Photos by Asia Morris.
The Aquarium of the Pacific announced last week that it is the first to successfully reproduce zebra sharks through artificial insemination, a step experts say may be the key to future conservation efforts involving endangered shark species.
The two female, 10-month-old sharks were released into the Aquarium's Shark Lagoon on Tuesday, January 27 and have since been thriving and learning how to live with their new tank-mates.
Zebra sharks, which are listed as vulnerable to extinction by the International Union of Conservation and Nature (IUCN) Red List, according to Perry Hampton, Vice President of Animal Husbandry, are sought after for food, their livers, which can be used to process vitamins, and especially their fins. According to Aquarium experts, more than 100 million sharks a year are killed by humans. For the Aquarium, being able to successfully reproduce and raise them is a giant leap toward being able to research zebra sharks—and sharks in general—more thoroughly.
Dr. Lance Adams, Staff Veterinarian at the Aquarium, who performed the artificial insemination, explained that "sharks in general [...] are very hard to study in the wild; especially their reproduction."
What you can't do, at least not in the wild, he continued, is study a shark's reproductive process from the time of conception to the point of birth, not to mention the newborn's entire process of development. Since these two females were hatched, Aquarium staff have been able to keep track of their development and record much more data than they have ever been able to beforehand.
"We can look at hormones, we can look at fetal development with ultrasound, we can track data for dates and size and growth and all of these things," Adams said.
Particularly with zebra sharks, which commonly reproduce in captivity, Adams explained that that's one of the reasons this species was chosen for the artificial insemination. The Aquarium has started to work with these sharks to find out if the process can be successful, as opposed to trying it for the first time with a more difficult type of shark.
"So we chose these animals as kind of our second step in the process of working toward understanding how to do this successfully on maybe some more complicated terms," he said. Being able to assist sharks in captivity, especially those that don't normally breed, with their reproduction will lessen the need for the Aquarium to pull more animals from the wild.
"From a conservation standpoint," Adams explained, "[the Aquarium could have a] sustainable population in captivity, so if anything did happen to the population out in the wild, there would still be some source of genetic material and brute stock that could then be used to replenish those in the world and to restart the population over again so those animals don't go extinct."
Zebra sharks going extinct is not a future Adams predicts; however, other species of shark are in greater danger of disappearing completely. "Something major would have to happen for that to occur and we'd probably all be in pretty bad shape if it did," he concluded. "But, there are other shark species that this technique could be used for that are currently in that status, where their numbers are low and they're more vulnerable, and we'd like to be able to understand this aspect of their biology very well so that if we needed to use this we could."
Zebra sharks are an elegant species made of mostly tail, a morphological adaptation designed to help them swim along the bottom of their natural habitats, within shallow brackish or inshore marine waters. Young zebra sharks tend to be dark brown or black with pale yellow or white vertical stripes; as they begin to mature, the stripes begin to fade and start to resemble dots or more circular shapes.
Called leopard sharks in Australia, they can be found throughout the Indo-West Pacific. When the pups, as they're called, hatch, usually after about five to six months, they are only 7.9 to 10 inches long, but can grow to be 5.5 to as much as 11.5 feet long. The two Aquarium pups are already longer, at about three feet, than most of the ocean creatures that thrive in the Aquarium's shallow Shark Lagoon pools. According to Dr. Adams, maturity is thought to occur between six to ten years of age when they reach their largest size, at which time the pups will have to be moved to the larger tank.
Zebra sharks are nocturnal foragers, with very tiny, pinpoint teeth that are meant to capture small bony fish, crabs, shrimp, squid, mollusks and hard-shelled food. "They don't generally go after swimming fishes; that would require too much effort for these guys," said Hampton.
As their underbellies graze the sandy bottom of the tank, Nicole Leier, a shark expert at the Aquarium who has been target training the teethy pups for the past three months, places a large dinner plate-sized disc attached to a pole, inside the tank, while another attendant lures the stingrays and other animals away with other bait.
Every animal in this tank is target trained in an effort to keep them separated so the experts doing the feeding know exactly how much food they're getting, said Leier. The Zebra Sharks need a certain amount of food every day, however target training also helps the sharks get accustomed to human interactions.
"It also helps us get close to them," she explained. "We can get a closer look at their eyes, at their body, make sure that nothing is wrong with them. So not only are we feeding but we're doing a physical exam every time for feeding."
Eventually, as the sharks mature, Leier hopes to train them to be lifted out of the water, just like the sharks' mother, Fern, has been trained to do. The mother, who weighs 145 lbs. is seven and a half feet long and lives in the Aquarium's larger Shark Lagoon tank, has been trained to swim into her "capture device," which is a constructed out of a small tarp her trainers can hang into the water. Once inside, Leier can hold onto Fern's dorsal fin so that blood can be drawn, measurements can be taken and a physical exam can be performed. Leir has even trained her to flip onto her back, an action that was critical for the artificial insemination performed in September of 2013.
Fern [above], who is approximately 20 years old, arrived at the Aquarium in 1997 and had both of her babies, the two female zebra sharks, in late March of 2014. While the shark pups, once hatched, are immediately able to swim and hunt on their own in the wild, because there are only two, Aquarium experts take extra special care of them before they're released into a tank with the several other marine species that live there.
Dr. Adams explained, "Certainly, if they were out in the wild those animals have selection pressure put on them and a lot of those babies would die in the wild, but we don't have a lot of babies here so we want to make sure that ours do as well as possible."
The public is invited to see these amazing creatures during normal Aquarium hours in the Aquarium's Shark Lagoon. For more information about visiting the sharks, click here.