How do tides and turbines affect sealife? Fundy study hopes to find out

In the Bay of Fundy, tidal power development offers as many challenges as opportunities, and researchers hope that creating a new atlas of vital fish species that depend on the area will answer questions that could lead to more sustainable development.

The Fundy Ocean Research Centre for Energy (FORCE) is leading a collaborative project to develop predictive models of where key species will be found in the Minas Passage, N.S., based on environmental conditions. This would then be used to establish the likelihood that fish would be present in the same area as tidal turbines. 

The risk assessment project is researching nine species, including ones important for commercial fisheries, like striped bass and alewife, as well as ecologically and culturally significant species such as American eel, tomcod, and white sharks.

"This is an area where we need to get information and data to support claims," said Dan Hasselman, science director for FORCE. "You can't develop tidal power alone. It's something that's a societal issue. And so the answer has to be a society-based answer. And that means going into this with our eyes wide open and understanding the risks of tidal power."

Risks are currently unknown

In the past, tidal energy projects in the area have been met with concerns from harvesters and Mi'kmaw groups over potential impact of collisions on culturally, economically and ecologically important species, as well as with a lack of baseline data of the environment.

Hasselman said there is a dearth of information about fish presence in the Minas Passage. This challenges the ability of regulators at the Department of Fisheries and Oceans to assess a potential project's impact on fish.

"Right now the risk, is to some extent, is unknown and we need information to make some decisions about how we go forward."

The project is using acoustic fish tagging to examine the movement of species in the Minas Passage, where FORCE has a demonstration turbine. That data, combined with data about environmental conditions in the Bay of Fundy, is being used to create models that predict where fish will be found.

Environmental factors that are being considered include water temperature, speed and direction, and sea surface height and depth.

Answering ecological questions

Charles Bangley, a research associate at Dalhousie University who's working with the project, said these are combined in a model that serves as a forecast of fish distribution.

"It could identify the times of year that we're likely to have Atlantic salmon moving through Minas Passage," he said. "But it can also get us down to the level of what tide stage are we more likely to see those salmon, and under what conditions, and are there times of the year where there actually are not very many salmon present at all."

For striped bass, project data suggests they surf the outgoing tide through the Minas Passage during their fall migration. White sharks and dogfish pass back and forth through the Minas Passage, and dogfish also hang around the area.

"Presumably, they're foraging. So they probably found some spots where they can hover in the water and let the prey get blown toward them, which is a behaviour that's been noticed in reef sharks elsewhere," said Bangley. "Even if tidal power wasn't part of this, the ecological questions we're answering are just really fascinating."

The intense tides of the Bay of Fundy could limit the reliability of acoustic tagging equipment, so the project will also study the range of the acoustic receivers to see how well they pick up fish when currents are scooting them along at high speeds.

Work on the project is expected to wrap up at the end of this year. 

'They're starting to catch up with what the fishermen know'

But some say there are significant issues that still need to be addressed. 

Darren Porter, a commercial fisherman in the area, said the risk assessment project can address existing questions about fish distribution in the Bay of Fundy, but says more research is needed on the impacts of tidal power.

"The project will not determine the effects of tidal power, that's not going to happen. But it will help with knowledge gaps that FORCE and the province have, with their understanding of how fish move in that system. And that's important because just because it's green, doesn't mean it's blue."

Porter, along with the Mi'kmaq Conservation Group, has been involved in the data collection for the project. He said while harvesters and Indigenous groups have been at odds with tidal power developers for years, the project allows for local knowledge to be harnessed in a way that creates a more accurate picture of marine life in the area.

"They're starting to catch up with what the fishermen know. The problem with the fishermen is we've never had a way to deliver our information in a way that they understand. So this is a better way to do it."

Porter said the information the project has gathered so far has underscored how much is at stake in developing tidal power, and why caution is needed, including with greater environmental monitoring. 

"The more information recorded, the more marine life we understand is there, the more risky this becomes," he said. "DFO has no choice as a regulator [but] to apply precaution. So the information from these projects will help them do that."

Potential risks

Andrea Copping, a senior research scientist at the Pacific Northwest National Laboratory in the U.S., works on the international regulation of marine renewable energy and is not involved in the project. She said there are a number of potential risks to marine life from tidal power.

These include underwater noise, electromagnetic fields, disturbance of bottom habitat, and displacement of animals from areas because they're avoiding turbines, although research suggests the first two are very low risk. Of the potential effects, she said the possibility of animals coming into contact with turbines remains the most difficult to assess. 

"Collision risk is the big one. And it's the one we've made the least headway on. You're trying to prove something won't happen; it's pretty hard."

An international body of research can be drawn on to help answer these questions, said Copping, who is part of a 16-nation initiative called Ocean Energy Systems Environmental. But site-specific data is important, as is taking concerns of collision risk seriously. 

"I'm very enthused about renewable energies. But I cannot say I'm pro-tidal or pro-any wave device; they need to prove themselves out — obviously, technically and economically and all that — but environmentally.

"The best we can do is try to move forward and say, 'We think we know this. If we collect these samples and model this, we can prove it, as much as we prove anything in science. But let's try to really focus on the questions that are really tough and evading us at the moment, and let's do it together.'"

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