100 NORTH SEA INVESTIGATIONS, 



the limits of maturity and immaturity in the females agree with those 

 seen in the sample examined at Grimsby : these limits are 9 in, and 

 14 in. Below 9 in. no females are mature, above 14 in. none immature. 

 The limits at Plymouth were almost exactly the same, except that three 

 specimens were found to be immature at 14 in. Mr. Holt's limits, on 

 the other hand, were 13 in. and 18 in., so that there is a difference of 

 4 in. between both the upper and lower limits in the two cases. There 

 is every reason to believe that the maximum size actually attained by 

 the fish corresponds to the size at which it begins to spawn. As a 

 matter of observation we find that the largest plaice caught in the 

 neighbourhood of the Brown Eidges are considerably smaller than the 

 largest caught on grounds further to the north. The largest plaice in 

 the samples above described does not exceed 20 in. in length. 



The ground named extends between thirty and fifty miles from the 

 Dutch Coast, and to a great distance in a north and south direction. It 

 is limited by the " edge of the deep water " towards the English coast, 

 and this boundary (the twenty fathom line) lies at about fifty-five miles 

 from the coast of Norfolk. The ground is undulating, being traversed 

 by ridges running north and south, over which the depth decreases to a 

 minimum of 11 fathoms, while, in the valleys between, there is, in some 

 places, a depth of 24 fathoms. The ground is therefore neither uniformly 

 shallow, nor close to the land. 



I was strongly inclined to think that the small plaice of the German 

 Bight would prove to be of the same character as those from the 

 Brown Ridges. My theory was that the race of smaller plaice actually 

 proved to exist off the coast of Holland would be found to extend 

 along the Dutch and German coasts, probably as far as the Horn Keef, 

 and that this would be the explanation of the small size of the plaice 

 landed at Hull and Grimsby, from the German or Heligoland Bight. 

 In order to examine samples of the plaice caught on these eastern 

 grounds in November and December, I considered whether it would be 

 advisable to go to the Biological Station of Heligoland, or to some 

 fishing port on the German coast, or to have samples sent over the sea 

 to me in London. I made enquiries from Dr. Heincke, the Director, 

 and Dr. Ehrenbaum, the Zoologist of the Biological Station, and have 

 much pleasure in here expressing my thanks for the courtesy and 

 thorough efficiency with which they assisted me to obtain the facilities 

 I required. They informed me that plaice were not landed in Heligoland 

 regularly or in large numbers, but that they would assist me in my under- 

 taking if I visited one of the fishing ports on the mainland. I thought, 

 however, that, under the circumstances, I might just as well have 

 samples sent to me in London, and accordingly Dr. Ehrenbaum put me 

 in communication with Herr Diige, the harbour-master at Geestemiiude, 



