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By Veronica Beltran

nechako white sturgeon

Otters munching on sturgeon released for conservation purposes, says study led by UNBC grad

Oct 30, 2020 | 10:57 AM

PRINCE GEORGE–It was suspected four years ago, by scientists with the Nechako White Sturgeon Recovery Initiative, that otters were eating some of the juvenile sturgeon being released into the river for conservation purposes. Now, a study by a UNBC graduate student is showing just how much the sturgeon are being affected.

Cale Babey, has spent the past two years tracking evidence of otter predation.

Sturgeon released from the Nechako White Sturgeon Conservation Centre in Vanderhoof are implanted with a passive integrated transponder (PIT) tag, a small device that works like a bar code, uniquely identifying each fish.

“These PIT tags are usually used to identify fish that are captured during a juvenile sturgeon monitoring program, but they also provide a useful tool to study otter predation,” says Babey.

“When an otter eats a sturgeon, the tag is often swallowed and later defecated at specific sites otters use as latrines.”–Cale Babey, UNBC Graduate

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Babey has visited dozens of latrine sites along the Nechako River and used a scanning device to locate the PIT tags.

So far, researchers have collected 1,170 juvenile sturgeon PIT tags from 59 identified latrine sites, including 524 tags collected between 2016 and 2019.

And it’s not just juveniles being released for conservation reasons, otters are targeting wild sturgeons too. Earlier this year researchers collected the first evidence of the predation of a wild juvenile white sturgeon. Based on the information from the PIT tag found in a latrine site, the wild fish was at least 19-years-old, 69.1 cm long, and weighed two kilograms.

“These findings suggest that even larger sturgeon and wild sturgeon that have lived several years in the river are susceptible to otter predation.”–Cale Babey, UNBC Graduate

The largest sturgeon that exhibited evidence of otter predation was 69.8 cm long and weighed 2.1 kilograms at the time of release.

These findings will help researchers find new strategies for future releases of the endangered Nechako white sturgeon.

“Studying and understanding this predation is just one piece of the larger recovery puzzle for the Nechako white sturgeon,” says Babey.