Possible 'cannibalistic behaviour' of sturgeon a 'big concern' for health of B.C.'s Fraser River: conservation group

A large white sturgeon spotted with a smaller sturgeon in its mouth. (Photo by Colin Bond/Fraser River Sturgeon Conservation Society)

A conservation group says it's concerned about the health of B.C.'s Fraser River after a large white sturgeon was spotted with a smaller sturgeon in its mouth earlier this month.

The Fraser River Sturgeon Conservation Society said last week one of its volunteers, Colin Bond, was conducting sturgeon sampling near the Golden Ears Bridge in the lower part of the river when he saw a large fish floating near the surface.

When he got closer, Bond saw the white sturgeon was about 160 centimetres long. Sticking out of that fish's mouth was a smaller sturgeon, about 50 centimetres in length. According to the conservation group, "the entire head and front third of the smaller sturgeon were past the gums and down the throat of the larger sturgeon."

"I have been fishing white sturgeon in the Fraser River for over 30 years, and I have seen many interesting and surprising sights, but I had never seen anything like this," Bond said in a statement shared by the conservation group.

When Bond got closer to the fish, he thought they both looked dead – the large fish wasn't moving at all and its gills were open. But suddenly, the smaller fish began to move. He reached down to touch the larger fish and it too seemed to "jolt back to life."

"It jerked and thrashed and flipped over, with the smaller fish still in its mouth, and it swam off and then down, and out of sight," he said. "It came the surface briefly and made one final splash, then went under."

White sturgeon are the largest species of freshwater fish in North America and B.C.'s Fraser River is home to its last wild population. The conservation group says the fish can live for up to 100 years and grow up to six metres, or more than 19 feet, in length.

FRSCS says the population of white sturgeon has been declining for more than a decade, adding that it's concerned for the species' survival with habitat loss and lack of food, especially after recent catastrophic weather events.

"This observation of, possibly, cannibalistic behaviour is a first for adult fish and occurs on the heels of a stressed environment for the Fraser River after the floods and low returns of salmon and eulachon," the conservation group said.

"It’s a big concern for the overall health of the Fraser River. Research indicates the sturgeon population is projected to continue to decline unless the health of the Fraser River improves."

While Bond searched the area for a while, he didn't see either fish again.

"Hopefully they will both survive and maybe someday I or another volunteer will sample one or both of those fish," he said.

"I know I will keep an eye out for a six-foot sturgeon with a very, very sore throat, and a smaller one with a serious headache."