98 Reproduction, Competition, and Predation 



Among the earliest spawners is the northern pike which spawns at 

 water temperatures of 40° to 46°F. Walleyes spawn at 45° to 50°F, yellow 

 perch a little after walleyes and muskellunge at 48° to 56°F.^* The pikes, 

 walleyes, and perch begin spawning soon after the ice goes out in the 

 early spring. Eschmeyer ^^ described the spawning of walleyes at Lake 

 Gogebic ( Michigan ) : "At Lake Gogebic walleyes arrived on the spawning 

 shoals immediately after tlie break-up of the ice in the spring. Usually 

 they occurred in small numbers at first, followed by rapidly increasing 

 numbers as the water warmed. . . . 



"Almost all spawning activity which has been observed at Lake 

 Gogebic has occurred within the shallow-water strip along the shoreline 

 —exposed by the lowered water level. . . . The entire shoreline along which 

 spawning occurs is densely wooded and is washed almost continuously 

 by waves as a result of its exposure to the prevailing northwest winds. 

 . . . Since spawning occurred almost exclusively at night, much of the 

 activity of fish on the shoals was observed with an automobile spotlight 

 powered by a storage battery carried in the rowboat from which the 

 observations were made. The eyes of walleyes reflect light, to appear as 

 bright orange-red globes, thus greatly facilitating the location of fish on 

 the shoals. 



"Walleye spawning seasons reported by other workers in various local- 

 ities extend from late March to early June, but always include a portion 

 of April or May." 



The nesting habits of the sunfishes (including largemouth and small- 

 mouth basses and black and white crappies) are among the most in- 

 teresting of warm-water fishes. Breder ^^ described the nesting behaviour 

 of many members of this family. Some nest in groups, such as bluegills 

 which select areas of shallow water 1 to 4 feet in depth and exposed to 

 the direct rays of the sun for at least a part of the day. Here they scoop 

 out their shallow nests often located so close together that only a narrow 

 ridge of earth separates one nest from others surrounding it. Bluegills 

 have a long nesting season; Fork Lake ( Illinois ) bluegills became ripe in 

 late May and some ripe fish were collected every month tliereafter until 

 mid-September. Bluegills usually show two peaks of spawning activity, 

 the first and largest at the beginning of the spawning season and a second 

 peak a month or so later, usually in early July in the north. However, 

 some bluegill reproduction continued throughout most of their long 

 spawning period. Some warmouths were found to be in spawning con- 

 dition from about May 15 until August 15 in central Illinois ^- although 

 no fish were completely spent until September 1. 



Both largemouth bass and crappies have short spawning seasons com- 

 pared to bluegills and other sunfish, although the spawning period of 

 crappies is somewhat longer than that of the largemouth. ^^ Crappies and 



