350 American Fisheries Society 



utiis, and luscus in their young stages eat Pseudocalanus more 

 than anything else, Acartia being taken when Pseudocalanus 

 is scarce, and Calanus by the larger specimens. The few ling 

 (Molva molva) and hake (Merluccius) examined had also 

 chiefly eaten Pseudocalanus and Calanus. Thus the young 

 gadoids as a group seem to prefer the same sort of food. 



On the other hand the wrasses, Labrus hergylta, L. mixtus 

 and Ctenolahrus rupestris, when young all prefer Temora, very 

 small specimens from 3.5 mm. containing Temora nauplii, 

 occasionally mollusk larvae being found. 



Temora nauplii are also almost exclusively the food of the 

 very young mackerel from 5 mm. long. Calanoid nauplii are 

 also eaten and eggs (probably copepod). Larger specimens 

 up to 9 mm. or more eat Temora, their favorite copepod, also 

 Podon and Evadne and an occasional Euphausiid larva. From 

 9 mm. upwards the usual food is young fishes although Crus- 

 tacea may still be eaten. Species of Trachinus, Blennius and 

 Gobius are often found inside the young mackerel. One of 

 13 mm. had eaten a blenny of 7 mm. Fish and Crustacea are 

 not found together inside the young mackerel. It is either one 

 or the other, a fact coinciding with the known feeding of the 

 older mackerel which may have half its stomach full of fish 

 remains, the other half full of planktonic organisms, but with a 

 hard and fast line of division showing that each meal consists 

 of a different food which is not mixed. It is thus seen that 

 the young fishes do select their food, and a certain kind of food 

 is characteristic of each species. 



(c) Do the fishes which still retain the yolk sac eat solid 

 food? Not many fishes at such young stages were examined 

 but in some cases it is most certain that food is taken in by the 

 mouth when the yolk sac is still present. The best example 

 of this is the herring. Young herring hatch at about 7 mm. 

 and are to be found in the plankton almost immediately, retain- 

 ing the yolk sac up to 9 and 10 mm., in rare cases even more. 

 Although the gut in these young herring is very often found 

 to be empty, yet several specimens had eaten larval mollusks. 



