More fishy friends join the project: fall 2022 update

I have a fall update to share.

Things are going well with the fish tracking work. In October, we spent more time on Stoney Lake trying to catch fish to tag. We were mostly catching fish by angling. When I say “we”, what I really mean is Dr. Jake Brownscombe and his crew from DFO. A few of my lab members and me were out to help on some days, but Jake and his crew continue to lead the field work and data management.

There’s a well-developed science of catch-and-release angling. Catch-and-release is stressful for fish, but when it’s done well, with minimal air exposure, most fish recover well. Water temperature plays a big part; if the water is cold, catch-and-release is usually benign, although what is defined as ‘cold’ is species-specific, and there are loads of other factors that can cause problems. Anyway, you may recall from an earlier post that we were out tagging fish (catching them and implanting transmitters) in early June (only 18 in total), but then stopped for the summer. We are avoiding warm water temperatures (20°C) when doing this work to maximize fish health and survival after they’re released. Fall weather (as warm as it’s been) has brought lower water temperatures, which is why we’ve been out again lately. We’re now done with catching and tagging fish for the season (I think). Here’s where we sit in terms of total numbers of fish we have swimming around in the lake with transmitters:

Walleye: 24

Smallmouth bass: 22

Yellow perch: 13

Muskellunge: 2

We’re still looking for donations to help bring these numbers up a lot, but we still have a few tags in hand and will now start preparing for a big spring tagging season. The muskellunge are big enough to handle larger tags: the transmitters we’ve put in them will last for 10 years! We’re excited about learning more about the lives of these fish, and the individual ‘personality’ of each animal.

While we were on the water in October, we caught up with Ed and Jackie from USLA, and Josh Feltham from Fleming College. Ed and Jackie have been helping develop a bioenvironmental monitoring plan for the lake, in partnership with the lake community including local First Nations. We spent some time checking out the long-term monitoring sites and continued our conversion about how we might add to what is up and running. It’s important that lake communities take environmental monitoring into their own hands, and we’re excited to (hopefully) help with developing that program. The information we’ll generate from the fish tracking work over the next several years will just be one part of how we can contribute to helping monitor ecosystem health.

(Above) En route to check out a long-term benthic biomonitoring site on Upper Stoney Lake.

Another fun update from today: one of the small walleye we tagged in late spring was captured and harvested this past weekend. Thanks to Trent U graduate Laura for getting in touch with me; I just picked up the tag (picture below), which I’ve now shut off so it can be re-used in a new fish next year. In the spring we’ll likely work on putting up notices around boat launches and post more info online to spread the word about what to do if you catch a tagged fish (i.e., how to get in touch).

(Above) The fish transmitter that was just recovered from one of our tagged walleye.

We’ll likely be out again once or twice between now and when the lake freezes. We need to check on our shallow water receiving stations once the water level drops, to make sure they’re not too shallow. Then we move into planning mode for a big 2023, with new students joining the project and (hopefully) a new research vessel we’ve ordered from Paris Marine.

Cheers,

Graham

Exploring the use of underwater video for fish monitoring in the Kawarthas

By Jacob Bowman, undergraduate research technician in the Raby Lab

As many local anglers know, Stoney Lake is home to a diverse assemblage of fish species. One important habitat for fish is the nearshore zone where light can easily penetrate, and plants grow in abundance to provide cover. As ecologists, we are interested in how fish relate to conditions in the nearshore habitat. One plant, the invasive starry stonewort (Nitellopsis obtusa) is of particular interest because it is spreading rapidly in Stoney Lake and the Kawarthas, and there is concern that it may negatively impact native organisms. We are investigating this concern by using Remote Underwater Video Systems (RUVS), while more broadly exploring whether RUVS might be useful for long-term monitoring of nearshore fish communities in the Kawartha Lakes. We are starting the project by focusing on Stoney Lake and the Otonabee River (around Trent U). My work on this project in 2022 was made possible by a donation from Ralph and Carol Ingleton.

What are RUVS?

RUVS are underwater camera stations that are deployed to film aquatic animals in their natural habitat. We are using videos from RUVS to count the number of fish species at a site and to estimate the number of individual fish there. Our RUVS setup consists of a GoPro camera attached to a cement base with a rope and small buoy. There is also a sighter arm that gives us a sense of how far we can see (the size of the visual field). RUVS are commonly used in studies of marine animals and are starting to be used more frequently in freshwater. RUVS have a few advantages when compared to the usual fisheries monitoring techniques like netting. They can be used by inexperienced researchers like students, volunteers, and community members, because very little training is required. Other types of fish monitoring that involve capturing fish may cause fish to be stressed or injured. RUVS on the other hand have little or no direct impact on fish, and don’t require a scientific collection permit.

RUVS in Stoney Lake

This summer we have been deploying RUVS at sample sites across the nearshore waters of Upper Stoney Lake. At each sample site we measure water temperature and clarity. We then deploy a RUVS and record a one-hour video. A big job for the winter will be reviewing the videos to count the fish and identify the plant species at each site. In the videos we have reviewed so-far, we have identified 11 fish species. The most common fish species in our videos so far have been pumpkinseed and bluegill sunfish. Some other fishes we have observed include golden shiner, brown bullhead, black crappie, and juvenile walleye. In addition to fish and plants, we were surprised that we also filmed a pair of otters checking out our camera at one site (scroll down for the video). RUVS could be potentially used to monitor the presence and abundance of many underwater animals like otters, invertebrates, or turtles.

Our hope with this project is that RUVS can be as a long-term option for the Stoney Lake community to monitor the nearshore fish assemblage, supplementing the fisheries monitoring work that is done by the Ontario MNRF every five years (using gillnets). Long term monitoring is essential for detecting environmental change. For example, as new invasive species enter Stoney Lake, a long term RUVS study could be used to quantify their impacts on the ecosystem and better understand why they're spreading.

Video (above): RUV footage from Upper Stoney Lake, with a pair of otters scaring away all the fish in sight.

Video (above) shows a curious smallmouth bass (Upper Stoney Lake) checking out or RUV setup.

Summer 2022 project update

It’s been a crazy summer for our lab with multiple projects getting off the ground. One of the big ones of course was this fish tracking project on Ston(e)y.

We got onto the water at the end of May, about a week after the big storm hit. We owe a huge thanks to Brent Whetung for providing temporary boat and equipment storage on the lake, and the use of his boat launch. We spent early June deploying the array of 60 underwater acoustic telemetry receivers (the fish ‘listening stations’), which provide full coverage of Stoney and Upper Stoney, and extend part of the way down into Clear Lake. It was kind of a nice time to be on the lake, because we mostly had it to ourselves – is was very quiet other than the distant sounds of chainsaws. The first week we were there, the hydro crews were all over the lake.

Some pictures and video clips of receiver deployment work are below. The receivers are suspended off the bottom, but everything including the floats is at least six feet below the surface. These receivers will be able to detect our tagged fish if they swim within ~500m of a receiver, although detection ranges can vary a lot depending on conditions – it is not uncommon with this technology for fish to be picked up from 1-2 km away. The fish are sending out their signals every 2 minutes, so they only have to swim within range of the receiver for 10-20 minutes and we have a good chance of detecting them. When we pull up the receivers next spring for downloads and battery changes, we’ll start to get a sense of the behaviour and habitat use of the fish in the system.

Speaking of fish, we also got started on tagging a few fish in June but were cut off by the water temperatures getting too warm. In total we tagged 18 fish – a mixture of walleye (pickerel), yellow perch, and smallmouth bass (pictures below). Warm water temperatures are bad news for fish health and survival when it comes to catch-and-release, although the effects of temperature vary a lot among species. Because the tags (transmitters) are expensive, and because the 3-min surgery adds extra stress, we are focusing our tagging on when water temperatures are cool to ensure fish recover quickly and go on to live for a long time. The tags we’re putting in these fish will last for 3 years in the case of the larger animals, and about 1 year for the mini tags we’re putting into perch. If tagged fish are harvested, the tags can be returned to us a re-used (tagged fish are safe to eat).

We plan to be back out in early fall to do some more tagging, and expect spring 2023 to be our big tagging effort where we’ll get the rest of our tags out. We’re still in need of funding to purchase more transmitters for 2023 so we can keep the project going, if you’re interested in donating please follow this link! https://mycommunity.trentu.ca/tarpgive

And get in touch with me if you have questions.

Graham

Video (above) showing the team lowering an acoustic receiver (the cylindrical black thing) into the lake on a calm day in early May, near Ship Island. The big orange float sits 6-10 feet below the surface, and keeps the receiver off the bottom, listening for tagged fish to swim by.

Photo (above) showing underwater shot taken from a DFO underwater drone (that's its claw you can see), looking down at one of our receivers. This receiver setup is designed for shallow areas, where the receiver sits inside a white PVC tube that is embedded into the concrete anchor. A small yellow float suspended off the anchor helps us spot the receiver.

The photos above show (top) Dr. Brownscombe and his assistant Amanda doing surgery on a walleye in Stoney Lake. The fish (sutured incision shown in 2nd photo) is now swimming around the lake, being tracked by our receivers.

Photo (above) of Dr. Raby with a smallmouth bass in Upper Stoney, ready to be released moments after being surgically implanted with a 3-year acoustic transmitter. This and the other fish that have been tagged so far were all caught by angling.