of the Fishery Board for Scotland. 



237 



maturity until at least the second year. In all probability, if the Flodevig 

 herring survive they will spawn next spring, and be from 7 to 8 inches 

 in length. It may be mentioned that the young cod reared at Flodevig 

 differ greatly in colour. This seems to indicate that they have descended 

 from fish which lived under different conditions — the darker specimens 

 from inshore * rock ' cod, the lighter from the ' silver ' or ' grey ' cod of 

 the open sea. 



Dannevig has thus proved beyond doubt (1) that sea fish can be 

 hatched in great numbers, and (2) that the artificially hatched fry have 

 energy enough to survive when set free. 



In this country the hatching of sea fish has only been attempted on a 

 small scale. In the spring of 1883 I hatched some thousands of herring 

 in the Eothesay Aquarium, and since then the eggs of most of our com- 

 mon food fishes have been hatched at one or other of the Board's marine 

 laboratories. 



The question of hatching sea fish is under consideration at the present 

 moment at Grimsby. Arrangements are being made to found a Fishery 

 Institute and Marine Fish Hatchery at Cleethorpes, where it is proposed 

 to propagate round and flat fish, with the view of replenishing if possible 

 the exhausted inshore waters of the North Sea. It is conceivable that 

 by fish hatching some firths and bays and some inshore banks might be 

 made more productive. It is, however, somewhat difficult to imagine how 

 the introduction of at the most a few millions of fry at one or two points 

 along the coast would, as some predict, have any influence in replenishing 

 the North Sea as a whole. But even although the Cleethorpes hatchery 

 should fail to improve the fisheries in its immediate neighbourhood, it is 

 extremely desirable that it should be established, for no industry more 

 than the fishery industry stands in need of technical education, and it is 

 only by means of institutions such as is proposed at Grimsby that the 

 much-needed information can be collected and spread broadcast amongst 

 those engaged in the fisheries. 



To successfully hatch sea fish in large numbers, the first and last requi- 

 site is an abundant supply of pure sea water. This necessitates a small 

 sea water pond and a number of large tanks, from which a constant 

 supply of pure filtered water can be readily obtained. In order to com- 

 mand suitable water, and at the same time provide accommodation for 

 large floating fish cars or pens, the United States Fish Commission has 

 constructed, at a cost of £10,000, a small harbour in connection with 

 their laboratory at Wood's Holl. Water is pumped from this sea pond or 

 harbour into a large wooden tank lodged in an adjacent tower. From 

 the tank the water is conveyed to the hatching and other tanks in the 

 laboratory. 



At Flodevig the fyord near which the hatching house stands is so pro- 

 tected, and the tides are so imperceptible, that the construction of an 

 expensive pond at the outset was unnecessary. The water was simply 

 pumped from the creek into a tank in the station, from which after being 

 filtered it passed to the hatching boxes. 



Even for floating eggs it is more essential to have the water pure than 

 to have a high specific gravity, for as soon as the eggs get coated with 

 sediment, development is arrested, and the embryos not only soon die, 

 but by undergoing putrefactive changes, seriously endanger all the other 

 eggs in the hatching apparatus. 



In addition to having at command an abundant supply of sea water, it 

 is, of course, necessary to have the hatching station in the vicinity of some 

 rich fishing ground, where plenty ripe fish may be obtained when wanted. 

 It is, however, hopeless to trust to obtaining fish ready to spawn. It is 



