Gillnet catches evaluation

Based on experiments carried out in two Czech reservoir in 2008, we developed a new approach for evaluating gillnet catches. A model of a gillnet catch was built to differentiate the effects of gillnet saturation, fish activity and fish escapement from the gillnet catch. We also observed the effects of soak time (2, 5, 8, 11 and 13 h) and sampling period (August vs. September) on the catch. Our results show that saturation and fish escapement from gillnets are important events occurring during each use, thus violating the assumption of a linear relationship between gillnet catch and fish density. We created a conversion table and a slide rule, from which the catchable biomass rates can be determined. We also developed a method for the conversion of catches based on different soak times. Our findings help to better understand the processes underlying gillnet catches and improve the interpretability and reliability of this method in comparing different gears used and assessing fish communities in general.

Prchalová, M., Peterka, J., Čech, M., Kubečka, J., 2013. A simple proof of gillnet saturation. Boreal Environment Research 18, 303-308.

Prchalová, M., Mrkvička, T., Peterka, J., Čech, M., Berec, L., Kubečka, J., 2011. A model of gillnet catch in relation to the catchable biomass, saturation and soak time. Fisheries Research 107, 201-209.

Prchalová, M., Mrkvička, T., Kubečka, J., Peterka, J., Čech, M., Muška, M., Kratochvíl, M., Vašek, M., 2010. Fish activity as determined by gillnet catch: A comparison of two reservoirs of different turbidity. Fisheries Research 102, 291-296.