A vastly changed landscape has allowed non-native species to flourish to the point they now "represent major impediments to the restoration of native salmonids in the Columbia River Basin," according to a recently completed Independent Scientific Advisory Board report.

"The negative impacts of non-native species invasions, along with habitat loss and degradation, are recognized as the two leading causes of native species imperilment in North American freshwater ecosystems," according to the report, "Non-native Species Impacts on Native Salmonids in the Columbia River Basin: Including Recommendations for Evaluating the Use of Non-Native Fish Species in Resident Fish Substitution Projects."

The panel recommends that the Northwest Power and Conservation Council and fish and wildlife agencies "elevate the issue of non-native species effects to a priority equivalent to that of habitat loss and degradation, climate change, and human population growth and development." Those species include fish, plants and invertebrates.

Climate change and human population growth and development themselves are "likely to effect the establishment and spread of non-native species with subsequent significant impacts on native species," according to the report. Most of the introduced fish species have a higher tolerance for warm water than do salmon. And population growth could bring calls for more non-native fisheries, according to the ISRP.

The 11 member panel advises the Northwest Power and Conservation Council, NOAA Fisheries and basin tribes.

The report issued July 18 says that "while intentional and unintentional introductions of non-native species have accounted for initial establishment of non-native species, habitat change is currently the major factor causing the expanding distribution and increasing abundance of non-native species in the Columbia River Basin."

"Most of the free-flowing river habitats in the Snake and Columbia rivers have been converted into reservoir habitats through dam building, intended for hydroelectric power generation and for flow regulation for irrigation diversion and flood control," the report says. "The reservoirs have created hotspots of non-native species, which become source populations of non-natives, facilitating secondary spread of these species throughout the basin."

The report says that there are 119 threatened or endangered species in the basin, most of which are plants. But the list does include 13 salmon and steelhead stocks.

It cites a 2007 survey that indicates non-natives now make up 46 percent, 54 percent and 60 percent of the resident fish species in Oregon, Washington, and Idaho, respectively.

Such non-native species as American shad, common carp, brook trout, bluegill, walleye, and smallmouth and largemouth bass, are widespread and have come to dominate many fish communities throughout the Basin. Some prey on young salmon; others compete for habitat and sustenance.

The number of non-native aquatic invertebrates, such as clams, in the lower Columbia River is rising fast. On average over the past 10 years a new invertebrate species was discovered about every five months.

"The increasing rate of new discovery is due both to the increasing frequency of introductions and to the number and type of surveys conducted," the report says.

"Non-native aquatic plants (i.e., macrophytes), such as Eurasian milfoil, have also become quite abundant and have altered littoral fish habitat in many mainstem reservoirs in the Columbia and Snake rivers."

The introduction of non-native fish, plants and invertebrates have come as a result of increases in inter-continental trade, travel, and tourism, as well as import and export of exotic pets, ornamental plants, foreign foods, and crop plants.

Walleye, smallmouth bass and channel catfish consume significant amounts of juvenile salmon. Largemouth bass, yellow perch, and crappie eat salmon as well.

The ISAB report is posted on the Council's website at this location:

http://www.nwcouncil.org/library/isab/isab2008-4.htm

A description of the ISAB, whose members are nominated by the National Academy of Sciences and appointed jointly by the Council, NOAA Fisheries, and the Columbia River Inter-Tribal Fish Commission, also is on the Council's website:

http://www.nwcouncil.org/fw/isab/Default.htm

The report on non-native species is timely for the Council because it is now in the process of amending its Columbia River Basin Fish and Wildlife Program, which will be released in draft form for public comment in late August or early September.

The program establishes strategies and goals aimed at protecting and enhancing fish and wildlife affected by the construction and operation of the federal Columbia/Snake river power system. The Bonneville Power Administration funds program implementation from revenues it collects from selling power generated in the system.

The report is intended to help the Council (1) develop guidelines for implementing the Fish and Wildlife Program to minimize future impacts from non-native species and (2) frame scientific guidance and propose criteria for deciding the limitations and appropriate use of non-native fishes to mitigate hydrosystem losses through resident fish substitution.

According to the report's executive summary:

-- Non-native species also compete with natives species for food and habitat. As an example, larval/juvenile American shad have reduced zooplankton species food base favored by subyearling chinook.

-- Nonnative fish can cause food web alterations (e.g., native resident fish communities in littoral habitats of Columbia River reservoirs are being replaced by non-native species).

--- Non-natives' interbreeding with native stocks and disease transmission and parasites (American shad is a carrier of a protozoan parasite of salmon) are also harmful.

-- Native species are also significantly impacted by non-native invertebrates and plants. Examples include the freshwater Asian clam, which has replaced native mollusks in the Columbia River Basin, and non-native plants like Eurasian milfoil, which is widespread in Columbia River reservoirs and is altering littoral habitats.

The ISAB's recommends that:

-- the Council urge the state agencies to relax (or eliminate) fishing regulations aimed at non-native predators.

"It would seem contradictory that the Council has continued to support the project aimed at reduction in abundance of the native northern pikeminnow, while state agencies in Washington, Oregon, and Idaho have simultaneously adopted management policies that in some cases seem aimed at perpetuating or even enhancing populations of these introduced predators," the report says.

"For example, all three states have regulations in place that limit the daily catch of bass by recreational anglers. In particular, Washington's Columbia River regulations seem to be designed to optimize the spawning capability and thus recruitment of bass, using the same type of regulations as in the sturgeon fishery. Similarly, Washington's regulations for the walleye fishery seem aimed at optimizing recruitment by protecting spawners.

-- habitats, including riparian habitats, be maintained and restored.

"Habitat restoration may be the best hope for protecting or restoring native species. When native species are provided with habitat for which they are best adapted, they have an improved chance of out-competing or persisting with non-native species.

"Restoring physical features (including natural flow and thermal regimes) may make native species more likely to persist in environments now occupied by non-natives."

-- efforts be made to increase public awareness of the threats that non-native invasive species pose to aquatic ecosystems and the native species therein. That awareness is critical for curtailing the introduction and spread of new non-native species.

-- a thorough Environmental Risk Assessment of potential negative impacts on native fish species should be completed and submitted, concurrently with project proposals, for all resident fish substitution projects in which a non-native species is to be selected for substitution.

"Research needs are many, including (1) mapping the vulnerability of the landscape to non-native species introduction, establishment, and spread; (2) examining the impacts of non-native predators on native salmonids and other native species at regional scales and where many species co-occur; (3) determining the potential for transmission of diseases and parasites to native species, (4) improving understanding of the effects of competition between non-native and native species, and (5) exploring the potential synergistic interactions of climate change, land use, and non-native species spread," the report says.

"Exploratory surveillance and monitoring of fish, plant, and invertebrate populations needs to be increased for early detection of invasive non-native species and tracking of their distribution and abundance in the future.

"Early detection of rare non-native species is challenging and may sometimes require use of sophisticated sampling designs and estimation techniques. However, the cost of control after spread of undesirable species thoroughly justifies the effort," according to the report.

And enforcement is a must.

"Federal, Regional, and State Policies and regulations regarding non-native species exist, but enforcement seems to be weak or non-existent. Improved enforcement of current regulations should be a high priority."