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Entries in Great Lakes (115)

Monday
May042015

Lionfish Threat Continues to Spread

As harmful invasive fish species, Asian carp seem to garner most of the headlines, mostly because of the threat that they pose to the Great Lakes.  But the lionfish, a marine invader from the Pacific Ocean, is decimating native species through much of the Caribbean, as well as spreading up the Atlantic coast and across the Gulf of Mexico. (See previous post.)

And now it’s been discovered off the coast of Brazil, which suggests the entire  coast of South America likely will be invaded.

“When the researchers analysed the fish’s DNA, they found that it matched the genetic signature of the Caribbean lionfish population, and not that of specimens from their native Indo-Pacific region. This suggests that the fish may have reached Brazil through natural larval dispersal from the Caribbean, the study’s authors say,” reports Nature.

“But Mark Hixon, a marine ecologist at the University of Hawaii at Manoa, says that ocean currents typically flow in the wrong direction for larval dispersal from the Caribbean to the southeastern Brazilian coast. He says that it is just as likely that the lionfish was brought to Brazil by humans. ‘Lionfish are easy to capture and make beautiful pets,’ says Hixon. ‘It’s easy to imagine boaters carrying lionfish as short-term pets in bait tanks or other containers on their vessels.’”

The Invasive Species Action Network adds this:

“Lionfish are vicious predators that eat any fish or invertebrate they can fit in their mouth. They reproduce easily and the rate at which they have expanded their range shows that they are thriving in this environment. With no predators in our waters they are rapidly impacting many habitats.

“Humans can have an impact. Fortunately, lionfish are very tasty and many restaurants have added them to the menu. In many areas concentrated spearfishing is keeping local populations in check but this is not a practical method of control across their range. In the USA, NOAA is the lead agency on this problem and they are the best source for lionfish information and research.

“NOAA has recently released the draft National Invasive Lionfish Prevention and Management Plan While the plan is still in draft form, it is scheduled to be approved at the next meeting of the Aquatic Nuisance Species Task Force meeting scheduled for the first full week in May.”

Wednesday
Apr292015

Survey Reveals Carp DNA Throughout Chicago Waterway System

If Asian carp aren’t in the Great Lakes, they can’t get much closer. Sampling of the Chicago Area Waterway System (CAWS) last fall revealed carp eDNA throughout the system, including near a lock in downtown Chicago, just one block from Lake Michigan.

“Prevention needs to happen now and the U.S. Army Corps of Engineers and other key decision-makers should take swift action,” said the non-profit Alliance for the Great Lakes (AGL), which charges that the Corps lacks direction, as revealed in its Great Lakes-Mississippi River Interbasin Study.

“DNA evidence is an early detection tool to understand the potential movement of carp, and testing results have consistently found DNA hits on a path closer and closer to the Great Lakes over the past several years of testing,” the group added.

The Corps report outlined eight possible ways to stop migration of Asian carp into the Great Lakes, with the most expensive being an $18.3 billion separation of the CAWS from Lake Michigan. Meanwhile, the Alliance supports measures to temporarily reduce risk, including construction of a new channel and control technologies in the approach to Brandon Road lock and research on reconfiguration of locks in general.

But long-term issues with Chicago’s water system infrastructure must be addressed to keep the carp out, emphasized Jennifer Caddick, AGL spokesperson.

“It’s complicated. You can’t just build one dam and solve the whole problem,” she said. “There’s a lot of work to be done, but we need intensive focus.”

If/when Asian carp become established in the Great Lakes, consequences could be catastrophic for the multi-billion-dollar sport fishery. That’s because the exotic fish are fast-growing, prolific, plankton eaters. They likely would outcompete the many young and adult native fishes that rely on phytoplankton and zooplankton for their primary forage.

Additionally, the U.S. Geological Survey has identified 22 rivers in the U.S. portion of the Great Lakes that would provide suitable spawning habitat for Asian carp.

Sunday
Dec282014

Despite Phase-Out, Pollutant Persists in Fish

Despite being phased out a dozen years ago, a persistent chemical formerly used in Scotchgard still contaminates bass and other fish in the Great Lakes, and urban rivers, according to a recent study by the U.S. Environmental Protection Agency (EPA).

Researchers found perfluorooctane sulfonic acid (PFOS) in all of the 157 fish sampled from nearshore waters in the Great Lakes and in 73 percent from 162 rivers.

“This just shows that PFOS still dominates,” said Craig Butt, a Duke University chemist. “Even though production stopped more than a decade ago, it’s still the main perfluorinated acid in the environment.”

PFOS is a suspected endocrine disruptor that has been linked to low birth weights, reduced immune system function in children, and high blood pressure during pregnancy. EPA hasn’t established a “safe” dose for humans, but Minnesota health officials recommend eating only one meal of fish per week if PFOS concentrations are 40 to 200 parts per billion, and only one meal per month if 200 to 800 parts per billion.

About 11 percent of the fish samples from U.S. rivers and 9 percent from the Great Lakes exceeded 40 parts per billion.

The 3M Company, a major manufacturer of PFOS, voluntarily stopped production in 2002, after scientists discovered the chemical was building up in water, wildlife, and people. PFOS and other perfluorinated compounds were used in oil- and water-resistant coatings for clothes, carpet, paper, cookware, and flame-retardant foams.

(This article appeared originally in B.A.S.S. Times.)

Wednesday
Nov122014

Atlantic Salmon Reproducing in Great Lakes

Atlantic salmon fingerlings. USFWS photo
A chance discovery by a college student reveals that Atlantic salmon are reproducing in the Great Lakes --- at least in the St. Mary’s River, which connects Superior and Huron.

“We were conducting research for my sturgeon thesis when we found the Atlantic salmon fry,” said StefanTucker, a Lake Superior State University graduate. “It was very exciting to everyone who was a part of my research to imagine what we had just stumbled upon.

“While sorting through my samples at the lab with Roger (Greil), we began to ID the salmonids and Roger had a suspicion that they were Atlantics,” he added. “We caught wild Atlantics in our next two sampling events, so we wanted to confirm our ID and we sent a few to Dr. Gerald Smith at University of Michigan, who confirmed the identification.

Atlantic salmon (Salmo salar) are native to Lake Ontario, but their populations severely declined by the late 1800s, according to Tucker’s abstract. During the early to mid-1900s, Atlantic salmon were stocked throughout the Great Lakes in effort to reestablish them into Lake Ontario and introduce the species into the upper Great Lakes. However, these efforts had minimal success.

In 1987, LSSU, in cooperation with MDNR Fisheries, began stocking Atlantic salmon in the St. Mary’s River. While the effort has resulted in a very successful recreational fishery, along with an excellent educational experience for students, it appeared that Atlantics were still not reproducing naturally even though they would return to the river spawning grounds every year. Biologists wondered if competition from other salmonids spawning in the St. Mary’s in greater numbers – including chinook and pink salmon – was keeping Atlantics from thriving.

While this is the first documentation of natural reproduction of Atlantic salmon in the upper Great Lakes, Tucker’s study concludes that “the extent of natural reproduction and mechanisms influencing reproductive success are unclear and warrant further attention.”

Monday
Oct272014

Artificial Reef Projects Expand to Shallow Water

We’ve been using artificial reefs to improve habitat for fish and other aquatic life in deepwater ocean habitat for awhile now. But we’ve just begun to tap their potential in shallow water.

For example, artificial reefs finally are going to be deployed in Florida’s St. Johns River, following years of research and discussion.

“While the artificial reefs will not replace the natural system, they will help. The nooks and crannies will offer small spaces for small fish to hide and live. The concrete will provide a surface for marine growth to occur. Barnacles and oysters are expected to become established on the rocks,” says the Times-Union.

“Not only do they become potential food for fish, they also filter sediment and other particles out of the water, thereby improving water quality. The small fish become food for the larger fish, and so grows the food chain.”

Up in the Great Lakes, meanwhile, a spawning reef of four acres is being built in the St. Clair River, to benefit walleye, sturgeon, and whitefish.

The project at Harts light is the sixth spawning habitat built by the Michigan Sea Grant in the St. Clair and Detroit rivers

During the late 1800s and early 1900s, those systems were dredged to create deep shipping channels. In the process, 800 to 1,000 acres of prime spawning habit were destroyed.

And out in California, scientists have discovered that offshore oil rigs provide some of the most productive fish habitat in the world. They determined that the structures are home to 27 times as many fish as natural rocky reefs in the area.