Investigation of Fish Swimming Performance in Ecological Channel by Video Techniques
Date Issued
2009
Date
2009
Author(s)
Yu, Ching-Hui
Abstract
This study using bi-camera method and simple mathematical operation as a non-invasive monitoring method to develop a XYZ-coordinates to calculate the fish length and fish swimming speed. In the field, the experiment used bi-camera method to monitor different ecological engineering channel sections in Chuan-Long channel in Miaoli County, to recognize the fish species and calculate the fish flux (fish/m3‧sec). The fish flux could compare with different sites with different visibility. The fish flux index was affected by different factors such as habitats and different filming time. By using Bayesian finite mixture distribution as the method and the fish flux index as weight values, the experiment estimated the optimum-Froude number curves in different species in order to find the intersection points. The results showed that the Gambusia affinis affinis predominated over other species when the Froude number was 0－0.01. The Acrossocheilus paradoxus predominated over other species when the Froude number was 0.01－0.20. The Gambusia affinis affinis predominated over other species when the Froude number was 0.20－0.31. The Candidia barbata predominated over other species when the Froude number was higher than 0.31. In addition, when the Froude number exceeded 0.58, the appearing probability of Candidia barbata multiplied by its weighted was less than 1%. The fish maturity affected the performances in different Froude number. The coefficients of variance of fish flux were smaller than 1 in the study sites which were judgment artificially to be habitats by behavior of fishes. That was to say, when the standard deviations were smaller than means of fish flux, the sites might more likely be fish habitats but corridors. In the laboratory, the lengths and swimming speeds of Candidia barbata and Oreochromis niloticus niloticus were estimated by bi-camera method in the modeling channel. The maximum error was 9.47%(1.23 cm), and the minimum error was 4.19%(0.18cm). The error occurs not only in turbidity and brightness, but also in the curvature of the fish body and the curvature of the fish tail. Moreover, the accuracy was affected whether the fish was parallel with the bi-camera or not. The laboratory experiment determined the tail-beat frequency in different velocities to estimate the maximum adapting Froude number for two fish species when they were in the field. The result showed that the small fish needed high tail-beat frequency to make the body in a stable situation. In addition, Candidia barbata was more suitable for the fast flow than Oreochromis niloticus niloticus. The laboratory experiment measured the critical swimming speed of two fish species by Increased Velocity Tests. The critical swimming speeds of Candidia barbata were 0.39m/s(total length=5.3cm)－0.74 m/s(total length=14.7cm), and the critical swimming speeds of Oreochromis niloticus niloticus were 0.30m/s(total length=8.3cm)－0.46 m/s(total length=13.8cm). This result can be designing parameters for field fish restoration.
Subjects
Candidia barbata
Acrossocheilus paradoxus
Gambusia affinis affinis
Oreochromis niloticus niloticus
ecological engineering
video monitor
bi-camera
tail-beat frequency
critical swimming speed
Type
thesis
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