Fish damage at pump stations

Study Extent

In Flanders (Belgium) polder water levels are maintained with numerous pumping stations.Fish damage caused by two different pumping stations is documented in 2 reports. 1-A research report results on fish mortality after natural downstream fish passage through an Archimedes screw pump station (the “Isabellagemaal” at Boekhoute) are presented. The pump station has three big screws (3,6 m³/sec and 21 revolutions/min) and two smaller ones (1,2 m³/sec and 25 revolutions/min). These five screws pump the excess water from the “Leopoldkanaal” towards the River Westerschelde in The Netherlands. We investigated a large and a small screw pump from 9/30/2009 until 12/09/2009. 2-The longitudinally connected Rivers Avrijevaart and Burggravenstroom are typical examples of a polder water. During and after (heavy) rainfall the excess of water is pumped out of both watercourses into the Ghent-Terneuzen Canal. The pumping station has 7 propeller pumps which have a rotation speed of 8 rotations per second. Total discharge capacity of the station is 8 m³s-1. One-way valves underneath the building prevent the water from flowing back into the polder but also block upstream fish migration. The Research Institute for Nature and Forest investigated the natural downstream fish migration through the pumping station. A 40 m long net was mounted on the outlet of one of the propeller pumps (1,6 m³s-1). Objectives were to find out in what state (dead or alive)fish pass these fast rotating propellers and what kind of injuries they sustain. Moreover we were interested in the timing and magnitude of downstream migrating European eel (Anguilla Anguilla) and their survival rate. Between August and November 2008 we caught 14 species and more than 4.000 fish.

Sampling

[1] Fyke nets installed on the outflow of the pumps collected all pumped fish. Generally, the fyke nets were emptied three times a week. All fish were measured, weighted and scored upon possible damage. Eels were also measured to define their silvering stage.We caught 1922 fish in total in both fyke nets (1024 at the end of the large screw and 898 at the end of the small one). [2] A 40 m long net was mounted on the outlet of one of the propeller pumps (1,6 m³s-1).

Method steps

1. Data recorded during sampling
2. Data imported in Recorder (NBN database)
3. Query created to map data to DwC
4. Data was published to GBIF

Fishes.

1. Rutilus rutilus
   common name: Roach rank: species
2. Blicca bjoerkna
   common name: White bream rank: species
3. Abramis brama
   common name: Bream rank: species
4. Anguilla anguilla
   common name: European eel rank: species
5. Perca fluviatilis
   common name: Perch rank: species
6. Esox lucius
   common name: Pike rank: species

Waterschap Krekenland, Isabellagemaal at Boekhoute, Leopoldkanaal and Isabellakanaal.