10 



Food of Fishes. 



I desire now to draw attention to the observations on 

 the food of Plaice as compared with that of Dabs caught 

 at the same time on the same groimd. It has often been 

 said that Plaice and Dab compete for the same food, but 

 this does not seem to be the case. Mr. Johnstone's 

 observations, made on the steamer and in the laboratory, 

 show that on the whole the adult Plaice feeds chiefly on 

 Mollusca (Scrobictdaria, Solen, Mactra, Tellina and 

 Nucula), less frequently on Polychaeta [Nereis, Pectinaria, 

 &c.) with an occasional Echinoderm or Amphipod; while 

 the Dabs of much the same size feed for the most part 

 (ui Ophiurids (''brittle stars "J and Crustacea, especially 

 •small crabs and hermit crabs (Pagurus, Carcinus, 

 Porcellana, Portanus, Hyas, Corystes, Crangon, &c.), with 

 some Polychaete Avorms, occasional Mollusca and 

 Zoophytes. The contrast is evidently between Molluscs 

 as .the main food of the Plaice and Ophiurids and 

 Crustacea as that of the Dab. But the Dab is evidently 

 a g-reedy and omnivorous feeder, and many kinds of 

 invertebrates may be found together in its stomach. 



Some years ago, in the 1st, 2nd, 3rd and 4th of these 

 Fisheries Laboratory Reports (for 1892-3-4 and 5j we 

 recorded a series of observations made on the food of 

 various fishes, both small and large, which showed fairly 

 similar results. In 1894, in the case of the Plaice, 

 Mollusca were found in over 72 per cent, of the stomachs 

 and Polychaeta in fully 22 per cent., so that these two 

 food matters occupied together about 95 per cent., and the 

 following year the same two groups, although reversed in 

 order, occupied 96 per cent, of the stomachs. In the case 

 of the Dab our former records give no such uniformity of 

 result, and merely shoAv that there is considerable variety 



