The Potential Use of Remote Underwater Video (RUV) to Evaluate Small-Bodied Fish Assemblages

• Published in: Hydrobiology
• Main Authors: John B. Tweedie, Jaclyn M.H. Cockburn, Paul V. Villard
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2023
• Subjects: fish habitat; fish length estimates; fish survey; juvenile Atlantic salmon; MaxN; passive observations; Ecology; QH540-549.5; Chemical technology; TP1-1185; Atlantic salmon
• Online Access: https://doi.org/10.3390/hydrobiology2030034; https://doaj.org/article/9d033cf2657d491ab18ef36b3b5b7b3f

Successful aquatic ecosystem conversation strategies depend on high-quality data from monitoring studies and improved habitat requirement knowledge. Remote Underwater Video (RUV) is a non-extractive alternative to capture-based techniques for studying and monitoring fish and is increasingly used in smaller channels. This study uses field observations made with waterproof Sony HDR-AS100V action cameras positioned in stream channels to determine species and population during various flow conditions across three sites within the Credit River Watershed, Ontario, Canada. Six fish species were identified, and individual fish lengths were estimated using the inverse square law to proportionally adjust size scales to fish positions relative to the camera. Successful identification and measurements were limited by turbidity, with camera placements in >6 NTU conditions (18% of all placements) resulting in at least one fish observed in the frame. With over 24 h of video recordings with 94 individual video clips, the optimal filming duration was determined to be 20–25 min. RUV surveys provide managers with useful monitoring data regarding fish present in an environment in a cost-effective and efficient manner. Additionally, as the method is largely non-invasive, RUV surveys are especially useful for studying fish behaviour, sensitive or endangered species, and working in difficult-to-access channels (e.g., shallow, faster flow).