore Study Area, particularly deeper portions, their presence is likely to be rare. There are no published records of Risso‘s dolphins occurring in coastal Newfoundland waters (nor stranding records). Given the available information on Risso‘s dolphins occurrence and preference for deep waters, their presence in the Nearshore Study Area is likely to be very rare. Common Bottlenose Dolphin Bottlenose dolphins are distributed widely in tropical and temperate waters, occupying a variety of habitats (Jefferson et al. 2008). In the Northwest Atlantic, there are two morphologically and genetically distinct stocks, referred to as the coastal and offshore forms (Hoelzel et al. 1998). The offshore form tends to occur along the outer continental shelf and slope in the Northwest Atlantic while the coastal form occurs from New York to the Gulf of Mexico along the Atlantic coast (Waring et al. 2009). The population of the offshore form, potentially ranging into eastern Newfoundland waters, is estimated to contain 81,588 individuals (Waring et al. 2009). Groups of 2 to 15 animals are common among bottlenose dolphins, but they can also be observed offshore in groups of hundreds (Shane et al. 1986). Group organization can be fluid or long-term and is based on several factors like age, sex, individual relatedness, and reproductive condition (Connor et al. 2000). Bottlenose dolphins consume a variety of fish species, cephalopods, 10-21 June 2010
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10 MARINE MAMMALS AND SEA TURTLES - Hebron Project

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