THE FISHES OF GEORGIAN BAY 39 



SESSIONAL PAPER No. 39b 



9 



reaching Muskoka Lake. It shows a preference for rocky ledges in the vicinity 

 of open water, where it is commonly seen in large numbers. 



Length usually 6 inches or less, specimens of 7^ inches being infrequent. 

 Body short, deep, and compressed, the depth 2-2 to 2-4 in the length. Head 2-5 

 to 2 • 8. The general coloration varies f i om olive with more or less brassy reflections, 

 in fish taken in lighter water, to almost black in fishes taken in muskeg water. 

 Sides with rectangular blotches, more definite dorsally, and especially conspicuous 

 in young specimens. Some of the scales below the lateral line with small dark 

 spots, forming about 10 longitudinal stripes. A black spot on the opercle. The 

 dorsal, caudal, and anal fins are more or less mottled or barred with pigment; lower 

 edges of ventrals and anal black. Dorsal fin with 10 or 11 spines and 11 (some- 

 times 10 or 12) soft rays. Anal with 6 spines and 10 soft rays, the length of its 

 base contained 1 • 5 to 1 • 6 in that of the dorsal. Lateral line high up on the body, 

 and curved, the scales 40 to 46. 



The food of the rock-bass consists of minnows, crayfish, and insects; the 

 chief food depending on whether the fish is small and inhabiting swampy areas, or 

 large and inhabiting more open shoaly places. During the period when mayflies 

 are abundant, the smaller fish feed largely upon them, leaving their shelters after 

 nightfall, and sucking the flies from the surface of the water. 



The spawning period is for the most part during the month of June. The nest- 

 ing habits are similar to those of other centrarchids. The nest is placed near shore 

 in a swampy bay, often in only a few inches of water. It is prepared by the male 

 fish, which usually works most energetically, fanning out the sediment with his 

 fins, thus making a basin-like depression, clean of all debris, and of 8 or 10 inches 

 in diameter. The female is driven into the nest and is carefully guarded until the 

 deposition of the eggs is accomplished. During the process of spawning and fer- 

 tilization the two fish lie side by side in the nest. Only a few eggs are extruded at 

 a time, and at each period mUt is extruded by the male. The operation continues 

 for an hour or more, and at the end of the period the female leaves the nest and 

 does not return. The eggs are carefully looked after by the male fish, which takes 

 up a position over the nest, and every now and then sets up a fanning motion with 

 the fins. In a few days, after the eggs are hatched, the fry gradually rise out of 

 nest, and are soon left by the male fish to shift for themselves. 



During the spawning period rock-bass nests are extremely common in the 

 swamps. Some contain live eggs; some are empty and abandoned, and some are 

 occupied by whitened, fungus-infested eggs which in many cases are still watched 

 over by the male fish. The number of fish spawning at one time and the difficulty 

 experienced by the males in getting the females into the nests, together with the 

 lively competition for their possession sometimes results in confusion. A female 

 for example has been observed to go alternately into two nests, and in some cases 

 a male has been observed hopelessly trying to look after two nests, evidently un- 

 decided as to which is his own property. 



The rock-bass is reported by certain authorities to reach a length of 12 inches. 

 Possibly the decrease in number of the larger predaceous fishes, such as bass, dore, 

 and pike, which is almost certain to take place as a result of the increase in game 



