175 
Abstract — Larvae of the genus Ice- 
linus are collected more frequently 
than any other sculpin larvae in ich- 
thyoplankton surveys in the Gulf of 
Alaska and Bering Sea, and larvae 
of the northern sculpin ( Icelinus 
borealis) are commonly found in the 
ichthyofauna in both regions. North- 
ern sculpin are geographically iso- 
lated north of the Aleutian Islands, 
Alaska, which allows for a definitive 
description of its early life history 
development in the Bering Sea. A 
combination of morphological char- 
acters, pigmentation, preopercular 
spine pattern, meristic counts, and 
squamation in later developmental 
stages is essential to identify Icelinus 
to the species level. Larvae of north- 
ern sculpin have 35-36 myomeres, 
pelvic fins with one spine and two 
rays, a bony preopercular shelf, four 
preopercular spines, 3-14 irregular 
postanal ventral melanophores, few, 
if any, melanophores ventrally on the 
gut, and in larger specimens, two rows 
of ctenoid scales directly beneath the 
dorsal fins extending onto the caudal 
peduncle. The taxonomic characters of 
the larvae of northern sculpin in this 
study may help differentiate north- 
ern sculpin larvae from its congeners, 
and other sympatric sculpin larvae, 
and further aid in solving complex 
systematic relationships within the 
family Cottidae. 
Manuscript submitted 18 September 2007. 
Manuscript accepted 29 October 2008. 
Fish. Bull. 107:175-185 (2009). 
The views and opinions expressed or 
implied in this article are those of 
the author and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Description of early life history stages 
of the northern sculpin ( Icelinus borealis 
Gilbert) (Teleostei: Cottidae) 
Rachael L. Cartwright 
Email address: rachcart@hotmail.com 
National Marine Fisheries Service, NOAA 
Alaska Fisheries Science Center 
7600 Sand Point Way NE, Building 4 
Seattle, Washington 98115 
The sculpin family, Cottidae, is a spe- 
ciose, morphologically diverse group of 
fishes with a worldwide distribution 
comprising as many as 275 species in 
about 70 genera (Nelson, 2006). Great- 
est diversity occurs in the Northeast 
Pacific Ocean and Bering Sea with 96 
species in 34 genera where they are 
found in almost every benthic habi- 
tat from the intertidal to the upper 
continental slope (Mecklenburg et al., 
2002; Nelson, 2006; Pietsch and Orr, 
2006). Cottids are primarily preda- 
tors of smaller fish and crustaceans, 
and many species are preyed upon by 
larger fishes and marine mammals, 
particularly pinnipeds (Browne et al., 
2002; Pietsch and Orr, 2006). Cot- 
tids are one of several prey species 
exploited by the harbor seal ( Phoca 
vitulina). Cottid species, including the 
northern sculpin ( Icelinus borealis), 
are abundant in waters surrounding 
rookeries of Steller sea lions (Eumeto- 
pias jubatus) where they contribute to 
the diversity of available prey species 
(Mueter and Norcross, 2000; Browne 
et al., 2002; Fritz and Hinckley, 
2005). New cottid species continue to 
be described; however, the systematics 
and life histories of most species are 
poorly known. A more complete under- 
standing of the diversity of the family 
is necessary to fully understand their 
role in the dynamics of North Pacific 
ecosystems (Hoff, 2006; Pietsch and 
Orr, 2006). 
Icelinus borealis is the most com- 
mon species of Icelinus in the Gulf of 
Alaska and the only species of Iceli- 
nus known from the Bering Sea. It 
is reported to be an important com- 
ponent of the ichthyofauna in both 
regions (Mueter and Norcross, 2000; 
Mecklenburg et al., 2002). Adults are 
distributed from Attu Island in the 
Aleutian Islands and Bristol Bay in 
the eastern Bering Sea to southern 
Puget Sound, Washington, at depths 
of 4-247 m, on nearly all types of 
substrate (Mecklenburg et al., 2002). 
Larvae of Icelinus are the most fre- 
quently collected larval cottids in the 
Northeast Pacific Ocean and Bering 
Sea, occurring in 9.3% (ranked 12 th 
of all taxa collected) of ichthyoplank- 
ton samples collected by the Alaska 
Fisheries Science Center (AFSC). 
Larvae of Icelinus have primar- 
ily been collected in continental 
shelf and slope waters of the Ber- 
ing Sea, through Unimak Pass to 
the Gulf of Alaska and Shelikof Sea 
Valley, around Kodiak Island, and 
southward to the west coast of the 
United States. In the Shelikof Sea 
Valley, they are most often collected 
along the northern side, closest to 
the Alaska Peninsula (Matarese et 
al., 2003). Icelinus comprises 11 spe- 
cies that are diagnosed by pelvic fins 
having one spine and two rays, four 
preopercular spines (the dorsalmost is 
longest and bifid or trifid), two rows 
of ctenoid scales directly beneath the 
dorsal fins, and gill membranes that 
are united and free from the isth- 
mus (Bolin, 1936; Yabe et al., 1983; 
Yabe et al., 2001; Nelson et al., 2004; 
Rosenblatt and Smith, 2004). Adult I. 
borealis reach 10 cm standard length 
and lack distinct postocular spines, 
possess a long cirrus at the base of 
the nasal spine, the first or second 
