THE BLACK SPOT
I remember reading Treasure Island when I was young and hoping
that no one would ever give me the Black Spot. The Spot was the
symbol given by pirates to those they considered guilty of some
dastardly crime against them.
But it wasn’t me that got it. It’s the trout in Spring, in Lower
Chain, in Swan Lake, and in a number of other pothole lakes, and I
don’t think they’re guilty of anything much.
You’ve probably seen it on some of the rainbows you’ve
caught. Lumps along the sides and belly, often looking like
blisters. When they’re filleted you see the black specks in the
flesh next to the skin. It’s fairly common and it seems to be
spreading quite rapidly around the local lakes. It’s a parasite. The
scientific name is cryptocotyle.
Apparently it first came to North America in snails off European
boats. The eggs of this little fluke mature in the water and first
penetrate snails. When they’re a little bigger they leave the snails
and penetrate the tissue of fish. The fish is eaten by a loon or
other bird and the adult worms live in the loon’s mouth where they
produce eggs. The eggs pass through the loon’s digestive system
unharmed and are released back into the water with the feces.
And the cycle repeats. Now one small hole doesn’t hurt, but lots
of them cause stress and, in extreme infections, death to the fish.
What makes it worse and what leads to the blistering and sores are
the bacteria in the water that collect in the hole made by the
parasite.
With lower water levels and increased temperatures lakes have
more bacteria. It’s probably the birds that spread it from lake to
lake although one Fish and Wildlife biologist told me it could even
be the stocking trucks dipping their hoses into an infected lake and
then moving on to the next one.
Sounds to me similar to how some other infections are spread!
What to do? Unfortunately not much. They can
live up to four years in a fish. I’m told they aren’t harmful to
humans and that cooking kills the parasite, but you can still get a
belly-ache from eating them. That comes not from the parasite but
from the bacteria that invade holes in the fish’s sides. So beware
the curse of the Black Spot, matey!
- By Peter Little
Reprinted with permission
The
Flycaster, Edmonton Trout Fishing Club.
