OF THE CORNISH PILCHARD FISHERY. 



23 



however, the species observed in the one were common to the 

 other, not necessarily in the same relative paucity or abund- 

 ance ; but in certain cases food of a different character to that 

 exhibited by the plankton samples taken from the same area, 

 has been found in stomach contents. 



Aofain, it has been seen that in common with the Channel 

 and Irish mackerel"" occasional samples have been observed 

 m which certain species of plankton orcranisms have been 

 distributed in sharply defined layers. 



Moreover, in 1906, when, as ma\" be seen from the plankton 

 tables published in the International Bulletins, phytoplankton 

 occurred in high preponderance over zooplankton at those 

 stations adjacent to the hshing area throughout the summer, 

 the majority of the stomach samples were composed solely of 

 animal matter. 



Further, it may now^ be stated that the same conditions as 

 those described in the case of mackerel from the Western 

 Fishery-*' have been consistently observed in the stomachs of 

 pilchards, viz., that where the contents consisted largely or 

 wholly of zooplankton the stomach walls were very thin, the 

 organ itself being capable of considerable expansion, whereas 

 in those cases where phytoplankton formed the bulk of the 

 food material, the stomach walls were of moderate thick- 

 ness, and the cavity of small size, incapable of being enlarged 

 under pressure. It follows therefore that, as we have invari- 

 abh' observed to be the c^ase, a far greater bulk of material 

 is to be found in the stomac^h of a pilchard which had been 

 recently feeding on pure zooplankton than in any in which 

 phytoplankton alone was in evidence. 



The majority of fishermen are agreed in stating that a 

 distinct movement is undertaken at nightfall b\' pilchards which 

 have been feeding during the daytime close inshore. Mr. 

 Howard Dunn informed the writers that, in his opinion, this 

 outward movement takes place even when they are situated 

 at some distance from the c^iast. The same observer sug- 

 gested that this might he prompted by a desire on the part 



-•5 Vide Bullen, " Plankton Studies, etc.," and Farran, " Rep. on Sea and 

 Inland Fisheries, Ireland," 1901, Pt. II., p. 122. 



Bullen, G. E., " Some notes upon the Feeding Habits, etc.," p. 395. 



