Project Description

Burbot abundance is typically estimated using mark-recapture experiments, a design which prohibits using traps deeper than >= 15 m to protect fish from decompression trauma. However, this approach assumes that a representative sample of the population is collected and that complete vertical mixing occurs between sampling events. For all burbot lakes studied within the Copper River drainage of Alaska, these assumptions have never been fully evaluated because the behavior and vertical movements of burbot have never been fully assessed. This project proposes to: (1) determine if burbot in Tanada and Copper lakes express differences in thermal and depth habitat preferences; and (2) use recorded movements of burbot surgically implanted with archival data loggers (time-depth-temperature) to evaluate the sampling design for a two-sample mark-recapture experiment due to burbot behavior relative to depth. Preliminary findings from tags recovered in summer 2010 at Tanada Lake indicate that there is a percentage of fish that are not within the study area during optimal sampling dates (September before ice up). This may indicate that current management strategies are missing a portion of the burbot population within this lake. With many Alaskan lakes, and especially Tanada and Copper lakes, the bathymetry (depths > 15 m) can preclude large sections of the lake from being sampled and, in these cases, the experiment relies heavily on mixing between events to attain a representative sample in the second event. In either lake, there exists the possibility of fish permanently residing at depths > 15 m, which would lead to any abundance estimates being biased. Recent developments of smaller high-capacity archival data loggers that record depth and temperature have permitted refined investigations of vertical movements and thermal-use patterns.

Project Funding

National Park Service
Amount: $39,150
Start Date: 2009-01-00
End Date: 2015-12-00

 

 

Research Team