LAS VEGAS (AP) — At the Shark Reef Aquarium within the Mandalay Bay Resort in Las Vegas, lead aquarist Becky O'Brien skillfully dangles herring over a large tank filled with over a dozen zebra sharks. Within seconds, one of these unique creatures snatches the fish from her tongs. O’Brien, who always dreamt about working with marine life, has carved out a niche as a shark dietitian responsible for feeding 15 species of sharks three times a week, as well as caring for over 3,400 animals in the facility's expansive 1.3 million-gallon tank.
"They eat, I would say, better than the tourists on the Strip," O'Brien notes, making a comparison to the gourmet offerings found in Las Vegas’ renowned dining establishments.
The Shark Reef Aquarium has become a significant tourist destination, attracting over 21 million visitors since its inception in 2000, according to Mandalay Bay statistics. The sharks' diet is meticulously planned to provide essential proteins and lipids, which help to maintain their fatty livers, necessary for their movement in water. Samantha Leigh, a professor specializing in marine animal nutritional physiology at California State University, Dominguez Hills, explains that in their natural habitat, sharks consume a diverse range of prey from zooplankton to seals, and the aquarium aims to replicate this in captivity.
At Mandalay Bay, O’Brien and her team serve a varied diet that includes mackerel, herring, blue runner, and sardines. Some of the fish are wild-caught, while others come from sustainable fisheries, ensuring that the sharks receive quality nutrition. In total, the aquarium utilizes over 300 pounds (136 kilograms) of fish each week. To enhance the sharks' health, these fish are stuffed with vitamins, ingeniously hidden within the meals to prevent the sharks from spitting them out—akin to giving a dog its medicine wrapped in peanut butter.
Feeding time also serves as an opportunity for staff to observe the health conditions of the sharks. Their eating habits can reveal a lot; a decreased appetite may indicate illness or even a desire to mate, as many male sharks experience reduced appetites during the breeding season from March to June. O’Brien emphasizes the importance of understanding individual feeding behaviors, as each species has its unique way of eating.
The zebra sharks, in particular, are notable as an endangered species whose populations have suffered due to fishing practices and coral reef habitat loss. The aquarium collaborates with various organizations worldwide to transport zebra shark eggs to Indonesia, where efforts to rewild the species aim to restore their populations in the wild. O’Brien expresses hope that by watching the feedings, visitors will cultivate a passion for ocean conservation and develop a love for marine life similar to that held by the aquarists.
As many sharks in the aquarium age beyond their typical lifespan in the wild, the staff faces unique challenges in care. Jack Jewell, the aquarium's general curator, points out an elderly sand tiger shark estimated to be between 33 and 36 years old—around 10 years older than their maximum age in the wild. The challenges of aging sharks include difficulty catching prey, necessitating a care approach likened to food delivery services that bring meals to their doorsteps.
During a recent visitor day, guests observed various species, including sharks, sea turtles, and lookdown fish gliding around a decorative shipwreck within the vast tank. One bowmouth guitarfish, recognized for its unique mouth structure designed for crushing crustaceans, elegantly swam up a vertical platform to snatch a fish from aquarist Lukas Seoane’s tongs. This particular female guitarfish displayed impressive appetite, consuming over 4 pounds (1.8 kilograms) of fish in a single feeding session, maintaining the traditions of a healthy predatory lifestyle in a controlled setting.
In light of their daily interactions with these fascinating marine creatures, each aquarist seems inspired by the high-quality food they handle. As Seoane remarked post feeding, “Every time I’m done feeding these guys, I think I want to go out and get some sushi. If it’s good enough for them, it’s good enough for me.”
