622 
Fishery Bulletin 96(3), 1998 
Table 1 
Sex ratio of winter flounder as determined by external palpation and gonad inspection. 
Sex ratio 
(female:male) 
Method 
Number 
of fish 
Location 
Source 
2.5:1 
External 
3711 
New England and New York 
Perlmutter, 1947 
2.3:1 
External 
601 
Rhode Island 
Saila, 1961 
2.6:1 
External 
1431 
New England 
Lux and Porter, 1963; Lux, 1969 
2.3:1 
External 
12,151 
Massachusetts 
Howe and Coates, 1975 
1.5:1 
Internal 
940 
Rhode Island 
Saila, 1962 
1.2:1 
Internal 
1569 
Rhode Island 
Berry et al., 1965 
1:1 
Internal 
227 
Newfoundland 
Kennedy and Steele, 1971 
1:1 
Internal 
1465 
Massachusetts 
Haedrich and Haedrich, 1974 
H Female - cycloid 
ED Female - ctenoid 
□ Male - ctenoid 
E3 Male - cycloid 
True Palpation 
Female 
True Palpation 
Male 
Figure 2 
Number of female and male winter flounder ( Pleuronectes americanus) 
identified by gonadal inspection and palpation in relation to scale type. 
males were misidentified, and six percent 
(23 of 398) of the females were identified 
as males. Similar differences between sex 
ratios derived from palpation of the scales 
and from gonadal inspection have been 
reported in the literature (Table 1). In the 
four studies that used palpation to de- 
termine sex, ratios ranged from 2.3 to 
2.6:1 compared with ratios of 1:1 to 1.5:1 
when gonads were used. 
Scales were collected and examined 
from 672 of the 730 fish. Sex ratios for 
this subset also differed significantly 
(X 2 =44.203, PcO.OOl) between the two 
sexing methods: 2.5:1 for palpation and 
1.2:1 for gonadal inspection (Fig. 2). In- 
dividual fish exhibited either cycloid (479 
fish) or ctenoid ( 199 ) scales, a finding that 
differs from Norman’s ( 1934) observation 
that scales on the blind side were cyc- 
loid. Female fish exhibited primarily cy- 
cloid scales (Fig. 2) which were present 
on 352 (98%) of the 361 females examined. Scale type 
for male fish, however, was variable; 120 (39%) fish 
exhibited cycloid scales and 191 (61%) ctenoid (Fig. 2). 
Discrepancies between texture determinations and 
scale type (observer error) occurred in 33 (5%) of the 
fish examined (Fig. 2). 
It is therefore apparent that the use of texture ac- 
cording to scale type for sexing winter flounder 
(Perlmutter, 1947; Lux and Porter, 1963; MacPhee, 
1978) is not accurate, resulting in a significantly fe- 
male-biased sex ratio. 
Literature cited 
Berry, R. <J., S. B. Saila, and D. B. Horton. 
1965. Growth studies of winter flounder, Pseudopleuro- 
nectes americanus (Walbaum), in Rhode Island. Trans. 
Am. Fish. Soc. 94:259-264. 
Driscoll, D. P. 
1969. Sexing the largemouth bass with an otoscope. Prog. 
Fish-Cult. 31:183-184. 
Flickinger, S. A. 
1969. Determination of sexes in the fathead minnow. Trans. 
Am. Fish. Soc. 98:526-527. 
Haedrich, R. L., and S. O. Haedrich. 
1974. A seasonal survey of the fishes of the Mystic River, a 
polluted estuary in downtown Boston, Massachusetts. Est- 
uarine Coastal Mar. Sci. 2:59-73. 
Howe, A. B., and P. G. Coates. 
1975. Winter flounder movements, growth, and mortality 
off Massachusetts. Trans. Am. Fish. Soc. 104:13-29. 
Kennedy, V. S., and D. H. Steele. 
1971. The winter flounder ( Pseudopleuronectes americanus) 
in Long Pond, Conception Bay, Newfoundland. J. Fish. 
Res. Board Can. 28:1153-1165. 
Lebeau, B., and G. Pageau. 
1989. Comparative urogenital morphology and external sex 
