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Fishery Bulletin 95(2), 1997 
reputed to contain a relatively high proportion of 
males. Of 200 animals identified as male, only one 
contained a testis with motile sperm. Holmgren 
(1946) suggested that either ripe males may have a 
different distribution or that the ripe males do not 
feed. The latter suggestion appears more plausible 
in view of the broad areas sampled by investigators 
over the last 100 years. 
Among hagfish, only Eptatretus burgeri has been 
shown to have an annual breeding cycle (Fernholm, 
1975; Patzner, 1977; Tsuneki et al., 1983). Our data, 
collected during the summer months (June-August), 
indicate that there is no correlation between the size 
of a female and the size of the eggs within the ovary. 
Thus at any given time, one can collect females with 
ova at any stage of maturation. This is consistent 
with the contention that M. glutinosa, like most other 
hagfishes studied, have no specific breeding season 
(Cunningham, 1886-87; Nansen, 1887; Walvig, 1963). 
The location of egg deposition also remains a mys- 
tery. Over the last 150 years, fewer than 200 eggs of 
My xine glutinosa have been recovered. Only 4 of these 
eggs were fertilized, and none of the embryos were 
in an ideal state of preservation when examined. A 
trawled and damaged embryo, described by Dean 
(1899), has been the only report of a fertilized hag- 
fish egg recovered in the western Atlantic. The great 
majority of the Myxine eggs — fertilized or not — de- 
scribed in the literature were collected in the east- 
ern Atlantic, primarily from the nets of trawlers 
working soft bottom substrates. Three embryos of M. 
glutinosa , in somewhat better condition than Dean’s 
specimen, served as the basis for papers by Holmgren 
(1946) and Fernholm (1969). Despite concerted ef- 
forts, no egg clusters were seen during winter and 
summer ROV surveys or summer submersible dives 
in an area supporting a large hagfish population, nor 
on the adjacent ledges (Martini and Heiser, 1989). 
It is not known where or when mating takes place, 
nor how males locate females (or vice versa). Al- 
though at least one species ( Eptatretus burgeri) has 
an annual reproductive season and migrates to re- 
productive sites that are used year after year (Tsuneki 
et al., 1983), such is not the case for M. glutinosa. The 
population at our primary study site appears to remain 
in place throughout the year; ROV work in June— Sep- 
tember and December-January did not reveal any ob- 
vious differences in abundance at our study site. 5 How- 
ever, these observations need to be supported by addi- 
tional collections and tagging studies. 
5 This conclusion is based on visual surveys only. Weather condi- 
tions and equipment problems made it impossible to collect 
specimens during the winter trips. 
Although our picture of reproduction in this spe- 
cies remains incomplete, it is clear that the popula- 
tion reproduces very slowly. Of 122 animals surveyed 
in the summers of 1989-90, only five were females 
with postovulatory follicles, and only one had fully 
developed shelled eggs loose in the coelom. In ani- 
mals with postovulatory follicles, the remaining ova- 
rian tissue did not contain eggs in advanced stages 
of development; there must therefore be a signifi- 
cant time period between reproductive cycles for a 
given individual. The time required for a female M. 
glutinosa to produce a clutch of eggs is not known, 
but it is probably longer than a year (Patzner and 
Adam, 1981). This makes good sense because the 
synthesis of large (25 mm x 10 mm) yolky eggs is a 
substantial energetic investment. It appears likely 
that the reproductive potential of the population as 
a whole is relatively low, because 1) many of the in- 
dividuals have no discernible gonads, 2) each ma- 
ture female produces only 20-30 eggs at a time, and 
3) a relatively small proportion of the females con- 
tain mature eggs at any given time. This low re- 
productive potential has obvious implications for the 
development of a sustainable fishery for these animals. 
Given the evidence, there is considerable risk that 
the Gulf of Maine industry will prove to be another 
boom-and-bust fishery. The processors accept only 
fish greater than 350 mm in length (Kuenstner, 
1996), which corresponds to a weight of more than 
43 g (see Fig. 1). Because the average weight for Gulf 
of Maine specimens greater than 350 mm was 140 g, 
the fishing years of 1993-94 probably represented a 
harvest of roughly 11 million individual hagfish. The 
actual impact on the population is considerably 
greater, however, because 1) smaller hagfish are 
caught in the traps and are discarded into the sur- 
face waters and 2) hagfish of all sizes escape from 
the trap as it ascends. Except in winter, when the 
fishery is relatively inactive, hagfish released or es- 
caping in this manner are unlikely to survive. The 
oceanographic conditions where these hagfish are 
collected are extremely stable, with summer tem- 
peratures of 4-6°C and a salinity of 33-34 ppt. Hag- 
fish held in aquaria at the Shoals Marine Labora- 
tory survive at 0-4°C but become increasingly agi- 
tated and soon die if the temperature rises above 
10°C. Surface temperatures in the inner Gulf of 
Maine reach 16-18°C or more in the top 25-50 m 
during July and August, and at least one other warm- 
water mass covers the cold bottom water ( Appollonio 
and Mann, 1995). When suddenly exposed to salini- 
ties below 31 ppt, individuals will struggle violently, 
produce copious slime, and then become moribund 
(Martini et al., pers. obs., and Adam and Strahan, 
1963a). Surface salinities are often below 30 ppt in 
