Canadian Rivers Institute, University of PEI
Swimming Performance and Movement Patterns of Migratory Fishes Through PEI Fishways
Collectively, our assessments over the last three springs have indicated that the ideal fishway design for PEI is the nature-like (bypass channel) type. This design represents the best compromise between cost and passage efficiency, and is particularly suitable for poorer swimming fishes. Moreover, the fieldwork completed in spring/summer 2016 has demonstrated that a key aspect of constructing fishways – nature-like designs in particular – is to properly locate the fishway entrance. Without doing so, the efficiency of the structure is greatly reduced, potentially negating any remediation measures intended by the construction of the structure. There are some caveats to our assertion, however. In addition to ensuring the location of the fishway is appropriately positioned, the depth of the structure should also be suitable to the size of the fish passing. This became particularly important as water temperatures increased during the transition from spring to summer and water levels concurrently dropped.
The project goals revisited:
- Determine the movement patterns of fish ascending fishways including metrics such as passage attempts, day/night behaviour and passage delay as well as how characteristics of each individual fish (e.g., fish length, sex, species) might relate to those metrics. A total of 324 rainbow smelts were detected in 2016 at Tuddy Mackinnon’s Pond. Smelt passing through the culvert took up to 22.3 hrs, with 98.3% taking less than 1 hr. Of the fish that passed through the culvert, 64.8% (162/250) were attracted to the area in front of the pool-and-weir fishway but they could not ascend. Passage through the bypass channel fishway was not significantly affected by smelt length, sex, or capture date. The majority of smelt entering the bypass channel in 2016 (85.7%) made a single passage attempt, with 77.3% of the 22 fish that successfully ascended needing just a single attempt to do so. The number of passage attempts at the bypass channel in 2016 ranged from 1 to 5. Rainbow smelt were detected at the antenna arrays predominantly at night with the highest frequency of detections for any 1 h period taking place between 0300 and 0400 hours (7.9% in 2014 and 8.1% in 2016). One hundred and fifty-five brook trout were tagged in 2016 and of these fish, 131 (84.5%) were detected at our arrays. Twelve were attracted to and entered the bypass channel (7.7%) with 11 fully ascending the fishway (passage efficiency = 91.7%). Water flowing over the dam attracted 122 brook trout (78.7%) to the area near the pool-and-weir fishway. Entrance efficiency was 95.9% (117) at the pool-and-weir fishway, with a passage rate of 99.1% (116) for the brook trout entering the structure. Passage duration averaged 2.2 hrs and did not vary with trout length. Diel movement patterns indicated most activity took place at night for alewife and brook trout and during the day for white perch.
- Assess modifications made to the bypass channel entrance and river channel below the dam at Tuddy MacKinnon’s Pond for multiple species of anadromous fishes (brook trout, alewife, smelt, and white perch). Attraction and entrance efficiencies for rainbow smelts at the bypass channel were not different before and after modifications. No smelts were observed passing the pool-and-weir fishway in either year, while 29.0% (9) and 31.4% (22) of those that entered the bypass channel successfully ascended the full length of the structure in 2014 and 2016, respectively. Fishway use by alewife and white perch was limited in both 2015 and 2016. In 2016, only 17.6% (38) of tagged alewife were detected in our arrays. Four alewives were attracted (1.8%) to the bypass channel, two entered, but none passed. Thirty-eight alewives were attracted (16.7%) to the pool-and-weir fishway with 12 of those entering (31.6%) the structure, but none passed. Seventeen white perch were tagged, but only one was detected in our array and only in front of the dam and pool-and-weir fishway.