USING TRAJECTORIES THROUGH A TIDAL ENERGY DEVELOPMENT SITE IN THE BAY OF FUNDY TO STUDY INTERACTION OF RENEWABLE ENERGY WITH LOCAL FISH

摘要

A tidal energy development site has been designated in Minas Passage (Bay of Fundy, Nova Scotia, Canada) for testing in-stream turbines and producing renewable energy. Concern remains that turbines might harm local populations of marine animals as they sweep by within a fast-flowing water mass. Drifters approximately track a water mass and can support instrumentation for detecting fish that carry an acoustic tag. A tagged Atlantic salmon tracked sufficiently similarly to the drifter for it to be continuously within detection range for three intervals of up to 56 minutes over a 21-hour period. The same fish was briefly detected near the drifter five days later. Two types of quasi-stable drifter trajectory were found to make many transits through the fast-flowing waters of Minas Passage, with tidal excursion extending far beyond the passage. Drifter trajectories characterize water areas that are likely to be influenced by fish-turbine interaction over the tidal timescale. One quasi-stable trajectory is associated with accumulations of floating debris that may interfere with tidal energy devices. Most drifter tracks passed south of the tidal energy development site. Less commonly, drifters passed through the development site during flood tide and these tracks are associated with northerly extremes of quasi-stable trajectories. Few drifter tracks passed through the development site on the ebb tide and those that did quickly transitioned to quasi-stable trajectories that mostly pass south of the development site. Regardless of drifters mostly bypassing the development site, the monthly probability of drifter collision with a 500 kW near-surface tidal energy device was estimated to be 0.18. Collision probability for fish is argued to be lower.