A pull-type fixed net for measuring the density of tidal flat fish and its application method

Abstract

The invention relates to a lifting-type fixed net used for measuring intertidal fish density, and an application method thereof. The lifting-type fixed net comprises a fixed net and pulley lifting devices. The fixed net comprises a square netting defining a cubic tube with openings on the upper and lower ends. A square frame is arranged on the upper opening of the square netting. A weight stone ring is arranged on the lower opening of the square netting. The fixed net is lifted with the pulley lifting devices. The pulley lifting devices comprise pulleys and diagonal drawing ropes wound on the pulleys. The pulleys are arranged on the tops of moso bamboo poles. One end of each diagonal drawing rope is connected to the square frame, and the other end is a free end passing the pulley. When a high tide reaches, the lifting net is lifted. When the tide ebbed, all catches in the net are collected at a tidal flat, and are brought to analysis in a laboratory. The net and the method provided by the invention are simple, feasible, effort-saving, and understandable. The net and the method are especially suitable for fish measuring under bare flat and salt marsh vegetation habitat types.

Description

technical field [0001] The invention belongs to the technical field of tidal flat fish density measurement, and in particular relates to a lifting type fixed net for measuring tidal flat fish density and a use method thereof. Background technique [0002] Intertidal waters (including light flats and salt marsh vegetation waters) are shallow and are greatly affected by the ebb and flow of tides. Therefore, the composition and quantity distribution of fish in this water area present certain particularities, which are different from those in subtidal waters. There is a big difference in the composition characteristics of fish communities in belts and tidal creeks. At the same time, intertidal waters are also the nursery and refuge places for many estuarine and marine larvae. Studying the structural characteristics and ecological functions of intertidal fish communities is helpful to understand the habitat value of intertidal wetlands. The intertidal zone generally has a very w...

AI Technical Summary

Problems solved by technology

[0003] In estuary waters, such as the Yangtze River estuary or the Yellow River estuary, the bottom of the intertidal zone is mainly muddy or silty, and salt marsh vegetation often grows in the middle and upper parts of the tidal flat, which is necessary for quantitative monitoring of tidal flat fish. brought great difficulties

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