The Development of Population Estimate Procedures in Small Trout Lakes

The development of suitable procedures of mark-and-recapture population estimation was undertaken on two small trout lakes. Effort was primarily applied toward evaluation of the assumption of equal vulnerability between marked and unmarked fish. Using traps and angling, four basic procedures were employed and the resulting estimates compared. Estimates obtained by angling and recapture by angling procedures were judged too high, apparently because marked fish had acquired a hook resistance. Estimates from a trap and recapture by trap procedure were too low when hoop nets were employed, but when hardware cloth traps were used the estimates were too high. Estimates obtained by procedures which involved making the recaptures by a different method, trap and recapture by angling and angling and recapture by trap, were considered best since they were compatible with known numbers present and numbers previously planted and agreed well with each other.