362 BULLETIN OF THE BUREAU OF FISHERIES 



late autumn and winter breeder in the Gulf of Maine. The eggs (by European 

 accounts) are about 2 mm. in diameter, whitish opaque, iridescent on the surface, 

 with a single globule of about 0.6 mm., and are laid in holes or crannies where they 

 stick together. In British waters the rock eel usually chooses empty oyster shells 

 or holes made in the limestone rocks by the boring bivalve Pholas, but there being 

 no oysters in the Gulf of Maine, except in Cape Cod Bay, and the local Pholas 

 being unable to bore into the hard granite rocks of our coast line, the rock eels 

 must seek other nesting sites. Perhaps large mussel shells may serve them, or any 

 crevice in lieu of the latter. The eggs are adhesive, and both the parents have been 

 observed rolling the eggs into balls or clumps an inch or so across, in which they 

 stick together, by coiling around them. In European waters incubation occupies 

 from 6 to 10 weeks, during which period the parent fish of both sexes have been 

 seen lying close beside the egg clumps, but since Ehrenbaum l8 described the parent 

 as "very negligent" of the latter in the aquarium it seems that they merely seek 

 the nesting holes as convenient shelters, and not that they actually guard the nest. 



In the North Sea region rock eels spawn from between tide marks, as in Scot- 

 land, down to 12 fathoms or more, as at Helgoland where eggs have been found in 

 the oyster beds, and probably the depth of spawning within these moderate limits 

 is governed by the ability of the fish to find suitable nesting sites. The larvae are 

 much larger at hatching (about 9 mm.) and further advanced in development 

 than those of most of the fishes that lay buoyant eggs, with the mouth already 

 formed and the yolk sac small, and the latter is absorbed by the time the little 

 fish have grown to about 13 or 14 mm. in length. Older larvae of the rock eel resem- 

 ble corresponding stages of the launce and of the snake blenny in their extremely 

 slender form, but they are among the most easily recognized of fish larvae in the 

 Gulf of Maine, being distinguishable from both these species by the presence of a 

 row of small black pigment spots below instead of above the intestine, and from 

 the herring (the only other very slender larvae apt to be met in any numbers in the 

 Gulf at the same season) by the location of the vent about midway of the body 

 (p. 97) and by the rounded, not forked, tail. 



The caudal rays are visible in larvae of 17 mm., the dorsal and anal fin rays 

 are fully formed and the ventrals present at 20 to 25 mm., and the 12 black dorsal 

 spots so characteristic of the adult are first noticeable against the transparent trunk 

 in young fry of 25 to 30 mm. Up to this time they live at the surface, where they 

 are taken at Woods Hole from April on. We have towed them (20 to 39 mm. long) 

 off Seal Island (Nova Scotia), on German Bank, near Mount Desert Island, off 

 Matinicus Island, and off Ipswich Bay, in April, May, June, and August (a total, 

 however, of only six stations), while Huntsman states that they are caught in early 

 summer in the Bay of Fundy. At a length of 30 to 40 mm. the young fish, now 

 showing most of the adult characters, sink to the bottom, an event which takes 

 place in late summer or early autumn in the Gulf of Maine, judging from what has 

 just been said. Nothing definite is known of the rate of growth of the rock eel 

 after its first autumn. This little fish is of no commercial importance. 



19 Wissenschaftliche Meeresuntersuchungen, Helgoland, neue Folge, Bund 6, 1904, p. 181. Kiel und Leipzig. 



