THE FOOD OF THE LARVAL AND POST-LARVAL 

 FISHES OF PLYMOUTH SOUND 



By Dr. Marie V. Lebour 



Naturalist, Plymouth Laboratory 



Plymouth, England 



The question of the food of larval and post-larval fishes 

 although carefully studied by those rearing them, yet has had 

 little attention paid to it with regard to the actual food taken 

 by the young fishes in the plankton. It was to supply this 

 deficiency that an investigation was undertaken by the writer 

 during the years 1917-19, many hundreds of pelagic young 

 from those newly hatched up to those of about 15 mm. in 

 length, with a few adolescent stages, being examined and the 

 food inside noted. A full account of the work is given in the 

 Journal of the Marine Biological Association of Plymouth 

 (Vol. XI, No. 4, 1918, Vol. XII, No. 1, 1919, and Vol. XII, 

 No. 2, in process of publication). 



By dissecting out the alimentary canal of fresh specimens 

 from the tow-nets and young-fish trawl and by mounting spec- 

 imens whole as balsam preparations, the food is usually well 

 seen. Young fishes were kept alive in small aerated aquaria 

 standing in tanks at an even temperature, and their feeding 

 habits watched in order to study the food taken and method of 

 feeding. 



Some of the most important questions in connection with 

 the food of the young fishes are the following : 



(a) What the fishes feed on and whether vegetable food 

 is much eaten. 



(b) Whether the young fishes select their food or take 

 it indiscriminately. 



(c) Whether fishes which still retain the yolk sac eat 

 solid food. 



(d) Whether fishes of different species or genera present 

 in the same place eat the same kind of food and thus those eco- 

 nomically unimportant compete with the food fishes. 



