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Chapter 10 - Cetaceanssubmerged for over 60 minutes at recorded depths of over2,000 m (Watkins et al. 1993), which makes them difficultto spot by surveyors.Sperm whale distribution on the East Coast of the UnitedStates is centered along the Continental Shelf break andover the Continental Slope from 100 to 2,000 m depthand in submarine canyons and edges of banks (CeTAP1982; Waring et al. 2008; Mitchell 1975b). Sperm whalesare also known to move into waters less than 100 m deepon the southern Scotian Shelf and south of New England,particularly between late spring and autumn (CeTAP1982; Scott and Sadove 1997). Those areas with historicallylarge numbers of sperm whales and resident populationsoften coincide with areas of high primary productivityfrom upwelling (Whitehead 2002b). In addition, spermwhale habitats usually have high levels of deep water biomass.Female sperm whales may be restricted by watertemperature, as they have only been sighted in areas withsea surface temperatures greater than 15°C.Sperm whale life span can be greater than 60 years (Rice1989). Adult female sperm whales reach up to 11 m inlength and 15 tons, while males are much larger at 16 mand 45 tons (Whitehead 2002b). Sperm whales have lowbirth rates, slow growth and maturation, and high survivalrates. Although much about sperm whale breedingis unknown, it is estimated that the peak breeding seasonin the North Atlantic occurs during spring (March/Aprilto May). Gestation for females is estimated to last 15-18months and calves average 4 m at birth (Perry et al. 1999).Female sperm whales reach physical maturity at 30 yearsold and 10.6 m long. Males continue growing into theirthirties and do not reach physical maturity until about 50years old. Males reach sexual maturity at 10-20 years ofage, but do not appear to breed until their late twenties(Whitehead 2002b). Female sperm whales are inherentlysocial, and related and unrelated female sperm whales livein groups of up to a dozen individuals accompanied bytheir male and female offspring (Christal and Whitehead1997). Males leave the female groups when they are 4-21years old, after which they live in “bachelor schools” ofother juvenile males (Whitehead 2002b). Male spermwhales in these bachelor schools in their late twentiesand older are known to rove among groups of females ontropical breeding grounds.Striped Dolphin (Stenella coeruleoalba)Striped dolphins are found around the world in warmtemperate and tropical seas (Archer and Perrin 1999).They appear to prefer Continental Slope waters offshoreto the Gulf Stream and have been sighted in dense aggregationsalong the 1,000-m depth contour in all seasons(CeTAP 1982; Perrin et al. 1994). Off the northeasterncoast of the United States, striped dolphins are knownto range along the Continental Shelf and out to the shelfslope from Cape Hatteras to the southern edge of GeorgesBank (CeTAP 1982). There are also striped dolphins offthe coast of the United Kingdom and throughout theMediterranean Sea (Archer 2002). Striped dolphins areusually uncommon in Canadian waters because of thecold temperatures, but sightings in the Nova Scotia regionin the past decade indicate that this species may rangefarther than previously thought (Gowans and Whitehead1995).Striped dolphins are usually found in association withconvergence and upwelling zones with high primary productivity.They appear to prefer temperatures of 18-22°C,but are sometimes seen in waters down to 10°C and up to26°C (Archer 2002). This species mates seasonally andgestation is 12-13 months. Calf length at birth is estimatedto be 93-100 cm and sexual maturity is reached at 7-15years for males and 5-13 years for females and at 2.1-2.2 mfor both sexes. Striped dolphins are known to live a maximumof 57.5 years (Archer and Perrin 1999).10-28Northwest Atlantic Marine Ecoregional Assessment • Phase 1 Report