Saturday, February 16, 2019

Boat electrofishing the Evros River: Summer 2018




The Evros
Sampling in September 2018

The Evros, Maritsa, Meriç...In Greece it is a shared river. It has about ten major tributaries entering the main stem from Greek territory. Shared with Turkey and Bulgaria. It is my favorite river.

We have been doing a lot of work here because we love big rivers, and this is perhaps the last "sturgeon river" in the Med and one of the richest in terms of a full sweep of biodiversity - in the Greek part, from its upland tributaries to the Delta.

I'm posting snap shots from our September HCMR visit. Water Framework Directive boat-fishing in the river at four sites (see our map below - near the end of the pics). And many thanks to the Hellenic Army that helped us in this peaceful endeaver.



The Evros is just full of fish! You definately need to nets here...


Sometimes they don't fit in the net: European wells (Silurus glanis).

One of the most interesting predatory fishes in the Evros: Asp (Leuciscus aspius).
Common Bream (Abramis brama)- not at all common in Greek river waters.

The Pikepearch (Sander lucioperca), another predatory species - this is its fry! 

Prussian carp (Carassius gibelio) - an alien from the orient that has led to the extirpation of its wild native cousin, the Crussian Carp - now a mystery fish for Greece (and probably extinct). 
Evros_md (see map below). First site on the Evros across from the Turkish border, south of Edirne/Adrianoupolis. 

Evros_up is across from the Bulgarian border. Here you can easily stray into uncharted waters if you are not careful - I think we officially visited Bulgaria on this survey. 

Erythro_dw is near the town of Didymoteicho. Water abstraction and pollution creates this kind of situation: a very interesting site for bioassessment (only 13 spp here). 

Erythro_dw and the common water chestnut (Trapa natans).

Erythro_dw: negotiating with the trees with military help, before we can dump the boat in the river.

European rudd (Scardinius erythophthalmus).

Top-mouth Gudgeon (Pseudorasbora parva), one of the most threatening aind notorius invasive aliens species in Europe.

Getting boats ready. Ours is a german-made skiff (5 m.). 

Me with the fishermen: Kostas and Alexandros!

Carp (Cyprinus carpio) are known to be native to the Evros.

Yours, Kostas and Vassilis. The tiny islet on the left belongs to Turkey, we think...(judging by Google maps...so we did'nt go near it...).

Some kind of huge water snail...abundant in the river, often on the artificial groynes.

One of my favorite fishes in the Evros - a Ponto-Caspian goby that is Native to the river, the tube-nosed goby (Proterorhinus semilunaris). It is abundant. 

The Pontian monkey goby (Neogobius fluviatilis) discovered by our team in 2011 and now after so many years caught again at two sites! This now-to-be sure alien/translocated species is surviving well in the area - but it is not easy to catch by boat-based electrofishing. 


And a new discovery for Greece and the Evros basin, The racer goby (Babka gymnotrachelus). This to our knowledge the first find of this Ponto-Caspian species in the Aegean drainage basins. A new alien species for Greece! We found them both at Evros_up and Evros_md and they should be searched carefully througout the basin.  


Our four sites on the Evros river (in Red). Intenational borderlines are approximate and copied from a widely circulated internet map - we appologise if they are not entirely accurate. The issue of borders is still very sensitive in this area (design by Alexandros Ntakis)



In the Evros we stay at the village of Dadia, inside the National Park. Yes a chance for us to take an early morning birding walk...