of the Fishery Board for Scotland. 



241 



fish, either round or flat, so that after introducing several millions of 

 artificially hatched haddocks and flounders, if local schools were formed, 

 there could be little doubt as to their origin. One great point about the 

 Cromarty Firth is that, like the Moray Firth, minute pelagic forms, such 

 as the young fry feed on, are remarkably abundant. A hatching station 

 with all the necessary appliances, exclusive of ponds, could be provided 

 for about .£1000. Unfortunately, hitherto the Board has not succeeded 

 in obtaining a vote for this purpose, but now that the hatching of sea fish 

 and lobsters may be considered as beyond the experimental stage, special 

 sums may be provided. 



Since the hatching operations began at Flodevig, a number of difficul- 

 ties have arisen, and a number of practical questions have been settled. 

 One of the most serious obstacles to extensive hatching was the difficulty 

 in obtaining ripe fish, but even worse than this was getting eggs capable 

 of being fertilised from the fish when once secured. Again and again the 

 eggs when taken from the fish were dead, or at least incapable of impreg- 

 nation. As is well known, living cod eggs float in water with a specific 

 gravity of 1*024, while dead eggs fall to the bottom even when the specific 

 gravity is considerably higher, hence it is easily ascertaining whether the 

 eggs are dead or alive, by introducing them into ordinary sea water. Dead 

 eggs can further be easily distinguished from living ones by microscopic 

 examination, or by their change in colour and loss of translucency. Dan- 

 nevig, after a time, discovered that the death of the eggs had resulted, not 

 so much from the handling, as from the rapid change in the surroundings 

 of the ripe fish, more especially in their being transferred from water with 

 a specific gravity above, to water with a specific gravity considerably below 

 1 -024. Fortunately the difficulty can be easily overcome by allowing the 

 fish time to adapt themselves to the altered conditions. 



In order to indicate the nature of the work of a hatchery for sea fish, I 

 shall now, by way of concluding this paper, give some extracts from the 

 report recently presented by Captain Dannevig to the Arendal branch 

 of the Society for Improving the Norwegian Fisheries. 



In discussing the influence of introducing fish from the open sea into 

 water with a low specific gravity, Dannevig writes as follows : — 



' Among the many cod purchased were a pair of remarkably fine 

 4 specimens of the light grey deep sea cod, one of which was a male, while 

 ' the other was a female. All the roe obtained from the female was, to my 

 - great regret, damaged, and I gave up all hope of making any use of her ; 

 1 but as the fish, apart from its handsome appearance, was of considerable 

 ' size, 1 determined, for the sake of our many visitors, to set it free into a 

 ' large tank in the hatching house, which was supplied with fresh sea water 

 ' from a depth of 9 fathoms. When I some time afterwards accidentally 

 ' took it up again, I obtained, to my great surprise, a considerable quantity 

 1 of ripe living eggs. A similar experiment was now made with a great 

 number of fish which, to a greater or less degree, yielded damaged roe, and 

 ' as the result always was the same, it was evident that the salinity of the 

 1 water played, in this matter, an important part. (It is to be observed 

 1 that the water pumped into the hatchway from 9 fathoms, has, on the 

 { average, about twice as much salt in it as the water from the surface of 

 ' the sea.) 



' It still remained to explain how only some fish were attacked, while the 

 ' whole of them lived in the same conditions and in the same place. I 

 ' observed that generally the smaller and dark-coloured fish gave hatchable 

 ' roe, while the reverse was the case with the lighter sorts ; and as the 

 £ latter generally keep off the coast in contrast to the others, which are 

 1 known as fjord cod, I came to the conclusion that it was not so much 

 2 H 



