314 
Fishery Bulletin 95(2), 1 997 
Table 2 
Number of gill pouches in Myxine glutinosa (n= 94). 
No. of gill pouches (total) 
10 11 12 13 14 
Incidence (%) 1.1 1.1 74.5 7.4 15.9 
weights of the harvested hagfish. This may in part 
reflect the effort required to immobilize and weigh 
individual hagfish. To address this problem we re- 
viewed the morphometric data for a relatively quick 
and reliable method of estimating sizes and weights 
in the field. The easiest and most accurate method 
found involved measuring the depth of the body at 
the cloaca, excluding the dorsal fin fold. The fin fold 
was excluded to make the measurement easier to 
perform at sea with unanesthetized animals. (A cali- 
per measurement of cloacal depth can be taken 
quickly, with minimal stress to the animal.) 
Figure 1 presents the relationship between total 
length and weight for a sample population of n- 83. 
Figure 2A is a length histogram for the entire sample 
population (n=306) which comprised 202 animals 
whose lengths were measured directly (see Table 1) 
and 104 lengths calculated on the basis of cloacal 
depth using the formula shown in Figure 2B. 
Figure 3A is a weight histogram for the entire 
sample population which comprised 80 direct mea- 
surements (see Table 1), 122 weights calculated on 
the basis of total length (see Fig. 1), and 104 weights 
calculated on the basis of cloacal depth with the for- 
mula shown in Figure 3B. 
Note the preponderance of adult specimens and 
the absence of juveniles smaller than 195 mm (7.6 
in.) at this collection site. No smaller individuals have 
been seen with ROV’s or manned submersibles in 
this area, either on the soft bottom or over the asso- 
ciated rocky ledges (Martini and Heiser, 1989; 1991). 
Data on 1,172 animals from other locations in the 
Gulf of Maine (details below) indicate animals as 
small as 170 mm TL. However, the size of M. 
glutinosa at hatching has been estimated to be ap- 
proximately 50 mm (Fernholm, 1969), and there has 
long been a general consensus that hagfishes, includ- 
ing Myxine, do not have a larval stage (Putnam, 1874; 
Dean, 1900; Worthington, 1905; Walvig, 1963). The 
absence of animals of 50-170 mm TL from traps at 
widespread locations and in visual surveys of bait 
stations suggests that newly hatched M. glutinosa 
may target different feeding resources from those 
targeted by older animals. Juveniles may, for ex- 
ample, feed solely on invertebrates within the sub- 
strate. 
No data are available concerning the reproductive 
cycle and behavior of M. glutinosa. The sampled 
population contained a mixture of sexually imma- 
ture and sexually mature individuals (Fig. 4). The 
following patterns can be recognized: 
1 Individuals shorter than 400 mm TL are sexually 
immature. These animals either lack macroscopi- 
cally visible gonads altogether or have granular 
tissue in the gonadal mesentery that cannot be 
identified as either testicular or ovarian in nature. 
2 Approximately 59% of the population is classified 
as females on the basis of egg development. Testicu- 
lar tissue is usually rudimentary in these animals. 
Figure 1 
Total length (mm) versus body weight (g) in a sample population of 
Atlantic hagfish, Myxine glutinosa (n=80). 
