that such information would be of h'ttle value because the fish had probably 

 travelled a considerable distance since ingesting the mollusks. 



W. F. Clapp has shown subsequently that this is probably not the case. 

 In November, 1911, while on George's Banks on a fishing trawler, he 

 found that the molluscan fauna represented in the digestive tracts of fish 

 corresponded almost exactly to the species obtained by dredging at the same 

 locality. This was repeated at a number of stations exhibiting a variety of 

 bottom conditions and supporting different assemblages of species. He 

 pointed out also that the relative position of the shells in the digestive tract 

 gave important information. If specimens were found in the stomach or 

 upper intestine, the fish could not have obtained the mollusks far away 

 from its point of capture. 



Depth records are now more easily available than ever before. Most 

 fishing boats employing more than a very few men are equipped with 

 electronic depth finders, and if fish or fish entrails are acquired from com- 

 mercial fishermen, they will probably know the depth at which the fish 

 were caught and the approximate location. Significant and reasonably 

 accurate data can therefore be easily obtained. 



Procuring the Fish. Whether the conchologist catches the fish or ob- 

 tains them commercially has little bearing on the final result. However, 

 unless your luck is exceedingly good, you probably won't get as many fish 

 as you could obtain from a fishing trawler or gill netter at much less cost. 



Practically all fish caught commercially are gutted at sea while the 

 boats are returning to port. Unless you are present while the fish are being 

 gutted, you may find it difficult to obtain the source material you desire, 

 and even if you are on board, the men may feel that you are in their way. 



One method that I have found to be most satisfactory is to supply the 

 captain of a small boat with large, covered cans or pails and offer to pay 

 him a reasonable price for the stomachs and intestines of bottom feeding 

 fish. In return, he will probably be glad to tell you the depth, the approxi- 

 mate location, and perhaps even the kind of bottom involved. Do not be 

 discouraged if he tells you there are no shells in the fish, there usually are 

 but he has failed to notice them because of their small size. 



Productive Species of Fish. Feeding habits of fish differ considerably. 

 Game fish (e.g. sharks, tunas, sailfish, etc.) will often contain pelagic mol- 

 lusks such as cephalopods, pteropods, and heteropods, but mackerel, her- 

 ring, and other small species which feed pelagically will contain very few 

 mollusks. 



The best sources of shells are probably those fish that feed on the 

 bottom, especially cod, haddock, and flounder. The following list includes 

 the commoner species of North American marine and freshwater fish known 

 to subsist in large part on benthic mollusks. 



(4U 



