Less effort but equal result: Introducing the daily run-size estimation method for quantifying fish passage in fishways

• DOI: 10.1371/journal.pone.0252183
• Publication Date: 2021-05-26T17:57:30Z
• Authors: Mariana O. Côrtes; Alexandre Peressin; Alexandre L. Godinho
• Keywords: Science; Q; R; Fisheries; Fishes; 04 agricultural and veterinary sciences; Medicine; Animals; 0401 agriculture, forestry, and fisheries; 14. Life underwater; Brazil; Swimming; Research Article

Determining the number of fish that use a fishway is essential to fisheries management but counting all can be impracticable due labor and cost. We present daily run-size estimation (DARSE) method, which uses systematic sampling estimate per species pass through (daily run size, D). The DARSE method makes it possible determine minimum fraction each hour (or hourly samples) day necessary D with known accuracy. apply seven most abundant (other grouped under ‘Others’) recorded in video images taken during 46 days one year at Igarapava Fish Ladder, Brazil. Accuracy estimating was influenced by sampled temporal pattern passage fishway. For more uniform passage, reduced time spent on up 96%, depending accuracy used D. Some these required counts an for hours while other done every 2 or, rarely, 3 hours. aggregated little reduction time.