Articles by Florian

Yesterday we recaptured the 18th of 19 eels we tagged and released upstream of the trap in Skärhultaån one month ago (22.08.2011). Watch out for missing No. 15, weight: 885 g, length: 785 mm, 1 orange mark at the dorsal fin. If he gonna be caught, we can call the catchability of the trap 100 %!

Additional, we marked two more groups with fancy green marks on there fins and released them at the same spots as we did last time. 5 dudes 500 m upstream of the trap and 5 dudes about 7 km upstream. One eel from the farther place in Kärnebygd allready returned last night (7 km!). Now, we are very curious if we can keep the good catchability with the new marking…

That beautiful Anguilla lady weights 2.63 kg and arrived at 05:13 am this morning.

Yesterday, they started to spill water at the dam in Ätrafors. At 19.00 the hatch was opened 2,4 m.

After several heavy rains during the last two days 19 eels entered the trap in Skärhultaån during the night. Nine days ago we tagged 13 eels with two different colour marks and released them at two different localtions upstream of the trap. The first group was released 0,5 km upstream, the second about 7 km. Surprisingly, we recaptured 3 eels last night but just one was from the nearby location. For a better understanding and deeper insights of the migration activity, we will tag and release more eels from today’s catches.

About two weeks ago, Eric and Flo from the University of Potsdam set up an Infrared-Video-Setup inside a wolf trap. The trap is located in a little creek called Skärhultaån, which drains several lakes into Högvasån, a tributary of the river Ätran.

The installation enables the exact timing of the arriving eels in the trap.

Until today, we got 30 eels on digital tape.

As Jonas allready mentioned earlier this week, the traps in Ätrafors seem to beat the other traps on the home stretch! During the last five days we caught almost 3 times the amount of the 5 weeks before.

But the questions remains. Which environmental factors trigger the eel to move downstream? Take a look at the following picture from early thursday. That’s what we like!

eel catch of two nights

People will most likely complain about the ‘nasty weather’ that reached south western Sweden by the beginning of this week. Eels will NOT!

They actually seem to like these rainy weather conditions for their long journey towards their spawning grounds in the Sargasso Sea located in the North Atlantic Ocean. After 8 days without any signs of migration activity upstream the power plant in Ätrafors we finally caught two eels during the last night! These both are number 21 and 22 since I started my survey during the last third of september. Compared to the other traps we run in the Ätran catchment that is just a little contibution to the sum of the Eel-O-Meter (check below).

BUT: during the last weeks/days we had been modifying the cages several times after we recognized that they seem to be capable to escape from the cages. These two catches in combination with some experiments we applied during the last days, finally show a satisfying result of the invested effort we spend on the modification.

I guess, now we are finally well prepared for the upcoming (hopefully…) migration peak that presumably will be accompanied by low pressure and rainy weather conditions.