NORTH SEA INVESTIGATIONS. 103 



A comparison between these plaice, caught off the German coast 

 in November and December, and those which I have described 

 in the previous number of the Journal, as caught under my own 

 observation in June, in the same neighbourhood, is worthy of careful 

 attention. Firstly, with regard to the locality of capture. The position 

 given by Herr Diige, for the second sample, is 2-4 miles west of 

 Amrum Light ; and in the cruise of the John Bull, the Amrum Light 

 was seen, on two nights, at a distance of 20 miles. Thus, the John 

 Bull was fishing on these occasions 4 miles nearer the land, and it 

 is true that sometimes she was steered nearer the land than this ; but 

 she was also fishing sometimes out of sight of the Amrum Light, and 

 the ground she covered must have included the position where the 

 December sample was taken. Next, with regard to the depth : during 

 the fishing of the John Bull, it varied from 1\ to 12h fathoms, while 

 the December sample was taken at 11 fathoms. At the seventh haul 

 in the record of the trip of the John Bull the depth was 12 fathoms, 

 and at this haul a number of plaice, 7J to 10 inches long, were taken, 

 two baskets 10 to 12 inches long, and two baskets 12 to 15 inches long. 

 The comparison shows, therefore, that although the John Bull extended 

 her operations to positions nearer the land than that where the 

 December sample was taken, yet it is clear that she also fished at 

 the same depth and distance from land, and obtained there numbers 

 of plaice of small sizes, which are not represented in that sample. 

 On the other hand, the December sample includes specimens 

 larger than any taken on the same ground in June, when the 

 maximum was 1G| inches. It appears to me quite probable that these 

 differences are due simply to the growth of the fish in the six months' 

 interval. We must either conclude that the fish taken on the German 

 grounds in early summer are of the same race as those taken in Decem- 

 ber, and therefore, with the exception of a small minority, principally 

 males, immature ; or we must suppose that they are fish of a smaller 

 race which migrate to these grounds from some other, e.g., more 

 southern region. This latter supposition is at present unsupported 

 by any evidence, and I think we must seek to explain the facts on 

 the view that the summer and winter fish are of the same race. This 

 is not difficult, if we suppose that the smaller fish — 6 to 10 inches 

 long — are the year-old fish, which move out from the shallow inshore 

 waters on to those grounds at the beginning of their second summer. 

 The larger immature fish, broadly speaking, from 10 to 15 inches long, 

 must be two-year-old fish, while the number of mature fish over three 

 years is in small proportion. The dispersal of the year-old fish to 

 greater distances from land, and their gradual increase in size, would 

 account for the fact that the fish on the Eastern Grounds become 



NEW SERIES.— VOL. IV. NO. 2. ■ I 



