Hi all,
Unfortunately for us we still have not had a single tag return since Sept. 2012, but fortunately for you those winter flounder are still out there and there is a $200 reward waiting for every fisher that brings an archival tag back to us. In addition, it is fishing season AND in breaking news, the fishing season has been extended! It is now open from Mar. 1st to Dec. 31st! If you would like to read an article about the extension you can find one here.
Have you ever wondered what the water temperature was like at the bottom of the ocean? Recently we were wondering this same question. If winter flounder move into estuaries in the late fall to spawn and out of the estuaries in the spring, using temperature as a trigger, would an offshore resident population feel this temperature change? What would be their cue when it came time to spawn? In the deep water, greater than 100m light is greatly diminished so they would not be able to tell if there was a change in season.
Here is a video made with model data from the Regional Ocean Modeling System (ROMS) based out of Rutgers. Currently this is made with model data that are a few degrees warmer at the bottom than in actuality but you still get the idea…The red box on the movie is where we released our tagged winter flounder
(Sorry this was written in January but not posted…)
I hope everyone was able to pull through after the storm, and hopefully everything is starting to get back to normal again.
While the storm caused horrible damage, a lot can be learned from such a tremendous force. Rutgers University had an autonomous under water vehicle called a glider out during Sandy to look at how storms affect the ocean temperatures and sedimentation, in an effort to enhance models for future predictions of storms and to understand how they effect the ocean. Two graduate students, Travis Miles and Greg Seroka, are tackling this data goldmine… you can read more about their daring mission here
My curiosity however is what do the fish do when a storm comes through? Fishermen say that the fish move offshore when a storm comes. Since our tags were out during the storm, once we get them back we will be able to look into these questions like what environmental parameters might trigger the fish to move offshore? How soon before the storm do they leave? How soon after the storm leaves do they come back?
Additionally this week we pulled all of our hydrophones out of the water since the batteries in both the hydrophones and the acoustic tags in the fish are dead. We had one minor set back when we realized the rope for the hydrophone in Point Pleasant had frayed and the hydrophone was no longer attached to the dock. First I tried to swim and search for the hydrophone with no luck. Next my advisor Motz tried, and since he used to be a free diver he was able to find it within a minute! Surprisingly, we had NO tagged fish swim into the estuaries via Shark River, Manasquan River, or the Navesink River. This is one of those cases though that no data is still good data, because our hypothesis is that the fish we tagged are part of a resident population that does not come into the estuary to spawn. Since they didn’t come in this could be the case! However this is not a method that can give us a definitive answer because those fish could’ve died, been eaten, or swam to another estuary further away. We’ll just need to keep looking for our archival tags and hope someone finds one soon!
To find the acoustic tags we’re using three different methods. One is a passive method to see if the flounder are coming into the estuary, and the other two are active methods searching for the flounder out in the ocean.
1) Passive Hydrophones placed at the entrances of the Manasquan River, Shark River, and Navesink River.
We’ve placed these hydrophones at narrow points in the rivers where the acoustic signal can stretch the whole distance across the river. This way if a winter flounder decides to come into these estuary areas, if they pass through that section of the river then the hydrophone will pick up the tag signal. Motz likes to describe them as working like an EZ-pass would with your car, if you drive through the array then the sensor picks up your tag. So much like we have these EZ-pass arrays on the major roads we’ve put hydrophones at the major rivers to track fish passage.
2) Actively searching for tags by towing hydrophones off the stern of a boat.
We’ve been searching an expanded area of where we deployed the tagged fish to see where they have moved over the last few weeks. The fish have dispersed outward from the drop point in all directions. Finding them out on the ocean shelf has already turned troublesome since the area has expanded and we can only cover so much ground. We tie a cannonball weight to the end of the load bearing rope coupled to the cable so that the hydrophone sinks trailing behind the boat. The rope gets tied to the boat, and then we just sit and wait for the hydrophones to pick up a tag. We drive the boat in circles, loops, or zip-zags about 500 meters or a little over a quarter of a mile apart to optimize how far the hydrophone can hear and to triangulate a position by picking the fish up from different angles.
Ken lower the cable in the water
Motz and Mike lower the hydrophone cable into the water
3) Searching for tags with a hydrophone attached to the nose section of an autonomous underwater vehicle.
Searching with the REMUS (Hydroid’s Remote Environmental Monitoring Units) and the towed hydrophones behind the boat expands our search area. This way the vehicle can search one area while we search another. Additionally the REMUS can fly a certain distance off of the sea floor which can detect the tags at a closer distance vertically than a boat on the surface. This can come in handy when there might be a thermocline (the water is stratified by temperature) which might disrupt the acoustic signal from communicating between tag and hydrophone, or if the winter flounder is buried in the mud on the sea floor, being closer to the tag might have an advantage over detecting from the sea surface.
The hydrophone is on the nose cone and protected by a cage in case we crash into something
REMUS in the water
Expanding on the use of tags, the REMUS has a radio tag attached to the top of it so that we can hear when it comes to the surface. This comes in handy if its been at the surface for too long then we can track it down with its GPS point, but in case of drift we can find it with a radio antennae.
The radio tag on top of the REMUS
Rose searches for REMUS with binoculars while Motz gets a direction with the antennae
Tagging flatfish can be a little different than tagging a round fish. Below is a description of how we placed the archival tags on the winter flounder.
Step 1) Catch the fish. For this we used a commercial trawl boat, the Viking II which unfortunately just sank. The trawl catches bottom fish and brings it onto the boat for us to sort through and find the winter flounder.
Step 2) Put the fish in a live-well which is a large plastic box that holds water to keep the fish alive. Here we can asses to see how healthy the fish is. We only want to tag the healthiest fish.
Step 3) Measure the length of the fish. We aimed for greater than 30cm because the tags are rather large.
Step 4) Next we place the fish on a board with hollow needles fastened in it. These needles put holes in the fish which we can then thread wire through the body to attach the tag. This may sound rough, but the majority of the fish don’t even bleed from the procedure. Its a lot like piercing someones ear. We want to place the fish as close to the center as possible without being on the vertebrae so that the center of the weight is balanced, which is best for the fish to swim normally.
Step 5) Once the wires are through we can flip the fish over on its underside. On this side of the fish we thread a second piece of plastic on the underside so that the wires don’t rub the skin. The cool cloth over the fish’s head helps to calm it.
Step 6) We use a standard ruler as a separator between the body of the fish and the plastic, then bend the wires in place. The ruler helps to make sure the wires are not too tight on the fish to make it as comfortable as possible. We can now twist the wires, bend them down, and trim the ends so they don’t scratch the fish. The fish now goes back into the live-well to relax before its release.
Step 7) Now the moment that the fish have been waiting for, their release. For this we use long handle nets to get them as close to the water as possible. We record the location of their release to see how far and in what direction they move.
Step 8) Now we just have to wait for the fish to be re-captured. From the tags we can asses where the fish like to live. The tags record temperature, salinity, and depth over time. The graph below show depth vs. time with the colored points as temperature. In the two weeks this fish was over you can see that once the water warmed up it moved into deeper cooler water.
This is the fish with tag 6663 which supplied the information for the graph above.
Our first tag was recovered on Wednesday, a few miles offshore from where it was deployed! I drove down to Point Pleasant to pick it up today and handed over the $200 reward in exchange for the tag. In this case the fisherman saved the flounder so I could measure it, determine it was a female, and take pictures of the fish to see how healthy it was compared to when we let it go. If you catch a tagged winter flounder when the season is closed please don’t keep the fish, but DO keep the tag. If you are able to measure the length of the fish that would be nice, but the priority is the tag and its location. I can’t wait to see what this flounder will tell us about where its been. Since the tag was recovered so early we’ll have the opportunity to reprogram it and get it back out on another flounder. Its always good to have data, even if its short!
51 archival tags have been released out at the mud hole (Hudson River Canyon area). We are offering a $200 reward for each archival tag retrieved!!
We have also released 12 acoustic tags and 118 American Littoral Society loop tags with more tags to go. We are not offering rewards for these two types of tags but if you’ve found one then you’re probably in the right area. The American Littoral Society will give you a patch and the history of your fish if you mail the tag back in. These tags are still worth while, so if you find one of these the length and location (GPS coordinates preferred) of where you caught the fish would be greatly appreciated!
In a future post I’ll go into detail about the tagging process, but I just wanted to get the word out that the tags are in the water. Operation follow that flounder is a go!
Below Nick Giraldi (RUMFS technician) and I put archival data logging tags on the winter flounder as Dr. Ken Able releases them off the boat using a long handled net.
Hello
My name is Kaycee and I am an Oceanography graduate student at Rutgers University. This blog’s primary objective will be to tell the story of catching, tagging, and tracking the fish we are studying at the Rutgers Univ. Marine Field Station (RUMFS). Currently there are two projects this blog will focus on. One study is on winter flounder seasonal migration off of New Jersey, which I will be writing about. The other is a study on sex change in black sea bass which will be covered by Mikaela Provost (another graduate student at Rutgers) and Chris Filosa (a technician at RUMFS).
Winter flounder are right-eyed flatfish, not to be confused with their left-eyed relatives the summer flounder. Winter flounder get their name because they lay their eggs in the winter. The reason Dr. Thomas Grothues (Motz), Dr. Ken Able, and I are studying winter flounder is to examine their seasonal spawning migration. To reproduce these fish move inshore into the estuaries, however we are interested in finding out if there is a resident population that lives out on the New Jersey coastal shelf like the resident population at Georges Bank. Winter flounder are harvested by recreational and commercial fishermen, but the limit on the number of winter flounder you can catch has been reduced due to their population declining. Read more about winter flounder here.
You may be wondering how we are planning on following these flounder. Sadly we do not have an underwater team of trained dolphins to handle the task. In order to track their migration, or lack of a migration if they stay out on the shelf, we are using three different kinds of tags to monitor movement.
Archival tags log data such as temperature, salinity, and pressure. While these tags gather large amounts of data, the disadvantage is that we need to catch the fish again to download the data off of the tag. For this reason we are offering a $200 reward for each archival tag recovered!! If you find one of these tags please let us know! They have a battery life of about four years recording data.
Acoustic tags have a shorter life span of about 3-4 months based on battery. They differ from the archival tags because we can find them again using hydrophones as long as we are in range of the tag. We use the hydrophones as a listening device to try to hear the signals that the tags emit. Here is a fun link about how these tags can be used.
3) American Littoral Society tags 
These tags do not record data but they are still useful in monitoring where fish are going. You can see how far a fish has traveled and how large a fish has grown in a given time. The American Littoral Society fish tagging program is one of “the largest volunteer, salt-water fish tagging program in the U.S.” If you would like to help out our project you can purchase 10 tags for $5 and become a fish tagger yourself!
As our adventures ensue I’ll update the blog, please follow along as we follow the flounder.
