Saturday, August 13, 2011

Well-Traveled Ray FInds a Home at the Tennessee Aquarium

The Tennessee Aquarium recently received a roughtail stingray, Dasyatis centroura, from the Virginia Aquarium & Marine Science Center. This female ray has a rather interesting past, including how many places she's travelled before coming to Chattanooga.
According to Beth Firchau, Curator of Fishes & Dive Operations Supervisor at the Virginia Aquarium, this ray almost became a shark snack. "This roughtail was born in 2006. She is the offspring of a female that was wild caught in 1996 off Wachapreague, Virginia and a wild caught male ray that came to us from the Adventure Aquarium," said Firchau. "The ray was born in the Norfolk Canyon Aquarium. Interestingly enough its mother had been bitten by one of our sharks and was in recovery when she pupped." The newborn ray was kept in an off-exhibit area until she was big enough to be placed on display in the Virginia Aquarium's ray touch tank. When she grew too big for that exhibit, she moved to Chattanooga.
Matt Hamilton, a Tennessee Aquarium aquarist, (seen above and below) and others have been target training this ray to "eat on cue" while she has been going through quarantine at the Animal Care Facility. Put simply, a target is lowered into the water which attracts the ray for feeding. By teaching the ray to come to one location to dine, it helps ensure that she'll get the proper amount of food and nutritional supplements.
Hamilton said this move from the ACF to the Tennessee Aquarium was one of the smoothest he's helped with. "It may be that because she was in a touch tank, she's used to a lot of contact," said Hamilton. "She's always seemed very calm and easy to work with."
In the transport container, this ray seemed used to moving day. Hamilton believes her light coloration reflects her relatively light-colored homes. Both the touch tank at the Virginia Aquarium and quarantine tank at the ACF were rather light. Her new home in the Secret Reef is darker, so she may end up looking like the southern stingrays that are already on exhibit in Ocean Journey.
So how will visitors tell her apart from the other rays? First of all, her tail is MUCH longer than the other stingrays. And eventually, she might be a rather large ray. Roughtails in the wild have been known to reach more than seven feet across! They sometimes tip the scales at nearly 450 pounds!
Fortunately for our aquarists, she found a new home at the Tennessee Aquarium before she got that big. It only took two people to carry her when she was moved from the transport container to the acclimation pool above the Secret Reef.
This ray is no longer a wayward ray. She's now a stay at home ray. She'll spend enough time in the acclimation pool to make sure she keeps responding to the target feeding. Once aquarists are certain she's eating well every time they "ring the dinner bell," then the gate will be lifted and she'll be free explore the rest of her new home.

Friday, August 12, 2011

Fond Memories Of A Very Old Shark


Tennessee Aquarium staffers were saddened by the loss of one of our bonnethead sharks today. For the past couple of weeks, we have been celebrating this “grand-daddy” of bonnetheads. You should have seen senior aquarist Rob Mottice while he talked about bringing this bonnethead to the Tennessee Aquarium from Florida in 1991. His eyes would light up and he would get a big smile on his face as he recalled putting this particular fish on exhibit.


As far as we know, this male was the world’s oldest of this species on public display. He was estimated to be 20 to 22 years old. (Scroll down for the complete story.) At least one shark researcher was interested to learn that our shark lived such a long life. Even though sharks on exhibit live longer than their wild counterparts, this new “record” adds to our understanding of bonnetheads. Will another one live longer on exhibit or an even older tagged shark be caught?

Up until his death, this shark seemed as active as the day he arrived at the Aquarium. So it appears that his advanced years finally caught up with him.

A technique called vertebrae ring analysis can be used to determine the exact age of sharks in the wild. Like tree rings, shark vertebrae exhibit growth rings that can be counted to tell how old the animal was. However, it’s believed that these growth rings are influenced by seasonality, so a shark on exhibit may not lay down such rings. We are going to attempt to have an expert examine this shark’s vertebrae. If growth rings appear in this case, our bonnethead may add a little more to our knowledge about this species.

Wayward Gecko from Firehall #1 - An Invasive Friend or Foe?

 Earlier this week we received an e-mail from Chattanooga Firefighter Gabriel Thrash. He and the other firefighters at Station #1 had a new friend. This "lizard" was scooped up after being observed hanging around the walls and ceiling of the firehouse. He wanted to know if an Aquarium expert could identify the creature. Dave Collins, the Aquarium's curator of forests, was able to quickly respond (Much like our firefighting friends.): "It’s a Mediterranean house gecko," said Collins. "It is an exotic from southern Europe but one of the most successful hitch-hikers in the world. This species has become established virtually around the globe including most of the Southeast. Like its name implies, it loves to cohabitate with humans-enjoying the heat, security and steady diet of bugs that our homes and buildings provide."

Anyone wishing to learn more about these friendly little house guests can go to the Alabama Department of Conservation and Natural Resource website.

Collins says that while it's enjoyable to watch these animals patrol for bugs on walls and around light fixtures, it's important to remember that this is an invasive species. In this case, Mediterranean house geckos don't seem to cause many problems.

Star Trek fans will recall one of the most famous episodes, The Trouble with Tribbles.

The crew of the Enterprise were quickly overrun by an invasive species brought aboard the Starship by a huckster selling the creatures for pets. According to Wikipedia, this science fiction episode was an early attempt to address environmental concerns.

From Wikipedia: In his 1973 memoir The Trouble With Tribbles: The Complete Story of One of Star Trek's Most Popular Episodes [1] author David Gerrold states that he had been a science fiction fan since childhood, and was a film student in college when the series was aired. Gerrold submitted five story premises to Producer Gene L. Coon. One of the five premises, "The Fuzzies", interested Coon, and Gerrold was commissioned to write the story outline (retitled A Fuzzy Thing Happened To Me. . .).


"Tribbles" was originally intended to be a serious take on the introduction of alien species to predator-free environments, as had happened with rabbits in Australia. In the book, Gerrold stated that his goal was to show how a species that seemed harmless could be quite dangerous.

Unfortunately this happens in the real world today when animals like lionfish are purchased for pets and turned loose in environments where they don't belong. Lionfish are rather gorgeous fish, but they are causing big problems from the U.S. east coast through the Bahamas, Florida Keys, Mexico and most recently the Flower Garden Banks National Marine Sanctuary.

Locally, mosquitofish were introduced to control the bloodsucking insect populations. But the mosquitofish also liked eating topminnows. And within a relatively short period of time, Barrens topminnows were in trouble in their native springs on the Cumberland Plateau because of another introduced species.

And it takes a lot of hard work to restore an endangered species once they are threatened by an invasive animal.



So while a gecko may not be a "fire" for local creatures, it does illustrate the "smoke" of invasive animals being very successful where they don't belong.

Monday, August 1, 2011

Shark Week - World's Oldest Bonnethead Shark at the Tennessee Aquarium?


O.K. shark fans, an interesting story surfaced off the coast of South Carolina recently which leads to the Tennessee Aquarium. It's a tale that begins in the Florida Keys nearly a quarter of a century ago. That's when Rob Mottice was beginning his career with the - yet to be opened - Tennessee Aquarium. "We drove a box van, like a U-Haul truck to near Marathon, Florida to pick up some bonnethead sharks. This was back in 1991 several months before the Aquarium opened in May of 1992," said Mottice. "It was a long drive back to Chattanooga and the sharks did great." Mottice said that two of the bonnetheads were about the same length which often indicates the animals are "in the same class," or about the same age. "The female had pups at the Aquarium later which leads us to believe she was about two years old when she got here. And we think the male was about the same age."
 
The male bonnethead is still swimming around in the Aquarium's Gulf of Mexico exhibit. If Mottice's estimate is correct, then this shark is 20 to 22 years old.


Far from being "long in the tooth," this shark is still a feisty fish. When volunteers enter the water to feed the Aquarium's and other reef fish in this exhibit, this shark is ready to chomp down on meals like a pup. "You still want to be quick while feeding this guy," said Mottice. "He's very quick and will occasionally nip at fingers if a diver doesn't release food fast enough."

According to fishbase.org, the maximum reported age of bonnethead sharks in the wild is twelve years. So a few eyebrows were raised recently when a significantly older bonnethead shark was recaptured off the coast of South Carolina by the South Carolina Department of Natural Resources Coastal Shark Survey Team. When this particular shark was originally tagged in 2002, it was already a full-grown adult. Through Vertebrae Ring Analysis, the age of this shark was determined to be 17 years old. Southern Fried Science, a science and nature website, reported the tagged shark as being the “World's oldest known bonnethead shark.”

Bryan Frazier, a marine biologist with the South Carolina Department of Natural Resources, believes that while the tagged shark was well beyond the average life span of around 15 years, there may be older bonnetheads in the sea. Frazier thinks that under-aging occurs in age and growth work. “It’s only when we have a long-term recapture such as this one, and a few others I have gotten over the years, that we see that these animals are really living longer than we first thought,” said Frazier. “I imagine as time goes on we will continue to encounter individuals that expand our knowledge.”

So is the Tennessee Aquarium's shark the world's oldest bonnethead? As far as Mottice knows, this guy holds the longevity record for members of this species on public display. "Obviously animals like this get excellent care. They get hand delivered, restaurant-quality groceries, volunteer divers routinely clean their home and they have an excellent health plan with regular house calls from our veterinarian."

Visitors can enjoy watching this "Grand-Daddy" of bonnetheads during Shark Week along with epaulette sharks in Stingray Bay and the sand tiger and sandbar sharks in the Secret Reef exhibit.