Restoration of native species is a strategic priority for most agencies on the Great Lakes. Stocking of hatchery-raised juvenile fish is the most common method used to re-introduce or maintain fish stocks. The fate of these released fish, particularly the immediate survival and habitat use, is largely unknown. Such information would be very valuable for assessing the efficacy and for improving the success of the restoration project. For example, does the size of the fish or release date alter the behaviour and ultimate survival of released fish? Acoustic telemetry provides a method for tracking the movement and survival of larger fish and has been very successful in increasing our understanding of Great Lakes fish through programs such as GLATOS. GLATOS has established a network of 69 kHz Vemco acoustic receivers throughout the Great Lakes for recording acoustically tagged fish but the smallest sized 69 kHz tags are too large for most released juvenile fish. The 180 kHz acoustic system tags are much smaller, and the smallest tag (V5, 0.65 g) can be put in fish as small as 15 g. These small tags have the potential to provide survival and habitat use data for small hatchery raised fish. However, an important first step in establishing and effective receiver array is to carry out range test studies of the 180 kHz tags. Our larger goal is to use acoustic telemetry to study the fate of hatchery raised juvenile bloater (Coregonus hoyi) in Lake Ontario. In November 2014, we surgically implanted 150 acoustic tags (180 kHz: V5; 69 kHz V7 and V9) in juvenile bloater (~21-96g) and as of January 14, 2015, all fish had survived, and we are moving forward with a proposal to implement an extensive acoustic telemetry project in western Lake Ontario. Acoustic telemetry detection range can vary with depth, so there exists a need to establish range detection for both 180 and 69 kHz tags at depth. We propose to quantify the detection range for a wide range of Vemco acoustic tags (180 kHz: V5, V6; 69 kHz: V7, V9 and V13) both at depth (~50-60 m) and above the thermocline to understand the effects of depth, temperature, and water column noise (i.e. wave action and currents) on acoustic detection range. Such information will inform our proposed bloater study as well as the larger Great Lakes acoustic telemetry community with respect to design of receiver arrays and choice of tags.
QUANTIFYING DETECTION RANGE OF ACOUSTIC TELEMETRY TAGS IN DEEP WATER: FIRST STEP FOR USE IN SPECIES RESTORATIONS