Beyond the Buffet: A Day in the Life of a Shark Dietitian
For Becky O’Brien, a lead aquarist at the Shark Reef Aquarium within Mandalay Bay Resort in Las Vegas, a typical workday involves a rather unusual culinary task: preparing and serving meals to a formidable array of sharks. Far from the glamorous image of the Strip, O’Brien’s role as a “shark dietitian” is crucial to the well-being of over 3,400 marine animals housed in the resort’s impressive 1.3-million-gallon tank. Her team is responsible for feeding 15 different species of sharks, a demanding job that sees them consuming a diet O’Brien cheekily admits is “better than the tourists on the Strip.”
Since opening its doors in 2000, the Shark Reef Aquarium has become a significant attraction, drawing more than 21 million visitors to the resort. The allure of these magnificent predators, however, extends beyond mere spectacle; it highlights the complex and vital work of ensuring their health and survival in a captive environment.
The Science of Shark Nutrition
Understanding the dietary requirements of sharks is a complex undertaking. Samantha Leigh, a professor at California State University, Dominguez Hills, who specialises in marine animal nutritional physiology, explains that sharks require diets rich in proteins and lipids. These essential components are vital for maintaining their fatty livers, which play a critical role in buoyancy control, allowing them to navigate the water with ease.
In their natural habitats, sharks are opportunistic feeders, consuming a wide variety of prey, from microscopic zooplankton to larger animals like seals and even other sharks. Replicating this diverse diet in captivity presents a unique challenge. While many captive sharks subsist on high-quality seafood, the team at Shark Reef Aquarium strives to mimic natural feeding patterns as closely as possible.
A Varied Menu for Apex Predators
The sharks at Mandalay Bay are treated to a carefully curated menu featuring a mix of mackerel, herring, blue runner, and sardines. This selection is designed to provide the nutritional variety they would encounter in the wild. Some of the fish are sourced from wild catches, while others come from accredited sustainable fisheries, ensuring a responsible approach to their food supply.
The sheer volume of food required is staggering. O’Brien reveals that the aquarium goes through over 300 pounds (approximately 136 kilograms) of fish in a single week. To ensure the animals receive all the necessary nutrients, the fish are often fortified with vitamins. These supplements are cleverly hidden within the fish, preventing the sharks from simply spitting them out – a strategy O’Brien likens to the familiar tactic of disguising medicine for a pet dog with peanut butter.
Training and Observation: More Than Just Feeding Time
Beyond the practicalities of nutrition, feeding time at the Shark Reef Aquarium offers a valuable opportunity for observation and training. Much like domestic animals, sharks can be trained to associate specific behaviours with rewards. For instance, zebra sharks are trained to touch a target to receive their meal, and other species learn to congregate in designated areas of the tank for feeding.
This routine allows the aquarists to closely monitor the health of each animal. “They eat, I would say, better than the tourists on the Strip,” Ms O’Brien remarked, referring to the gourmet restaurants in Las Vegas’s bustling tourism hub. The way a shark eats – or doesn’t eat – can provide crucial insights into its well-being. A refusal to eat can signal illness or even indicate that the shark is preparing for mating.
Understanding Shark Behaviour
Sharks exhibit distinct behavioural patterns, particularly around breeding season. O’Brien notes that sharks become particularly ravenous in the lead-up to breeding, which typically runs from March to June. Conversely, many male sharks tend to eat very little during this period.
“Once you get to work with these guys on a daily basis, you do learn little nuances of how each one feeds a little bit differently,” O’Brien explains. “Each species is a little bit different.” This intimate understanding of individual and species-specific behaviours is paramount to providing optimal care.
Conservation Efforts: A Glimmer of Hope
The Shark Reef Aquarium is not just a public attraction; it is also a vital hub for conservation. Zebra sharks, for example, are an endangered species whose wild populations have been severely impacted by overfishing and the loss of their coral reef habitats. The aquarium actively participates in global conservation initiatives, including the transportation of zebra shark eggs to Indonesia for rewilding efforts, aiming to bolster wild populations.
O’Brien expresses a profound hope that by witnessing these feedings, future generations will develop a deep connection with the ocean. “I hope people watching the feedings will raise future generations to ‘care about the ocean and then hopefully protect it, to love it as much as we do’,” she stated.
Longevity in Captivity: A Testament to Care
The dedication of the aquarist team has led to remarkable outcomes in terms of animal longevity. Jack Jewell, the aquarium’s general curator, points out that many of the sharks at the facility are living well beyond their typical lifespans in the wild. He highlights an aging sand tiger shark, estimated to be between 33 and 36 years old – approximately a decade longer than its average maximum age in the wild.
As sharks age, their ability to hunt and catch prey naturally diminishes. Jewell draws a parallel between the work of the resort staff and food delivery drivers, emphasizing how they bring essential sustenance directly to the animals.
During recent visitor viewings, the diverse marine life within the 1.3-million-gallon tank was on full display. Sharks, sea turtles, and the aptly named lookdown fish – so called for their characteristic downward gaze – gracefully navigated around a striking shipwreck replica.
The bow mouth guitarfish, distinguished by their unique bow-shaped mouths designed for crushing crustaceans, were also observed engaging with aquarist Lukas Seoane. In one instance, a particularly assertive female guitarfish consumed over 4 pounds (1.8 kilograms) of fish in a single feeding, while a younger male patiently waited its turn. Seoane, reflecting on the experience, quipped, “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.”
