Category Archives: RFID (PIT) telemetry

Never place solar panels directly below a railroad track.

Because when LIRR replaces railroad ties they add new gravel and push the old gravel off the tracks right onto…

Seven of eight panels have extensive cracks. Somehow they still work. I taped the surface with clear packing tape to decrease water damage.

Day 2 of Operation Wild Brook Trout

The plan yesterday was to test the swimming performance of the 4 wild brook trout we caught electrofishing. The reason we want to do this is based on the results we are getting from our radiotelemetry studies on hatchery trout released into Shu Swamp. We see a lot of downstream movement right after release. We believe that one factor that may influence  movement patterns of hatchery trout released  is that they are not in top  physical condition. We notice a lot of fin damage due to the high density conditions in the hatchery.


Hatchery trout showing damage to the caudal fin, oen pectroal fin, and a deformed opercular plate.

Furthermore hatchery fish may not get all that much exercise since the flow rates in the hatchery are much lower than they are in a stream. To test this we determine the water speed necessary to cause swimming fatigue (called critical swim velocity). In the lab this is done by placing the fish in a special swim tank similar to an Endless Pool” for people. The fish swim upstream against the flow and the flow can be gradually increased until fatigue is observed. This video, using a juvenile brook trout, shows what should happen. Fatigue occurs when the fish rests its tail against the downstream grid and stops swimming.

Unfortunately when we tried to determine swim performance in the wild trout, they would not cooperate. They just rested against the downstream grid even at very low speeds. We tried a number of approaches to get them to swim but to no avail. The fish we are using are pretty big – 8 to 10″. On the other hand there has been no problem testing swim performance in smaller 5-6″ fish. For now it’s back to the drawing board.

After giving up for now on swim performance tests, we moved on to tagging. In short order Brian had radiotagged the 4 fish and they were groggily recovering in their temporary holding tanks. Each fish received a PIT tag (if it didn’t have one already) and a radiotag. In the figure on the right you can see the incision in the abdominal cavity where the tag is implanted. The antenna leaves the body through a small puncture above 2 inches posterior to the incision. The trout will be released today. These tags should last about 160-180 days. They emit a individually coded radio pulse once every 20 sec. To extend the battery life we have the tag active for 12 hours during daylight.

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You can find more about the tagging procedure at the Tracking Trout link.

Day 1 of Operation Wild Brook Trout

Over the next three days, we are catching, radio-tagging and releasing wild brook trout living in Shu Swamp. The plan is to compare their movements and habitat preferences to the hatchery-reared brook trout. The tags we are using can last 5 – 6 months so we may even see evidence of spawning if we are really lucky. Over the summer we hope to tag and release 10 wild trout. We just received our first batch of 5 tags and today we set out to catch 5 wild trout to take back to the Hofstra Animal Lab for a short stay: swim performance tests, tagging and then release, all within the next 48 hours. Sounds like a fun weekend at the health spa doesn’t it?

Maryanne, Brian, and I met up with Steve DeSimone, CSHFH director and operator of the backpack electrofisher you see here.

We immediately startied catching fish. The problem was they were the hatchery fish we released last month. We knew because we checked them with our portable PIT-tag reader which allowed us to identify each individual. All in all we caught and released six of the 28 we had released. Three of these had been detected before at the PIT-tag antenna downstream at the railroad bridge entering Beaver Lake, and one had been detected at the spillway antenna a mile away just 5 days ago!

Fortunately things started to pick up. All in all we managed to catch 4 wild trout, one short of our goal, before we ran out of stream to fish (we reached Frost Mill Road Dam). Three  of the trout had PIT-tags attached at the previous electrofishing event back in early March and one was newbie.

Along the way we also caught some other critters including some spiny-cheeked crayfish:

And a few YOY brook trout including this beauty (be sure to compare its size to the one shown at the March survey link.

YOYAs usual there were some beautiful wildflowers in bloom. Anybody know what this is?

We lso had a surprise visit from about 30 students from Pasadena Elementary School in Plainview who were there to release the fingerlings they had raised through the TITC program. They got to see the brook trout we had caught as well as the crayfish featured above. The adults we had caught might very well have had their origin a few years ago in a Long Island TITC classroom maybe even their own! I think they were really excited to think that maybe their “babies” might one day reach adulthood in its native habitat.  As part of the TITC experience, participating classrooms visit CSHFH in November to learn about brook trout and see the egg fertilization process. Their visit was featured on Long Island News .

The four “keepers” were transported in coolers and now reside in the animal facility at Hofstra. Here is one that is about 10″ and a 1/2 pound:

Wild trout back at lab

Tomorrow they all go for a swim and a quick surgical procedure. Stay tuned!

Latest Electrofishing Survey at Shu Swamp

Steve operating the electrofishing equipment

Steve operating the electrofishing equipment

On Tuesday, March 11, we conducted an electrofishing survey of Beaver Brook. Steve DeSimone of CSHFH operated the backpacker, Heidi O’Riordan and Bob O’Connell of NYSDEC collected data, Maryanne Grey, Brian Bartlett (my Hofstra U grad students), and John Fischer (LITU) took on the netting responsibilities, while I helped with PIT-tagging captured brook trout.

Our biggest find was the collection of two YOY brook trout, each about 2 cm length. These guys were probably about 3 weeks old. Last year we didn’t detect brook trout during the electrofishing survey which occurred the first week of March. Our first observation of YOY last year was 3/11/2013 so that’s pretty close to the same time as this year. At any rate YOY have become a pretty regular happening at Shu Swamp.

Our first Young of the Year!

Our first Young of the Year!

We also caught 18 one year or older trout (last year we caught 19). For the first time we PIT-tagged wild trout before release. Now we will be able to see if there are any differences in their movements downstream. We also mapped the position of all captures. The online map will be updated to include these positions.

A yearling brook trout captured in our survey.

A yearling brook trout captured in our survey.

None of these fish had PIT-tagged. This was the same result we got last year. The 230+ hatchery fish we have PIT-tagged and released thus far have simply vanished!

Heat of swamp cabbage melted the snow in its vicinity.

Heat of swamp cabbage melted the snow in its vicinity.

Short Summary of PIT-Tagged Brook Trout Movements

Over the past two years we have PIT-tagged and released over 200 brook trout into Beaver Brook in the Shu Swamp Sanctuary. There are two detection antennas: one at the entrance of the brook into Beaver Lake (“SS”) and the other at the spillway at the other end of the lake (“BL”). The spillway empties into the estuarine Mill Neck Creek. The distance between the two antennas is about 1 km. You can learn more about the release sites and antenna positions along with a cool map through this link: PIT-Tagging Data.

Here is a summary graph of detections at the two sites broken down by season of release. (We don’t have winter since there are no winter releases or detections).

detection summary


A lot of fish make it downstream to the SS antenna particularly in the spring. A much smaller number make it to the Beaver Lake antenna. In the summer only one trout was detected there likely because of lethally-high temperatures.

Here is breakdown of detections by days following release.

Detection Time

The vast majority of detections occur right after release. It looks like our hatchery fish are on the move right after release. I suspect this behavior is not typical of a wild trout acclimated to its natural environment.

This study was initiated to explore the feasibility of providing access to saltwater habitats for sea run brook trout. As a first step we wanted to see if trout in Shu Swamp could reach the Beaver Lake spillway using hatchery trout as a proxy for wild trout. These results show that they can. However there is no evidence that the results we observe are “sea run” in behavior.  It is known that sea run trout enter estuaries in early winter and return to streams in the early spring. We have never observed any detections at the BL antenna in the winter.

Winter at Beaver Lake

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Winter is almost over and we are getting ready for a new season of tagging and tracking. We kept the Beaver Lake spillway antenna going through the winter largely running on its solar panel (which recharged marine batteries so it could run through the night). There hasn’t been a detection since early November. These are the same results we got last winter – no detections in the winter. These are some pictures I took in late January after one of our many snowfalls.  As you can see from the slideshow, snow and solar panels are not a good combination. The lake has been frozen since mid January and still remains so.  Lots of geese collected below the spillway as this one of the few spots that wasn’t frozen. In the midst of that crowd are some orange-collared geese from Canada. The same Canucks were here last winter too.



PIT-Tag Antennae Go Solar

sola--panelCarrying 120 pounds of batteries once a week back and forth to our two antenna stations over the past year and a half has been tiresome. Thanks to a generous grant from the Norcross Wildlife Foundation we are able to install solar panels to keep our batteries charged. The photo shows the installation of the panels at the Shu Swamp Railroad antenna supervised by master electrician Rory Metas. The panels also help increase the likelihood that we get 100% coverage (right now we are closer to 90-95% as sometimes the batteries run down before we get a chance to change them). On Saturday we hope to have the solar panels installed at the Beaver Lake Dam station..

PIT-Tag Update

I have just completed an update of the PIT-tag releases thus far. You can download and see the results here: PIT-tagged trout data.

We have released 174 PIT-tagged trout since last summer. 65 of these have been detected at the Shu Swamp RR antenna and 10 at the Beaver Lake dam antenna. It looks like there is more dispersal when temperatures are cooler. In fact none of the 10 detected at the dam antenna were detected in summer months. So far there is no evidence of any kind of “migratory anadromous” movement as most of what we observe are detections soon after release.

We plan on releasing another 50 or 60 trout to complete the study.


More PIT-tagged and Radio-tagged Trout Released

Last Friday we released 34 PIT-tagged 8-9″ brookies into Beaver Brook just upstream of the concrete bridge. Three of them were tagged with the three remaining large radiotags donated by LITU. I was helped by my two graduate students, Maryanne and Brian, as well as two of the Commack High School crew, Eric and Alinur.

The two trout  that were released April 10 are still alive and kicking. One has remained in the same spot well upstream since April 25 while the other is still in the same general area in the lake sincei it entered the lake April 20 despite the fact that surface water temperatures have reached 29 C (84 F). While I couldn’t get a visual confirmation on this trout signal strength was changing when pointing the antenna at fixed spot indicating it was moving.

I checked the whereabouts of the newly released radiotagged fish yesterday and was able to locate all three. One was at the release site, another was about 25 yards upstream, and the third was at the mouth of Beaver Brook where it enters the lake. Surface temperatures in all three places were around 21 C (70 F).