Rapid colonization of Flemish rivers and canals by invasive Ponto-Caspian gobies

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FishBase symposium 5th September 2017, Tervuren

Rapid colonization of Flemish rivers and canals by invasive Ponto-Caspian gobies
Hugo Verreycken
Research Institute for Nature and Forest (INBO), [email protected]
ABSTRACT
Ponto-Caspian gobies (PCG) have invaded most of Europe with the most recent invasion in the western part. Since 2010, tubenose goby Proterorhinus semilunaris, round goby Neogobius melanostomus and bighead goby Ponticola kessleri (since 2012) are spreading fast over de Scheldt and Meuse basins in Belgium. A fourth PCG, the monkey goby N. fluviatilis, was detected in the Albert canal in 2015, but in very low numbers. The invasive populations of these species are closely monitored by the Research Institute for Nature and Forest in order to study their distribution, population density and dynamics and also their impact on native fish species.
Here we present the results of the assessment of the PCG in Flanders (North Belgium) with emphasis on the Border Meuse and the Albert canal.
The Meuse constitutes the border between Flanders and the Netherlands and the main river bed and its tributaries harbour many rheophilic species that are rare or absent in the rest of the Flanders. As the river bottom of the Meuse is constituted of small and big boulders and the banks often are strengthened by rip rap, the river acts as an ideal habitat for benthic native fish species but also provides the benthic, invasive gobies with a perfect surrounding for a rapid invasion. The Meuse was first colonized by the tubenose goby, followed by bighead and round goby in 2013. Especially the latter species has proliferated since 2014. As a result, tubenose goby populations declined rapidly but also most small benthic native fish species seem to have nearly disappeared from the sampled sites. The latest results show a still increasing population of round goby and suggest a high negative ecological impact on native benthic species.
Also the Albert canal contains high densities of round goby. This canal is the main connection between the two largest river systems, Meuse and Scheldt basin, in Flanders. Since this waterway is a busy shipping canal, it was the first in Flanders to become infested with round goby, probably as a consequence of ballast water exchange. Round goby found an ideal habitat in the with gabion fortified banks. Traditional survey methods e.g. electrofishing and fyke nets failed to catch round goby adequately. Therefore an alternative method, i.e. standardized angling, was used to monitor the round goby population. Round goby can easily be caught with a fishing rod and bait so recreational anglers consider round goby as a nuisance species. Our results show a still increasing catch per unit of effort (i.e. number of round gobies caught per angling hour).
Since these PCG are widespread and often abundant in Flemish waterways, eradication or even management actions to reduce numbers seem unrealizable. Therefore, efforts should be focused on limiting the spread, especially into upstream parts of ecologically valuable rivers.
Oorspronkelijke taalEngels
PublicatiestatusGepubliceerd - 5-sep.-2017

Taxonomische lijst

  • grondels (Gobiidae)

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