— 17 — LATER STAGES: PLEUR0NECT1DS 



Sylt and Amrum grounds very large numbers of spawning fish were found and this ap- 

 pears to be one of their chief grounds. A former report showed that they also spawned 

 in the shallow Hats off the coast of Norfolk and Suffolk. 



Turbot. 



Turbot are distributed sparsely over the whole region investigated. In no case were 

 they taken in large numbers, and except in the eastern grounds were seldom more than 

 two or three to each haul ; often none were taken. They show a very similar distribution 

 to that of soles, except that their rate of diminution in the offshore areas is not nearly 

 so great. In the north-eastern areas and the Dogger they are even more numerous. 

 Their most productive area is some little way from the German coast line. 



A great contrast is shown in the productivity of this species between the western 

 and eastern grounds. The mean values for the year in areas B 2 and D t are oniy be- 

 tween l and 2 per 10 hours' fishing. 



The small fish are predominant forming some two-thirds of the total number, but 

 diminishing their proportions according to the distance from land. They are rarely found 

 amongst the turbot from the north-eastern areas. 



Yearly variation. Taking all the catches together there was found to be a marked 

 decrease between 1904 and 1907. This is especially noticeable in areas N and Q. though 

 certain areas have 1905 as their best year. On the whole they are declining. 



Seasonal fluctuations are definite. The Turbot are congregated on the extreme 

 eastern coastal grounds during the summer and disappear in the winter. Their appear- 

 ance is sudden, coinciding with the oncoming of the spawning season, and the large 

 fish only take their departure immediately this is over. In the central area adjacent to 

 these there are two maxima at the beginning and end of a long period of maximum 

 abundance and separated by a small depression in the summer. Where the catches are 

 large there is in all cases a period of minimum abundance from February to April. Where 

 they are small the fluctuations are indefinite and irregular: in the Northern areas it is 

 suggested that the winter catches are higher than the summer ones, but the difference is 

 not marked. 



Spawning turbot are numerous on the eastern grounds where the fish are naturally 

 most abundant but they are also found all over the North Sea in those areas examined 

 during the spawning season. They are recorded as maturing during the months from 

 December to April and as actually spawning in May, June and July, which are the chief 

 months. 



Brill. 



Brill, with a very similar distribution to turbot are even less abundant. The general 

 occurrence is for one or two fish to be caught after several hauls but on the eastern 

 grounds at the best time of the year they may be as many as five or six per haul. As 

 for the other Pleuronectidae in this report they are very scarce on the Dogger Bank and 

 the grounds north of it, the mean catch per 10 hours being from o to 0.5 in number. 



Yearly and seasonal variations. Increase in the stock is shown in the last two years 

 1906 and 1907 when compared with 1904 and 1905. The number taken is small but 



