satellite tags – NOAA Teacher at Sea Blog

August 25, 2013August 20, 2021

Liz Harrington: Back into Action, August 23, 2013

NOAA Teacher At Sea
Liz Harrington
Aboard NOAA Ship Oregon II
August 10 – 25, 2013

Mission : Shark/Red Snapper Bottom Longline
Geographical area of cruise: Western Atlantic Ocean and Gulf of Mexico
Date: Aug. 23, 2013

Weather: current conditions from the bridge:
Partly cloudy
Lat. 29.31 °N Lon. 84.18 °W
Temp. 83 °F (28.8 °C)
Humidity 79%
Wind speed 10-15 kts
Barometer 30.03 in ( 1017.15mb)
Visibility 10 mi

Science and Technology Log:

The weather hasn’t been cooperating with us too well as we have run in to an occasional squall. It is amazing just how quickly that wind can pick up. Yesterday in the course of hauling in the line the wind increased from 18 to 34 knots (A knot is similar to mph, but it uses a nautical mile as a distance. One knot = 1.15 mph).

Red Grouper await processing. Occasionally the catch becomes the bait and we pull in half of a fish.

But the fish have been cooperating. The lull is over and the catch has increased. For the most part we are catching Red Grouper, an occasional Red Snapper and a variety of sharks. Click here to see the shark species found in the Gulf of Mexico. The majority of the sharks have been large enough to cradle. When we hear “hard hats that means it’s a big one” and our team jumps into action. Some of the sharks come up in the cradle quietly, but others come up thrashing about. They are quickly held down by the fishermen of the deck crew which keeps the sharks quiet and safe. Then the science team steps in to collect the data and insert a tag. As the cradle is lowered back down it is paused to obtain the shark’s weight. There is an electronic scale located at the top of the cradle. It is then lowered into the water and the shark swims away. I’m still amazed at how efficient the process is. The sharks are measured, tagged and weighed in a matter of just a few minutes.

There is a level of excitement when catching any of these fish and sharks, but the exceptional catch raises that level. This occurred a couple of days ago. We had something on the line and it was big – really big. Even the crew was yelling about its size. I knew it was something special. As it got closer to the boat it was identified as a huge Tiger Shark (Galeocerdo cuvier). The crane operator was bringing the cradle and the science team was getting ready when ……it was gone. It had bitten through the line. I guess there always has to be that big one that got away.

The level of excitement rose again when the next day we caught a Great Hammerhead shark (Sphyrna mokarran). Any of the larger Hammerheads or Tiger Sharks are being fitted with a satellite tag. This is attached to their dorsal fin (the large fin on their back). Whenever the shark comes to the surface, the tag will transmit its location via radio waves to a satellite. The satellite will then send the signal back down to a receiving antennae and on to various labs. This is a type of remote sensing that is commonly used to track animals. It gives scientists information about animal’s behavior and migration patterns. These particular satellite tags are from the Louisiana Department of Wildlife and Fisheries. It is a collaborative effort to get the tags on as many sharks as possible so they can study where they go after being caught.

Satellite tag on Great Hammerhead — Attaching a satellite tag to the dorsal fin of a Great Hammerhead Shark.

While working with the scientists I noticed that they use a combination of metric units, maritime units and imperial units. The fish are measured in millimeters, the electronic scale measured in pounds (normally it measures in kilograms, but there was a technical issue that required changing to pounds), the handheld scale measure in kilograms, the water current is measured in knots, the depth for the CTD is measured in meters, the distance is measured in nautical miles and the survey areas are divided by fathoms ( 1 fathom = 6 feet), just to name a few. It is helpful to be familiar with all of them and be able to convert from one type of unit to another. It has made me think that we should be practicing our metric conversions even more than we currently do in class. So, my incoming freshmen, get ready.

Personal Log :

The time is passing so quickly here on the ship. I think that is because there is always something happening here. My daily routine consists of rising around 7:30 am, grabbing a light breakfast and then going to see what the night shift is doing. Often times they are preparing to haul in the line and I can’t resist watching that. I have an early lunch since my shift will begin at noon, but we are usually prepared to go before that time. For the next twelve hours we will set the line, run the CTD, haul in the line and move on to the next site. Dinner is at 17:00 ( 5:00 pm) but if we are busy we can request a plate be set aside for us. The distance between sites can be anywhere from less than a nautical mile (nm) to over 60 nm. The ship can travel about 10 knots depending upon the wind and the current. So, there are times when we have a number of hours between sites. On these occasions I check my email, work on my blog, edit my pictures or just stand on the deck and look out over the water. I always have my eyes open for animals, but it isn’t often that I see any. Just water as far as the eye can see. It gives me a sense of the vastness of the ocean. And I am seeing lots of beautiful cloud features and sunsets.

A beautiful sunset over the Gulf of Mexico.

I had the special privilege of getting a tour by the Chief Marine Engineer, Sean Pfarrer, of the engine room. It is very loud down there so we had to wear ear plugs. Sean pointed to different things and I took pictures. Then upstairs, in the relative quiet of the galley, he took the time to explain to me the role of each component. We had a really interesting discussion. Any mechanical questions that arose after that, Sean was the one I’d go to. When I return, anyone interested in mechanics can listen to my presentation of the engine room – it’s more interesting than you may think.

As the wind picks up the day team scurries to clean up and put gear away because it is too rough to fish. Amy and Cliff clean and rinse the deck.

Weighing a Sharpnose Shark. photo courtesy of David Seay.

A closer view of the satellite tag attached to the dorsal fin.

measuring shark — Kristin calls out measurements to Amy as Daniel and Eric help hold the shark still.

A pair of otoliths from a Red Grouper (Epinephelus morio).

yellowedge grouper — The day team only caught one Yellowedge Grouper (Hyporthodus flavolimbatus). Photo courtesy of David Seay.

June 30, 2006March 19, 2021

Brenton Burnett, June 30, 2006

NOAA Teacher at Sea
Brenton Burnett
Onboard NOAA Ship David Starr Jordan
June 26 – July 6, 2006

Mission: Shark Abundance Survey
Geographical Area: California Coast
Date: June 30, 2006

Weather Data from Bridge
Visibility: 10 nautical miles (nm)
Wind direction: 250 degrees
Wind speed: 9 kts
Sea wave height: <1
Swell wave height: 1-2’
Seawater temperature: 17.6 degrees C
Sea level pressure: 1015 mb
Cloud cover: Clear

Russ Vetter and Rand Rasmussen position a blue shark so they can measure its length and remove the hook.

Science and Technology Log

Today was a slower day in terms of numbers of sharks—we only caught three. But the mood was good because each of the sharks caught was large enough to accommodate satellite tags. And, we caught one of each species of shark that we anticipate seeing—a blue, a thresher and a mako. The mako was particularly lively giving a good kick as it left the shark trough. Any of the sharks tagged on this trip, or others in the same effort, can be monitored here. On this cruise we have attached SPOT tags to two makos (on Tuesday #60986 and today, #60998), a blue (#60989) and a thresher (#53797). Note: I’m told that all four of these MAY be listed as blues on the website until the website is fully updated, but the tracks of all four sharks should be viewable right now!

All sharks are in the phylum Chordata. They, along with rays and skates, and a strange and even more ancient group of fish called chimera, make up Class Chondrichthyes, which are the fish with skeletons made of cartilage. The only bony material in a shark is its teeth and for this reason very few shark fossils beyond teeth are found. The other classes of chordates are the jawless fishes (hagfish and lamprey), the bony fishes (minnows, mola, cod, seahorses, etc.), amphibians, reptiles, mammals and birds.

The goblin shark—perhaps the ugliest shark ever!

Each class is divided up into orders, and there are eight orders of sharks— one order includes the sawsharks, another the whale shark and wobbegong, and another the angelsharks (which have some resemblance to rays). The frilled and cow sharks make up another order, the bullhead sharks another, and there is an order for the dogfish sharks (including the spiny dogfish which might be the most numerous of all shark species—closer to shore, we may hook one). All of these orders are sharks but when people think of sharks they typically envision either mackeral sharks, which include great whites, makos, tigers and threshers, or the ground sharks, which include leopard sharks, hammerheads and blue sharks.

The 16 species of mackeral sharks are among the most specialized of sharks. Many, like the mako, are swift swimmers. Threshers have a tail that is as long as the rest of their body is. It is believed that they use this tail to “corral” fish and then slap the fish to stun them. The goblin shark lives in the dark of the deep and has a strange snout jaw structure that makes it arguably the ugliest shark. The first of these was caught in 1897 near Japan. A scientist there delivered it to Professor David Starr Jordan, for whom the National Oceanic and Atmospheric Administration ship we are on is named.

The DAVID STARR JORDAN awaits the return of its Zodiac boat. — The ship awaits the return of its Zodiac boat.

With over 200 species, the ground sharks are the most diverse and varied order of sharks. The blue shark is a generalist living in open waters in nearly all of the world’s oceans. Others, like the catsharks are benthic, or bottom-dwelling. Most are small and harmless but some are the largest of predatory sharks. All of them have what’s called a nictitating eyelid which covers the eyes to protect them as the shark bites.

Personal Log

During today’s afternoon set, we inadvertently lost a buoy that was intended to be clipped to the longline. Fortunately, such a mishap is occasion to let loose the ship’s two engine Zodiac. Myself, Stephanie Snyder (an intern with NOAA), Miguel Olvera, and crewmembers Chico Gomez and David Gothan, set out to retrieve it. The buoy was dropped early in the set so we had to travel a couple miles out. On the way, we briefly saw four molas. Later a sea lion passed by.

An adventure here, an adventure there—the fifth day is as interesting as the first!

June 28, 2006March 19, 2021

Brenton Burnett, June 28, 2006

NOAA Teacher at Sea
Brenton Burnett
Onboard NOAA Ship David Starr Jordan
June 26 – July 6, 2006

Mission: Shark Abundance Survey
Geographical Area: California Coast
Date: June 28, 2006

Weather Data from Bridge
Visibility: 10 nautical miles (nm)
Wind direction: 300 degrees
Wind speed: 17 kts
Sea wave height: 2-3’
Swell wave height: 3’
Seawater temperature: 19.6 degrees C
Sea level pressure: 1015 mb
Cloud cover: Scattered clouds

A National Marine Fisheries Service (NMFS) tag and insertion tool. — NOAA Fisheries tag and insertion tool

Science and Technology Log

Dr. Kohin, our chief scientist, tapped me to assist on the shark platform this morning! This means I helped remove the hook from sharks’ mouths and helped with the tagging. Note: I didn’t get bit once nor was I lost overboard. And the sharks did well, too. There are many tasks that lead up to shark tagging and hook removal. As the long line is drawn in by electric winch, one member of the science team unclips the gangion (or the buoy) and passes it on to others for stowing. If no catch was made on that hook (which is the case most of the time), the bait has to be removed before stowing. If there is a shark, however, it is walked “on its leash” to the stern (back) of the ship to the shark platform where Russ Vetter and Rand Rasmussen (and often Suzy Kohin though she is also busy coordinating the efforts of everyone) work to collect data and release the animal. Others record data and provide the materials necessary for tagging. As is often the case when conducting scientific research, much of this work can be repetitive. But when something comes in on the line, or when something unexpected happens like when a gangion is twisted on a line, there is lots of activity and excitement.

To be sure, the most excitement is on the shark platform. This 4 foot by 8 foot (approximate) platform is connected along its long side to the shark trough. The shark platform is accessed from the deck by a large chute that is as wide as the platform is long.

The shark trough is lowered just under the water until the shark (still on the line) can be maneuvered into the shark trough by Russ. Once there, Russ and Rand are quick to hold down the shark so that they can safely work on it. Rand uses a small thick blanket to cover the shark’s mouth and sharp teeth. Before releasing the animal, however, he needs to remove the hook. While the two of them hold the shark, another person (which was me this morning) cuts the hook or wire lead. By this time the sex of the shark has been determined. This is easily accomplished by observing the rear underside of the shark— two finger like “claspers” near the pelvic fins are present if the shark is a male. The last step before releasing the shark is to measure its length. A meter stick along the edge of the trough makes this an easy task.

If the shark is a mako or a thresher, however, a number of other tasks are undertaken before hook removal and release of the shark. First, a National Marine Fisheries Service (NMFS)”spaghetti tag” is attached just forward and to the side of the dorsal fin. These are “conventional tags” which give the animal a number and provide an address to send the tag to if the animal were recaught. The spaghetti tag is barely more than a plastic wire attached to a pointed piece of metal. To insert it, a small incision is first made in the shark’s back. Then, using an awl shaped tool, the metallic portion of the tag is wedged through the incision just under the skin. Because these tags may not stay in for life, a backup tag is also used. These are called ROTO tags and they are attached directly to the dorsal fin. Sharks returned with ROTO tags also indicate to researchers that oxytetracycline has been injected into the shark. These tags, like others, contain reward information for the return of specimens or information about them.

For larger and healthier sharks, satellite tags, of which there are two, may be attached to the shark. The SPOT tag (smart position and temperature tag) is a bit thinner and smaller than a computer mouse. Attached to the dorsal fin (in lieu of the ROTO tag), the SPOT tag has two metal washers on its exterior. If the shark rises to the surface, with its dorsal fin out of the water, these washers dry long enough to disrupt the electrical current that normally passes between them through the water. This cues the tag to transmit the shark’s position to a satellite. Using these tags costs more than $2,000 each, so it is important to use them with animals that are large enough to receive them and ones who are in good health.

If a shark receives a SPOT tag, a PAT tag (popoff and archival tag) will also be attached. The PAT tag records water temperature, depth and light levels at one minute intervals. After a few months or some other specified time, the tag is designed to pop off and float to the surface. At that time the tag transmits a summary of its data collection to researchers via satellite. If the PAT tag can actually be recovered, the full set of data at its full resolution can be retrieved.

It is interesting to note that light levels act as a proxy for time of day given that noon and midnight can easily be determined from them. And, in turn, this information can be translated into a longitudinal position as one notes the shift of day time from the location of tagging. Light level can also be used to determine latitude as on all days except those nearest the equinoxes, the length of day is dependent upon how far one is north or south.

Between the SPOT and PAT tags, the horizontal as well as vertical movement of the animal can be tracked over a period of time. Using only conventional tags, only one additional location can be mapped, and that only with a recatching of the animal. With these methods, it is hoped that the travels of these young makos and threshers, will be better understood as they feed and breed.

Personal Log

Every day has been exciting, but today helping on the shark platform has topped it all. I was lucky, too, as that set was the most productive, so far. We caught 57 sharks on 202 hooks—a pretty good batting average. And five of these were makos. We also caught a larger thresher shark, rare out this far. I was thrilled to think I’d get to see this guy up close, but alas it was not to be. The thresher threw the hook and escaped—the big one got away! Fortunately, later in the trip we’ll likely be more in thresher waters!