5 1 8 Memoir Sears Foundation for Marine Research 



a net was kept out there for a week in early August 1936" (^7: 128), It seems well 

 established, also, that their wanderings along shore are so brief that but little inter- 

 mingling takes place between local populations. The supporting evidence for this is 

 of two sorts: (i) the development of an intensive fishery has, in at least two documented 

 instances, been followed within a few years by a precipitous decline in the number of 

 fish taken; (2) it has been found by Andrews and Lear that the number of fin rays 

 and of vertebrae average progressively higher from south to north along the north- 

 eastern Labrador coast (2: 854, tab. 8, 856, tab. 9, 860), which would not be the case 

 if much intermingling took place between the populations that are produced in the 

 various rivers along this stretch of coast. 



Food. Sea-run Arctic Charr, like the closely related sea-run fontinalis (p. 536), 

 feed on active organisms; to all intents and purposes this limits the diet to fishes smaller 

 than themselves and to Crustacea, supplemented on occasion by nereid worms. In Un- 

 gava Bay, for example, alpinus have been reported as feeding chiefly, if not exclusively, 

 on the crustacean genera Gammarus and Pseudaliprotus, fish not having been mentioned 

 at all {16: 100). On the coast of southern Spitsbergen also, large gammarids {Gam- 

 marus locustd) as well as mysid shrimps provide their chief sustenance, with fishes 

 (capelin, small cottids, small liparids) of secondary importance (jJ: 8). Similarly, 

 in Frobisher Bay, Baffin Island, the gammarid genera Pseudaliprotus and Gammara- 

 canthus, together with liparids, were dominant items in their diet; among the 34 food 

 species listed was a variety of small crustaceans (copepods, euphausiid shrimps, clad- 

 ocerans, and decapod larvae), nereid worms, and fishes (such as Eumicrotremus spinosus, 

 small cottids, liparids, launce, and Boreogadus saida, together with young of their own) ; 

 even a few insects were included (28: 366, 367). 



In Hudson Bay and along northeastern Labrador the recorded diet has been divided 

 in varying proportion between fish (chiefly launce, Lumpenus, capelin, cottids, and 

 Cyclopterus) and amphipods and euphausiids. Table x, showing the percentages of 

 diflFerent items in the stomach contents, illustrates the variation to be expected from 

 place to place. 



Table X. Percentages, by Volume, of Different Species in the Stomach Contents of 

 Arctic Charr Taken at Successive Localities from South to North along the Coast of 



Northeastern Labrador* 



Fish 



^ ^'~~~. ^ 



T ,- _ . r 1 • Amphipods and 



Locality Lapelm Launce bculpins -r,"^ , .. , 



■^ Luphausnds 



Adlok 88.0 3.0 o o 



Nain, specimen i .... 75.2 10.7 o 13.5 



Nain, specimen 2 .... 15.0 12.7 61.2 ii.i 



Okkak Bay 99.3 0.2 o 0.5 



Hebron 2.9 0.3 14.9 81.3 



Ramah 3.9 13.5 24.7 56.2 



* From Andrews and Lear, 2: 858. 



