Floating platforms for sampling fish survey in tidal channels at high and low tides and quantitative assessment method

A method for quantitative assessment of fish in tidal channels at high and low tides, using a floating platform for sampling fish survey in tidal channels at high and low tides, the floating platform comprising a floating platform frame and a survey sampling net;

• wherein the survey sampling net comprises an opening welded by galvanized tubes, and two ends of the opening welded by galvanized tubes are provided with circular bearings, and the survey sampling net and the floating platform frame are connected with galvanized tubes and circular bearings;
• wherein the opening of the survey sampling net rotates, retracts and drops down by a cable;
• a mesh bag is attached to a rear section of the survey sampling net, and a set of stainless steel rings are provided on an inside of the mesh bag, and each stainless steel ring is provided with an inverted whisker made of fishing mesh sheets;
• wherein the floating platform is constructed from a foam float, a galvanized tube frame, and an anticorrosive wooden board, and fixed to a center of the tidal channels by anchors around a perimeter, and the floating platform frame is welded with a set of iron rings;
• wherein a flow meter is provided at the opening of the survey sampling net, a nylon rope is provided on an outer surface of the opening of the survey sampling net, the nylon rope is fixed to the iron ring on the platform frame, and a fishing net is provided on the outer surface of the opening of the survey sampling net welded by galvanized tubes;
• the method comprising:
• S1, constructing the floating platform of 3 m*4 m using the foam float, the galvanized tube frame and the anticorrosive wooden board, and fixing the floating platform to a central position of the tidal channels by the anchors;
• S2, assembling the opening welded by the galvanized tube and a mesh coat into the survey sampling net, connecting the mesh bag at the rear section of the survey sampling net, and installing the flow meter of the opening and related connection parts;
• S3, putting all nets upright on the floating platform before the survey to reduce water flow resistance and interference with aquatic organisms;
• S4, putting down the fishing net at high tide when a depth of high tide reaches more than 1.5 m, pulling up the fishing net to collect fishery products after collection is completed, reading data of the flow meter before and after putting the fishing net in and calculating the tidal flow, and recording read data at the high tide;
• S5, putting down the fishing net at low tide, pulling up the fishing net to collect the fishery products after collection is completed, reading data of the flow meter before and after putting the fishing net in and calculating the tidal flow, and recording read data at the low tide;
• and
• S6, conducting detailed analysis and assessment based on the fishery products and tidal flow data to understand the biological and material transport situation of the tidal channels, assessing an ecological function and health status of the tidal channels, and providing data support and decision-making basis for research and ecological protection;
• wherein the S6 conducting detailed analysis comprises:
• organizing and classifying species and quantity of fishery products and the tide flow data recorded in the high tide and the low tide;
• counting the types and quantities of fishery products, and calculating the frequency of occurrence and quantity distribution index of each fish species;
• analyzing changes in tidal flow, comprising a difference in flow at high and low tide, and a trend of flow over time;
• and
• finding the correlation between fishery products species and numbers and tidal flows to obtain a relationship between biological and material transport in the tidal channels.