Composite Training Unit Exercises and Joint Task ... - Govsupport.us

COMPTUEX/JTFEX EA/OEA Final Chapter 3The overall abundance of these species increased rapidly on the Channel Islands between the end ofcommercial exploitation in the 1920s and the mid-1980s. The growth rates of populations of somespecies appear to have declined after the mid-1980s, and some survey data suggested that localizedpopulations of some species were declining. The declines may have been a result of either inter-specificcompetition or population numbers having exceeded the carrying capacity of the environment (Stewart etal., 1993; Hanan, 1996). More recently, most populations are increasing (Carretta et al., 2004), and insome cases seals have recently occupied new rookeries and haul-out areas. The aforementioned pinnipedspecies are not listed as endangered or threatened under the ESA (Barlow et al., 1997).3.3.2.6 Species Accounts3.3.2.6.1 Mysticete Cetaceans (Baleen Whales)All species of baleen whales that could occur in and near the SOCAL OPAREA have extensive ranges inthe North Pacific, extending from high-latitude feeding grounds in the summer to subtropical calvinggrounds in the winter (Bonnell and Dailey, 1993).Blue, fin, and humpback whales are present in southern California offshore waters during the summer andautumn months (Heyning and Lewis, 1990). Minke whales appear to be present year-round off theChannel Islands (Rice, 1974; Leatherwood et al., 1987). In the winter and spring, migrating gray whalesare abundant both close to shore and in offshore migration corridors along and between the ChannelIslands. North Pacific right, sei, and Bryde’s whales are uncommon or rare in the area.Blue Whale (Balaenoptera musculus)Status—The blue whale is listed as endangered under the ESA, and the Eastern North Pacific Stock is,therefore, considered depleted and strategic under the MMPA. The population estimate for blue whalesin the Eastern North Pacific Stock is 1,744 (CV=0.28) individuals (Calambokidis et al., 2003; Carretta etal., 2006). The population using California waters may be increasing but it is not known if this is due toan increase in the stock or an increase in animals foraging in California waters (Barlow, 1997).Distribution—The blue whale has a worldwide distribution in circumpolar and temperate waters. Thepopulation that uses coastal waters of California is present there primarily from June to November, with apeak in blue whale calling intensity observed in September (Burtenshaw et al.,. 2004). Foraging areasinclude the edges of continental shelves and upwelling regions (Reilly and Thayer 1990; Schoenherr1991). Feeding grounds have been identified in coastal upwelling zones off the coast of California (Crollet al.,. 1998; Fiedler et al.,. 1998; Burtenshaw et al.,. 2004), Baja California (Reilly and Thayer, 1990).Blue whales are found around the Northern Channel Islands, Santa Rosa and San Miguel Islands, fromsummer through the fall where currents provide dense layers of euphausiids for them to feed on. Thispopulation is thought to inhabit waters off Central America from December to May (Calambokidis 1995).During the cold-water months, very few blue whales are present in waters off California (Forney andBarlow, 1998; Larkman and Veit, 1998; U.S. Navy, 1998). These seasonal movement patterns arethought to coincide with productivity, particularly abundance of euphausiids which are the main foodsource of blue whales. Blue whales are not expected to be in the SOCAL OPAREA from Decemberthrough May (Calambokidis, 1995; Burtenshaw et al., 2004).A few blue whales were observed in or near the SOCAL Range Complex in early to mid spring (U.S.Navy, 1998), but were most common during July–September (Hill and Barlow, 1992; Mangels andGerrodette, 1994; Teranishi et al.,. 1997; Larkman and Veit, 1998; U.S. Navy, 1998). During theSWFSC/NMFS surveys in 1998–1999, blue whales arrived in late May and were common into August,with one whale seen as late as November (Carretta et al., 2000). In other years, blue whales wereFebruary 2007 3-32