By Mark Petrie, Ph.D., and Jacob Katz, Ph.D.
Many of us entered the outdoor world by watching a bobber, not holding a gun. We were fishermen before we were hunters. Although we may have graduated to more elaborate and expensive tackle, most of us continue to fish outside of the duck season. It may surprise some folks that our pursuit of both fish and waterfowl depends on the same foundation of healthy and abundant wetlands. The connection between wetlands and waterfowl is a familiar one, but the link between fish and wetlands is sometimes less obvious. A salmon hooked 10 miles off the Oregon coast appears to have no such connection, yet that fish depended on wetlands to the same extent as any mallard hatched on the prairies.
One way to illustrate the connection between fish and wetlands is to highlight some of the fish species that are popular quarry among DU members. Of course it only makes sense to start with the most popular game fish of all, the black bass (largemouth and smallmouth bass). Adult largemouth bass lurk on the shallow margins of wetlands at the edges of lakes, and in floodplain wetlands associated with slow-moving rivers. Those same freshwater wetlands provide important nursery areas for juvenile bass as well. Bass may not eat wetland plants, but they certainly dine on red swamp crawfish, which eat the detritus of wetland plants. Many bass fishermen also pursue crappie, and these fish frequently spawn in forested scrub-shrub wetlands, flooded timber or brush, or in stands of shallow emergent vegetation, where they build their nests. Since 1990, DU and its conservation partners have reforested over 1 million acres of bottomland hardwood forest throughout the Mississippi Alluvial Valley. Those same forested wetlands also provide spawning habitat for alligator gar, the largest freshwater fish in the Mississippi River system and its apex predator.
If you enjoy pursuing prehistoric predator fish and you live in the Northeast or upper Midwest, DU's work is important to you too. Take the northern pike, that indiscriminate glutton whose willingness to chase most hardware makes it a popular target in the high-latitude parts of the country. Pike spawn in the shallows of freshwater wetlands soon after ice-out, and DU is helping to provide pike access to these habitats even as we work on behalf of waterfowl. Although early wetland restoration efforts did not always meet the needs of spawning fish, those needs are now routinely included in our wetland designs. For example, DU is helping to restore and enhance spawning habitat for pike and their bigger cousin, the muskellunge, in several marshes along the St. Lawrence River in New York by installing fish ladders, creating channels for fish passage, and excavating spawning pools in the marsh interiors. Similar efforts to improve fish passage and create spawning habitat are now under way in the marshes that border Wisconsin's Green Bay.
If you fish salt water, wetlands can be just as important to your quarry as they are for many freshwater species. Spotted or speckled trout are probably the most popular game fish on the Gulf Coast, followed closely by flounder and redfish. Each of these species relies heavily on seagrass meadows and salt marshes for nursery habitats, and DU has restored or enhanced nearly 400,000 acres of estuarine habitat along the Gulf Coast, including many areas important to fish as well as shrimp and crabs, which serve as their prey.
In the Pacific Northwest, coho salmon spend most of their adult life at sea; however, they rely heavily on wetlands before they ever reach the ocean. As young coho make their way to the coast, they seek out floodplain wetlands that provide an abundance of invertebrate foods, and young salmon in these habitats enjoy greater growth and survival compared to those that remain in stream channels. Juvenile chinook, or king salmon, may spend several months feeding in tidal marshes before heading out to sea, and DU has benefited both species of salmon by restoring floodplain and coastal wetlands throughout Washington and Oregon.
Following the widespread loss of natural wetlands across the United States, many waterfowl, including the majority of North America's northern pintails, now rely heavily on flooded rice fields for wintering habitat. In California's Central Valley, where the last century has seen 95 percent of wetlands converted to agriculture and other forms of development, DU has been partnering with farmers to improve the conservation benefits of agricultural lands for birds and wildlife, primarily by flooding rice fields after harvest. Ducks dabble in these winter-flooded fields in the heart of the Pacific Flyway for waste grain, weed seeds, and aquatic invertebrates. Geese also eat rice grain, as well as the roots of rice stalks and young green shoots sprouting in the fields. In fact, research has shown that flooded rice fields provide habitat for more than 150 species of birds, 28 species of mammals, and 24 species of reptiles.
Now science is showing that these same fields are also critically important for chinook salmon. Five years of experiments conducted by DU's conservation partner, California Trout (CalTrout), in collaboration with top researchers from the University of California−Davis and state and federal agencies, have shown that these shallowly inundated floodplain croplands produce phenomenal concentrations of bugs, which provide food for baby salmon and other native species. In addition, young salmon reared in these flooded agricultural habitats are 10 times larger on average than young river salmon, making them much more likely to survive at sea and return as large game fish.
Nigiri sushi is a slice of fish atop a compact wedge of rice. The Nigiri Project is a collaborative effort between farmers, conservationists, and government agencies to rebuild salmon populations by introducing juvenile fish into winter-flooded rice fields that will remain in summer production. While these fertile farmlands will never again be pristine wetlands, they can be managed to replicate natural wetland flooding patterns during winter—when crops aren't grown—and to produce food and habitat for birds, fish, and wildlife.
The science is clear: floodplain agricultural lands provide vital food resources for salmon. By comparison, adjacent leveed stream channels are relative food deserts. Now DU and its partners, including CalTrout and the California Rice Commission, are putting this science into action and pioneering new techniques that reintegrate wetland productivity into the way farm landscapes and river systems are managed to support robust populations of both fish and waterfowl. These real-world science-based conservation solutions will help secure the future of both hunting and fishing and are a win-win-win for farmers, fish, and waterfowl.
Dr. Mark Petrie is director of conservation planning in DU's Western Region. Dr. Jacob Katz is senior scientist with California Trout.