KEPORT OF THE COUNCIL. 333 



on the results of the experiments carried out on this matter by the 

 H^Lxley. The fish tested were derived from 12 Otter- and 16 Beam- 

 trawl hauls of different duration. The catches varied in nature and 

 weight. Each catch was tested in sections, batches of fish being placed 

 in tanks of circulating sea-water after various periods of exposure ; the 

 total number of such batches was 89. 



Consideration of the data obtained leads to the conclusion that few 

 of the small plaice captured in the process of commercial trawling 

 would survive if returned to the sea immediately after they reached 

 the deck ; while if returned, as in practice they would be returned, 

 after the fishermen had dealt with the marketable catch, the percentage 

 surviving would be extremely small. 



The Otter trawl is found to injure a far greater proportion of the fish 

 than the Beam trawl, though probably the very long hauls of the 

 latter which are quite commonly taken by the sailing vessels using 

 these trawls would produce the same effect as the hauls with the Otter 

 trawl. Long hauls, the presence of Meduscv in the net, hot sunshine 

 during the time the fish are on deck and probably heavy catches are 

 all detrimental to the fish. 



Migration of Cod. — A brief report on this subject has also been 

 completed. 



It is based on the 252 cod marked on the Huxley and the 42 

 recaptures recorded up to the date of writing. Most of the recaptures, 

 constituting 13 % of the healthy fish liberated, took place within six 

 months of liberation. 



The fish below 60 cm. in length appear to have remained in water 

 of depth similar to that in which they were first caught, and had not 

 travelled far. Most of those which had moved some distance from 

 the liberation point were recaptured south or west of it. 



The number of these is however small. Fifteen cod which remained 

 for more than three months at liberty showed an average rate of growth of 

 1'5 cm., but afforded no indications of different growth rates at different 

 seasons. 



Food of Fishes. — Since the conclusion of the second report on this 

 subject the stomachs of 2,040 fish, belonging to 24 species have been 

 examined and their contents identified. The total number of fish 

 subjected to examination during the investigations is 11,866, drawn 

 from 39 species. 



Invertebrate Fauna. — The preparation of a report on the distribu- 

 tion of invertebrates in the North Sea, based on the operations of the 

 Huxley, is in progress. The report will deal with 2,168 hauls made 

 before the end of 1907. 



