Although the Kaiyukan Aquarium is located right on Osaka Bay, it is truly a case of “water, water everywhere, ne’er any drop to drink” for the 39,000 fish and 580 species of other sea creatures kept there in 15 large tanks.
The aquarium in Osaka’s Minato Ward may boast a world-class range of exhibits, but its denizens of the deep wouldn’t last long in water taken from off their doorstep — just as no one now dares even to swim in the expansive bay.
As a result, the original 11,000 tons of seawater required when the aquarium opened 14 years ago came from off Kochi Prefecture, on the Pacific coast of Shikoku. Now, even though ferries deliver several 300-ton loads of ocean water every month to refresh the aquarium’s marine environment, the condition of the water in their tanks is still the single most important consideration for the aquarium operators.
“Because Kaiyukan is an urban aquarium, its water system is a closed circuit. This makes it difficult to maintain the quality of the seawater,” said Hirakazu Tatsuki, a senior keeper at the aquarium.
So, naturally, the first thing Tatsuki and the other keepers do each morning is check the quality of the seawater in each of the aquarium’s 40 tanks — ranging from the largest, which contains 5,400 tons of seawater, to small breeding tanks, which visitors don’t see.
“Ideally, the seawater should be kept at pH 8 or more, but as it gradually loses pH we have to monitor it very carefully because the fish and sea animals would become ill if it stayed too low for too long,” Tatsuki said.
“As we cannot afford artificial seawater, the maintenance of the water quality is still our prime concern.”
After water quality, next on the scale of priorities for Kaiyukan’s keepers is to watch closely for any abnormal behavior in the tanks, as this is often a symptom of sickness.
“In addition to being on the lookout for sickness caused by parasitic worms, which is quite easy to spot, we have to observe if any fish are moving slower than usual or banging themselves against the tank walls,” Tatsuki said. “Such behavior often signifies illness.”
Once removed from the tank, sick fish may be treated in a variety of ways, including being given a medicated bath or oral medication. The nightmare scenario, of course, is that a disease might spread to most or all of the fish in a tank.
“Noticing unusual behavior at its outset is,” said Tatsuki, “the best preventive measure we have, but it’s only possible through daily observation by keepers who really know what they’re looking for.”
According to Tatsuki, fish and sea animals usually live in peaceful communities as long as their environment resembles that of the wild. In the largest of Kaiyukan’s tanks, there are no fewer than 8,000 fish and 80 species of other sea creatures.
“Normally, problems don’t occur between different species, except in species with a strong sense of territorial demarcation. For example, a Napoleonfish that had been in the tank for some time did not allow a new Napoleonfish to settle in. After a couple of days, we had to take out the newcomer,” he said.
Monitoring sea animals is a whole different ballgame, says Kazushi Chimoto, who takes care of creatures such as penguins, dolphins, sea otters, seals and other marine animals: “While fish are fish, sea animals are similar to humans.”
Since sea animals are treated individually, Chimoto likens the job to parenting. “They get sick, mentally and physically, just like humans,” he said. But as Chimoto and his colleagues feed them by hand, they can keep close tabs on their health.
Of all the creatures under their care, sea otters are the most picky eaters, Chimoto said. “Their main food is squid. But some individuals won’t eat the liver, while others don’t touch the head. Then there are some that take the parts they don’t like and try to hide them from us.”
However, when an animal becomes extremely fussy about its food, it may be a sign that it is ill. On such occasions, it is examined just like a person would be, with blood tests, temperature checks, X-rays and the like. If the case is serious, animals such as dolphins might be put on an intravenous drip.
“Dolphins are calm once they are taken out of water and laid down on a stretcher,” Chimoto said. “But when they are not well, it is hard to catch them in the first place.”
He also stressed the importance of early detection of any abnormal behavior to prevent serious illnesses developing. “But this isn’t so difficult,” he said. “If I see they’ve got sleepy eyes, they are breathing fast or losing their appetite, I just put myself in their position.”
Chimoto said that a keeper’s job is not necessarily always enjoyable. “It is all about life. While they are alive, it is fine. But sometimes you have to face the death of an animal, which can be really hard to take.”
At present, of course, the keeper’s job — and those of all the staff — are not made any easier by the continuing recession and the recent opening of Universal Studios Japan nearby as a rival attraction. In fact, the last fiscal year’s 2.2 million visitors to Kaiyukan was the lowest number for five years, though hopes are high that the current year will see an improvement thanks to the knock-on effect of a food museum the company has opened next door.
Meanwhile, at the Suma Aqualife Park, which has 20,000 fish and other sea creatures kept in clean water drawn from off Kobe’s adjacent Suma Beach, perhaps it’s the regular dolphin shows that they have been staging for the last 14 years that have kept its attendances steady at just over a million for several years.
“When it comes to training dolphins, you have to make them enjoy what they do because you can’t force them to perform. What people see is them performing various moves for fun,” said Michihiro Taki, the park’s chief dolphin trainer.
Reflecting this philosophy, the performances are called “dolphins live” — not “dolphin shows” — because, as Taki put it, “it is not that the animals are controlled by humans for the pleasure of humans.”
Similarly, so as not to give an impression that these highly intelligent marine mammals are pets like dogs and cats, each one is simply assigned a kind of registration number, such as A1 or F2, instead of a name. Of the seven dolphins kept in the Suma Aquarium, the only exception to this rule is Smile, a 30-month-old youngster who was born there.
As for the training itself, Taki explained that the key is to praise the dolphins when they jump or do flips high in the air. “We never force them to jump or perform other moves in return for food. They are fed even if they don’t perform. We lead the dolphins to think it is more fun if they can perform by encouraging them and showing our happiness.
“We hope visitors gain a better understanding of the kind of animals dolphins are,” said Taki, who added that he never tires of communicating with his playmates.