Martini et at.: Population profile of Gulf of Maine Myxine glutinosa 
317 
Figure 4 
A scattergram of the reproductive state of the population of Atlantic 
hagfish as a function of total body length (n = 122). Key: -3 = male, swol- 
len testicular follicles; -2 = male, testicular follicles containing fluid; 
-1 = male, testicular tissue present; 0 = no macroscopically visible go- 
nadal tissue; 1 = female, eggs <5 mm; 2 = female, eggs 5-9 mm; 3 = 
female, eggs 10-14 mm; 4 = female, eggs 15-19 mm; 5 = female, eggs 
>20 mm; 6 = female, shelled eggs in coelom; and 7 = female, 
postovulatory follicles. 
0 100 200 300 400 500 600 700 800 900 1000 
Total length (mm) 
Figure 5 
A length (total length) histogram for Atlantic hagfish, prepared from 
data provided by the New England Fisheries Development Association 
(n=l,172). For these data: Mean=529 mm, SD=104 mm, range=170- 
950 mm. Compare with Figure 2A, P=0.000. 
maphrodites: sexually immature animals 
are found at some stage of female differ- 
entiation, and mature animals are usually 
differentiated as either males or females. 
Mature females are longer than 200 mm 
TL and males are longer than 280 mm TL. 
The largest animals are usually females. 
The incidence of hermaphroditism in ani- 
mals over 230 mm TL is very low (0.3% 
[Gorbman, 1990]), but there is evidence 
that this condition may persist through- 
out the life of the individual (Johnson, 
1994). 
In our study of M. glutinosa, animals at 
any size above 400 mm TL, the minimum 
size at which gonadal tissues become mac- 
roscopically identifiable, may have no dis- 
cernible gonads or possess an immature 
ovary and immature testis, a mature ovary 
and immature testis, an immature ovary 
and a mature testis, or a mature ovary 
only. Animals with only mature testes were 
not seen, and only one animal was ob- 
served with what appeared to be a mature 
ovary and a mature testis. There was no 
apparent relation between total length and 
sex of the individual, nor between length 
and the lack of visible gonadal tissue. An 
incidence of sterility of 25% in animals 
over 400 mm TL is higher than the 13% 
incidence reported by Schreiner ( 1955) for 
mature eastern Atlantic M. glutinosa. 
The sex ratio of females to males in 
many Eptatretus species has been reported 
to be skewed, from slightly to strongly in 
favor of females. For example, Johnson 
(1994) reported a sex ratio for E. deani of 
2.58:1 and for E. stouti a sex ratio that 
gradually decreased from 1.8:1 at small 
sizes to roughly 1:1 for animals near 380 
mm TL. Because sizes and sexes are un- 
evenly distributed over the depth range 
where E. stouti is abundant (100-400 m), 
the sex ratio can vary widely depending 
on the depth of and season at the collec- 
tion site. This may explain the broad range 
of sex ratios (0.58:1 to 4.38:1) reported for 
E. stouti above 200 mm TL collected from a single 
area in British Columbia (Leaman 4 ). 
The sex ratio of females to males in our sample of 
M. glutinosa was highly skewed, at 9.8:1. This highly 
4 Leaman, B. M., ed. 1992. Groundfish stock assessments for 
the west coast of Canada in 1991 and recommended yield op- 
tions for 1992. Biological Sciences Branch, Dep. Fisheries and 
Oceans, Pacific Biological Station, Nanaimo, British Columbia. 
skewed sex ratio is typical for the species as a whole. 
The paucity of males in populations on both sides of 
the Atlantic has long been recognized, but it remains 
unexplained (Schreiner and Schreiner, 1904; Conel, 
1931; Holmgren, 1946; Schreiner, 1955; Walvig, 1963; 
Cunningham, 1886-87). Males whose testes contain 
mature spermatozoa are even more unusual. 
Jespersen ( 1975) collected 1,000 specimens at a fjord 
