Mote shark scientist returns to Sarasota after successful expedition on M/V OCEARCH
Mote Postdoctoral Research Fellow Dr. Heather Marshall just returned home to Sarasota from a two-week shark-research expedition aboard the internationally known M/V OCEARCH in the Gulf of Mexico. Marshall collected shark blood samples in this team effort to gather previously unattainable data on these important top predators.
The multi-partner expedition — led by OCEARCH with scientific leaders from Texas A&M University — departed Nov. 4 from Corpus Christi, Texas, and completed its voyage on Nov. 13 in Morgan City, La.
Since Marshall’s last update, which was posted Nov. 10 and detailed the deployment of various scientific tags on four sharks, participants caught three more sharks, including a pregnant 8-foot sandbar shark, a 6.5-foot female sandbar shark and a 10-foot tiger shark named Finley. The tiger shark was fitted with a SPOT tag, a type of satellite tag that tracks the shark’s location and sends data back to scientists when the shark’s dorsal fin breaks the water’s surface.
- The public can track four tagged sharks from the expedition at www.ocearch.org. Look for “Joseph” the 10-foot 6-inch tiger shark, “Buddy” the 7-foot, 10-inch hammerhead, “Reveille” the 8-foot scalloped hammerhead and “Finley” the 10-foot tiger shark.
Joseph, Buddy and Reveille were tagged Nov. 5 and fitted with a satellite transmitter tag that tracks its location and provides real-time updates to scientists when the shark’s fin surfaces.
Since Nov. 5, Joseph has traveled 501 miles and has pinged over 50 times, Buddy has traveled 136 miles and has pinged over 10 times and Reveille has traveled 214 miles and pinged five times.
As of Nov. 10, Finley, the last sharked tagged during the expedition, has traveled 85 miles and has pinged 10 times.
Marshall collected blood samples from Joseph the tiger shark, a 6-foot, 9-inch bull shark and an 8-foot scalloped hammerhead on Nov. 5, and then she collected samples from both of the sandbar sharks and Finley the tiger shark on Nov. 10. These blood samples are used for projects by multiple researchers on board, including Marshall’s own research on stress in caught-and-released sharks.
After anglers catch and release a shark, it is relatively unknown how the animal is affected, how long it takes to recover or if it will survive after release and how survival rates vary with different circumstances and species. This is vital information to assess shark’s vulnerability to being overfished and/or becoming accidental bycatch and maintaining healthy shark populations while preserving the top predators that help keep ecosystems in balance.
Overall, the expedition aimed to tag, sample and release hammerhead, tiger, mako sharks and other keystone species of the Gulf of Mexico. With the results coming in from tagged sharks, along with analyses of blood and other samples, participants hope to better understand how the sharks travel in relation to Gulf habitats and structures, including natural and artificial reefs and oil/gas platforms; how shark habitats connect among the U.S., Mexico and Cuba — important information for international conservation efforts; and what physiology and health traits the sharks show, especially related to stress, body condition at release and capacity to reproduce.
Read Marshall’s daily log below for a first-hand account of her research adventures aboard the M/V OCEARCH on Nov. 10.
Mote scientist Dr. Heather Marshall’s daily log of shark research aboard M/V OCEARCH, November 2015
Tuesday, Nov. 10, 2015
Today all on board were up around sunrise and I grabbed some coffee around 6:15 a.m. Today is Fernanda’s birthday! In the past we have had lucky shark days on birthdays (we tagged Betsy the white shark on my 30th), so we were hoping for the birthday momentum to continue. We knew the weather window was only going to give us this day for fishing, so we all wanted to give full effort to get some sharks on the cradle of the M/V OCEARCH, which lifts sharks out of the water temporarily for tagging and collecting samples
After a quick egg breakfast, Brandon, scientist Hannah Hart from UNF, cameraman Dan and I, among others, got a nice chum slick going off the M/V OCEARCH stern. We had out two sets of floating buoys with attached baited hooks, with a line attached to two rod & reels so we could bring in the gear and check the baits without having to use the safeboat. We got some music playing on the stern as well, so we all were feeling quite hopeful.
The Contender was out working hard, and we knew the Harte Yellowfin research boat would be joining us, too. Around 11 a.m., we saw our white indicator buoy get suddenly jerked below the waterline on our deepset gear (which we had just re-baited and deployed), indicating a fish had attempted to take the baited hook it was attached to.
We held our breaths and looked for more indication that a shark was on the line, which we got when the second, larger, orange buoy on the gear got hauled under as well. We all let out a celebratory yell, and let the Contender know that we thought we had a shark on the line. Just in time, the Yellowfin arrived and we cut the line to the rod & reel, and they took the buoy gear and checked the fish, which turned out to be a sandbar shark! The Contender came over and took the fish as we prepared to do our work on the cradle, since it was a calm enough day to actually use it! The science team made sure we had everything ready, reviewed our plan for executing the work, and eventually all was in place and we watched the Contender walk the shark toward the boat.
Captain Brett jumped in the water, and the sandbar shark was brought up. She was a beautiful 8-foot sandbar shark, and we quickly got to work to minimize stress on the animal. I got a blood sample, and Hannah did an ultrasound. We later found out that her images revealed this female was in the early stages of pregnancy! The blood samples we took will help Dr. Jim Gelschleiter’s lab correlate pregnancy hormones with pregnancy! Matt deployed an external acoustic tag on her, and we were able to get all the other science work done as well (measurements, fin clip, parasite collection, second blood sample, etc.).
This was the first time our whole team worked together on the cradle during this expedition, and it was great and felt productive to get all our work done in one shot, on the cradle. She swam off strong after release, and I got to work processing all the blood samples.
Soon after, we got lunch, but then we heard the team had another sandbar shark, a 6.5-foot female! We worked her up on the cradle as well and I took a blood sample. Spirits were quite high on deck. There was a palpable change in energy once we were all working together to do the jobs we had all come here to do.
Fernanda was ecstatic, because she was getting her birthday sharks, and after we released the second sandbar, she predicted a third shark, and that it would be a tiger. Sure enough, about an hour later, we got word that the team had hooked up with a tiger shark! Again, everything went great on the cradle as we worked up the 10-foot tiger shark and I collected a sample. This shark was SPOT-tagged and named Finley. The SPOT tag is a type of satellite tag that tracks the shark’s location and sends data back to scientists when the shark’s dorsal fin breaks the water’s surface. We continued fishing until sunset, and Finley was our last shark , but what a wonderful shark to end on. What a great last day of the expedition!
After sunset, we had birthday dinner and celebration for Fernanda! Luis made a delicious German chocolate cake with coconut frosting.Then the crew readied the boat to be moved further inshore as we knew our weather window was closing. We moved about 20 miles inshore, then anchored for the night.
- Read Mote’s previous update with more details about the expedition and Dr. Marshall’s daily log of shark research aboard M/V OCEARCH from Nov. 4-6.