Atlantic Hagfish - Status of Fishery Resources off the Northeastern US

Figure 29.1 Statistical Areas Used

Distribution, Biology and Management

The Atlantic hagfish or “slime eel”, Myxine glutinosa, is found in deep, cold waters to depths of at least 1100 m. In the western north Atlantic, hagfish are distributed from Davis Straits, Greenland to the continental slope waters off of Florida. In the Gulf of Maine the distribution of hagfish is primarily affected by salinity, temperature and substrate type (Collette and Klein-MacPhee 2002).

Hagfish is considered to be the most primitive vertebrate species either living or extinct (Collette and Klein-MacPhee 2002, Powell et al 2005). Hagfish evolved over at least 300 million years and have the same basic morphological traits of fossilized specimens (Bardack 1991).

Hagfish lack bones, paired fins, and a true jaw. The hagfish skeleton is composed of cartilage, the dorsal fin is actually a skin fold, and the jaw is a rasping plate with horn-like teeth. Atlantic hagfish belong to the family Myxinidae which have one pair of gill openings attached to 6-7 internal gill pouches per opening. The species has paired barbels on the tip of its snout and four barbels surrounding the mouth. Hagfish are almost blind because their eyes are rudimentary but their sense of smell is keen. The skin of the Atlantic hagfish is smooth and scale-less with a series of slime glands along both sides of the ventral midline (Collette and Klein-MacPhee 2002). These glands produce fibrous mucus that protects hagfish from predators and possibly parasites.

Atlantic hagfish inhabit soft clay or muddy sediments and spend much of their time in temporary burrows in the sea floor (Collette and Klein-MacPhee 2002). They prey primarily on shrimp, worms and small crabs (Gustafson 1935, Shelton 1978, Collette and Klein-MacPhee 2002). They are also scavengers that feed upon dead and dying fish, mammals and shellfish. Hagfish are often considered a nuisance by commercial fishermen because they can feed on targeted species (Martini et al 1997, Collette and Klein-MacPhee 2002).

Age at maturity and life expectancy are unknown in the Gulf of Maine, as are spawning locations. Length at 50% maturity for Grand Banks hagfish is estimated at 378 mm (Grant 2006). Spawning may occur at any time of year, as females have been observed in various stages of oogenesis during all seasons (Collette and MacPhee 2002, Martini et al 1997). Hagfish can possess both mature male and female sexual organs but it is unknown if both are functional at the same time (Powell et al 2005). Females produce clutches containing an average of 20-30 yolky eggs (Collette and MacPhee 2002). Time required to develop a clutch of eggs is unknown but has been estimated at 1-2 years. Development from egg to hatchling may be several months based on egg yolk volume (NEFSC 2003). Studies in the Gulf of Maine suggest that the population is composed of 10% sexually immature individuals, 59% females, roughly 6% males and approximately 25 % of the adult population of unknown gender (Martini et al 1997).

Although a hagfish fishery exists in the Gulf of Maine, the resource is not actively managed at present.

Research Vessel Survey Indices

Hagfish are encountered infrequently in the NEFSC research vessel Bottom Trawl Surveys. The stratified mean number per tow index in the Spring NEFSC survey series peaked in the mid-1970’s and remained low ever since (Figure 29.5 [Fig 29.5 Data]). A slight increase in 2001 and 2002 was observed but the index subsequently declined.

NEFSC autumn survey abundance indices are generally higher than in the spring (Figure 29.6 [Fig 29.6 Data]). The autumn indices peaked in the early 1970’s and were low during 1980’s. Recent indices are among the highest in the autumn time series.

Summary

Hagfish have been harvested commercially in the Gulf of Maine since the early 1990’s with peak landings of 3,000 metric tons occurring in 2000 (Figure 29.2 [Fig 29.2 Data]). Survey indices have been variable but have been higher than average in recent years (Figure 29.5 [Fig 29.5 Data]) and (Figure 29.6 [Fig 29.6 Data]).