James Murie

“ Migratory habits are gradually getting law-evolved. As to cases in point, there is that of the to-and-fro movement from offshore to inshore, and the reverse. Of a certainty it can now be said of some fish, that on hatching the larva and post-larva uniformly and gradually make for shore or shallow water, there to spend their young stage, to retreat again to deep water on becoming older, and this in a definite course. There is regular congregation and migration during spawning season, partial dispersion thereafter. ”

“ It cannot be affirmed with absolute certainty that there has been material increase in British fisheries since the advent of the laboratory and out-of-door investigations. But there is no gainsaying the fact that a sound foundation has been laid for a study of their economy; witness Mcintosh and Cunningham's volumes aforesaid. Take, for example, investigations of embryotic and postlarval conditions: it is a long jump from 0 to over eighty species to be recorded. ”

“ Thus step by step are we likely to arrive at reasons for the annual gluts or dearths of fish, early or lateness of seasonal appearance, food migrations, &c. The more pressing or immediate interests of fisheries' industries, meanwhile, have not been lost sight of by the scientific inquirer. Much has already been accomplished towards ascertaining the limits of sexual maturity in both sexes, and the vexed questions of trawling and temporary closure of areas have received due attention. ”

“ The former estuarine fish come and go within a limited area, the latter offshore have a wider sea migration. In both cases, though, it is a see-saw towards and away from the coast, the so-called summer Herring spawning in deeper water further distant from land.
The supposed mystery of the fish returning to their own special grounds, Cunningham thinks is due to their habit of herding in shoals. Temperature and food drive the fry up an estuary, and there as they grow, meeting older brethren, associate and accompany them back to the sea-spawning ground. ”

“ When arrived at about an inch long or over, the fish has assumed quite an adult facies, with barbel and fins complete. From the rock-pools and upper water they descend among the shore algæ. By the late autumn they are four or five inches, and by the spring a foot long. A seaward migration then takes place, and in their third or fourth year they return in immense companies as full-grown Cod.
Sexual maturity, according to Holt, is when the Cod are from twenty-two inches to three feet long, though Mcintosh is inclined to deem twenty inches a fair average. ”

“ Growth and maturation are complicated and confused by a double spawning period. Data give a length of three inches the first twelvemonth, to five inches the second year, and to eight or nine inches the third year, when sexual maturity is attained; but British and foreign observers are not quite in unanimity thereon. It would appear though that in the case of the Baltic as well as British Herring there are two marked spawning seasons, the so-called winter and summer Herrings. ”

“ The egg, very characteristic, has a ring of minute oil-drops and a segmented yolk. Incubation lasts four to ten days. The larva is hardy and restless; the post-larval changes in the main resemble those of the Plaice. At nine months it is two and half inches, a year old six or seven inches, second year nine to eleven inches, and third year nine to fifteen inches long. There is a migratory movement analogous to the Plaice, but Soles seek the deep water during cold weather, and vice versâ. The Turbot, though not an abundant fish, would seem prolific, judging from its one to ten million ova. ”

“ At first the larval Cod are impelled about helplessly, often the yolk-sac uppermost. These tiny fish have black transverse bars, giving them quite a characteristic appearance. In a week's time the yolk-sac is absorbed—the post-larval stage—and the barred pigmentation becomes tesselated or tartan-like. The future back and belly fins are originally continuous membranes. When about three weeks old the head becomes pigmented, while the body assumes more of a greenish yellow hue. ”

“ There are quite a number of species of Pleuronectid food-fish in household use. If not individually of the most intrinsic value, yet collectively the Plaice probably heads the list in mercantile superiority. Its life-history consequently has received due attention. Broadly speaking, the old fish are quite offshore dwellers, whereas the young are estuarine, bay and sandy shore frequenters. The cycle pursued is thus traced. The ovarium may contain from 250,000 to double that number, the spawning process being by driblets. ”

“ The Halibut, king of Pleuronectidæ in size, when about a foot long, are occasionally found shorewards, but the adults are quite deeper sea dwellers, and are fish and crustacean feeders. The Flounder, though closely allied to the Plaice, differs widely in habits and migration. It arrives early at maturity, and is exceptionally fecund. There is much disparity in the sexes, the females largest, the males most numerous. ”

“ There the currents trend to the Heligoland bight, the ova floating in that direction, where the post-larval fish spend a period, again to return to the offshore spawning areas. Their chief food is molluscs of various kinds and marine worms.
The Sole has had a finely illustrated monograph devoted to it by Cunningham (Mar. Biol. Assoc) . In this its embryology, adult structure, and economy are fully treated, and various species of Solea meet descriptive notice. ”

“ When verging on half an inch long the body broadens, the eye has got well towards the right, the dorsal fin has advanced to its hinder border, the lateral line looms up, and brown pigment is diffused throughout the upper or right surface of the fish. ”

“ It would seem to be a racial peculiarity of the British community concerning those matters in which ultimately they attain preeminence, that they should, more often than otherwise, only be arrived at through a series of blundering experiences. Expressed otherwise, the English slow-to-move habit and perfect do-as-you-like freedom beget a tendency to let things move in their old circle until personal interests of a few spread to the many. ”

“ When first hatched the larva is more advanced than in the Sprat, a buoyant egg-form. The larval Herring has a biggish head, attenuated colourless body, and the gut passes to proximal tail-end; a broad fin-membrane extends posteriorly from yolk-sac uniformly over back and belly. In the early post-larval stages growth is lengthwise, thickening of body not increasing in the same ratio. ”

“ Even the methods of science, as of political economists, hitherto have failed to unravel the laws of, still less to point out modes of relief to, the fishing industries, though there is a dawn, it is to be hoped, of better things in store. Wherefore non-agreement between fishermen and ichthyologists is easier accounted for. Why inquire about common things, our catch, or where a particular sort of fish is found, &c.? ”

“ According to Mcintosh Sprats spawn well up reaches in estuaries, but Cunningham avers that spawning occurs in the deep water. From such data it may be inferred that they have a summer and winter spawning season in different areas like the Herring. Yet there are manifest physical differences in their entire career. In the Sprat the female but carries 5400 ova; the eggs are pelagic, though inclining ground wards, and they are markedly reticulate; incubation short, three to four days; a slower larval and post-larval development ”

“ The same Herrings, however, do not spawn twice annually, the summer and winter stock being races apart, whose spawning localities essentially differ. Winter spawners frequent inshore brackish waters, whereas summer spawners are more strictly sea-dwellers, coming near the coast, but not into estuaries at spawning season. ”

“ Then follow surging and activity, seldom resting until leeway is made up, and they are abreast of, perchance push beyond, the nations started earlier and more systematically disciplined in the given field. ”

“ Port Erin (=Liverpool) , with voluntary workers, does a fair share of investigation, chiefly, not exclusively, of a local character. The Lancashire County Council contribute towards sea fisheries and technical instruction, otherwise all is private energy. ”