Invasive peach blossom jellyfish are seen in water samples taken from Killarny Lake in Saanich, BC in 2022.

Image Credit: SUBMITTED/ Invasive Species Council of BC/ Florian Luskow

The presence of invasive jellyfish in Osoyoos Lake was discovered in recent years, yet the full impact of the invaders on native ecosystems isn’t clear yet.

The peach blossom jellyfish originates in China and it isn’t clear how they’ve made it into 34 B.C. lakes since the first recorded sighting was made three decades ago. 

All the infected lakes are located on Vancouver Island, Sunshine Coast and Lower Mainland except for Pavilion Lake located between Lillooet and Cache Creek, and most recently Osoyoos Lake that got its first recorded jellyfish sighting in 2022.

“These tiny invaders can directly impact our freshwater ecosystems because the jellyfish eat plankton that juvenile salmon or trout depend on,” said Lisa Scott with the Okanagan and Similkameen Invasive Species Society. “We are still trying to understand the scale and scope of the issue, including the level of risk to our indigenous species.”

The society has been monitoring Osoyoos Lake for over a decade in partnership with the province to collect water samples that are sent to a lab in Vancouver to be tested for invasive zebra and quagga mussels. 

“Lab technicians look for microscopic organisms, and the jellyfish are small but still visible,” she said. “We are well positioned to do lake monitoring and some sort of sampling program but I don’t know what that looks like yet."

The society is working with the BC government to determine the next steps to take for managing the jellyfish in local water bodies.

“Knowing the invasives are in the area is an important first step but we need to get a good grasp on how widespread they are, the impacts and how they are being spread to develop a management plan," Scott said.

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Dr. Florian Luskow was one of two authors behind a report on the jellyfish published in the Canadian Journal of Zoology in September, 2024. He completed the research during his postdoctoral fellowship at UBC’s department of earth, ocean and atmospheric sciences last year. 

He's also the one who received the report of the jellyfish sighting in Osoyoos Lake on July 31, 2022.

“The reporter was a woman that reached out directly to me,” Luskow said in an email to iNFOnews.ca. “The description of the sighting was pretty accurate and I don’t have reason to believe in a mis-identification or false news.

“The report came from a shallow bay and from what I know about the species, polyps may be already widely distributed but the production of jellyfish is not yet happening regularly.”

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Future sightings of the jellyfish could increase rapidly as climate change extends its range, according to a UBC interview with Luskow and fellow researcher and author Dr. Evgeny Pakhomov conducted in September, 2024.

Due to a lack of research, not much is known about how the jellyfish impacts ecosystems and biodiversity, but the concern is they harm indigenous species by competing with them for space and food.

So far only male jellyfish made up of the same genetic material have been found, indicating they are clones originating from the same polyp. The fact male jellyfish cannot complete sexual reproduction will limit their ability to adapt to new environments.

A polyp is a stage of a jellyfish that lives at the bottom of the water at roughly a millimetre size that produce a floating medusa form of jellyfish that floats in water when the temperature is more than 21C. Peach blossom jellyfish medusae are roughly one inch long and delicate looking while armed with hundreds of tentacles used to sting and paralyze fish, and have been spotted both individually and in groups of thousands.

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The jellyfish need mild winters and high summer temperatures to reproduce so as freshwater temperatures increase with climate change, they are likely to spread and increase their range to higher latitudes. While jellyfish stings cannot pierce human skin, they can potentially alter fresh water ecosystems and negatively impact native fish.

Scott said public can help prevent further spread of peach blossom jellyfish by cleaning, draining and drying watercraft, equipment and gear when moving between water bodies. Local residents are encouraged to report any sightings of the jellyfish to Okanagan and Similkameen Invasive Species Society and try to include a photo of the specimens.

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