The 2009 season for the Fish and Watershed Program brought a relatively unused fish enumeration technique into Alberta. Arctic Grayling (Thymallus arcticus) is listed in Alberta as a sensitive species, which has many implications for industry and recreation alike. Research for Arctic Grayling has historically concentrated on large rivers and small shallow streams. This has left a gap in mid-sized streams because they are too deep to sample with backpack electrofish and too shallow for a watercraft to float electrofish. This is where night snorkeling may play a role.
In total, six stream reaches were studied. Mark recapture was the method used to estimate the population of the Arctic Grayling. Angling was utilized to capture fish that were marked using fin clips and snorkeling was employed for recapture. Both day and night snorkeling were evaluated in this study. We found that night snorkeling was much more effective. In one reach, 24 Arctic Grayling were angled, three were observed during the day snorkel and 122 were observed during the night snorkel. In another stream no fish were captured while electrofishing, one fish was captured by angling, one fish observed during the day and three fish were observed during the night. We did find that snorkeling was difficult in shallow riffle sections and during the night, these areas were better sampled by wading with a light.
The average underwater visibility in these stained boreal streams was 1.5 metres. We used two snorkelers, however another set of eyes would reduce the number of missed fish. . To improve the confidence of the population estimates anglers should catch more fish in the initial survey – so we may be looking for volunteers if the project continues in the future.
This pilot study established that the research technique of night snorkeling was feasible within mid-sized streams in Alberta’s Foothills and this technique could provide valuable data in regional assessments of Arctic Grayling status. To top it off, the crew had an amazing experience.
Stay tuned! An upcoming eNote will alert you to a report about the pilot study area and the results.