THE DISTRIBUTION OF PLAICE EGGS IN THE 

 NORTHERN NORTH SEA. 



(Prom the collections made by the Fishery Re?;earch Vessel " Goldseeker " during the 

 months November to March in the years 1904 to 1913 inclusive.) 



By ALEXANDER BOWMAN, D.Sc, Aberdeen. 



Plaice {Pleuronectes platessa) are distributed in the shallower zones 

 all round the Scottish Coast. While usually found in depths of 

 less than fifty fathoms, a few individuals are sometimes taken in deeper 

 water. Professor D'Arcy W. Thompson (1913) gives two charts 

 which illustrate by means of contour lines the quantities of plaice cap- 

 tured per 100 hours fishing by Aberdeen trawlers in the Northern North 

 Sea, the quantities represented being the meansof the period 1901-1910. 

 His general conclusion is given as follows : — " The region throughout 

 which the catch of plaice is for the most part insignificant corresponds 

 pretty closely with that part of the North Sea which is over 50 fathoms 

 deep ; that region where the catch varies from 5 to 10 cwts. per 100 

 hours trawling coincides equally closely with the zone of depth from 

 about 30 to rather less than 50 fathoms while in the region under 30 

 fathoms in depth we find mean catches of plaice that exceed 10 cwts. 

 per 100 hours " (p. 65). And again : — " The charts show how the 

 small plaice are practically absent in our deeper waters, and how both 

 actually and relatively to the other sizes they increase in numbers as 

 we pass to the shallower zones " (p. 65). 



Dr. Fulton (1913) states that in the Northern North Sea " the 

 greatest density of plaice is along the eastern coast of Scotland and 

 around the Northern Isles, and the next greatest density is in the area 

 lying in the neighbourhood of the Great Fisher Bank and towards the 

 Danish Coast. In the areas between the two, where the depths are 

 greater, as well as the distance from the shore, the abundance of the 

 plaice is much less " (p. 123). 



The area examined by the " Goldseeker " in the Northern North 

 Sea during the period under observation extends far beyond the limits 

 of the distribution of adult plaice. The stations visited are shown in 

 the accompanying chart, and the number of times each station has 

 been sampled in December, January, February, and March respectively, 

 during the ten years, is given in tabular form. Over such a wide area 

 some localities have necessarily been visited much less frequently than 

 others. 



At all the observation stations the collections were made with conical 

 cheese-cloth nets, having a diameter of one metre. The texture of the 



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