OBSERVATIONS ON HABITS AND A METHOD OF TRAPPING 

 CHANNELED WHELKS NEAR CHATHAM, MASSACHUSETTS 



by 



William N. Shaw 



U. S. Fish and Wildlife Service 



Woods Hole, Massachusetts 



ABSTRACT 



A wooden trap for the purpose of removing the majority of channeled \v4ielks from 

 oyster beds was designed and successfully tested on Oyster Pond River, Chatham, Massachusetts. 

 In 1957 and 1948, 2, 174 channeled whelks were trapped from, a 2-acre lease. This paper gives 

 the design of trap, types of bait, trapping procedure, catch rate, and rate of whelk predation on 

 oysters. It appears advisable for oyster growers to undertake trapping operations each spring to 

 minimize oyster losses inflicted by the channeled whelk. 



In the spring of 1957 the oyster 

 growers of Chatham, Mass. reported high 

 losses of oysters from predation by two 

 species of large snail, the cheinneled whelk, 

 Busycon canaliculatum (fig. 1), and the 

 knobbed whelk, Busycon carica (fig. 2). In 

 response to their request for help the Woods 

 Hole Biological Laboratory of the U. S. 

 Bureau of Commercial Fisheries conducted 

 studies in 1957 and 1958 on the habits and 

 possible methods of controlling these pre- 

 dators. Trapping appeared to be the most 

 efficient, safest, and cheapest method of 

 removing the whelks from the oyster grounds. 

 Since previously devised traps were ineffi- 

 cient, it was necessary to devise a new 

 type and test its operation and efficiency 

 in the field. This paper reports the re- 

 sults of those studies. 



The author is indebted to J. C. Ham- 

 mond, commercial oyster grower, whose help 

 in the field made this project possible; and 

 to Robert K. Brighara of the U. S. Fish and 

 Wildlife Service for permission to publish 

 the photographs of the channeled and knobbed 

 whelk. 



STUDY AREA 

 The study was conducted on Oyster 



Pond River, a small indentation of Stage 

 Harbor, 2 miles west of Chatham, Mass. Depth 

 of water on the oyster grounds ranges from 

 2 to 8 feet at mean low water. The average 

 height of tide is approximately 4 feet. 

 Water salinity ranges from 29 °/oo to 32 

 "Ao. The substrate over most of the area 

 consists of fairly hard-packed sand, but in 

 deeper water away from shore the bottom is 

 rather soft owing to a higher percentage of 

 silt £ind clay. 



This locality is near the northern 

 limits of distribution of the whelks. Ac- 

 cording to Sumner, Osborn, and Cole (1913) 

 the range of the channeled whelks extends 

 from Beverly, Mass. (north of Cape Cod) to 

 the Gulf of Mexico, and that of the knobbed 

 from Cape Cod to St. Thomas, West Indies. 

 Though frequently not distinguished, both 

 species occur throughout the length of Oys- 

 ter River, but most of them concentrate on 

 the commercial oyster beds. 



FOOD HABITS OF BUSYCON 



The diet or Busycon consists of 

 several species of pelecypods, annelids, 

 and occasionally dead fishes and gastro- 

 pods (Magalhaes 1948). Some of the more 

 favored species, as observed by Magalhaes 



