March i3, 19^0] 



NATURE 



^ 



tuted. a size-limit of nearly lo in., but that Holland. did 

 not f&voUr'oTie of more than about 8 in. The repre- 

 sentatives of Great Britain considered that the effect 

 of the closure of areas on the. industry had not been 

 sufficient studied ; that the closed areas must be as 

 small as possible, consistent with the preservation of 

 the plaice stock of the North Sea; and that the study 

 of tne effect of the war in having closed great areas 

 would materially assist the Council in arriving at the 

 most practical results. 



The British view was finally adopted, and it was 

 iK'cided to undertake a year's intensive plaice inves- 

 tigation with the view of considering the whole ques- 

 tion in 192 1 and making recommendations. The 

 committee then proceeded to draw up a programme 

 of investigations. A thorough collection of statistics 

 of plaice marketed was deemed essential. Further- 

 more, an accurate knowledge of the sizes of the fish 

 both as marketed and as caught on commercial 

 trawlers was recommended. The liberation after 

 marking of a series of fish would be necessary to 

 show their wandering during the year. Further ex- 

 periments in the liberation of marked fish of small 

 size on the Dogger Bank were recommended. The 

 spawning-grounds should be more fully investigated 

 and charted. The liberation of a large series of drift- 

 bottles, both surface and bottom, was deemed essential 

 so as to ascertain the drift of the eggs and vou'ng 

 larvae which float for many weeks in the water. The 

 examination of numbers of eggs so as to ascertain 

 the intensity of spawning in different areas was 

 deemed advisable, as well as an investigation into the 

 food on which the larvae feed. 



As most of the spawning areas of the plaice'are off 

 the east coasts of Great Britain, it was generally recog- 

 nised that this country would have to concentrate in the 

 present year mainly on these plaice investigations, but 

 the hope w^as expressed that the examination of the 

 life-history and wanderings of the lemon-sole would 

 not be neglected, while the other fish occupying 

 |)laice grounds should be carefullv recorded. The con- 

 tinued examination of the constitution of the herring 

 shoals and of the other work on the life-history, 

 iirowth, etc., of the herring was recommended. Great 

 BVitain being requested to collect samples and to send 

 them to Norway, the representatives of which (Dr. 

 fljort. Prof. Gran, and Dr. Lea) undertook to examine 

 them.- 



The Danish representatives described their plans 

 for a second great expedition in the North Atlantic 

 to search, among other objects, for the spawning- 

 ijroutids of the fresh-w-ater eel, which their previous 

 work showed to be somewhere in the latitude of 

 r Madeira and at depths of at least 1000 or 1500 

 fathoms. They also gave an account of the com- 

 mercial results obtained bv the importation of the 

 young eels (elvers) and their liberation in Danish 

 •. rivers and lakes. Dr. Johansen (Denmark) and Dr. 

 Rosen (Sweden) described the work of their respec- 

 tive coimtries on the movements of salmon and sea- 

 trout, the ages of these fishes for spawning, the libera- 

 tion of fry, etc., showing results of considerable 

 economic importance — results capable of immediate 

 application in manv British rivers could the difficulties 

 in respect to pollution be overcome. 



The Hvdrogrnohical and Plankton Committee 

 divided into sub-committees for, its two subjects. 

 The former is mainlv concerned with the currents on 

 the fishind-grounds in respect both to the movements 

 of such fish as herrinf. mackerel, and pilchards, and 

 to the drifting of fish-eggs and young-. It was 

 generally considered that the hope of foretelling the 

 movements of the fish and the success or otherwise 

 of the spawning vear by year depended on a more; 

 extensive studv of the movements of Girif Stream 

 NO. 2629, VOL. 105] 



waters from Barents Sea to Iceland and down the 

 European coasts to Mogador, with more intensive 

 mvesLigations in the North Sea. Ihe nature of the 

 spawnuig was deemed peculiarly imporunt, as on 

 tnis depends to a large degree the success of the 

 fishing some years afterwards when the spawn has 

 grown into fish of marketable size. Extensive tem- 

 perature records and water samples from a series of 

 transoceanic hners month by month were recom- 

 mended, and the hope was expressed that the United 

 States would co-operate by collecting samples on 

 liners cutting the Gulf Stream nearer where it leaves 

 the Straits of Florida. 



A full programme of hjdrographic work was recom- 

 mended in ttie southern half of the North Sea in view 

 of the plaice investigations. Here the sea is so 

 shallow that the water is thoroughly churned up from 

 surface to bottom, and, in consequence, surface 

 samples only, mostly from passenger ships, were pro- 

 posed. The drift-bottle programme was approved and 

 somewhat extended in the hope of understanding 

 better the isobaric, temperature, and salinity charts 

 of the region in respect to the movements of fish, 

 with the view of making them usable by fishermen. 



The plankton sub-committee, under Prof. Gran, 

 drew up a very small programme on account of 

 present difficulties, but it decided to recommend 

 researches on the physico-chemical conditions of sea- 

 water in respect to the life in the sea. It regarded 

 this basal research as impossible either to initiate or 

 carry out under the Council, and so decided to record 

 its opinion as to the necessity of such researches 

 on living animals in respect to the water in which 

 they live. It was pointed out that the acid or alka- 

 line nature of the water affects the rate of growth of 

 young fish, and that further knowledge here in respect 

 to trout, salmon, and plaice might become at once 

 of economic importance. Animals, too, show growth 

 in the most carefully filtei-ed sea-water— a matter of 

 the greatest importance, the meaning and utility of 

 which could not be foretold. It is well known that 

 the blood of human beings can be replaced by sea- 

 water, but not so effectively by artificial sea-water, 

 which is made from distilled water by dissolving in 

 it the various salts. The possible meaning of this 

 was discovered by Dr. Allen (Plymouth) working on 

 minute marine animals, and points to those mys- 

 terious substances "vitamines," of which so much 

 has been heard in the last six years and so little 

 is known. The searcher for economic results in 

 fisheries must have the basal theory and knowledge in 

 respect to his living: fish duly developed as the founda- 

 tion on which he has to build. Incidentally, an 

 increase in knowledge of this soluble food, etc., should 

 be rapidly applicable to oyster- and mussel-farming, 

 and the sub-committee could only hope that the 

 requisite genius to give further ideas would soon be 

 found. 



The development of lakes and rivers for the pro- 

 duction of food was of special interest to Mr. Holt 

 (Ireland), the Swedish and Finnish representatives, 

 and Dr. Redeke (Holland), the last giving an 

 account of the very great development of the fresh- 

 waters of his country So far as fish were concerned 

 —salmon is treated separately — the subject is of little 

 importance to Great Britain, but the possibility of 

 the development of a button industry by the cultiva- 

 tion of mussels was thought worthy of investitratlon. 

 France was represented by M. Kersoncuf (Director 

 of Marine Fisheries), accompanied by M. Tissier, 

 Prof. Behal, Prof. Toubin, and Dr. le Danois. A 

 meeting with the English and Irish representatives 

 resulted in the formation of a special committee to 

 consider and report as to fisheries off the mouth of 



