OF THE CORNISH PH. CHARD FISHERY. 



25 



the shore, one very important possibility has to be taken into 

 consideration, namely, that of the vertical, diurnal and 

 nocturnal distribution of those plankton org-anisms which, as 

 has been shown, constitute the principal food of the pilchard. 



In those areas or stations on the Cornish seaboard from 

 whence these observations have been derived, unfortunately 

 up to the present no plankton samples have been taken with 

 a view^ to showing the bathymetrical rise and fall of certain 

 individual species. 



We have ourselves, however, taken sufficient observations-" 

 to show that the majority of Calanoid C^opepods materially 

 lessened in quantity in surface tow-nettings taken within a 

 close proximity to the shore in the one area, viz., Mevagissey 

 and St. Austell's Bays, in which we have made an intensive 

 (diurnal) planktonic survey. From this we may adduce some 

 evidence in support of a theory that the richer feeding grounds 

 do not lie close to the shore, and that pilchards at dusk seek 

 the deeper water for feeding purposes. 



Again, although we have personally had but few oppor- 

 tunities of examining fish taken in daylight, we have often 

 heard it stated by fish curers and others that seined fish appear 

 to have little or no food in the stomach. This is certainly 

 slender evidence in support of any theory that pilchards feed 

 more readih' by night, but when taken in association with other 

 considerations, some importance has necessarily to be given 

 to it. 



For it has been determined that in the case of certain 

 Calanoids, notably C^nlaints funiia) rh'icus^ the maximum 

 surface distribution occurs between the late evenino- and early 

 morning."^ Now this condition coincides in the matter 

 of time with the pilchard's movement into dee{)er water, 

 to which we have already referred. We thus have some 

 evidence to show that this off shore migration is actuated by a 

 desire on the part of the fish to seek the most suitable feeding 



Note. — The full results of these observations will be embodied in a 

 later paper. 



Esterley, C. O., "The Occurrence and X'ertical distribution of the 

 Copepoda of the San Dieg-o Region, with particular reference to nineteen 

 Species," I'niv. of California publications in Zoology. \'ol. ix.. No. 6, and 

 certain other papers. 



