[ 9T ] 



North Sea Investigations. 



{CONTINUED.) 



By 



J. T. Cunningham, M.A. 



PAGE 



I. The Size of mature Plaice, Turbot, and Brill, on different Fishing Grounds 97 

 II. Observations at Sea and in the Markets : — 



1. Grimsby ..... 



2. Scarborough ..... 



3. Hull — The Adoption of the Otter Trawl in Steam Trawling 



4. Lowestoft ..... 



III. Causes of the Observed Distribution of Fish in the North Sea , 



IV. Proposed Restrictions on the Landing of Undersized Plaice in the light of 



the New Evidence . . . . . .138 



108 

 112 

 114 

 121 

 133 



I. The Size of mature Plaice, Turbot, and Brill, on different 



Fishing Grounds. 



In the previous number of the Journal, I described my reasons for 

 doubting whether the conclusions drawn by Mr. Holt, concerning the 

 size at which plaice become mature, would hold good for the whole 

 of the North Sea ; and also whether the evidence he relied upon, 

 in distinguishing mature and immature plaice, was sufficient. I stated 

 that, as an actual fact, one sample of mature plaice, which were much 

 below the limits of size determined by Mr. Holt, had come into 

 my hands. I suggested, as a probability, that the presence of dead 

 degenerating eggs in the tissue of the ovary was a proof that the fish 

 had spawned, was a spent, and therefore a mature specimen. My 

 words were : " It cannot be asserted as a certainty that these granular 

 masses never occur in an immature ovary ; to settle the doubt it will be 

 necessary to make a careful examination of plaice in November and 

 December, when all fish which are about to spawn will have a 

 large amount of yolk in the eggs, and all fish in which the eggs are 

 transparent and yolkless must be immature." It was already known 

 that these degenerating eggs do occur in spent ovaries, from 

 which the ripe eggs have recently been discharged, and which bear 



