Improvement of the method to apprise the fish stock of inland waters
Project code: 9312137800019
Project duration: 18.07.2013-31.12.2014
EFF funding: 62000€

We started the project with a trial of the drag-net in the fishing situation on lake Võrtsjärv. First we had to replace and fix the following items: the rollers of winches, V-belts, rails of the raft and the contacts between the separate parts of the raft. While tuning we also had to rebuild the drag-net. An overview of analogous fishing attempts and results in foreign countries made planning easier. To make field works possible we had to procure, order and buy the trailer suitable for the conveyance of the rafts for drag-netting. The bathymetric charts for lakes chosen for sample fishing were looked in the archive. We compiled the logistic schedule so that three fishing periods were determined for drag-, gill- and fyke-netting into three periods – vernal, summery and autumnal. To reach the lake we had to make trespass agreements with lakeside landowners – some of which failed later on. Searching data basis for and later on reading the scientific papers covering the themes of the given project. In field, lakes were surveyed for fish with different gear, massive analysis of fish according to the drag-netting effort was carried out, material for lab studies was gathered. Previously chosen sampling areas needed adjustments as in some of the chosen areas for drag-netting was obstructed by stones or/and bottom dropped trees. We found several habitats of species previously not known as like on lake Saadjärv the juveniles of whitefish were found to feed vernally around the area called Luigelaht. After key-boarding gathered data an overview of catches were presented and discussed internationally on the conference in Bohemian University (the Czech Republic). Statistical analysis and summarization of data allowed to make the following conclusions: all used fishing gear were selective with drag-net overestimated the share of roach and bream whereas underestimated the share of white bream. The species composition in drag-net responded the most to that in Nordic type of gill nets. The coefficients to transform CPUE values from one gear to the other appeared to be seasonal. The distribution of fished species in survived lakes was presented as a BA thesis, whereas the appraisal of fish assemblages based on data gathered with drag-netting was presented as a MA thesis. Finally we had to conclude that at low water level drag-netting with our gear might be impossible on lakes without the slip.