Floating mist nets are probably your best bet.

Hi Andrea,

I haven’t experience with common mergansers but when I worked on Trasimeno Lake I remember that my friends captured surface-feeding ducks to be ringed in a great fence placed in low waters. This fence had doors “corral type” and the operators used maize as bait.

For your work, you could think on floating fence, to be transferred and to be anchored in mergansers feeding area.

You could create a trap with a fish farming cage with the insertion on the emerging upper side of net walls (with corral-type doors) and a roof. So you would have a cage with an underwater side used to place bait (live fish) and a surface side to capture the adult birds.

It will be important to consider the possible “stress level” of birds when captured to be marked.

Good luck!

Andrea

We used submerged foot- trap with bamboo pole implants.Its quite successful for all ducks and geese.

Unfortunately we had the experience in trapping females in nests in late incubation stages, or newly hatched chicks in nests, and never trapped other individuals outside nests. Recommendations of colleagues above should be appropriate.

We have successfully dazzled Mergus serrator before. If you can get the birds during their flightless period this works reasonably well as they group together.  Cannon netting can work as well if you can find the haul out sites - we have had mixed success catching Mergus merganser and Mergus serrator - the birds can quickly dive out of the net. 

I have experience to capture scaly-sided mergansers. In breeding season, they usually forage in narrow forest river. I set mist nets across the river, and it works especially at twilight or foggy days. However, pls be very careful to set the net at least one meter above river, and always monitor nearby, to avoid trapped birds drowned.