All through the year cod frequent the British coasts; but it is two or three months before the spawning-season, which commences in January or later according to the locality, that they gather in vast shoals and come close inshore. First come the small codling of a pound or so, and as the winter approaches the longshore fish are found gradually to increase in size, until by Christmas-time it is no uncommon thing on the east coast of England and Scotland for fish of from 10 to 20 lbs. to be caught from the beach.
As a rule the eggs of cod float, owing to a little globule of oil which each one contains, but in water which lacks salinity they sink. The quantities of eggs shed by each fish are enormous; nearly two millions were counted in a cod of a little under 12 lbs. It is fairly certain, however, that not more than two or three, if so many, mature fish are the product of the two million eggs; for if each fish even doubled itself in numbers (if we may use the expression) every year, the sea would soon contain more fish than water. Millions upon millions of eggs are destroyed when there is an on-shore wind during the spawning-season. Sometimes the shore on which they have been wafted has been seen to glisten with them.
By the end of summer such of the young cod-fish as have escaped their many dangers attain about 1 inch in length. They are very varied in colour, which depends on that of the seaweed and their other surroundings. The parent fish, too, vary somewhat in appearance, those round the English coast as a rule having brown backs with irregular spotty markings on the sides, while those from more northern waters usually have darker backs and are less often spotted. Cod are most enormous feeders, and in consequence grow very rapidly. At the Southport Aquarium codling of only ¾ lb. increased in weight to 6 or 7 lbs. in about sixteen months.
So voracious is the cod that it is very apt to swallow anything it sees moving, without considering whether it is wholesome. In 1879 a black guillemot in perfect condition was removed from the stomach of one of these fish; while among other strange finds by cod-fishermen from the same receptacle was a piece of tallow candle 7 inches long, a hare, a partridge, a white turnip, and, going back to the year 1626, a "work in three treatises," which was found in the stomach of a fish captured in Lynn Deeps on midsummer eve, and brought to the Vice-Chancellor of Cambridge. The usual food of cod is, however, small fish of various kinds—herrings, pilchards, sprats, crabs, and sea-worms; but the species is not particular what it seizes when shoaling before the spawning-season and food is scarce owing to the number of mouths.
CHAPTER IX.
CAVE-FISHES, SAND-EELS AND THEIR ALLIES, AND FLAT-FISHES.
BY W. P. PYCRAFT, A.L.S., F.Z.S.
The subterranean fresh-water caves of Cuba furnish the most interesting and most remarkable members of the family in certain small fishes known as Cave-fishes. Living in complete darkness, the eyes have degenerated so as to be no longer useful as organs of sight; indeed, in many species they are entirely wanting. By way of compensation delicate organs of touch have been developed, taking the form, in different species, of barbels, hair-like processes, or tubercles. These blind fishes are closely allied to certain marine forms found in the tropical Atlantic and Indian Oceans, and it is curious to note that amongst these about seven very rare species are found at great depths in the southern oceans, so great that light fails to reach them, and they too are blind.
The Sand-eels, or Launces, are extremely common on the sandy shores of Europe and North America, living in vast shoals, and displaying a wonderful unison in their movements, rising and falling as with one accord. They burrow in the sand with amazing rapidity, forcing their way by means of a horny projection on the lower jaw, and remaining buried at ebb-tide some 5 or 6 inches under the sand, when they are captured by fishermen, armed with rakes, for bait. When swimming in shoals, their presence is often betrayed by schools of porpoises, which feed greedily upon them, preventing their return to the bottom by getting under the shoal, whilst others swim round it. Mackerel also make large raids upon the ranks of such shoals.