FISHES OF THE GULF OF MAINE 17 



on the Boon Island — Isles of Shoals fishing ground and about Jeffreys Ledge, where 

 we found it plentiful enough in the spring of 1913 to have gutted 3 to 5 per cent of 

 all the haddock in the gill nets. Fishermen report it as equally numerous in the 

 deeper parts of Massachusetts Bay. On the offshore banks the hag is well known, 

 and it has been trawled at various localities along the outer edge of the continental 

 shelf off New England at depths of from 100 to 200 fathoms, and deeper. We 

 ourselves took 1 1 large ones in one set of the Monaco deep-sea trap in 260 fathoms 

 off Nantucket on July 9, 1908, and it has been taken in from 300 to 500 fathoms 

 off Marthas Vineyard. 



Habits. — The hag is not a true parasite, as has sometimes been suggested, there 

 being no reason to believe it ever attacks living, uninjured fish, but it is a scavenger. 

 Judging from its habits during the brief time it survives in aquaria, it spends its 

 time lying embedded in the clay or mud with the tip of the snout projecting, but it 

 is an active swimmer. Probably it finds its food by its greatly specialized olfactory 

 apparatus. So far as is known it feeds chiefly on fish, dead or disabled, though no 

 doubt any other carrion would serve it equally well, were such available. It is 

 best known for its troublesome habit of boring into the body cavities of hooked or 

 gilled fishes, eating out first intestines and then the meat, finally to leave nothing 

 but a bag of skin and bones, inside of which, or clinging to the sides of a fish it has 

 just attacked, the hag itself is often hauled aboard. In fact, it is only in this way, 

 or entangled on lines, that hags ordinarily are taken or seen. Being worthless 

 itself, it is an unmitigated nuisance and a particularly loathsome one, owing to its 

 habit of pouring out slime from its mucus sacs in quantity out of all proportion to 

 its small size. One hag, it is said, can easily fill a 2-gallon bucket, nor do we think 

 this is any exaggeration. 



The hag is at home only in comparatively low temperatures — cooler, probably, 

 than 50° — and this confines it to depths of 15 to 20 fathoms or more in the Gulf of 

 Maine in summer. 



Breeding habits. — The hag and its immediate relatives are hermaphrodites — 

 the only regularly effective ones in the whole vertebrate series, except for a very few 

 species of bony fishes. Its single unpaired sex organ first develops sperm in the 

 rear, then eggs in the forward portion. 8 



Further than this our knowledge of its breeding habits is still of the scantiest. 

 Probably there is no definite spawning season, but eggs may be laid at any time of 

 the year, for females near ripeness and others nearly spent have been recorded for 

 various months, winter and spring as well as summer and autumn, and eggs have been 

 taken in Norwegian waters from November to May. It has long been known that 

 the eggs are large (up to 20 mm. in length), tough-shelled, and comparatively few 

 (only 19 to 25 nearly ripe eggs having been counted in any one fish), and that they 

 are very characteristic in appearance, for at each end they bear a cluster of barb or 

 anchor tipped filaments (fig. 2b). Up until 1900 none had been found about which 

 it could be asserted without hesitation that they had been laid naturally. In that 

 year, however, Dean (1900) described hag eggs from the northwest part of Georges 



8 For an account of the sex organ of the hag see Schreiner (Biologisches Centralblatt, XXIV Band, Nr. 3, February, 1904, 

 pp. 91-104). For a summary of earlier studies see Smitt (Scandinavian Fishes, 1892, p. 1205). 



