178 
Fishery Bulletin 107(2) 
Table 1 
Body proportions of larvae and juveniles of northern sculpin (Icelinus borealis). Values for each body proportion are expressed as 
percentage of standard length (SL) or head length (HL): mean, standard deviation, and range. 
Body proportion 
Flexion 
Postflexion 
Juvenile 
Sample size 
9 
27 
8 
Standard length 
9.1 ±0.74(8.0-10.2) 
14.9 ±2.40 (11.1-22.7) 
38.6 ±10.3 (24.1-51.7) 
Head length/SL 
25.2 ±0.02 (22.2-28.4) 
34.3 ±0.04 (26.2-41.5) 
37.9 ±0.02 (35.2-39.8) 
Snout length/HL 
27.9 ±0.04 (24.8-37.9) 
26.8 ±0.03 (20.0-32.4) 
27.9 ±0.05 (21.8-39.0) 
Eye diameter/HL 
31.0 ±0.03 (25.3-33.7) 
24.3 ±0.02 (20.2-30.3) 
27.8 ±0.01 (26.1-30.6) 
Snout-to-anus length/SL 
44.6 ±0.03 (38.7-48.6) 
47.2 ±0.03 (42.3-54.0) 
50.6 ±0.04 (46.4-57.7) 
Body depth/SL 
20.3+0.02(17.6-23.2) 
21.9 ±0.02 (17.6-27.1) 
20.5 ±0.02 (17.4-22.7) 
Pectoral-fin length/SL 
10.1 ±0.02 (6.6-13.4) 
24.2 ±4.30 (13.8-32.4) 
24.5 ±2.80 (19.6-28.8) 
Miller Freeman ; UW 105169, 1 (24.9 mm), Bering Sea, 
56°31.2'N, 169°28.8'W, 68 m depth, 11 September 1997, 
RV Miller Freeman-, UW 105172, 1 (24.1 mm), Bering 
Sea, 57°17.3'N, 170°09.3'W, 39 m depth, 16 September 
1997, RV Miller Freeman-, UW 105174, 1 (22.7 mm), 
Bering Sea, 57°16.3'N, 170°11.0'W, 16 September 1997, 
RV Miller Freeman. 
Adults: 22 specimens examined, 32.0-77.0 mm. 
UW 027383, 4 (41.0-50.0 mm), eastern North Pacific, 
60°12.0'N, 147°45.0'W, 30 m depth, 1 August 1989, RV 
Discovery, J. W. Orr; UW 029499, 5 (32.0-55.0 mm), 
eastern North Pacific, 60°21.0'N, 147°49.0'W, 40 m depth, 
6 August 1989, RV Discovery, J. W. Orr; UW 040432, 
3 (45.0-64.0 mm), eastern North Pacific, 60°18.0'N, 
147°50.0'W, 142 m depth, 31 July 1989, RV Discovery, 
C. Eaton; UW 111416, 2 (55.0-62.0 mm), eastern North 
Pacific, 52°39.8'N, 169°21.6'W, 114 m depth, 24 May 
2003, FV Northwest Explorer, J. W. Orr; UW 040955, 
4 (44.0-45.0 mm), eastern North Pacific, 60°33.2'N, 
147°35.0'W, 40 m depth, 1 October 1989, A. M. Shedlock; 
UW 027174, 4 (60.0-77.0 mm), eastern North Pacific, 
Gulf of Alaska, Yakutat Bay, FV Resolution. 
Results 
Morphology 
The smallest larva examined in this study was 7.4 
mm notochord length (NL) and in preflexion (Fig. 2A). 
Notochord flexion began at approximately 8.0 mm and 
was complete around 11.0 mm (Fig. 2B). Postflexion 
larvae were 11.0-16.0 mm (Fig. 2C). Transformation to 
the juvenile stage occurred between 16.0 mm and 24.0 
mm (Fig. 2D). Specimens larger than 24.0 mm were 
considered juveniles and identified using adult charac- 
ters (Fig. 2E). 
During preflexion, the head was small and round, 
measuring 18% SL, increasing to 38% SL by the juve- 
nile stage (Table 1). The snout was initially rounded, 
but became notably pointed by flexion; snout length was 
24% head length (HL) during preflexion, increasing 
to approximately 28% HL during flexion through the 
juvenile stage. Snout-to-anus length steadily increased 
from 39% SL during preflexion to 51% SL in juveniles. 
Body depth was initially 17% SL during preflexion, but 
increased to approximately 20% SL in later stages. 
Pigmentation 
Two preflexion specimens were available for study: one 
7.4 mm NL and one 7.9 mm NL. Both specimens were 
lightly pigmented (Fig. 2 A). A single melanophore was 
present on the lower jaw angle. Pigment on the gut 
consisted of one to three individual melanophores ante- 
riorly, and moderate pigmentation on the anus. A single 
row of nine postanal ventral melanophores (PVMs) was 
present on both specimens. Pigmentation on the caudal 
finfold was present on the 7.4 mm NL specimen. Pigment 
on the head, gut, and anus steadily increased during 
flexion (Fig. 2B). 
Twenty-six postflexion and transforming specimens 
were examined. Melanophores were present dorsally 
over the mid- and hind-brain (Fig. 2C). Minute melano- 
phores were present on the orbital rim. Loosely grouped 
melanophores were present in postorbital and suborbital 
regions, upper and lower jaws, on the cheek, opercu- 
lum, chin, and isthmus. Pigment was present on the 
nape. The gut was pigmented along the anterodorsal 
surface and extended dorsolaterally toward the anus. 
Three to 14 PVMs were present on specimens between 
preflexion and postflexion stages; nine was the modal 
value (Table 2). The size, shape, and location of PVMs 
were variable among specimens. Lateral body pigment 
developed as vertical (dorsal to ventral) bands that were 
composed of densely aggregated small melanophores. 
The anterior (first) lateral band was located directly 
under the first dorsal fin and extended ventrally to the 
gut. The second band developed as a small aggregation 
of melanophores located mediolaterally on the body. 
When fully developed, the second band extended from 
the anterior portion of the second dorsal fin to the me- 
diolateral part of the body. Pigment developed on the 
first dorsal fin, particularly on the membrane between 
