Location vs. ‘catchability’ in recreational fishing, salmon and the evolution of a newborn stream ecosystem, and the expanding threat to freshwater resources from natural gas exploration
This month in ecological science: the evolution of a stream, from barren moonscape to salmon run, modeling the contribution of sport fishermen’s skills and preferences to patterns of overfishing, and the unknown risks of fracking for nearby streams and rivers. These articles are published in the October issues of the Ecological Society of America’s (ESA) journals.
Evolution of a Stream: Plants and sea-life claim new territory as glaciers retreat in Glacier Bay, Alaska
As tidewater glaciers beat a hasty retreat up Glacier Bay in southeast Alaska, they uncover rocky, barren landscapes and feed cold lakes and streams – new habitat for life’s hardy explorers. In the October issue ofEcology, researchers from the Universities of Birmingham, Roehampton and Leeds describe the evolution and assembly of a stream ecosystem in newly de-glaciated terrain, from early insect and crustacean invaders to the arrival of migrating salmon.
Sampling began at Stonefly Creek in the early 1990s, after retreating ice, a remnant of the lost Plateau Glacier, began revealing the creek’s lower reaches in the late 1970s. Together with work at nearby Wolf Point Creek the study is the most complete and long-running catalog of stream development.
Now originating in a clearwater lake, Stonefly Creek tumbles over falls, fills a second, murkier lake, and merges with a stream from a third pond and wetlands before emptying into Wachusett Inlet. This complex geography, the researchers found, buffers the young stream from abrupt changes in water level and provides a diversity of habitats that welcome species with different specialties. Twenty-seven species of tiny crustaceans, armored aquatic animals from the same big family as barnacles, crabs and krill, arrived without obvious means of transport. Within ten years, pink salmon and Dolly Varden char had established spawning grounds in the stream. Coho (silver) salmon, Sockeye (red) salmon, and other fish species followed.
Shrinking glaciers are changing large expanses of northern coastline. The speed and pattern of colonization across Stonefly Creek’s watershed will aid our understanding of watershed restoration and conservation of biodiversity in a changing climate.
“Salmon stocks are under threat and decline in many regions of the world due to human activities,” said lead author Alexander Milner. “The creation of these new runs has important potential to help balance the losses.” Read more…
Skill triumphs over fish scarcity and draws experienced anglers back to overfished lakes
Fishermen care about more than the quantity of fish in a pond. Access, beauty, distance from home and fishing regulations play into the choice of which lake to fish on a given Saturday. How deep into the woods will fishermen hike to find a lake brimming with fish? Do recreational fishermen avoid overfished lakes?
In the October Ecological Applications, Len Hunt (Centre for Northern Forest Ecosystem Research, Ontario Ministry of Natural Resources) and colleagues report that when catching fish is at the top of the priority list, overfishing goes down in regions with few fishermen, but up in regions with many. Because motivations are mixed and feedback on choices isn’t obvious, a self-regulating system in which fishermen naturally pick the most productive lakes and spread their impact evenly over a region can’t be expected, according to the authors.
Some fish species are actually as easy, or easier, to catch when their numbers are few because they school together and stick to predictable habitat corners. Experienced anglers use knowledge, and tools like bathymetric maps and depth-sounders, to locate fish, and may catch almost as many in an overfished lake as in a thriving one.
Drawing on data from 157 lakes and diaries tracking fisherman’s preferences, the authors model the effects of weighting different priorities on the health of walleye stocks in the Thunder Bay region of Ontario, on the north shore of Lake Superior. The authors recommend adapting management strategies to usage patterns, the arrangement of lakes throughout the landscape lake biology, and the dynamic relationships between them.. Simple, region-wide solutions like limiting fishing licenses can exacerbate population crashes at popular lakes. But they note that the ongoing monitoring required to tailor management is expensive and that modeling could help target landscape-scale efforts.
“Because timely monitoring of literally hundreds of lakes in a landscape will be virtually impossible, “adaptive,” integrative social-ecological models such as ours, extended to include regulatory tools, might provide informed solutions that are open to experimental reassessments and modification.” Read more…
How close is too close? Hydrofracking to access natural gas reservoirs poses risks to surface water
Natural gas mining has drawn fire recently after claims that hydraulic fracturing, an increasingly popular technique for tapping hard-to-reach reservoirs, contaminates groundwater. Surface lakes, rivers and streams may also be at risk.
In an eView paper of Frontiers in Ecology and the Environment, researchers from the University of Central Arkansas, University of Arkansas and the Environmental Protection Agency estimate the average proximity of drill platforms to surface lakes and streams for two large shale basins underlying much of the eastern US. They review available information on potential threats to surface waters, and conclude that policy makers have woefully little data to guide accelerating natural gas development.
Hydrofracking wells expose nearby streams to loose sediments and hazardous fracturing fluids, and draw away large amounts of water. The technique forces high pressure fluid into dense rock, creating cracks through which trapped natural gas escapes and can be collected from the drill shaft. Developed in the 1940s, the technique gained wide application in the 1990s as gas prices rose and technology to drill horizontally away from a vertical well shaft made “unconventional” drilling profitable. Demand is up for natural gas because it burns cleaner than coal or petroleum, producing less greenhouse gas and smog.
But concerns about toxic components of fracking fluids, such as diesel, lead, formaldehyde, and other organic solvents, are undermining the green reputation of natural gas. “What will happen as fracking doubles, triples, over the next 25 years? How should we set policy to protect resources and ecosystems?” the authors ask. “We don’t have the data to decide. We need to generate it.” Read more…