i 394 ] 



Some Notes upon the Feeding Habits of Mackerel and 

 certain Clupeoids in the English Channel. 



By 

 G. E. Bullen. 



Several previous authors* have shown that the food of the mackerel, 

 when in coastal waters, is of two different kinds, and that the fish 

 adopts two distinct methods of procuring it. In the first place it feeds 

 by a system of filtration upon planktonic organisms, and secondly upon 

 prey of a larger character which is hunted by sight. 



The exact nature of the food taken whilst the fish is in its winter 

 quarters has not as yet been thoroughly investigated ; but the present 

 writer, in making examination of the stomach contents of mackerel 

 taken on the ground in March, 1907, 25 miles S.W. of Start Point, 

 found that it consisted entirely of zoo- and phytoplankton of a nature 

 similar to that existing in the water itself.f A close similarity in 

 general character appeared to exist between the nature of these samples 

 and others from fish taken in the Bristol Channel at the surface during 

 the early part of April of the same year.^ 



It was also observed that during the three months forming the more 

 important part of the " drifting " season in the western area, viz. 

 April, May, and June, the fish were feeding exclusively upon plankton, 

 and that the nature of this food gradually changed from being largely 

 vegetable to almost wholly animal. 



It was not until the middle of June that food of a larger character, 

 but still wholly of the latter type, began to appear in stomach con- 

 tents, and it is a well-known fact that at about this time every year 

 the drift fishery in the area under consideration begins to decline, and 

 hand-lining commences. This condition is due to the fact that the 

 dense shoals break up, and the system of nutrition, which has hitherto 

 been one of filtration, gives place to one of, what we may term, "selective 

 feeding." 



From the evidence before us, in the form of the plankton results for 



* Fide Allen, E. J., "Rep. on the Present State of our Knowledge with Regard to the 

 Habits and Migrations of the Mackerel,"' Journ. Mar. Biol. Assoc, N.S., Vol, V, p. 9. 



t "Plankton Studies in Relation to the AVestern Mackerel Fishery," Journ. Mar.. 

 Biol. Assoc, K.S., A^ol. XVIII., pp. 285-6. 



+ Id. Table No. IV, Nos. 76 to 83, and Table Xo. V, Xo. 111. 



