FOOD OF YOUNG WINTER FLOUNDERS.^ 



By Edwin I.inton, 

 Temporary Investigator, U. S. Bureau of Fisheries. 



Contribution from the U. S. Fisheries Biological Station, Woods Hole, Mass. 



In connection with work on the parasites of fishes it has been tlie 

 author's practice to keep a record ol the food of the fishes which were 

 being examined for Entozoa. Such miscellaneous data, while not 

 without value, are lacking in that definiteness which is afforded by 

 quantitative studies. It was therefore suggested by the Bureau of 

 fisheries that an intensive study of the food of one or two families 

 or groups of fishes, preferably those of economic importance, be 

 undertaken. 



During the summers of 1915 and 1916 the author spent a part of 

 his time in tlic examination of small winter ilounders {Pseudopleuro- 

 nectes americaiiits) for their food. The lish were seined by Vmal N. 

 Edwards at 30 stations at Woods Hole, Mass., and vicinity, on dates 

 ranging from May 2 to November 2. The total number of fish 

 examined was 398. 



Fishes collected in the months of May, June, September, October, 

 and Noveniber were preserved in foininldeliydc; and examined in 

 the summer of 191(3. Fish seined in 'luly and August were bi'ought 

 to the laboratory soon after they were taken from the water. If 

 taken at some distance from the laboratory, they were placed in a 

 strong preservative as soon as they were talven from the water. At 

 first the smaller lish were preserved entire in 95 per cent alcohol, 

 after opening the abdominal cavity. The viscera of the larger fish 

 were remcncd and kept in dishes of formaldehyde. It was soon 

 found that the formahlehyde material was the moi'c satisfactory for 

 study, and, when well washed in water, could be looked over without 

 discomfort. In each case the alimentary canal was opened through- 

 out its entire len<^th and examined in alcohol or water. The material 

 was separated with the aid of a dissecting lens, tlic compound micro- 

 scope being used when necessary for the identification of material. 

 Quantitative estimates were then made, using the smallest lot as a 

 imit. 



It often happens that much of the contents of the alimentary 

 canal of the fish does not admit of satisfactory separation into distinct 

 lots, even when its general character is more or less identiliable. 

 For example, in cases where annelids, having much sand in their 

 intestines, have been eaten, what at first appeared to be a mass of 



« Ai>iKn<!ix IV to the U. 8. Report of the Commlssioucr of Fisheries for 19:^1. U. F. Doc. 907. 

 47119°— 2t ;j 



