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Introduced predators can have harmful top-down effects on their newly colonized system through competition with and direct predation on native species. Following an initial introduction of muskellunge in Lac Frontière, Québec in the 1970s at the headwaters of the Wolastoq | Saint John River, the species rapidly migrated downstream expanding its range by ~500 km over ~20 years. Despite this expansive colonization and concern over possible threats to native species, little is known about the basic ecology of muskellunge in this system. The last downstream barrier is the hydroelectric facility, Mactaquac Generating Station (MGS)), 150 km upstream of the sea. While there are no downstream fish passage facilities at MGS, adult muskellunge have been recorded downstream. In this study, muskellunge (n=23) were surgically tagged with VHF (very high frequency) radio or CART (Combined Acoustic Radio Telemetry) tags and tracked them over 2 spawning seasons. We sought to determine if there was a reproducing population downstream MGS. and tracked them over 2 spawning seasons. We tracked fish to locate and confirm spawning sites and followed up with egg and/or juvenile sampling surveys. Tagged muskellunge (90%) moved upstream towards the MGS during the spawning period in each year (20162017), where they remained throughout the entire spawning period. No spawning or nursery sites were confirmed near MGS; however, in 2016, three distinct spawning locations and six distinct nursery sites were confirmed 10-12 km downstream amongst a chain of flooded islands. In 2016, eggs, sac-fry, and juveniles were collected and confirmed as muskellunge by genetic sequencing, providing the first empirical observation of successfully spawning downstream of MGS. This article is protected by copyright. All rights reserved. |
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