This tropical fish, the Jack Dempsey, now
is established in South Dakota.
What resource managers long have feared
would happen because of irresponsible fish hobbyists has become reality: An
exotic species has established itself in a waterway far north of where it
should be able to survive.
Earlier this summer, biologists confirmed
that the Jack Dempsey, a South American cichlid related to the peacock bass, is
reproducing in South Dakota’s Fall River.
How it that possible?
“The hot springs in the river makes it
perfect for cichlids,” said Mike Smith, aquatic nuisance species coordinator
for South Dakota Game, Fish and Parks. “We first found a Jack Dempsey there in
2009. Then, two weeks ago, we found multiple-year classes.
“And there’s no way that the fish could
have gotten there except aquarium release.”
Water nearest the springs stays at about 70
degrees year around, which allows the exotic fish to survive brutal South
Dakota winters.
In this case, the Jack Dempsey’s impact on
native species likely will be minimal. Few other predators live in the shallow
water, and forage species gobbled up by the aggressive cichlid can be
replenished from populations outside the range of the hot spring’s influence.
But the discovery is significant because it
confirms that exotics can use thermal refuges provided by springs or warm-water
releases from power plants to survive in cold climates.
Jack Dempsey and another popular aquarium
species, the red-rimmed melania snail, now live in the hot springs of South
Dakota's Fall River because of irresponsible aquarium owners. Photo courtesy of
South Dakota Game, Fish & Parks.
Could the piranha be the next exotic fish
to become established? Or its much larger cousin, the pacu? Every summer, media
across the country report catches of both fish in ponds, lakes, and reservoirs.
For example, a pacu was caught in Illinois’ Lake Lou Yaeger in June. And at
Missouri’s Lake of the Ozarks, piranha captures have been reported several times
since 2007.
Fish hobbyists also have contributed to
troublesome infestations of plants such as Brazilian elodea, parrot feather,
yellow floating heart, and even hydrilla.
“At a lot of our lakes, people just dump
their aquariums to get rid of whatever they don’t want anymore,” said Tim
Banek, invasive species coordinator for the Missouri Department of
Conservation.
Bill Frazier, conservation director for the
North Carolina B.A.S.S. Federation Nation, also has seen evidence of aquarium
dumping while serving as monitor of water quality for the city of High Point.
He thinks the time is long past for directing blame primarily at anglers,
especially bass fishermen.
Much of the problem, he insists, lies
squarely with aquarium hobbyists and the pet industry that supplies them, as
well as with nurseries that sell exotic aquatic plants.
“I haven’t seen a single trace of any
invasive (plant) at the ramps, transferred by boat in 28 years,” he said.
“I know the overall perception is that
weeds can be spread by anyone with a watercraft. I am not denying this
pathway,” Frazier continued. “I just do not believe it as significant as
everyone would have you believe.”
The North Carolina water expert has found
parrot feather upstream of a submerged roadbed, where boats can’t go. He has
discovered water hyacinth just downstream from a farmer’s market that featured
the exotic in a water fountain. And he has seen a discarded aquarium underneath
a parrot feather infestation, where the shoreline borders a large apartment
complex.
“Some time later, a bank fisherman caught a
skillet-sized pacu there,” he added.
And while anglers and the fishing industry
pay license fees and excise taxes to finance management of aquatic resources
degraded by aquatic invaders, these special interests are allowed to escape
responsibility for the damage they do.
“This is what we need to be attacking and
taxing,” he said.
The North Carolina conservation director
added that waterfowl, wading birds, and even mammals can spread plants as well.
“I have seen beavers moving this stuff from
decorative ponds to natural lakes,” Frazier said. “I watched a momma beaver
taking parrot feather by the truckload from a decorative pond to a stream below
--- and her den.”
Water quality expert Bill Frazier found
invasive water hyacinth at this farmers market, just a short distance from a
river.
Yes, anglers do contribute, transporting
plant fragments and --- more likely --- mussels on boats, trailers, and tow
vehicles, as do owners of jet skis, cabin cruisers, and pontoon pleasure boats.
Resource managers are combating this threat with both mandatory and voluntary
boat inspections at put-in and take-out sites, as well as check points at state
borders.
“This year alone, nearly 80 infested boats
have been stopped on the borders of Idaho, Montana, Oregon, and Washington,
most coming from Lake Mead,” reported the San Francisco Chronicle.
In those western states, mussels are
considered the primary danger, because they can impede water flow by blocking
intakes at major reservoirs.
For much of the country, though, Asian carp
are the major concern. They are spreading up the Missouri and Mississippi and
east and south in the Ohio, Cumberland, and Tennessee River systems, well as
threatening to enter the Great Lakes.
“Asian carp are the No. 1 threat for us,”
said Missouri’s Banek. “The floods of 2011 made it worse, and they have the
potential to be more detrimental than zebra mussels.”
South Dakota’s Smith echoes that sentiment.
“We’re seeing exponential growth in their numbers,” he said.
And while floods have helped bighead and
silver carp move into new areas, anglers also might have contributed.
“Most people don’t know how to identify
fish,” Banek explained. “In collecting bait below dams, they could be getting
juvenile Asian carp as well as shad.”
Uneducated anglers might even unknowingly
move adult Asian carp from one fishery to another, as a South Dakota creel
survey clerk learned on Lewis and Clark Reservoir.
He approached two young anglers who said
that they had fished all day and caught “only one walleye and one salmon.”
That “salmon” turned out to be a bighead
carp that the two had caught in the river below the dam, before they moved
their boat up into the lake in the afternoon.
The clerk reported that the anglers never
had heard of Asian carp.
“This is what we are up against in trying
to stop the spread of these fish,” said South Dakota biologist Sam Stukel.
“It’s going to take a miracle.”
Bait fishermen also are unknowingly
spreading invasive crawfish species. About half of U.S. states and Canadian
provinces have restricted use, sale, and transport of crawfish, or are
considering doing so because the threat that these invaders pose to native
crawfish and the fisheries that they inhabit.
In considering regulations to prohibit the
import and sale of crawfish, the Missouri Department of Conservation discovered
25 invasions in its streams. It also learned that 40 percent of anglers
surveyed release live bait that they don’t use, more than 50 percent of bait
shops sell species not native to regions where they are sold, and 97 percent of
bait shop owners admitted or showed that they didn’t know what species they
were selling.
“It is important for anglers to understand
that any crawfish species moved from its natural range to new water bodies has
the potential to become invasive in those new waters and to adversely affect
fisheries,” said Missouri biologist Bob DiStefano.
Not surprisingly, the aquaculture industry
and Farm Bureau oppose Missouri’s proposed regulations, citing economic hardship
for those who import, grow, and/or sell crawfish. In the Mid-South years ago,
fish farmers made the same argument in convincing resource managers to allow
them to import and sell bighead and silver carp.
