Oil the Movements and Food of the Herring, etc. 397 



in examining the contents of their stomachs ; over a thousand 

 of the largest were dissected, and it was found that not more 

 than three or four in a hundred contained food. It is some- 

 what remarkable that this food consisted almost entirely of 

 young fish. One of the most perfect specimens was kindly 

 identified for me by Dr Francis Day {Gadus pollachius). It 

 is worthy of note that no young fish of the above species 

 were taken in the surface gatherings, while others of the 

 genus Ammodytes and Motella were in some localities quite 

 common. After examining my notes on previous investi- 

 gations upon the same subject, I am convinced that the 

 herring feed upon most, if not all, of the minute animals 

 which live in or near the surface waters of the sea; and 

 wherever these are abundant, there the herring will be found 

 in the largest quantities. There can be no doubt that the 

 herring, like most other fish, is a voracious feeder : nothing in 

 the way of food seeming to come amiss. The abundance of 

 its food, as well as suitable localities for depositing ova, are, 

 in my opinion, the principal causes of their apparently hap- 

 hazard movements. The temperature of the water does not 

 seem to me to have much, if any, effect on the movements 

 of the herring ; but this may not hold good as far as the 

 propagation of their young on the spawning grounds is con- 

 cerned. It is, however, impossible to draw definite conclu- 

 sions on such extremely short investigations. It will be for 

 future investigators to show whether the variation of tem- 

 perature has anything to do with their movements. The 

 average temperature of the sea surface all round the Shetland 

 Islands from the 24th June to the 12th July was 52° Fahr., 

 and the bottom temperature 50°. Where our greatest catch 

 of herring was taken, the surface temperature was 52°'5 

 when the nets were laid out, and 51°'9 when hauled in. 



This change of temperature took place during six hours 

 while the " Energy " was drifting slowly with the nets. On 

 the east side of the Shetland Islands, as far as could be 

 made out by the position of the nets and the way the herring 

 were caught in them, they were swimming in a south-eas^ 

 direction ; while on the west s^ of the islands they were 

 swimming in a ^o\xi\i-west direction. 



