25 



food fishes.* Since that time, many investigations have confirmed the close 

 relationship that exists between the movements of the sea -water and the life- 

 histories of edible fish. In this comitry, the investigations in particular of Professor 

 Meek on the coast of Northumberland may be specially mentioned, f and among 

 those on the Continent perhaps the most remarkable are those of Dr. Johan Hjort 

 on the migratory movements of the cod on the north and west coasts of Norway. 

 Although full information in regard to all species oi fish has not yet been obtained, 

 the results so far appear to justify the statement that, in the case of fishes with 

 pelagic eggs, when the prevailing current carries these floating eggs in one direction 

 — whether that be towards the south on the east coast of this country, or towards 

 the north as on the west coast of Norway — there is a migration of the adult or 

 adolescent fish in the opposite direction. The Norwegian experiments have 

 shown that codfish may migrate from Finmarken to the Lofoten Isles, and even 

 farther south to the coast of Romsdal, in connection with spawning, and return 

 north again, a journey of many hundreds of miles, after spawning is over. 



The experiments described in the present Report show that the great majority 

 ol the " spawning " plaice move northward and westward agaiiist the prevailing 

 current. This fact is shown very clearly on the charts appended. It is 

 evident, however, that this habit, in the case of the plaice, is not without excep- 

 tions, for a few of the " spawning " plaice were found to the south of the locality 

 where they were Hberated. As elsewhere stated, a striking feature of the experi- 

 ments is the large number of adult plaice which pass from the Firth of Forth area 

 northwards into the Moray Firth and there spawn. In several cases, the fish 

 which were marked in the Firth of Forth, or off the Isle of May, in the late months 

 of the year, were recaptured in a " spawning " or " ripe " condition in the Moray 

 Firth in the early months of the following year, having in the interval made a rapid 

 journey between the two firths. On the other hand, there are some instances, 

 referred to in the text of this Report, which show that an adult plaice may remain 

 a long time in the same locaUty in which it was hberated, and spawn there ; this 

 seems to be true more particularly of the very large fish. It is evident, therefore, 

 that, while there is a general migration, for spawning purposes, of the plaice in 

 the contrary direction to the current, it cannot be said that the habit is a rigid 

 one. 



III. Geowth. 



The rate of growth of the plaice has now been tolerably well estabhshed by the 

 numerous researches which have been made on the subject, particularly in connec- 

 tion with the International Fishery Investigations. The matter will, therefore, 

 be only briefly considered here. In the case of recaptured fish, which were sent 

 on to the laboratory and came into my possession, it was customary to keep them 

 covered for a day, or longer, in a wet cloth, until the tail fin was quite soft, and the 

 measurement of length was then made. Li the case of fish landed at English or 

 foreign ports, however, only the records were available to me, and it is evident 

 from them that the fish, in many cases, when measured, were more or less dry, 

 so that the length was not the true length. This was especially noteworthy in 

 records from German ports, the measurement in some instances being less than the 

 length of the fish when it was liberated, even although several months had elapsed 

 before it was recaptured. 



In these experiments, as in those described in my former Report, it was notice- 

 able that the marked plaice, recaptured within a short period after their hberation, 

 usually showed no increase in length, and often a measurable decrease. This was 

 most noticeable in the experiments which were made in the winter months, when 

 gi'owth is naturally slow, or arrested altogether, but it was by no means confined 

 to these months. In experiments in spring and in summer, the same thing was 



* (1) " The Relation of Marine Currents to Offshore Spawning Areas and Inshore Nurseries." 

 13th S.F.B. Report, Part III., pp. 153-164 (1894). 



(2) "The Currents of the North Sea and their Relation to Fisheries." 15th S.F.B. Report 

 Part III., pp. 334-395 (1896). 



(3) " An Additional Note on the Surface Currents of the Nc ith Sea." 18th S.F.B. Report 

 PartllL, pp. 370-381(1891). ' 



I Northumberland Sea Fisheries Committee. Reports on the Scientific Investigations. 



