Leopard Shark 1, Western Grebe 0

We are always looking for new and better ways to capture oiled wildlife during spill events.  As part of efforts to capture Western Grebes to put satellite tags on them (a subject for a later blog), we were out on rainy, stormy San Francisco Bay  two weekends ago setting out floating nets to try to catch grebes out on the water.  On one day, the Marin Rod and Gun Club let us use their boat launch right next to the Richmond Bridge.

Marin Rod and Gun Club

We had hoped to catch 15 grebes, but due to a lack of grebes and very poor weather we ended up catching one Leopard Shark over two days of trapping.  However, we learned a lot about the skill needed to deploy these nets.  Andre Breault of the Canadian Wildlife Service and Joe Evenson of Washington Department of Fish and Wildlife use the floating nets up in Washington and Canada to catch thousands of diving ducks and grebes for a variety of ecological studies, and they came down to assist. The nets they use are neutrally buoyant nets that float like invisible mist nets from the water surface to 16 feet down in the water column.

Close up of net

When we found groups of grebes (and we did not find many, perhaps because of the very cold weather we had been having) we would drop the nets and then herd the grebes with other boats.  The trick is to get the grebes swimming right up to the net, and then cause the grebes to dive into the water where they get caught by the net.  The great thing about the net is that when the bird gets caught, it is light enough that the bird floats up to the surface of the water where it can be removed.

Pulling in a net

In the Bay, the grebes are fast, the tides strong , and the birds won out this time.  We will try again in the next couple of months.

Best for the holidays.

– Nils

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