OF THE CORNISH PILCHARD FISHERY. 



19 



occurred in quantity. The zooplankton samples taken at 

 several positions were not large, but exhibited a variety of 

 species, including certain oceanic Copepods, e.g., Oithona 

 plumifera, Microsctella atlantica. etc., in sparing numbers. 

 The bulk of such tow-nettings were made up by two species 

 of Copepods, C entrofages typicus and Temora longicornis, 

 but it was a noticeable fact that where the heavier gatherings 

 of phytoplankton were taken the quantity of zooplankton was 

 slighter in proportion. 



It is now a well-known fact that throughout the whole of 

 August the Mounts Bay fishery was practically non-existent 

 for, as may be gleaned from the pages of the " Fish Trades 

 Gazette," the majority of the local drifters were catching only 

 a few hundred fish per night ; in fact during the short period 

 in which material for the above series of observations wxre 

 gathered it was occasionally a difficult matter to obtain even a 

 sufficient supply of fish for examination. 



It will be seen that the majority of the stomach samples 

 examined exhibited food essentially of a vegetable character 

 with a slight admixture of animal matter, a few showed layers 

 consisting of phyto- and zooplankton respectively, not sharply 

 defined it is true, but sufficiently well marked to be determined 

 by a difference in colour, whilst a minority were composed 

 almost entirely of zooplankton with but a slight admixture of 

 vegetable matter. 



Much valuable evidence is afforded by this series of obser- 

 vations, when considered in comparison with the tow-nettings, 

 in support of a theory that the extent of migration is determined 

 to a large extent by the condition of the food supply, but this 

 is a question beyond the province of the present paper. It 

 certainly appears that phytoplankton does not constitute a 

 type of food selected by choice, otherwise Mounts Bay would 

 have proved an ideal feeding ground. 



At the middle of September of the present year Mr. 

 Howard Dunn of Mevagissey informed us that incoming 

 vessels reported large masses of pilchards congregated in mid- 



1" A possible explanation of this feature may lie in the fact of the rapid 

 clogging- of the nets at these stations, referred to above. 



