NWT RESEARCH DATABASE

Regions: Dehcho Region

Tags: physical sciences, spawning areas, arctic grayling

Objective(s): To determine if fish are returning each year to spawn and if spring breakup allows for arctic grayling to return upriver to spawn or if there is blockage, also to measure dissolved oxygen, water level, flow and temperature to determine if conditions permit successful spawning and use the data collected to apply to other tributaries down the Mackenzie River which have also seen decreases in arctic grayling populations.

Project Description: This licence has been issued for the scientific research application No.5208. The objectives for this project are the following: 1) Tag 65 arctic grayling from Kakisa River with acoustic tags to determine is fish are returning each year to spawn. 2) Determine if spring breakup allows for arctic grayling to return upriver to spawn or if there is blockage. 3) Measure dissolved oxygen, water level, flow and temperature to determine if conditions permit successful spawning. 4) Use the data collected to apply to other tributaries down the Mackenzie River which have also seen decreases in arctic grayling populations. The purpose of this standard operating procedure is to describe a safe, effective, and humane method of electroimmobilizing fish. Electroimmobilization involves exposing a fish to an electrical current in order to induce temporary sedation with muscle relaxation, with near immediate (< 5 seconds) recovery from the effect once the electric current is removed. Exposing fish to an electrical current results in a suite of physiological responses that can range from benign to fatal, depending on the method and intensity of application. Improper electrofishing practices have been found to cause hemorrhages, spinal injury, and death in a variety of fish species. However, when properly employed, both pulsed direct current (DC) and non-pulsed DC represent safe and highly effective methods of fish capture, sedation, and immobilization. When using the electric fish handling gloves (FHG) or the transcutaneous nerve simulation (TENS) unit, a crew member constantly monitors opercular movements. If the electrical current is too high, the operculum movement will be suspended until a lower electrical current setting has been selected. Both the FHG and TENS units provide a means of fish immobilization using low electrical current settings, and once an electric glove is removed from the fish, the current is broken, resulting in immediate recovery. Fish held with FHG have been determined to show negligible reflex impairment after the electrical current is terminated. Smith-Root FHG power settings are set to deliver a current of 4 mA, the lowest power setting initially. Higher settings (including 6.3, 10, 16, and 25 mA) can be successively used if required to provide effective immobilization for larger fish. TENS units can be used in place of the Smith-Root FHG, and provide a greater range of power settings. When handling fish, TENS 3000 units are set to a pulse width of 30 µS, at a 150 Hz pulse rate. These settings ensure a constant flow of electric current throughout the procedure. The electric current power settings are manipulated using a continuous dial ranging from 0 mA to 80 mA. TENS units are initially set to deliver a current of 5 mA and adjusted accordingly to provide effective immobilization (as per manufacturer’s guidelines). All equipment and tanks should be placed as close as possible to the holding tank to minimize handling and the amount of time the fish spends out of water. Set up sampling trough and recovery tank. During surgery, fish are typically held in a padded, V-shaped sampling trough with heads submerged in water to allow gill ventilation, but alternative handling locations are possible provided the fish remain in contact with water. Using a net, remove fish from the holding tank. The person wearing the FHGs grasps the fish firmly but gently around the caudal peduncle and posterior to the opercular cover. The TENS unit has two insulated conductive gloves and are also positioned around the caudal peduncle and posterior to the opercular cover. Immobilization will occur immediately when both gloves have made contact with the fish. Test the depth of immobilization by applying slight pressure to the caudal peduncle or tail; when there is no reaction, the procedure may continue. If the fish reacts, increase the current on the FHGs or TENS unit until there is no longer a reaction. Fish are typically held in a padded, V-shaped sampling trough with heads submerged in water to allow gill ventilation, but alternative handling locations are possible provided the fish remain in contact with water. Fish remain in contact with the electric gloves throughout the duration of the procedure. Fish are able to engage in volitional locomotion with negligible behavioural impairments immediately upon release from contact with the electric gloves. Fish should initially placed in a holding tank after contact with the electric gloves to monitor for any impairment, but are ready for release after a brief observational period. The research team will keep fish in holding for as limited a time as possible. Monitor the condition of the fish throughout the process, including prior to, during and post-manipulations/release. Only plan to work with as many fish as can be comfortably handled by the tagging team. Keep in mind that water temperature will affect fish survival and recovery and air and water temperature can affect the abilities of the tagger. If the water is too warm or fish are having difficulty recovering, adjust your techniques (if possible) or cease working with the fish. Only tag the number of fish as required for the study. Captured fish must be maintained in an oxygenated environment at water temperatures that will not cause thermal stress if being retained for site measurement and counting. Accordingly, water in holding tanks must be actively oxygenated and water temperatures monitored. If fish are being sampled for other purposes, they must be appropriately housed or euthanized. The research team will use these procedures to insert tags into live fish (field or laboratory) associated with ecological study: Pre-operative and post-operative care is as critical as the physical surgery procedure. Where possible fish surgery should be completed with constant flow of water over the gills. Water must flow caudal from the entrance of the mouth and exit through the operculum. Scales should not be removed prior to surgery when possible as this can lead to severe tissue necrosis. However, the need to remove scales prior to surgery is species dependent. Fish produce a layer of mucus that is constantly replaced and contains high numbers of bacteria. Incisions must be made through this mucus layer and removal of this layer is not recommended as it may hinder wound healing. Also once fish return to water the maintenance of a sterile site is impossible. Consulting the literature and researchers/vets with experience working on a given species is advisable before embarking on efforts to tag a new species. Intracoelomic implantation of a transmitter generally requires the incision to be made on the ventral side of the fish. A line block of lidocaine (6 mg/kg) must be administered subcutaneously in the area of the incision prior to making an incision. Depending on the species of fish and its anatomy, the incision will either be anterior or posterior to the pelvic girdle, and can be either on the ventral midline along the linea alba or lateral and parallel to this region. When making the incision with a sharp scalpel, it is important to protect the soft tissues and organs inside the body cavity such as the pyloric cecae and the spleen. By making small shallow cuts through the tissue layers during the initial incision the viscera can be protected. A fiber optic or LED white light (such as head lamp), which does not generate heat, can be used to help discern when the peritoneum has been cut. Curved, blunt forceps can be inserted into the body cavity through this small opening, lifting the body wall gently with the forceps to create space above the viscera while the incision is lengthened to the desire size. Care should be taken to not make the incision larger than necessary, but rather a few millimeters wider than the diameter of the transmitter. To insert the tag, gently guide the top end into the abdominal cavity, and then decrease the angle of insertion while continuing to push the tag anteriorly until the entire tag is within the abdominal cavity. Generally, the tag should be repositioned away from the incision site, after closure, by gently stroking the body of the fish. If a radio transmitter is being implanted, use a shielded needle (e.g., 16 gauge, ½ inch needle) to create a separate exit wound for the antenna posterior and off to one side of the posterior end of the incision. Simple interrupted sutures should be used to close abdominal incisions as they sufficiently appose all tissue layers, minimize trauma, and leave less foreign material in fish compared with the vertical mattress patterns. It is important not to use excessive tension when tying the suture as this can cut the tissue or lead to ischemic necrosis. The length of the incision will dictate the number of sutures required to close it. At a minimum, the wound margins of the incision should be touching and the tissue layers aligned to aid in healing. For most freshwater fish applications, PDS II (or equivalent) absorbable monofilament suture material should be used. Vet bond or other tissue adhesives do not promote healing and are this inappropriate for long-term studies. Post-operative care is also an important component of the surgical procedure. Fish should be recovered from anesthesia or electroimmoblisation before being released. Fish are ready for release when they are able to maintain equilibrium and burst away when their tails are grabbed. Ka'a'gee Tu First Nation- Engagement will be continuous through out the project with formal meetings scheduled each spring to plan and go over results. Results will be presented at the annual Dehcho K'ehodi gathering which Ka'agee Tu attends as well as other Dehcho communities. A final report will be produced by the researchers for the community as well as a plain language presentation. This work will also go towards a master thesis. The fieldwork for this study will be conducted from May 6, 2022 to May 20, 2022