Hungary Case Study – Fish Ponds

Ecological impact assessment (EIA) of Hungarian fish ponds


Case study description

BackgroundCommon carp is accounted for the 25% of freshwater fish production in Europe. This species is characteristically reared in semi-extensive earthen ponds. These earthen ponds usually connected to natural watercourses directly or indirectly (via sluices and canals). According to literature data, the biggest environmental issues of these producing systems are the alterations of a nutrient regime of recipient watercourse (eutrophication) and the strong modification of the original fish assemblage structure by facilitating the occurrence of non-indigenous species.

Aims

  • Discover the patterns of the fish fauna- environmental factor- fishpond relations
  • Assess the environmental impacts of different fish ponds
  • Identify the most important environmental and management variables
  • Based on the results: Determine the „best practice” of carp pond management in order to minimize the impacts

 
 
 
Methods

Eleven aquaculture facilities, representing various management practices have been chosen. Fish fauna composition will be studied with electrofishing (protocols used according to WFD) in the inflow and outflow (within 50m, 300m, 500m). Water chemistry (basic parameters (temperature, dissolved O2, conductivity, pH, TSS, NO3-N, NO2-N, NH4-N, PO4-P, chlorophyll-A) would be measured parallelly. Pond/system level management variables would be also interviewed from managers (Chemical usage; Manure/Fertilizer usage and volume (kg/ha); stocking (abundance%; density(kg/ha) spring and autumn); Frequency of harvesting; date of last harvesting; area (ha); depth (m); shoreline length; shoreline vegetation; Feed (quantity/quality);Water supply: gravity/pumping).

Analyses and Expected ResultsTo analyze our expected dataset multivariate analyses (unconstrained ordination) based variable selection (forward selection) and variance partitioning would be used. This approach enables us to identify the “least impacting” management scenario and to develop the “best practice” management offerings

The use of case study data in TAPAS
The main outcomes of the case study research in Hungary will be fed directly in the following work packages and tasks:

  • The collected data will be used in WP5 and WP 7.

The state of the case study research in June 2017
The sampling campaign has been started in May 2017, on progress and will finish in late October 2017. Sample processing is continuous.