EPA's Vessel General Permit and Small Vessel General

the population has experienced a contraction in its overall distribution (Speckman and Piatt.
2000, Hobbs et al. 2008, Rugh et al. 2010). According to Hobbs et al., (2008) 90% of the whales
in the 1970s were observed within 70 nmi of the western tip of Anchorage (Point Woronzof),
whereas more recently (1998-2007) 90% were detected within 20 nmi. Although the precise
reason for the range contraction is not known, the shrinking summer distribution likely reflects
the reduction in the population size over the same intervals and the beluga whale’s preference for
dense aggregations of preferred prey species.
Analyses of beluga whale stomach contents indicate that beluga whales are opportunistic feeders,
but specific species form the bulk of the prey when they are seasonally abundant (Hobbs et al.
2008). For instance, eulachon (Thaleichthys pacificus) also known as smelt or candlefish, are a
small anadromous fish return that their natal rivers in spring for spawning. The high fat content
of this species confers a significant source of energy for beluga whales, including calving whales
that occur in the upper inlet during the same period (Calkins 1989). Based on stomach sample
analyses from 2002-2007 fish compose the majority of the prey species, with gadids (cod and
walleye pollock) and salmonids composing the majority of the fish eaten (Hobbs et al. 2008).
Anadromous salmonids begin concentrating at the river mouths and intertidal flats in upper Cook
Inlet in late spring and early summer as emigrating smolts and immigrating adult spawners. Like
eulachon, salmon are another source of lipid-rich prey for the beluga whale and represent the
greatest percent frequency of occurrence of the prey species found in Cook Inlet beluga whale
stomachs (Hobbs et al. 2008). As salmonid numbers dwindle in the fall and winter, beluga
whales return to feed on nearshore or deeper water species including cod, sculpin, flounder, sole,
shrimp, crab and others (Hobbs et al. 2008).
Beluga whale calving is not well documented but the presence of cow/calf pairs in large river
estuaries in the upper inlet, and accounts of Alaskan Natives, suggests that calving and nursery
areas are located near the mouths of the Beluga and Susitna Rivers, Chickaloon Bay and
Turnagain Arm (see NMFS 2008b). Recent surveys suggest that cow/calf pairs also make
extensive use of Knik Arm in the summer and fall (Funk et al. 2005 as cited in NMFS 2008b).
Neonates are often not seen until June in Cook Inlet (Burns and Seaman 1986). Some researchers
have suggested that the shallow waters of Cook Inlet may be important for reproduction and
calving, as the shallower water is warmer which may confer an important thermal advantage for
calf survival as they have relatively limited fat deposits at birth (see NMFS 2008b). A beluga
female’s first parturition is at age five or six. Breeding is presumed to occur shortly after calving,
in the late summer after about 14-15 months of gestation (Calkins 1989). Lactation lasts about
two years, with breeding occurring during lactation (Calkins 1989).
Status and Trends
On October 22, 2008, NMFS listed the Cook Inlet beluga whale as endangered (73 FR 62919).
Historic numbers of beluga whales in Cook Inlet are unknown. Dedicated surveys began in
earnest in the 1990s when NMFS began conducting aerial surveys for beluga whales in Cook
Inlet. Prior to then, survey efforts were inconsistent, part of larger sea bird and marine mammal
surveys, made by vessel, or estimated following interviews with fishermen (Klinkhart 1966). In
many cases the survey methodology or confidence intervals were not described. For instance,
Klinkhart (1966) conducted aerial surveys in 1964 and 1965, where he describes having
172