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Ice to 2 inches thick already covers the Navesink from Red Bank to Coopers Bridge during the December 13 acoustic survey.


The following image set shows how sub-ice anchors are deployed. We tested the rig from a high pier into very shallow water, essentially a dry run, so that we could see the process  clearly.

 Sub-Ice pipe anchors Steel pipes are 5 ft long and have a float line running up the center (1). Most of the anchor pipe gets pushed into the river bottom, leaving enough sticking out to hold a hydrophone shuttle. A line running from inside the pipe to the surface guides the shuttle into place after the anchor is set .  The line is covered with foam pipe insulation to stiffen it and help it float without a buoy. The stiffening and floatation both prevents the line from wrapping into snarls around the anchor and hydrophone during tidal flow. A buoy could do the same, but could get caught in ice and tear away, loosing the gear.

 1. .

Pipe anchor deployment- Pipes anchors are pushed into a PVC push pipe until they seat against a stopper bolt (2). The anchor line is run up through the push pipe and tied tight at the top. The push pipe is turned vertical and lowered until the anchor pipe hits the bottom (3). Then we push down until the pipe is buried in the mud up to the end of the push pipe (4). A toilet flange on the end of the push pipe lets us feel when we have hit the right depth. The anchor line is untied from the top of the push pipe and the push pipe is retracted (5), leaving the anchor post on the bottom deep under the surface (shown dry in image 6). 

 2. 3. 

4. 5.  


The hydrophone is attached to a 4 inch PVC pipe shuttle. The anchor line is threaded through the shuttle (7), and the shuttle dropped overboard. A tight anchor line guides the shuttle down to set down flush over the pipe anchor (8). A retrieval line runs parallel to the anchor line and is sistered to it near the surface.


Installing pipe anchors on a foggy January day in the Navesink. We extended the push pole to 16 ft for the actual deployment to allow deeper sets.


The first four winter flounder are tagged in the Sandy Hook NMFS lab. Two sterilized plastic coated stainless steel wires from the tag are passed through a neoprene pad (saddle), then through the dorsal fin musculature on the eyed (left) side, then through another pad and nylon washer on the blind side and crimped with a size 1.0 B double sleeve. The ends are tied over the crimp, sealed with super glue and trimmed.

The first three fish are kept for two days of observation and releases, the fourth is moved to a large observation tank to test reception of the signal if the flounder buries itself.


Two ripe males and an egg-swollen ripe female collected by fyke net.



The shallow water moorings are moored near Red Bank with 8 antennas on surface stakes and two on buoys.