Category: Fish

Research Results: If You Restore It, Will Pike Come?

It’s well known that some migratory fish species, like salmon, are able to trace their way back to the stream where they were born. However, conservationists have no idea if this is the case for hundreds of other fish species.

Do pike return to spawn in the streams where they were born, a la salmon?

Not necessarily, at least in the Green Bay watershed. If there’s suitable habitat, pike will find it and spawn. That’s the central finding of research conducted by the University of Wisconsin’s Pete McIntyre and Dan Oele.

This result may sound like a let-down, but in reality it’s a relief for conservationists in the Green Bay area. The Nature Conservancy and other conservation groups are focused on restoring streams for pike and other fish, but the best methods to accomplish that goal remain uncertain. If pike returned to their natal streams to spawn, they may never find a restored stream even if it contained suitable habitat.

That’s not the case, which is good news for conservation efforts.

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Notes from Silver Creek: Computer Modeling for Stream Conservation

What effects will land use changes have on a stream and its wildlife? How do conservation managers know what will happen in a stream when a restoration project takes place? Will it really lower water temperatures? Will fish thrive?

Surely conservationists can’t see into the future? 

Actually, stream managers now use sophisticated computer modeling to predict the outcomes of their activities. These models allow them to see how planting native shrubs, for instance, will alter stream flows and water temperatures.

In 2010, The Nature Conservancy was contacted by Maria Loinaz, a PhD candidate  at the Technical University of Denmark and the University of Idaho.  She was interested in developing a hydrologic model of the Silver Creek watershed using software called MIKE SHE/Ecolab.

This software is changing the way stream managers engage in restoration. It incorporates data on both groundwater and surface water, including stream flow, precipitation, vegetation and soils to accurately predict the effects of a new activity on a stream.

Maria proposed using the MIKE SHE program to model the groundwater and surface water systems and use the EcoLab program to build a water temperature model. Together these would allow her to model what happens to stream temperatures when riparian buffers were planted or stream flows increased.  Maria also wanted to incorporate fish data to see whether she could model where, based on the hydrology and temperature, fish would thrive in the system.

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Discovery: New Cave Fish Species Sees “Light of Day”

Deep inside a remote cave in northern Vietnam, Craig Leisher aimed his headlamp at the water. Several small, strange-looking fish flashed by. He readied his butterfly net and quickly tried to scoop one up but missed. He tried again.

Leisher eventually caught four species of fish. Further analysis revealed that two species were already known to science, one was a new species and one was a mystery.

The new species, Schistura mobbsi, has no eyes, no pigmentation and a limited ability to sense motion. It is a type of loach — a river-dwelling genus that includes both subterranean and above-ground species.

Leisher and ichthyologist Maurice Kottelat recently published the discovery in Ichthyological Explorations of Freshwaters … 10 years after the fact.

Why did it take 10 years for Schistura mobbsi to make its public appearance in the scientific literature?

Let’s re-wind.

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Science at Emiquon: Restoring a “Wetland of Dreams”

The airboat whirs over the shallow wetland, as huge flocks of coots, ducks, herons and other birds flush before me.

It’s the kind of scene that could entice one to wax rhapsodic on the beauties of untrammeled nature.

Except this isn’t. Not quite.

Just six years ago, this expansive wetland was cornfields and a cattle feedlot.

It’s now Emiquon Preserve, a 6,600-acre project on the Illinois River that is one of the largest floodplain restoration projects in the Midwest.

How do you go from cornfield to wildlife paradise?

The easy answer is to invoke Field of Dreams: Build it, and they will come.

The hard answer: Research, and lots of it. Behind Emiquon’s incredible conservation success is an extensive science program.

Each March, the University of Illinois at Springfield’s Therkilsden Field Station at Emiquon—the preserve’s flagship research center—convenes a gathering of researchers to share results from their studies.

While it may look like the wetland is nature primeval, it is this research that is restoring what once was known as the “inland fishing capital of North America.”

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Indonesia’s First Shark Sanctuary – Raja Ampat Leads the Way

This week has without a doubt been the highlight of my career as a marine conservationist. And, as someone who has had a long-term love affair with the world’s oceans, it’s been a life highlight as well.

On 20 February 2013, the Raja Ampat government officially announced that it has declared its entire 4 million hectares of coastal and marine waters a shark sanctuary.

This means that all harvesting of sharks is now prohibited in its waters. In addition, the sanctuary also gives full protection to a number ecologically and economically important ocean species, such as manta rays, dugongs, whales, turtles, dolphins and ornamental fish species.

Why is this important and why should we care?

Well, sharks have a really hard time in our oceans. Beyond the often over-amplified fear people have of sharks, they are also targeted for their high-priced fins or are caught accidently in fishing nets.

It is estimated that at least 26-73 million sharks are killed each year globally, mostly for their fins. Shark finning is one of the cruelest practices around—it involves throwing a still-breathing shark overboard with its fins cut off and its body bleeding into the water.

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Big Fish: Roadside Pike

Northern pike have always conjured images of wilderness: big, wild lakes, the scent of pine trees, a loon calling in the background.

Large, predatory fish, pike do indeed hunt lake shallows. They’re found in big places—from remote Alaskan and Canadian waters to the Great Lakes.

Come spring, they actually are on the move—traveling up rather small streams in order to spawn.

Researchers in Green Bay, Wisconsin have been tracking pike movements by doing chemical analyses of pike otoliths, also known as ear stones. Otoliths have annual growth rings, like trees, and accumulate trace chemicals from the surrounding water column as they form.

Many streams have a specific—and unique—combination of chemicals, and this chemical profile shows up in the otolith when fish move from one chemically distinct water body to another.

As such, researchers can determine where pike spent different years of their lives – and if they return to the streams where they were born, or if they use different streams.

This knowledge, in turn, helps conservationists focus on restoring streams that will actually be used by pike.

When I headed out with researchers, I imagined we’d search for pike in wild, lonely places. Instead, we immediately drove to an area across from a small, rural housing development, cars whizzing by as we checked pike traps.

Where could the pike possibly be?

It turns out: In a roadside ditch.

These little ditches— the kinds designed to keep water off the road—have been used for a very long time by pike as spawning sites.

With hundreds of lakes, streams and wetlands within miles of Green Bay, it may seem odd to focus on ditches. But those little channels may be vital in restoring pike populations.

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Big Fish: Return of the Alligator Gar

Once they were the river’s top predator: a fish that could reach ten feet or more, with thick armored plates as scales and imposing jagged teeth.

You would see their long, tooth snouts poking out from the river’s surface, gulping air—their adaptation for thriving in warm, deoxygenated water.

Alligator gar.

They thrived in a large swath of mid-western and southern waters, but by the early 1900s, they were already starting to disappear, a trend that continues to this day.

They were declared extinct in Illinois in 1994. But a new restoration and research effort aims to bring back these incredible fish, and help conservationists at other rivers and waters better protect them.

When fisheries biologists Rod Hilsabeck and Trent Thomas of the Illinois Department of Natural Resources decided to return the alligator gar to their state, they knew they needed a perfect location. The Nature Conservancy’s Spunky Bottoms Preserve fit everything they sought.

Formerly farmland, Spunky Bottoms is now 2000 acres of restored wetlands and uplands. It consisted of perfect gar habitat: backwaters and sluggish pools with lots of vegetation. It also was not connected to the adjacent Illinois River, making it easier for researchers to capture and study the fish.

Research is a key component to the reintroduction. Nathan Grider, a master’s student in biology at the University of Illinois-Springfield, is working with Dr. Michael Lemke and partners to study two key aspects of gar restoration.

They are studying how fast gar will grow when restocked into an area. They are also analyzing their diet, and in particular, if the gar will eat (and control) the non-native carp that swim Spunky Bottoms and so many other waters.

This information will help inform gar reintroduction and protection efforts throughout their range.

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Big Fish: Rodent-Eating Trout

As an avid fly fisher, I had heard the stories.

By day, the trout of Silver Creek—a clear, spring-fed stream in southern Idaho—fed on tiny mayflies and caddis flies. The water dimpled as trout sipped the profuse insect life from the surface. People like me used equally tiny artificial flies to try to  mimic said insects, often an exercise in extreme frustration.

By night, though, river monsters ruled: giant brown trout cruised the depths, occasionally surfacing to gulp down any hapless rodents that fell into the stream.

There’s something appealing, at least to an angler, about a trout that attacks mammals. Maybe it’s the thought of our favorite water transforming into a scene from Jaws.

Maybe it’s an antidote to the frustrations of tying delicate flies that practically require a microscope:  If I came back at night, I could just chuck a giant hairball!

But these mice-gulping trout always carried a strong whiff of, well, the classic fishing story. High on drama. Short on fact.

Silver Creek, after all, is one of the most-studied trout streams in the world. And there were no confirmed reports of trout dining on rodents.

Silver Creek also has one of the highest densities of aquatic invertebrates anywhere. The trout surely had easier prey than the occasional mouse.

Then biologists examined some brown trout stomachs.

What they found wasn’t pretty.

But it sure did validate some heretofore questionable fishing stories.

Full Article


Salmon Cam Returns

We’re pleased to return Salmon Cam, a live view of spawning Chinook and coho salmon and steelhead trout.

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