Movement and habitat use by lake whitefish during spawning in a boreallake: Integrating acoustic telemetry and geographic information systems

摘要

To quantify lake whitefish swimming behavior, substrate selection, and theinfluence of water level variation on spawning behavior and success, wetracked lake whitefish Coregonus clupeaformis during two consecutivespawning seasons (October-November) in a small boreal lake in northwesternOntario, Canada. The lake was subjected to an experimental drawdown of 1.4m in 1995 and 0.75 m in 1996 at the time tracking started. We used aradio-linked, acoustic positioning system that produced positions every100 s for 18 tagged lake whitefish, eight of which provided depthinformation. Fish position and depth were put into a geographicinformation system database with information on substratum, slope, anddepth. Mean daily locomotor activity declined as the spawning seasonprogressed. Two patterns of behavior occurred in both years.Offshore-oriented fish spent their time along bottom contours, whichincreased in depth through the spawning season. Inshore-oriented fishspent their time along the shoreline, and exhibited site fidelity duringspawning before moving to deeper offshore areas, where movement wasreduced. For inshore-oriented fish, spawning positions were determinedbased on their presence in the littoral zone and a low instantaneousswimming speed of less than 6 cm/s. For these positions, only threesubstrata-boulder, cobble, and detritus-comprised 50% of these locations.Mean depth ranged from 2.7 m (+/-1.3, SD) to 3.5 m (+/-1.2) with meanslopes of 36% (+/-13.2%). We confirmed spawning by recapturing spenttagged fish; scuba divers also confirmed the presence of lake whitefisheggs at one site. Water level reductions apparently caused mortality ofeggs laid at depths less than 3.5 m. Overall, lake whitefish displayedhigh fidelity toward specific substrate and slope characteristics, usingnew sites as water levels rose. [References: 60]