Penguins at Tokyo’s Kasai Rinkai Aquarium are practicing a hunting technique called “flowing sardines” to keep cool and active during the summer [1, 2].
This training is significant because it promotes natural hunting behaviors in a captive environment while mitigating the effects of high temperatures on the birds [2]. By simulating a moving current of prey, the aquarium provides both physical exercise and mental stimulation.
The practice, known in Japanese as “nagashi-aji,” involves sardines flowing down a channel for the penguins to chase [1, 2]. This method is a play on “nagashi-somen,” a traditional Japanese summer dish where cold noodles are slid down bamboo flutes [2].
One particular penguin, aged one year [2], has struggled to successfully eat the sardines during the exercise [1, 2]. While older penguins have adapted to the flow of the fish, the juvenile bird has yet to master the timing required to capture the prey [1].
Aquarium staff said the flowing sardines were devised so penguins could play and stay cool during the hot season [2]. The activity serves as a form of environmental enrichment, ensuring the animals remain engaged with their surroundings [2].
Public reaction to the training has been positive on social media. Some viewers wrote “It is interesting” and “Do your best” in response to the juvenile penguin's attempts [2]. The aquarium continues to monitor the penguins' progress as they refine their hunting skills in the simulated current [1, 2].
“The flowing sardines were devised so penguins could play and stay cool during the hot season”
The use of 'flowing sardines' demonstrates a trend in zoological management toward dynamic enrichment. By mimicking the movement of prey in the wild, aquariums can reduce stereotypical behaviors associated with captivity and manage heat stress in species not adapted to Tokyo's summer humidity.
