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Entries in quagga mussels (35)

Tuesday
Feb242015

Mussels Could Be Contributing to Toxic Algae Blooms

Proposed reductions in phosphorous runoff from agricultural lands might not be enough to counter Lake Erie’s increasing susceptibility to toxic algae blooms, according to University of Michigan researchers.

"Our results suggest that current phosphorus loading targets will be insufficient for reducing the intensity of cyanobacteria blooms to desired levels, so long as the lake remains in a heightened state of bloom susceptibility," said lead author Daniel Obenour of the university’s Water Center.

That “heightened state” led to nearly half a million Ohio and Michigan residents being deprived of drinking water for several days in early August because of a cyanobacteria bloom containing the toxin microsystin.

The problem seems to be that the blooms are becoming more sensitive to phosphorus, according to the scientists.

But what has caused this and the corresponding increase in size of cyanobacteria blooms since the mid 1990s? That’s not so easy to explain.

Computer modeling revealed that a special form of phosphorus, DRP (dissolved reactive phosphorus) is more readily absorbed by algae, but it did not explain increased bloom susceptibility. Also, late-summer surface water temperatures did not increase enough to exacerbate the problem.

Exotic quagga and zebra mussels, however, could be a factor. The filter-feeding shellfish gorge on many species of phytoplankton, but avoid those that produce toxins. In other words, the latter now have less competition for nutrients, including phosphorus.

"We tested to see if the increase in the DRP fraction could be the cause, and it did not pass the test. It also does not look like water temperature is driving the increased susceptibility,” said Don Scavia, co-author and aquatic ecologist. “We're thinking it may have been the increase in mussels.

"As long as the lake remains in this heightened state of susceptibility, this problem is likely to persist,” he added. “That means we need to better understand what is driving the increased susceptibility and whether it can be controlled, or if deeper phosphorus reductions are needed.”

Friday
Mar282014

Mapping the Invasion

This screen shot shows zebra and quagga mussel invasion as of 2006.

Nature Conservancy has produced some great interactive maps showing how invasive aquatic species have spread out across the country from their point of introduction.

Featured species include bighead and silver carp, zebra and quagga mussels, Eurasian ruffe, round goby, sea lamprey, and black carp.

Also, in late 2012, the organization released a report saying that aquatic invasive species “cost businesses and consumer in the Great Lakes region hundreds of millions of dollars annually in direct costs and even more from indirect costs related to removal, maintenance, and management of those species.

“Meanwhile, state and federal governments are currently forced to spend additional millions as they attempt to control the impacts and prevent the spread of AIS (aquatic invasive species).”

According to the report, the largest industry affected by AIS in the Great Lakes is tourism and recreation, which is responsible for employing more than 90,000 people in the region, generating $30.3 billion annually in revenue. Costs range from monitoring and controlling AIS to lost revenue from beach closings affecting hotels, restaurants and other tourism-related businesses.

Tuesday
Feb252014

Providing Quality Fisheries Is Complicated Challenge

Photo by Robert Montgomery

Fisheries management often is an enigma wrapped inside a riddle, and the more we learn, the more we realize how much we don’t know. That’s why I respect fisheries biologists.

To provide us with quality fisheries, they must “manage” not only the fish, but the fishermen. Plus, they must factor in the effects of development, pollution, water degradation, introduction of exotic species, and many other variables.

Up in Minnesota, anglers and biologists have compiled some impressive statistics regarding the fragility of a fishery.

On a 160-acre private lake this winter, 97 northern pike have been caught and released 431 times. Additionally, 24 measured 30 inches or longer and had been caught an average of 6.83 times each.

“Now think about how long it takes a fish to grow,” said Dallas Hudson, one of the anglers who initiated the idea of not spearing or keeping northern pike caught on hook and line. “A northern in our lake will take six years to reach 24 inches and nine years to reach 30 inches and weigh 7 or 8 pounds.

“So it becomes pretty obvious what happens if people keep not only the bigger fish, but the medium-sized fish, say 24 to 30-inch northern. You end up with what we have in many Minnesota lakes: stunted fish.”

Fisheries supervisor Doug Kingsley added, “Dallas’ work shows us pretty clearly how vulnerable northerns, in particular, are to being caught. When you can catch the same fish 15 times over, and sometimes two times in the same day, it seems clear that in many lakes we need to limit the harvest of larger fish if we want bigger northern pike in our lakes.’’

For example, the work by Hudson and his associates clearly suggests that--- at least on smaller lakes--- larger northern pike can be overharvested. Still, many Minnesota anglers likely would oppose reducing the current harvest regulation, which allows three northern daily, with one longer than 30 inches. Plus, spear fishermen convinced the legislature to pass a law in 2011 that limits the establishment of length-based harvest regulations on 100 state lakes.

Arizona Game and Fish photo

Out in Arizona, fisheries managers are trying to figure out how to reign in an exploding population on non-native gizzard shad that threatens the health of bass and crappie fisheries at Apache and other Salt River impoundments.

In Lake Havasu, however, the combination of two introduced species seems to have ignited a premiere fishery for redear sunfish, also known as “shellcracker.”  Just recently, Hector Brito caught a 5.8-pound lunker, which likely will be declared a world record. In 2011, Bob Lawler caught the previous record --- 5.55 pounds--- also at Lake Havasu.

In the Northwest, meanwhile, champions of native species have been blaming bass for decades for the decline of salmon fisheries. In truth, dams destroyed salmon habitat and blocked habitat, while creating impoundments where bass have thrived.

Still, nature is resilient. That’s why this year’s projected spawning run of fall-run Chinook (king) salmon on the Columbia could be the largest since 1938. That was the year after the Bonneville Dam was completed, blocking their migration route and enabling the fish to be counted.

Fisheries managers suspect that the healthy run is attributable to good ocean conditions for the salmon while they are out at sea, as well as a mandated  water releases from spill gates at dams on the Columbia and Snake River dams, allowing small salmon to move downstream.

Friday
Jan102014

Mussel Threat Grows in West

Unlike zebras, quagga mussels can colonize soft substrates as well as hard surfaces, such as this boat prop.

Out West, resource managers are waging a fierce battle to keep zebra and quagga mussels out of their lakes and reservoirs.  I wish them well, but all it takes is one boat out of thousands launched to infect a waterway.

At Lake Tahoe last year, boat inspectors found 36 vessels infested with exotic species, as they inspected more than 7,000 and decontaminated more than 4,000. Most importantly, though, managers found no evidence of mussels in the lake.

Other fisheries were not as lucky, as a quagga infestation was discovered in California’s Lake Piru, with boat quarantines implemented at Cachuma and Casitas.

By the way, quaggas are even more troublesome than zebras, as they can withstand colder water than their cousins and they can colonize soft substrates.

According to the Great Lakes Echo:

“These abilities have helped it colonize most of benthic Lake Michigan. Just like zebra mussels, quagga mussels are quite effective at clogging water intake pipes and other infrastructure. Mitigating these impacts has cost Great Lakes residents millions of dollars.”

The Echo annually publishes Tim Campbell’s invasive-species rewrite of “The Twelve Days of Christmas, which he created in 2011 for the Wisconsin Sea Grant.

“Twelve quaggas clogging, ‘leven gobies gobbling, ten alewives croaking, nine eggs in resting, eight shrimp ‘a swarming, seven carp and counting, six lamprey leapingFIVE BOAT-WASH STATIONS! Four perch on ice, three clean boat steps, two red swamp crayfish and a carp barrier in the city!”

Monday
Nov182013

Safe Launch Saves Boaters Coming and Going

Photo from www.boattest.com

If you haven’t forgotten to put in the drain plug before you launch, chances are that you know someone who has.

Consequences can range from aggravating--- fishing is delayed--- to catastrophic--- the boat sinks.

But did you know that pulling that plug when you exit the water also is important? That’s because of the threat posed to our fisheries by exotic mussels and other invasive aquatic species, which can hitchhike in water left in the boat. Once established in a new water body, they crowd out native species, smother fish habitat, and block intakes, endangering public water supplies.

As zebra and quagga mussels have spread into Minnesota, across Texas, and over the Rocky Mountains, the danger has become even more acute, and resource managers are taking action. For example, the Texas Parks and Wildlife Commission recently approved a rule requiring anyone leaving or approaching public waters in 17 north Texas counties to drain their boats and is proposing that 28 additional north and central counties be added to the mandate.

In some places, forgetting to take out that plug is going to hit anglers and other boat owners in the pocketbook, as they are fined for violating the law. That’s how seriously resource managers are taking this threat.

But for a few bucks you can be pro-active to protect yourself, your boat, and the resource, courtesy of the Safe Launch Drain Plug Reminder System developed by Steve Colsher and Ray Haber.

It’s ingenious, but simple and easy to install. You just place a metal flex hook into the drain hole.  The hook is attached to a lanyard with a split ring carabineer that easily attaches to one of the transom/trailer tie-down straps. When you disconnect the tie-downs, you can’t help but be reminded to remove the hook and insert the plug.

Conversely, when leaving the water, you will see the Safe Launch lanyard, which will remind you to remove the plug and insert the hook, which does not impede water drainage.

Colsher told Activist Angler that he originally came up with the idea as a way to remind himself to put in the plug on his own boat. “But as time went on, and we were looking into things, we began to see this as a safety product that could save people $500 or $600 if they forget to plug out the plug.”

It also can help prevent the spread of invasive species, which is why the Lake Havasu Marine Association is partnering with Safe Launch. It promotes Safe Launch as part of its “clean, drain and dry” program for boats, while the company donates a percentage of sales to the association.

“This is a model that I think will work well with other associations,” Colsher said. “It’s a win-win for both.”