Immediately improving estuary survival of Atlantic salmon smolts by active management in the Miramichi River

Description: Through previous research work, combined effort from UNB-INTEL and ASF has unequivocally determined that the largest factor currently negatively affecting survival of ocean-bound salmon smolts in Miramichi River is the predation by another native fish species, the striped bass (SB). Telemetry studies using specific predation-sensing transmitters (2018-2023 data) consistently pinpoints the exact location of the high predation-induced mortality, which is a relatively short tidal section in the Northwest Miramichi. If migrating salmon smolts could “by-pass” this section, it is hypothesized that survival would increase. Therefore, the specific objectives of this program are to 1) establish an experimental “smolt barging program” wherein migrating salmon smolts are captured using rotatory screw traps upstream of the “predatory hot-spot”, 2) are tagged with transmitters and barged daily through the 20 km “predatory hot-spot”, 3) are released into estuary downstream of “predatory hot-spot”, and 4) are monitored for survival (acoustic tags) to the Strait of Belle Isle acoustic receiver array in the Gulf of St. Lawrence and back to adult returns (using PIT tags) one or two years later in the Miramichi River. The survival of barged smolts is compared to a similarly sized control group that is allowed to naturally migrate through the “predatory hot-spot” carrying similar electronic transmitters. This work is repeated for three migration seasons to determine the consistency in increases in survival and demonstrating that no unwanted/unanticipated effects (e.g. altering the homing ability of the barged smolts) are present. The program also establishes a first direct smolt-to-adult (ocean) survival estimate by PIT tagging individuals during smolt migration, and monitoring the survival to adults using large across-river PIT antenna arrays.