How do environmental factors affect the yield of European eel (Anguilla anguilla) in a restocked population?

• Published in: Fisheries Research
• Main Authors: Bernotas, Priit, Öglü, Burak, Nõges, Peeter
• Other Authors: Chair of Hydrobiology and Fishery. Institute of Agricultural and Environmental Sciences
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2020
• Subjects: eel; fisheries; articles; Anguilla anguilla; European eel
• Online Access: http://hdl.handle.net/10492/7966; https://doi.org/10.1016/j.fishres.2020.105649

Restocking of European eel (Anguilla anguilla) is a widespread practice throughout Europe. Conditions during restocking activities and mortality related to restocking practices have been discussed, however, factors affecting these restocked populations afterwards are mostly not considered. In this study we used a machine learning method followed by generalized linear model to analyze long time eel restocking, commercial fishery and environmental data from Lake Võrtsjärv, Estonia, to detect whether significant relationships exist within these data. It was found that environmental parameters can have an effect on the commercial eel yield both retrospectively and during the particular fishing year. Considering that 7-year old eel was the most common age group in commercial catch, we introduced a 7-year gap between eel restocking and yield to study the most important abiotic and biotic factors during the first year of eel restocking that have an effect on the yield. According to our results, cyanobacterial biomass and summer water temperature during the year of restocking had the strongest negative impact on the yield 7 years after, while the number of restocked individuals and copepod biomass had a positive effect. During particular fishing year, however, the yield was most notably positively affected by total phosphorous concentration, number of individuals restocked 7 years before and metazooplankton biomass in the lake. This research was funded by Estonian Environmental Investment Centre projectT180209PKKH, Estonia-Russia Cross Border Cooperation Programme 2014-2020 project ER80 “Restocking of European eel as a measure of recovery of endangered species and preservation of natural diversity “, Estonian Research Council Grant PRG709 and institutional research funding IUT 21-2 of the Estonian Ministry of Education and Research. This research was funded by Estonian Environmental Investment Centre projectT180209PKKH, Estonia-Russia Cross Border Cooperation Programme 2014-2020 project ER80 “Restocking of European ...