The otter side of Vancouver’s stolen koi story
A rogue otter stole koi from Vancouver’s classical Chinese garden. UBC stepped in to help. But how do you trap and transport koi across a major North American city?
By Koby Michaels (UBC Focus assistant editor) with input from Katie Teed (Senior Manager, Marketing and Communication, UBC Botanical Garden)
It was not your typical headline: Otter loose in Vancouver’s classical Chinese garden. Yet last November, Vancouverites across the city woke up to this very strange scenario.
And while the story has made its way through the news cycle, the behind-the-science tale of the koi rescue has never been told. Until now.
The otter caper
On November 18 a river otter, Lontra canadensis, happily discovered that the Dr. Sun Yat-Sen Classical Chinese Garden in Vancouver is home to a pond of delicious koi, Cyprinus carpio. The otter cleverly snuck its way past the garden’s wall (no one really knows how), and proceeded to feast on ten of the resident koi. After about two weeks, the otter slipped away. It remains at large, though upgraded security at the Garden means it hopefully won’t be enjoying another koi buffet in Chinatown.
River otters may look cute, but they have sharp claws on each toe which help them hook prey. Even their adorable whiskers help them sense prey. And unlike their sea otter cousins, they are agile on land as well as in water — but usually have a permanent den on land. River otters are carnivorous, eating crayfish, bugs, rats, birds, and koi (apparently).
Koi are a variety of coloured Amur carp native to East Asia. They were originally domesticated to be used as fish food (as in to be food for other fish) but nowadays enjoy a relaxing life, often as garden decoration. Though they may look beautiful and delicate, koi are hearty fish able to survive many different climates and water conditions.
They also hold cultural significance to many communities and have a mythical origin story in China. The legend goes that a school of koi were swimming upstream in a river, becoming stronger the farther they swam. Eventually, they reached a waterfall, causing the school to turn back. A few koi tried to jump up the falls without success. A demon saw their struggles and, out of malice, made the waterfall even taller. The fish kept jumping until, hundreds of years later, one finally conquered the falls. The gods, recognizing the koi’s resilience and perseverance, turned the fish into a golden dragon.
When the UBC Botanical Garden heard of their fellow garden’s otter issue, they reached out with an offer to donate koi from the Nitobe Memorial Garden, a traditional Japanese stroll and tea garden on the university’s campus. But how do you trap and then transport koi across a major North American city?
Catching the koi
Before there could be any exchange, the Nitobe koi had to be caught. And it was important to capture the fish as gently as possible to minimize stress and injury.
Over winter, koi remain in torpor, a sort of hibernation caused by changes in temperature. They hardly move at all to conserve energy, putting many of their essential biological functions on pause. To catch a koi safely, you need to wait until they wake up for spring and start moving.
During a site inspection it was determined that trapping koi in a small channel between the Garden pond’s island and the shore would give the team the best chance at nabbing the fish. Over a few weeks the koi were encouraged to frequent the channel by feeding them there at the same time of day that the salvage would begin.
On the day of the transfer, the salvage professional (the technical title of people who catch fish) entered the pond in hip waders armed with a seine net. A seine net’s top edge floats on the surface while its bottom edge is weighted, sinking it to the bottom and forming a curtain in the water. Slowly, the koi catchers circle around the fish with the net, cutting off their escape and trapping them in a small channel.
Then the clock started ticking. In order to stress the fish as little as possible, the team gave themselves one hour to catch up to ten fish to donate. Within the area restricted by the seine net, they used hand nets to scoop up the fish one at a time. It was a slow process and it seemed unlikely they would catch ten. Just as time was running out the group had a lucky break and caught several fish in a row, reaching their donation goal.
Cross town traffic
Once the fish were caught, they were placed in camping coolers filled with pond water and carried on a hand cart to the covered bed of a pickup truck. Depending on the size of the koi, some were placed into larger plastic storage containers or camping coolers. No more than a few where placed in each container so they had enough room to move. Bubblers were added to keep the oxygen saturation level comfortable during transport. Think of it like traveling business class, koi style — lots of fin room.
The rest required steady driving from UBC to the Dr. Sun Yat-Sen Classical Chinese Garden downtown — avoiding steep hills and unnecessarily harsh acceleration. Time was again a constraint — the team didn’t want the water to get too warm in the sun.
Just the right pH
Once the koi arrived at their new home, they needed to acclimatize. Water from Dr. Sun Yat-Sen Garden’s pond was gradually combined with the water in the holding tanks. This prevented the fish from going into shock due to differences in water temperature or pH. Then the fish were slowly released into the garden’s pond. The koi appear to be settling in well and have learned that the daily sound of the gong is their new dinner bell.
More than greenery
It’s a feel-good story, and it also highlights the important work of Vancouver’s gardens. They’re more than a nice place to get away from the city. They’re habitats used by some very real wildlife — from otters to herons to pollinating insects. Sometimes, even in a city like Vancouver, species can come into conflict. The gardens may be curated and cultivated, but they perform important ecological functions.