Assessing Spawning Site Fidelity of Brook Trout (Salvelinus fontinalis) Using Multiple, Independent, Small-Scale PIT Arrays

Passive integrated transponder (PIT) tags are a commonly used technique for identifying and tracking fishes.  These tags are often detected using permanent, stream-width arrays capable of identifying nearly all tagged organisms passing a particular point, but require significant infrastructure to install and maintain. Portable backpack detection units are more suited to small streams and short-term work, but rely on labor-intensive manual surveys and may be disruptive to fish behavior.  To complement these methods, we developed a technique using multiple, independent, small-scale PIT readers. An array of these readers is cost-effective and can collect data autonomously. The use of pass-over antennas allows for placement in nonlinear waterbodies, such as lakes, where travel direction cannot be assumed. We evaluated the feasibility of this technique for studying spawning movement within a recovering brook trout (Salvelinus fontinalis) population in Honnedaga Lake, NY. Nine readers were installed at known spawning locations and operated for a period of 25 days.  A total of 183 adult fish were collected, tagged, and released. During sampling, 21% of tagged fish were redetected and 19.5% of those detected were recorded at multiple locations. These results suggest that fish do move between spawning locations and confirm the utility such arrays.