New fish detectors in the San Juans

Thanks to a calm weather window and the on-going support of collaborators at the University of Washington and NOAA/NWFSC, we were able to re-deploy two fish tag detectors along the west side of San Juan Island in the first days of 2010. We plan to re-deploy a third in the first quarter of 2010. Stay tuned for a separate post summarizing what fish were detected in the last year or so. In the interim, here are some notes and photos from the field work.

Saturday 1/2/10:

During a hydrophone maintenance dive, Jason Wood and I deployed a new Vemco fish tag receiver (VR2W SN#100905) at Lime Kiln lighthouse. We supported the receiver on doubled crab pot line with a salvaged WDFW float (#3398) and anchored it with about 10 liters of concrete in a paint bucket with rebar/PVC legs. A length of chain embedded in the concrete served as an attachment point for both the receiver mooring (clipped on with a taped SS carabiner) and a tether which was tied to the first hydrophone stand.

The Lime Kiln mooring location is about 30m west of the iron bar near the high tide mark adjacent to the SW corner of the lighthouse. The mooring anchor depth is about 10m.

The highlight of the dive was Jason finding the old VR2W (SN#100914). After we had been led astray by an old yellow line, I was pretty sure we were in the wrong spot and wouldn’t have enough air to search for the old mooring. Yet we had to be close because we had encountered one of the old hydrophone stands whose pair should have been within about 10m. I was thinking about whether the old hydrophone stand might have been moved by the pesky Lime Kiln currents when Jason waved in front of my face. I looked up to see him smiling around his mouthpiece, the algae-encrusted old mooring in his grasp. It was a cinch to raise it with the lift bag and the exfoliated kelp hardly slowed our return to shore.

The VR2W looked great and the red light was confirmed still flashing once uncovered at the lighthouse picnic tables. The float was pretty overgrown with algae and the indelible ink was no longer legible.

Orcasound mooring ready to deploy

Orcasound mooring ready to deploy

Sunday 1/3/10:

While the leaded line tethering the Orcasound VR2W to shore was intact as recently as NN months ago, when we looked for it late last night we found only a short section still attached to the intertidal eyebolt. Luckily the other end was found only a few meters away, pinned under a boulder by 10 cm of gravel. The remainder was entangled in nearshore subtidal rocks, but I managed to tease it out by wading around. I was able to wade to where it was attached to a braided nylon line. There I attached a crab pot float and then re-secured the leaded line to shore.

This morning, Liam helped Val and I pick up the float and back away from shore while taking up the nylon line. The mooring came up fine (though a thicker line for that concrete weight would be easier on the hands) and the red light on the VR2W (SN#100913) was still flashing!

After laying out the new hydrophones (to ensure we didn’t overlay the new Vemco tether), Jason paid out some extra slack in the leaded line. I reattached the nylon line to the leaded line and we drew this longer line tight above the water and maneuvered Cat’s Cradle until we had a clear path straight offshore through the kelp. I attached the new VR2W (Serial Number 100912 moored on the line/float from Lime Kiln recovered yesterday) to the SS hoop in the concrete mooring weight, lowered away, and Liam helped me slip the line. It was pretty slick and fast. It should be interesting to see how the leaded line fares this next round.

The Orcasound mooring location is about 30m offshore of the lowest eyebolt (latitude = 48.55823212, longitude = -123.1737158; UTM y = 5378363, UTM x = 487182). The mooring anchor depth is about 7.7 meters below mean zero tide level.

Here is a spreadsheet that lists all Beam Reach deployments of Vemco receivers:

1 Comment

  1. scott

    April 4th, 2010 at 23:39

    2/4/10 update: Orcasound leaded line is found severed about 3′ from where it was tied to the hydrophone cable protectors. Perhaps it was too taut? Will need to snorkel wade for loose end as it was not immediately visible from shore at low tide.

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