316 
Fishery Bulletin 95(2), 1 997 
Weight (g) 
' 1 ' 1 > 1 ■ 1 i 1 1 1 1 1 T , 1 , 
5 7.5 1 0 12.5 1 5 17.5 20 22.5 25 27 5 30 
Cloacal depth (mm) 
Figure 3 
Body weight (g) in the sample population of Atlantic hagfish. (A) A fre- 
quency histogram for body weight (rc=306). This graph includes direct 
measurements {n= 80), weights calculated from the equation in Figure 
1 (n=22), and weights calculated from the equation in part (B) (rc=04). 
(B) The relationship between cloacal depth and body weight (n=53). r 2 
=0.864, P=0.0001 
TL) was comparable to that found at the Nipper 
(range: 195-724 mm TL; average: 509 mm TL). Al- 
though the small size of the Stellwagen sample con- 
strains the power of statistical comparison, the only 
statistically significant differences found between 
these groups were that the maximum depth and 
width (in percent of body length) of animals from 
Stellwagen Bank were greater than those from the 
original study site. This may reflect differences in 
the substrate and food availability between the two 
locations, or it may be an artifact of the small sample 
size. 
We next compared our length distribution data 
with catch statistics collected between 19 May and 
28 July 1994 by the New England Fisheries Devel- 
opment Association (Kuenstner, 1996). The close 
agreement between the data sets (Fig. 2A vs. Fig. 5) 
suggests that the sampling reported here is repre- 
sentative of hagfish populations throughout the Gulf 
of Maine. 
Discussion 
The gonads in hagfishes develop within a mesenterial 
fold located to the right of the dorsal mesentery that 
supports the gut. The anterior 2/3 of the gonad may 
develop into ovarian tissue, and the posterior 1/3 may 
develop into testicular tissue. Details of sexual dif- 
ferentiation are known for only a few species, nota- 
bly the Pacific hagfish, Eptatretus stouti. Gorbman 
(1990) reported that E. stouti are protogynous her- 
