COUNCIL — APRIL 1912 — APPENDIX D — 68 — 



Prof. Ehrenbaum was of opinion that it would be the most practical to mark 

 the mackerel by means of a narrow rubber ring, with a small number plate 

 attached, the ring to be placed round the body, in the neighbourhood of the 

 pectoral fin. 



Prof. Henking remarked upon the use af various metals for purposes of 

 marking. Aluminium was very useful in waters where the salinity was not very 

 great, as for instance in the true Baltic, but was not adapted to use in salter 

 waters. Silver was the best metal for marking purposes. 



Dr. Hoek found it difficult to distinguish between Scomber scomber and 

 Scomber colias in the Mediterranean, and asked Prof. Ehrenbaüm whether the two 

 forms were clearly defined species. 



Prof. Ehrenbaum considered Scomber scomber and Scomber colias as two well 

 defined species. Their dorsal fins differ in regard to the number of rays. More- 

 over, the Scomber colias is furnished with a swim-bladder, while this is lacking in 

 the case of Scomber scomber. 



Dr. Green stated that it had been noticed in Ireland that the rubber ring 

 had in several cases cut into the flesh of the fish so marked. He suggested that 

 a silver ring, which could be easily attached to the fish, should be used for marking. 



Third Sitting: Wednesday, 24th April 1912, 10a.m. 

 Chairman: Dr. Hoek. 



(Agenda a). 



Dr. Redeke laid before the meeting the first part of his report on the present 

 stage of our knowledge regarding the races of the chief food fishes. The part in 

 question was of a general nature; a later portion would deal with the special 

 questions of race origin among some of the most important species of food fish. 



Dr. Masterman laid before the meeting his third report on the later stages of the 

 Pleuronectid fishes in the North Sea, and mentioned a number of results which 

 had been obtained by means of statistics as regards the frequency of the plaice 

 and other flat fishes in various areas and at different times, in the North Sea. 

 He thereafter made mention of a plan for investigations as to the variations in 

 frequency of plaice of different years in the North Sea. 



In the discussion of Dr. Masterman's report Dr. Johansen, Prof. D'Argy 

 Thompson and Prof. Heincke took part. 



