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Chapter 10 - Cetaceansseason. The validity of sightings was carefully screenedand verified by Navy contractors before inclusion in themodel. Invalid records were not included in the analysis.Using the formula above, SPUE was calculated for eachtarget species, for each season, and for each ten minutesquare.Maps, Analysis, and Areas of ImportanceBaleen WhalesFin WhaleFin whales appeared to move throughout the region, bothinshore and offshore, and aggregate in some spots. Aswith other baleen whales, they typically used the southernpart of the region for migration and the northern partsfor feeding during months with large abundances of preyspecies. Distribution maps indicated the presence of somefin whales along the southeast portion of the region duringthe winter months (Figure 10-2a). Data also indicatedlarger aggregations of fin whales in the highly productivewaters of the Gulf of Maine and Bay of Fundy inthe spring and summer inshore of the Continental Shelfbreak, with a significant congregation at the 100 m isobatharound Georges Bank in the spring (Figures 10-2band 10-2c). Other studies have presented similar findings,reporting that the most important northern areas for finwhales appeared to be the Great South Channel, along the50 m isobath past Cape Cod, Stellwagen Bank, and CapeAnn to Jeffreys Ledge (Hain et al. 1992).Important Marine Areas for Fin WhaleGulf of Maine (Cape Cod Bay, Jeffreys Ledge,Stellwagen Bank, Georges Bank and Great SouthChannel), Bay of FundyHumpback WhaleThe humpback whale population included in this studytravels annually between winter breeding grounds inthe Caribbean and summer feeding areas in the Gulf ofMaine, Georges Bank and the Bay of Fundy (Figure 10-3a). This species is therefore largely absent from thosefeeding areas in winter, but it has been sighted off theMid-Atlantic states and the southeast United States(Swingle et al. 1993; Barco et al. 2002). In spring, thegreatest concentrations of humpback whales occurred inthe southwestern Gulf of Maine and Massachusetts Bay(Figure 10-3b). This species was more broadly distributedin summer and fall, with areas of concentration in thesouthern Gulf of Maine and the Bay of Fundy (Figure 10-3c and 10-3d).These results are largely consistent with the results of priorstudies using older datasets (CeTAP 1982). Prior workhas also shown that humpback whale distribution acrossthe northern study range depends on physical factorssuch as bottom depth and slope (CeTAP 1982; Hamazaki2002) as well as the abundance and distribution of herringand sand lance (Payne et al. 1986; Payne et al. 1990;Weinrich et al. 1997). Prey fish distribution can also resultin significant temporal variation in distribution patterns,even from one year to the next (Payne et al. 1986; Payneet al. 1990; Weinrich et al. 1997). On an individual level,humpback whales are known to return preferentially toone or more areas within their feeding range, but also tomove among available feeding sites within and betweenyears (Robbins 2007). In addition, although all ages andsexes can be found across the feeding range of this species,the southern Gulf of Maine is more frequently usedby mature females and juveniles as compared to northernGulf of Maine and Bay of Fundy areas (Robbins 2007).This distribution suggests that there may be other demographicfactors to consider when evaluating habitat importance,in addition to observed densities. However, suchinformation is rarely available for the other species underinvestigation.Important Marine Areas for HumpbackWhaleGulf of Maine (Massachusetts Bay, Jeffreys Ledge,Stellwagen Bank, Great South Channel, northernedge of Georges Bank), Bay of FundyNorthwest 6-4 Atlantic Marine Ecoregional Assessment • Phase 1 Report 10-