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Chapter 11 Sea Turtles© Donna A. Dewhurst, U.S. Fish & WildlifeLoggerhead TurtleBased on the observations (n = 1,876; years = 1979 to2003), the loggerhead turtle was the most abundant of thetarget turtles in the region (Figure 11-3). The assessmentresults indicate that the distribution of loggerheads withinthe region varied by season. During the winter months(December – February), individuals were confined tosouthern portions of the region on the shelf or alongthe shelf break. During the spring (March – May) andparticularlythe summermonths (June– August),the numberandnorthwardextent ofobservationsincreased.Areas of frequentobservationswereconcentratedon the shelffrom CapeHatteras upto Delaware Bay during the spring. During the summermonths, the distribution extended up to Long Island,New York with a higher number of observations in closerproximity to the coast. A contraction in distribution andabundance of observations was apparent during the fall(September – November). Areas of loggerhead turtle concentrationidentified in the ESI data were in the southernpart of the region, specifically northern North Carolina,mouth of the Chesapeake Bay, and the Virginia coast.Nesting by loggerhead turtles was confined to primarilythe northern North Carolina and secondarily in Virginiaalong the ocean coast south of Chesapeake Bay with a totalof 503 documented nests. Nesting dates have rangedfrom May through September with peaks during Juneand July.Interpretation of the aggregate dataset suggests that thesouthern portion of the region, in association with thecontinental shelf and shelf break, were utilized year roundparticularly off of Cape Hatteras. The Continental Shelf,coupled with adjoining coastal systems in the south centralportion (Long Island to Cape Hatteras), representedrelatively high concentrations or potential areas of greaterimportance. Furthermore, the concentration of observationsalong the shelf break in the warmer months is noteworthy.The data set precludes an assessment of habitatuse by life stage (adult, juvenile) as well as use of largercoastal estuaries such as Chesapeake Bay, Delaware Bay,and Long Island Sound.Human InteractionsThreats to sea turtles in the region vary by species. Forloggerheads, the most comprehensive threat assessment todate is provided in the Recovery Plan for the NorthwestAtlantic population (NMFS USFWS 2008), perhapsthe largest nesting aggregation globally. This study assessedthe impacts of seven threat categories (i.e., fisheriesbycatch, resource use (nonfisheries), construction anddevelopment, ecosystem alterations, pollution, speciesinteractions, and other factors) for eight life stages acrossthree ecosystems utilized by this species (terrestrial (nestingbeaches), neritic, and oceanic). The study quantifiedimpacts using a stage-based demographic model with aconversion to a “total estimated adjusted annual mortality”(units = number of adult females) by threat category,life stage, and ecosystem type.The results indicate that the principal threats to loggerheadsin the Northwest Atlantic are fisheries bycatch;specifically, in order of magnitude of the threat, bottomtrawl (neritic – juvenile and adult), demersal longline(neritic – juvenile and adult), demersal large mesh gillnet(neritic – juvenile and adult), and pelagic longline(oceanic – juvenile). Total estimated annual mortalitywas greatest within this threat category for the neritic juvenilesfollowed by the neritic adults. There is currentlyinsufficient data to accurately estimate mortality of oceanicadults and neritic juveniles and adults due to pelagiclonglines in the Northwest Atlantic. The resource use11-Northwest Atlantic Marine Ecoregional Assessment • Phase 1 Report