Carpe Carp III: Know Your Enemy

Carp, an invasive species of fish, has had a huge negative impact on Malheur NWR.  They compete directly with fish and plant-eating ducks and totally destroy sago pondweed, an important food for ducks.  They cause the water to turn from clear to so turbid, it looks like chocolate milk. The turbidity kills some of the invertebrates that the ducks feed on.  So the refuge is committed to reducing the numbers of carp.

But they don't know how carp move, where they like to congregate, and ways the staff can get the best of the carp. So the first step is to track where carp go in a couple of ponds so the staff can predict where they will be.  If they know this, a professional fisherman may be able to come in and remove them when they are in a big group.

To study carp movement, Linda, the fish biologist, is planing to put  radio tags in 25 carp in Bocca Lake, a fairly large lake on the refuge. She has already tagged five carp.  Today she recruited several staff members, including John, the Law Enforcement officer, who is a great airboat operator, her new technician, Kris, and me.  The plan was to put out gill nets to catch the carp and also to fish for them.  Last year they found that carp LOVE corn marinated in garlic so we were all charged with adding garlic to a can of corn last night. I was out of corn so I marinated black-eyed peas.instead.

This morning dawned cloudy, cold, very windy, and with rain in the forecast. That didn't even put a blip in the packing up and leaving.  However when we got to to lake, we found that Jess, who was supposed to operate the motorboat that Carla, the archeologist, and I were to fish from, found that he couldn't control the boat easily in the wind and didn't want to risk us taking a dip in the frigid waters. So we fished from the bank  instead - and found a nice place out of the wind. Meanwhile John, the airboat operator, Linda and Kris went out to put the gill nets out.  They got them out before 11:00  A.M. and then had to wait until 2:00 P. M. to go back and pull them in. Meanwhile we all tried to fish with corn on our hooks. I found that black-eyed peas won't stay on the hook, so just chummed with them. But no one caught a fish.  I think they were all huddled up in deeper water and not eating.

Finally after we ate our lunches, and sat around looking at our poles and chatting,  it was time to go bring in the nets. John, Kris, and Linda fought their way through big waves to the nets and pulled them in but only got 4 carp of big enough to implant the radio tags in.

I was the official carp holder.  First we had to anesthetize them by putting  a small amount of clove oil in a bin of water and then putting a carp in it.  As soon as it went to sleep, we took it out and added another while we operated on the first one.

The pictures tell the rest of the story. The characters were: Surgeon: Linda, Fish deliver/holder: Marilyn, Fish Recovery: Kris, and data enterer and photographer of the surgery: Karla

Linda showing Kris how to operate the radio antenea

Leaving to pull up the nets

Untangling the fish from the net

Fish in anesthetized in clove solution

Bringing the anesthetized fish to be measured

Holding fish ready for surgery

Figuring where to make the first cut

The slit is finished and she adds a needle to thread the antenna out

Pushing in the radio tag

 

Pulling the antenea out through the  needle

Suturing the fish - took 3 - 4 sutures

All done

Recovery room - Kris had to swish the fish until the effect of the cloves wore off and it could swim - the coldest job

This was a really interesting job.  If we had had sun, little or no wind, and had caught fish on out hooks, it would have been a superior day.  But we managed to have fun anyway.  And now there are 9 fish in Bocca Lake with radio tags.  And I'm invited to go help next time.