174 



BULLETIN OP THE BUREAU OF FISHERIES 



The writer feels that future scientific research into the Ufe history of the black 

 dnim might take up, with profit, a more intensive study of the various seasonal 

 movements or migrations of the species than was possible during this investigation. 



FOOD HABITS 



The feeding habits of the black drum bear out the belief that the fish is generally 

 a strictly bottom feeder. Possessing heavily paved pharyngeal teeth, the species 

 has long been known to frequent oyster beds or reefs, the supposition being that the 

 young oysters are crushed and eaten in great quantities. Observations on the stom- 

 ach contents of many Texas drum, particularly those of a large size, failed to show 

 that oysters of any size make up any considerable percentage of the regular diet. 



The main food of the drum after it has attained a length of about 20 centimeters 

 (7.8 inches) is a small mollusk or "clam" — Mulinia transversa corbuloides — which 

 abounds in the more muddy and shallow bays, such as Nueces and Oso, in the vicinity 

 of Corpus Christi. Bottoms containing this mollusk invariably are covered with heavy 

 mud, and along such bottoms the drum delights to feed. Certain localities in the 

 more or less grassj^-bottomed coves are well known as good "drum hauls" because 

 the drum usually may be found feeding in these localities, which in all cases possess 

 a clear but muddy bottom in which Mulinia may be found in varying abundance. 

 The mollusks lie deeply buried in the mud but are sucked up by the drum, which 

 retains them and proceeds to crush the shells by means of its strong pharyngeal 

 teeth. As much as 2 pounds of broken shell from this small mollusk have been taken 

 from a large fish. Whether or not the fish swallows dead shells can not be stated 

 definitely, but in great numbers of fish examined, the intestines literally were filled 

 with hundreds of fragments of the thin shell of Mulinia. The drum often nearly 

 stand on their heads in feeding, with their tails out of water, so shallow is the water 

 and so intent are the fish on sucking up the mud. 



Various other mollusks, such as mussels (Mytilus) and oysters (Ostrea), are 

 eaten in some abundance. Small crabs rank second in quantity to Mulinia, and 

 shrimp also are consumed at times. The smaller-sized drum (under 20 centimeters, 

 or 7.8 inches), with less powerful crushing teeth, tends to prey upon the softer food 

 organisms, such as small fishes, annelid worms, and the smaller crustaceans. Surf 

 fishing along the Gulf beaches, with dead mullet or shrimp for bait, yields catches 

 of drum. 



Table 17. — Food preference of 117 black drum, ■presented in percentages of total number of fish in each 

 length group that feed exclusively on the various organisms, the food named in the parentheses occurring 

 most commonly 



