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Chapter 11 Sea TurtlesIn the Northwest Atlantic, the most comprehensive studyof the distribution of loggerhead and leatherback turtleswas completed by Shoop and Kenney (1992). Based onthree years of aerial and shipboard surveys, they estimatedthat the total summer population of loggerhead was between2,200 and 11,000 individuals and the leatherbackpopulation was between 100 and 900 individuals (Shoopand Kenney 1992).Ecosystem Interactions andEcological DependenciesSea turtle diet varies by species, life stage and habitat zone(i.e., oceanic, neritic (< 200m)). During the loggerhead’spost-hatchling transition stage, individuals forage on organismsassociated with floating material such as Sargassumincluding hydroids and copepods (Witherington 2002).During the oceanic stage, juveniles typically consumecoelenterates and salps (Bjorndal 1997, 2003). Asjuveniles transition from oceanic to neritic habitats, dietsbecome more diverse and shift according to season andgeographic position. In the North Atlantic, neritic stageadults forage primarily on mollusks and benthic crabs.The diet of oceanic stage adults is currently unknown(NMFS USFWS 2008).Information regarding green turtle ecosystem interactionsduring the juvenile oceanic stage is largely unknown.Upon recruitment back to coastal areas, neritic juvenilessubsist primarily on sea grasses and marine algae (NMFSUSFWS 2007a). The availability of food items withincoastal foraging areas may vary seasonally and interannually.The diet of migratory oceanic adults is currentlyunknown.Leatherbacks forage primarily on pelagic gelatinous organismsincluding jellyfish (medusae), siphonophores, andsalps in temperate and boreal latitudes (NMFS USFWS1992, 2007b). Surface feeding is the most commonly observedforaging habit for leatherbacks, but dive data indicatethat they may forage throughout the water column.The ecological significance of these species within boththe neritic and oceanic zones during juvenile and adult lifestages may be relatively limited due to current populationsizes in the Northwest Atlantic. As populations of theselong-lived, slow growing species recover, their importanceand potential habitat modification ability (e.g., bioturbation,infaunal mining) may become more apparent particularlyfor loggerhead and green turtles within coastalestuaries of the Northwest Atlantic (Bjorndal 2003). Thelarge migrations undertaken by leatherback turtles acrossgeographically disparate habitats may further limit thisspecies’ ecological influence; however, this species’ highlyspecialized diet may help regulate population levels ofpreferred prey items in certain coastal and shelf habitatswithin the region.Northwest Atlantic Distributionand Important AreasMethodsGeospatial data for turtles were obtained from the UnitedStates Navy’s Marine Resource Assessments, primarilycollected via aerial and shipboard surveys during daylighthours, weather permitting. Data used were from theNavy’s Northeast Marine Resource Assessment studyregion, which covers the entire region except for themouth of the Chesapeake Bay west of 75.67°W longitude.This gap was filled with data from the Navy’s SoutheastMarine Resource Assessment study region, shown in pinkin Figure 1. The seasons used in the Northeast were winter:January – March; spring: April – June; summer: July– September; and fall: October - December. The datesused in the Southeast were winter: December 6 - April 5;spring: April 6 - July 13; summer: July 14 - September 16;and fall: September 17 - December 5. Therefore, data foreach study were processed independently, but displayedtogether on the map.A standard approach to overcoming potential survey biasintroduced by uneven effort (actual sightings or artifact ofenhanced survey effort) is by using effort-corrected sightingsdata (Kenney and Winn 1986; Shoop and KenneyNorthwest Atlantic Marine Ecoregional Assessment • Phase 1 Report 11-