REPRODUCTIVE TIMING AND USE OF REDD SITES BY LAKE-SPAWNING BROOK TROUT (SALVELINUS-FONTINALIS)

We provide a detailed description of a salmonine mating system based o n daily observations of tagged individuals in a lake-spawning populati on of brook trout (Salvelinus fontinalis) throughout two breeding seas ons. Actual spawning occurred over a period of similar to 50 d. Over 9 0% of spawning males were present soon after spawning commenced and ou tnumbered females for the duration of the spawning period. The amount of time males and females remained on the spawning grounds increased w ith body size; however, males were present over a longer period than f emales of equivalent size. A distinct seasonal peak in spawning activi ty (similar to 15 d) accounted for 58 and 84% (1994 and 1995) of all r eproduction and was coincident with a decline in water temperature bel ow 11 degrees C and increased rainfall. Selection of redd sites by fem ale brook trout was determined by groundwater flow which was significa ntly greater than at nonspawning sites. A preference for certain redd sites was observed, with 50% of spawnings occurring at 11 sites. The c onstruction of multiple redds and duration in spawning activity by fem ales increased with body size. Extensive reuse of redd sites and rapid replacement of females during removal experiments indicate that redd sites are a limiting resource.