Two species are shown in this photograph.
The River-eels and Congers are perhaps the best known, and are also highly important food-fishes. That they are fishes of comparatively slow growth seems to be shown by the fact that the common eel takes about four or five years to attain a weight of between 5 and 6 lbs. The males are smaller than the females, the greatest length attained by the former being a little over 1 foot 7 inches, whilst the latter may attain a length of nearly 4 feet. For a long while what is now known to be the female river-eel was regarded as a distinct species—the Sharp-nosed Eel. The two sexes have quite different habits, the smaller males being found mostly in the brackish water of river-mouths, and rarely above the reach of the tides, whilst the females ascend the rivers for great distances, thousands finding their way into isolated ponds, which they reach by travelling overland. Here they appear to remain till they have reached maturity, when they migrate with one accord to the sea. Coming down the rivers during the months of October and November, hundreds are taken in large niches with traps, the mouths of which are directed up-stream.
Photo by W. Saville-Kent, F.Z.S.] [Milford-on-Sea.
CONGER-EEL.
The females of this species often swallow the males.
The migration of eels to the sea is for the sole purpose of spawning and fertilising the eggs, which done, they die. The spawning appears to take place in extremely deep water, where the young eels pass the earlier stages of their development. Like the majority of young fishes, the fry are at first very different in form from the adults, and many have from time to time been described as distinct species, no suspicion of their true nature having been aroused. And this is not to be wondered at, for at this stage they are perfectly transparent and compressed from side to side, so as to be but little thicker than a sheet of stout paper; the head is ridiculously small, and only median fins are present. As development proceeds, having reached a certain maximum size, they, strangely enough, begin to slowly diminish, growing shorter and at the same time rounder, so that eventually, by the time the characteristic eel form is attained, they are considerably shorter than they were at the maximum period of larval life.
By the time the adult eel form has been attained, the larvæ have made their way to the mouths of various rivers, preparatory to making their ascent, which takes place between February and May. They are then from 2 to 5 inches long, and perfectly transparent save for a black line inside the body, running along the spinal cord. The numbers passing up a single river during this ascent are almost beyond belief. In one of these migrations, or "eel-fares," upwards of three tons were captured in a single day in the Gloucester district in 1886, and it has been calculated that more than 14,000 go to make a pound weight. In the previous year the annual consumption of eels was estimated at a minimum of 1,650 tons, with a total value of £130,000. Few obstacles seem too great to be overcome in their ascent, for they will ascend the flood-gates of locks, or even travel overland if the ground be wet, till a desirable resting-place is found. In some parts of England these young eels, or "elvers," as they are called, are salted and made into cakes.
The Conger-eel is a marine species, differing from the river-eel, amongst other things, in its larger head and eyes, and in the arrangement of its teeth and the large size of the gill-openings. The conger is also greatly superior in size, examples of between 6 and 7 feet in length and 60 lbs. in weight being common. The females are larger than the males, and an instance is on record of a female which was over 8 feet in length and weighed 128 lbs. Congers feed on other fishes, cuttle-fishes, and lobsters, as well as upon one another, the larger females eating the smaller males.
