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Part III. — Seventeenth Annual Report 



VI. — OX THE RATE OF GROWTH OF PLAICE. 

 By Harald C. Dannevig. 

 (Plate IX.) 



In connection with various researches that are being carried on at the 

 present time it is a matter of some importance to be able to determine 

 the approximate age of young flat-fishes at different times of the year. 

 Records of observations conducted in their respective countries with 

 regard to several species have been published by Dr. J. G. Joh. Petersen 

 in Denmark, Mr. J. T. Cunningham in England, and several other 

 investigators. But the rate of growth of flat-fishes has been found some- 

 times to differ considerably in various parts of the North Sea and its 

 branches, so that the information supplied from elsewhere might be at 

 variance with the conditions in Scottish waters. In connection with 

 experiments carried on at present with a view to test the utility of sea- 

 fish hatching in this country it has become of much importance to be able, 

 if possible, to distinguish between the fishes from the different years' 

 hatching ; or, in other words, to determine the age of the young plaice 

 found on shallow beaches at the various seasons of the year. With this 

 object in view it was deemed desirable to obtain further information 

 regarding the conditions in this respect in Scottish waters, and in the 

 following report an account is given of some observations that have been 

 made at Duubar for this purpose. 



A very simple method by which information might lie gathered 

 regarding the growth of young fishes is to keep specimens in suitable 

 tanks where observations of their growth can be made with ease and 

 accuracy at regular intervals. This was also tried in this case ; but it was 

 found that the results thus arrived at did not always correspond with 

 what the case appeared to be in nature. And after all, there are many 

 and strong reasons why fishes reared artificially from the size of a few 

 inches might differ in the rate of growth from those living in the sea. 

 Information gathered in the one case might only be of doubtful value in 

 regard to the other, although useful for comparison. For this reason 

 in particular, but partly also on account of the inconvenience con- 

 nected with the maintenance of a constant circulation at the time of the 

 year when the hatchery was not working, these experiments were dis- 

 continued after the lapse of six months. Another method had in the 

 meantime been adopted — viz., to make observations at regular intervals 

 on young plaice captured in the sea. The Tyningham sands were selected 

 as a suitable locality for such observations, since they form the most 

 important nursery for plaice in this district. These sands, which are 

 situated about one mile to the west of Dunbar, are about two miles long 

 and about half a mile broad between high and low water marks at spring 

 tide. The distance from low-water mark to a depth of four and a half 

 fathoms, where the stony nature of the bottom renders trawling impossible, 

 is also about half a mile. The sands lie open to the north-east, and are fully 

 exposed to the rough weather that is sometimes experienced from that 

 quarter. A shrimp-trawl with a twelve-foot beam was used for the 

 capture of the fish. It was generally towed by a small steam launch, but 

 in a few cases by a fishing yawl. Examination of the sands was made at 

 intervals from July 1896 till June 1897, and on each occasion hauls were 

 made at low water in the various depths from one to four fathoms. It 

 was thought that such trawling might also furnish information with 

 regard to increase or decrease in the abundance of young plaice on the 



