AEP biologist releasing captured Bull Trout back into the river after processing.
How do you run a fish trap?-Earlier this year, TUC and AEP collaborated to set up a bi-directional fish trap in the lower Tay River to help us track fish movement and determine whether a Bull Trout spawning run still exists here. In late September, Michael Short of Let’s Go Outdoors made a video about the effort, and the other work being with our partners in the watershed—check it out! Now, after two months of running the trap, we would like to take you through what was involved.
The trap took 10 people 9 hours to set up. First, biologists and technicians had to move two trailers full of metal boxes, wings, and braces down to the river to set up the frame of the trap. The wings had to block off the river completely, so fish could not dodge the trap by swimming under or around the wings. To accomplish this, we had to dig trenches into the bottom and sides of the river, to ensure that the wings were flush and level with each other, and with the river bed. Then, we had to move over 500 conduits—aluminum rods that create the barrier in the wings, allowing small fish and water to pass freely, but excluding the larger target fish, forcing them to enter the box through a funnel where they could be held and then processed. These conduits had to be inserted one by one into the holes in the wings and the boxes and then hammered down into the substrate to ensure that no fish could get underneath and bypass the trap. Heavy braces were then placed at each joint of the trap to protect it against the water current and debris, reaching into the chilly 8C water to bolt them in place. We then carried about 6 dozen sandbags into the river, to further armour the wings and the braces, and finally, installed lids on the trap boxes.
Technicians checking the trap for fish. Technicians often had to jump into the trap to find fish; they are great at hiding!
Running the trap was quite labour intensive. Someone had to check the trap at least twice a day for fish—once in the morning, and once in the evening—so there was always at least one technician on site every day. As the trap was quite remote, staff had to live in trailers at the Tay River Campsite for the duration of their shift. If fish were present in the trap, technicians would catch and process them. Non-sportfish (Longnose Suckers and White Suckers) were measured and marked by a pelvic fin clip so that technicians could identify recaptured fish in the future. Pelvic fin clips are a common method to temporarily mark fish because the fin will regrow on its own after a couple of weeks. Sportfish (Mountain Whitefish, Brown Trout, Brook Trout, and Bull Trout) were measured, anesthetized, implanted with PIT (passive integrated transponder) tags, and marked by both pelvic and adipose fin clips. The PIT tags will allow us to identify individual fish if we re-capture them at another time and location, providing important info about their movements. The tissue samples from the pelvic fins were saved to be used in future DNA and gene classification studies. Unlike the other fins, adipose fins cannot regenerate, so it is an effective, low-stress method of permanently marking fish. After processing, fish were given some time to recover from anesthesia, and then returned to the river in the direction that they were moving.
Technicians on shift also had to keep the trap clean of debris. This mainly meant removing fallen leaves from the upstream end of the trap, as the river was surrounded by many large poplar and willow trees. After cleaning the trap, technicians would walk the river, looking for any trap shy fish holding in pools. These are fish that would encounter the trap, but be too wary or confused to enter it, and swim back to a nearby pool to wait there, hoping for the trap to disappear, and allow them to move freely. In early October, three trap shy Bull Trout were spotted holding in a pool for several days straight, so biologists used a tangle net to capture them for processing. These fish had previously moved upstream and were now on their way back downstream. Additionally, the trap was frequented by visiting anglers, curious passersby, and people from the area; trap staff were always happy to speak to anyone curious about the project and learn about their personal experiences with the Tay River. TUC also hosted several volunteer workdays at the Tay River trap. Volunteers were able to be involved in every step of the process, from catching the fish in the trap to handling them, taking measurements, and releasing them. It was a pleasure to have so many volunteers interested and involved in the project!
TUC and AEP staff working hard to take down the trap.
After a successful run without incident, the fish trap was finally taken down in mid-October. Takedown occurred in some surprising conditions—there was over a foot of snow on the ground, ice had formed in some of the shallower pockets of the river, and the water was a balmy 4C. The sandbags armouring the trap, as well as many of the conduits, had frozen into the ground. Nonetheless, the show must go on, and despite these conditions, the takedown went quite smoothly. It took 10 people only 3 hours to dismantle and load the trap for transport back to the AEP warehouse.
Over the time that the trap was up, biologists captured over 30 Brown Trout, a handful of Brook Trout and Mountain Whitefish, an innumerable amount of suckers, and nine Bull Trout. In the coming months, the data will be processed and posted on Alberta’s publically available FWMIS database, and biologists will use this information to make management decisions regarding the future of the Tay River watershed and Bull Trout recovery.
Thank you to Angela and Kelly for running the fish trap; to our partners at Alberta Environment and Parks Fisheries Management for working with us on all aspects of the project; to the Alberta Conservation Association for lending equipment and advice, and to AEP’s Watershed Resiliency and Restoration Program for supporting our broader Tay River Bringing Back Bull Trout Project. Additional support was also provided through the Canada Nature Fund for Aquatic Species at Risk. Thanks also to Cows and Fish and the University of Calgary for their contributions to our broader Tay River project.
The first Bull Trout captured in the trap. This big male was over 60cm long!
How can you help? If you have recent or historic information on Bull Trout in the Tay River watershed, we want to hear from you! E-mail Trout Unlimited Canada or BullTrout@gov.ab.ca to share your observations.
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