THE ZOOLOGIST 



No. 816.— June, 1909. 



NOTES FROM MILLPORT MARINE BIOLOGICAL 



STATION. 



By Richard Elmhirst, F.L.S., Superintendent. 



The Whelk [Buceinum undatum) as Food of the Cod 



(Gadus callarius). 



While examining the contents of some Cods' stomachs from 

 off the south end of Bute I was struck by the large number of 

 opercula (door-plates) of the Whelk or Buckie present. It is 

 well known that Crustacea constitute the greater part of the 

 Cod's food (see " Second Report on the Food of Fishes " (North 

 Sea, 1904-5, International Fishery Investigations), by R. A. 

 Todd) ; although, there, two cases are recorded in which large 

 numbers of Whelks are present. Mr. McNeil, the line fisherman, 

 who caught them, informs me that Whelks are very abundant in 

 that locality ; certainly a great number do come up on the lines, 

 and are used for bait. When used for bait the operculum is 

 generally cut off, although I have found opercula inside Cod 

 which certainly had been on bait, as they had been cut in two 

 by a knife. Now, the number of opercula present indicated 

 beyond all doubt that they had not all been taken as bait. On 

 one occasion thirteen stomachs yielded fifty-two opercula, one 

 four-pound Cod containing as many as fourteen. 



Knowing the difficulty of extracting a live Whelk from its 

 shell without breaking it, I wondered how the Cod got them 

 Zool. 4th ser. vol. XIII.. June, 1909. r 



