Since 2007, Stan Orchard and his small crew of four have kept one of the most ravenous and invasive species in the region from overwhelming the Greater Victoria Water Supply.
At the corridor between Esquimalt Lagoon and Finlayson Arm, located at the narrowest point of the Saanich Peninsula, his control operation stems the flow of the American bullfrog approaching from unmanaged populations to the east.
Due to the size of the crew, patrolling can be a B次元官网网址渂igB次元官网网址 problem, he said.
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B次元官网网址淵ouB次元官网网址檙e dealing with a species that every female can produce 20,000 and more eggs in a year.B次元官网网址
The frogs migrate in search of food and water, often gobbling up native species along the way. Their ecological footprint is B次元官网网址渉uge,B次元官网网址 he explained.
B次元官网网址淭heyB次元官网网址檙e eating everything thatB次元官网网址檒l fit in their mouth, both above and below the water.B次元官网网址
A 2013 study co-authored by Orchard, found the stomach contents of 5,200 American bullfrogs contained 15 classes of organisms. This included smaller native frogs, local salamanders and songbirds that come down to the waterB次元官网网址檚 edge to drink.
B次元官网网址淲eB次元官网网址檝e taken coho salmon and bats out of their stomachs,B次元官网网址 he noted. At Langford Lake, they indulge in the eggs of endangered western painted turtles.
As part of CRDB次元官网网址檚 control program, at least one of OrchardB次元官网网址檚 two two-person crews work throughout the active bullfrog season, from late-April to mid-October. Currently, the crew focuses on 12 sites in the CRD, including Langford, Florence and Glen Lakes and associated ponds.
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To capture the frogs, a team cruises out to shallow waters on sturdy inflatable boats. One person rows the boat backwards while the other uses a spotlight to catch a reflection of the frogB次元官网网址檚 eyes. While theyB次元官网网址檙e dazzled by the bright light, the crew can row closer.
Using OrchardB次元官网网址檚 patented B次元官网网址榚lectro-froggerB次元官网网址 B次元官网网址 a seven-foot pole that generates an electrical field 15 inches across B次元官网网址 the frog is zapped, scooped up and placed in a bucket.
Once the pole is engaged, the frogB次元官网网址檚 B次元官网网址渉ind legs go straight out, and it goes stiff as a board for about a minute,B次元官网网址 he added. The captured frogs are subsequently B次元官网网址渉umanelyB次元官网网址 euthanized, measured and composted.
Covering all 12 sites can be difficult for several reasons. B次元官网网址淲eB次元官网网址檙e trying to deploy at least one crew every one of those 175 days,B次元官网网址 Orchard said. However, the inflatable boats tend to blow around when the breeze gets above 15 kilometers an hour, and crews arenB次元官网网址檛 able to work when itB次元官网网址檚 raining.
Funding is another challenge.
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Although it varies from site to site, B次元官网网址渨e can cover about two kilometers of margin in an evening,B次元官网网址 Orchard said. When it comes to Langford Lake, which is about eight kilometers around, it takes B次元官网网址渇ive to six nights, probably, to comprehensively cover all the margins,B次元官网网址 he noted.
B次元官网网址淲eB次元官网网址檙e a bit undermanned given the geographical scope.B次元官网网址
Recently, the district of Metchosin municipal hall has been requesting OrchardB次元官网网址檚 service and deciding on funding because of their own bullfrog problem.
The frogs have been moving around Happy Valley Road at Lindholm Road and Bennett Road. TheyB次元官网网址檝e also been spotted expanding toward Blinkhorn Lake on Kangaroo Road, Orchard said.
With no clear migration path spotted, Orchard said he believes a human introduced them to the area.
The first generation of bullfrogs are thought to be introduced to the IslandB次元官网网址檚 ecosystem in Saanich by two people who claimed to be farming for frog legs in their backyard and a child releasing his pet into the wild.
People need to educate themselves or they can be very destructive when it comes to getting rid of tadpoles, Orchard said. He receives calls B次元官网网址渆very year around MarchB次元官网网址 from people who say they have gone out and collected bullfrog eggs and destroyed them.
B次元官网网址淏ullfrogs donB次元官网网址檛 reproduce in March. Those are native Northwestern salamanders, red-legged frogs, Pacific tree frogs,B次元官网网址 he said. Bullfrog eggs hatch around mid-summer, when water temperatures are around 25 degrees, and quickly grow to around six inches long, he noted.
B次元官网网址淎nd so, they wiped out a whole generation.B次元官网网址
swikar.oli@goldstreamgazette.com
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