Use: Mosquito Control, Monitoring, and Research
Refuge Name: Franz Lake National Wildlife Refuge, located in Skamania County, Washington, as part of the Ridgefield National Wildlife Refuge Complex.
Fish and Wildlife Act of 1956 (16 U.S.C. 742)Refuge Purpose(s): "...for the development, advancement, management, conservation and protection of fish and wildlife resources..." 16 U.S.C. 742(a)(4).
"for the benefit of the United States Fish and Wildlife Service, in performing its activities and services. Such acceptance may be subject to the terms of any restrictive or affirmative covenant or condition of servitude..." 16 U.S.C. 742f(b)(1).
These activities are not priority public uses, as identified in the National Wildlife Refuge System Improvement Act of 1997. This legislation clearly states that no refuge use will be allowed unless it is first determined to be compatible with the mission of the National Wildlife Refuge System and the purposes of the refuge. This Act also mandated that all refuges would develop Comprehensive Conservation Plans (CCPs). As part of the development of the Comprehensive Conservation Plan for the three Columbia River Gorge refuges (Franz Lake, Pierce, and Steigerwald Lake NWRs), which we expect to be completed by spring 2003, the refuge is required to develop new Compatibility Determinations for mosquito monitoring, research, and control (for both non-emergency and emergency situations). For this reason, mosquito monitoring, and research, and control as proposed in this Compatibility Determination, are only proposed for one year, to be reassessed as part of the CCP process. This may result in a new Compatibility Determination for these uses at that time. In decision-making, each Refuge Manager is required to use sound professional judgement based on many factors, including experience, knowledge, the best science available, and adherence to the National Wildlife Refuge System Administration Act, as amended by the National Wildlife Refuge System Improvement Act of 1997, and other applicable laws, regulations, and policies.During the past three years (1999-2001), the Clark County Mosquito Control District has been granted a Special Use Permit (SUP) to monitor Franz Lake NWR (see map, Appendix 1) for mosquito larvae, and apply the larvicide Bacillus thuringiensis israelensis (B.t.i.) when district personnel determined that larvae had reached threshold levels. The current threshold used by the local mosquito districts is 5 mosquito larvae per dip net sample. Threshold levels used by mosquito control districts on refuges around the country range from 1 larvae to 15 larvae per dip, with an average of five (Higgins 2002, pers. comm.). The Skamania County Mosquito Control Board has proposed that the refuge issue a SUP to the Clark County Mosquito Control District, working for Skamania County, to monitor the shores of Franz and Arthur Lakes for mosquito larvae and mosquito-borne diseases, and apply B.t.i. as needed.
5 larvae per dip. Mosquito larvae numbers could be affected by a number of factors, such as weather conditions, precipitation, and time of year. Probably one of the most important factors contributing to the production of these floodwater mosquitos is the degree of water fluctuation in Franz and Arthur Lakes and on their shorelines, where the mosquitos lay their eggs and subsequently hatch. Although there is some fluctuation due to precipitation, tidal influences, and floodwaters, the primary source of fluctuating water levels in the Franz Lake basin are the result of changes in water releases from Bonneville Dam, which is located approximately 10 miles upstream. Due to the uncertainty of the mosquito hatches, the total amount of larvicide to be used, and the times, dates, and exact locations of application (magnitude and frequency) cannot be predicted.
Since 1998, Clark County Mosquito Control District has contracted with Multnomah County Vector and Nuisance Control (Multnomah County's Mosquito Control District) to conduct adult mosquito monitoring in Clark County, Washington, to include Ridgefield NWR. The monitoring consisted of setting out 5 standard encephalitis traps, each consisting of a CO2 (dry ice) mosquito attractant and small collection container. Mosquitos were trapped in adult traps in each of three locations on the refuge. Trapping provided information about local mosquito populations (species and relative numbers) and a source for samples to be sent to California for testing for Western and St. Louis encephalitis, and West Nile Virus. The Skamania County Mosquito Control Board has requested a Special Use Permit to allow the same monitoring on Franz Lake NWR, with samples sent to Olympia, Washington for testing.Last year (2001), Clark County Mosquito Control District personnel, contracted by the Skamania County Mosquito Control Board to conduct research activities under their SUP, were scheduled to collect mosquito larvae from Franz Lake NWR. These larvae were to have been reared to adult stage at the Multnomah County Mosquito Control District laboratory, marked, then released back at Franz Lake NWR. This was to be the first phase of a mark/recapture study to determine if Franz Lake was the source of nuisance mosquitoes and/or mosquito-borne diseases in the City of Skamania area. The second phase would require an experienced entomologist be hired to capture adult mosquitoes using CO2 traps set around Skamania and surrounding areas. Adult mosquitoes would be brought back to the lab, identified as to species, and checked for previous marking. The number of marked individuals would be calculated as a proportion of the total number of mosquitoes captured. Last year the Columbia River experienced low water levels, with larvae numbers too low to be available for capture and rearing. Although the mosquito control districts do not currently have enough funds to conduct the second phase of the study, they have requested permission to conduct phase one activities. They hope to obtain funding in the future to complete this research, and obtain sufficient information to justify mosquito control on Franz Lake NWR. Both phases are jointly assessed for compatibility herein.
Herein, we will assess the potential impacts of the larvicide proposed for use, B.t.i., to control nuisance mosquitoes, as well as the impacts anticipated from the proposed monitoring and research efforts.
Residents living near the lake shore have indicated that, prior to the acquisition of the refuge, summertime mosquito populations were frequently high on the flats in the vicinity of Franz Lake. Historically, during years of mosquito outbreaks in Skamania, Washington, local residents thought that mosquitoes hatched in the area that is now the Franz Lake NWR would fly up the Indian Mary Creek drainage toward the town of Skamania and neighboring residences. The Skamania County Mosquito Control Board responded by fogging areas suspected of providing mosquitoes by vehicle, including what is now the Franz Lake NWR, using an unknown adulticide. When the refuge was acquired in 1990, the District had been inactive since 1979-1980 (Holm 2002, pers. comm.; Price 2002, pers. comm.).During the early 1990s, grazing in the bottomlands surrounding Franz and Arthur Lakes was discontinued to eliminate damage to the wetlands and riparian habitat in the vicinity of the lakes. The Columbia River experienced extremely high flooding in 1996 and extended periods of flooding in 1997, which although not quite as high, were persistent until mid-July. Local residents believed that these factors, combined with extended rains during 1998 and 1999, caused increases in mosquito populations large enough that the mosquitos dispersed from the refuge up the Indian Mary Creek drainage into Skamania and the surrounding areas. This prompted numerous complaints of overabundant mosquitoes to refuge staff, news media, and local legislative staff. Residents expressed concerns about the nuisance caused by the mosquitoes, as well as the potential for the transmission of mosquito-born diseases, such as West Nile Virus, St. Louis encephalitis, and western equine encephalitis.
In 1999, the Skamania County Commissioner of District 1, learned that nearby Clark County, Washington, was using B.t.i. at the Ridgefield NWR for the control of mosquito larvae and requested that it also be used at Franz Lake NWR. Ridgefield NWR still allows treatment of mosquitos using B.t.i. One of the chief differences between the two sites is the prevalence of rearing salmonids. Franz Lake is a rearing site for endangered salmonids, whereas the mosquito control activities at the Ridgefield NWR occur on managed wetlands that are inaccessible to salmonids.
A Compatibility Determination for integrated pest management at Franz Lake NWR was issued in 1999, based on initial research into the effects of B.t.i. on non-target invertebrates. A literature search at that time revealed that its effects were relatively specific, affecting mosquitoes, craneflies, blackflies, and non-biting midges (chironomids). For this reason, B.t.i. was considered a significantly better choice for mosquito control than chemical adulticides, which may impact other invertebrates, fish, and wildlife. The justification for initiating pesticide applications at that time was that it did not appear to pose significant adverse effects to non-target species, and refuge staff sought to cooperate with nearby residents of Skamania County by reducing nuisance mosquitoes and the possibility of the transmission of mosquito-borne human diseases. Special Use Permits were issued for mosquito monitoring and control with B.t.i. in 1999, 2000, and 2001.
When mosquito monitoring and control were first conducted under authority of a Special Use Permit on Franz Lake NWR in 1999, Alpine Pest Management Specialists (subcontracted by Clark County Mosquito Control District for 1999 and 2000) conducted activities on approximately 60 acres in the easternmost section of the lake that contained reed canary grass and shallow water. In 2000, they extended their treatment area to the south edge of the shoreline, adding approximately 20 acres. Treatment in this area was outside the scope of their SUP due to the presence of a bald eagle nest and high salmonid concentrations. The areas previously authorized for monitoring and control were shallow wetland areas of Franz Lake, approximately 10 percent of the total 550 acres of the refuge. The other mosquito control districts (Multnomah County, Oregon; Columbia County, Oregon; and Clark County, Washington) do not conduct their control activities within at least 15 miles of Franz Lake, reducing the potential for any adverse cumulative impacts that may occur from temporarily disrupting the salmonid food source across a large area.
Since the issuance of the 1999 Compatibility Determination, refuge staff have expressed concerns about the lack of information documenting whether the mosquitoes using Franz Lake NWR are the mosquitoes found in the nearby community of Skamania, or if they are produced in residential backyards and nearby heavily vegetated lands. Therefore, since 2000, refuge staff have been working with personnel from three local mosquito control districts. Mosquito control personnel from Multnomah County, Oregon; Columbia County, Oregon; and Clark County, Washington have worked together for several years under a mutual agreement to conduct coordinated mosquito control activities, especially aerial spraying along their boundaries. Refuge personnel initially met with this group in January 2000 to share concerns about nuisance complaints and mosquito-borne diseases; U.S. Fish and Wildlife Service responsibilities for wildlife, fish, and public health; and to develop strategies and identify responsibilities for upcoming years. Annual meetings have continued, and one of the leading issues has been to investigate methods to learn the specifics of mosquito movement from Franz Lake NWR. A Mosquito Control Board was formed in Skamania County in 2001 and is currently part of this group.
Also, since the issuance of the 1999 Compatibility Determination, refuge staff have learned of additional information concerning the adverse effects of B.t.i. on several important aquatic invertebrates, and the listing and anticipated listing under the Endangered Species Act of several salmonid fish species present on Franz Lake NWR. The potential non-target impacts to aquatic invertebrate species from exposure to B.t.i. may reduce food resources for federally listed salmonids which use portions of Franz and Arthur Lakes as rearing areas. This information is summarized in the Wildlife and Wetland, and Fisheries Impacts from Mosquito Control sections below, with additional details about fisheries impacts described in Appendix 3 to this Compatibility Determination.
Our research on the potential for transmission of mosquito-borne diseases reveals that there have been 31 human cases state-wide of western equine and St. Louis encephalitis (with no deaths) between 1950 and 2000, and no reported cases of these diseases in Clark or Skamania Counties (Grendon 2000). Also, as of March 2002, the West Nile Virus (WNV) has been limited to the eastern half of the United States (U.S. Geological Survey - Center for Integration of Natural Disaster Information 2002), although some experts believe that it will be present in the west within two or three years. The State of Washington recently completed the first year of a West Nile Virus surveillance project, with 12 Washington counties participating. A mosquito species found in the eastern United States capable of carrying the West Nile Virus was found for the first time in the western United States near Seattle, Washington in January 2002. State health department officials were unable to determine if the species was new to the area or was identified as a result of new surveillance efforts. Although Clark County has had adult mosquito capture/testing conducted at Ridgefield NWR the past four years under a contract with Multnomah County, they are not planning to do so this year. Skamania County has not been involved in monitoring for mosquito-borne diseases to this date. This year, however, the Skamania County Mosquito Control Board has been provided with carbon dioxide traps and test tubes to capture adult mosquitos in locations of activity and send them to the Washington State Department of Health to test for mosquito-borne diseases. They would like to include Franz Lake NWR as one of their sampling sites.
In the event that the mosquitoes produced on Franz Lake NWR are determined to be causing a human-health emergency, the most appropriate control technique would be utilized and all Stipulations listed herein would be implemented.
Availability of Resources: While adequate funding and staff exist to manage the proposed mosquito monitoring and research activities at Franz Lake NWR, current and perceived future staffing levels are inadequate for the level of oversight that would be required for the proposed nuisance mosquito control program.
When staff from the Clark County Mosquito Control District visit Franz Lake NWR for monitoring/control activities, they usually spend a portion of the first day of the week taking samples, then they return and apply the treatment on another day. In the Gorge, there is also considerable travel time involved. The Control District schedule is fairly irregular and pinning their staff down to a schedule has been virtually impossible at Ridgefield NWR, and would be even more difficult to do at Franz Lake NWR. In 1999, mosquito activity was severe, but the Special Use Permit authorizing monitoring and control at Franz Lake NWR by Alpine Pest Management Specialists (subcontracted by Clark County Mosquito Control District for 1999 and 2000) was not in place until August. In spite of the late start, Alpine still made 8 monitoring/control trips. The year 2000 was a relatively low mosquito year because of few fluctuations in Columbia River water releases from the Bonneville Dam, but Alpine still made 7 visits to the refuge. The year 2001 was an extremely low-water year and resulted in two trips to Franz Lake by Clark County Mosquiot Control District staff, with no larvae dip thresholds reached due to the low-water levels.
Ideally, refuge staff would accompany mosquito control district personnel whenever they came onto the refuge to ensure their compliance with the stipulations presented herein and the terms and conditions of the SUP issued for the control treatment. That would amount to a full day or more of staff time every week or two when they schedule a visit, considering the disruptions in the regular work schedule, inability to schedule meetings, etc. The refuge complex does not have adequate staff available to monitor the mosquito control solely for nuisance purposes. That said, the refuge would ensure staff were made available to coordinate mosquito control by the districts in the event of a health-related emergency.
Anticipated Impacts of the Use(s):
Wildlife and Wetland Impacts Anticipated from Mosquito Control
The waters and wetlands of Franz Lake NWR provide habitat for a variety of wildlife that use mosquitoes (adults and larvae) and other invertebrates as food resources. Five species of swallows (tree, violet-green, barn, cliff, and rough-winged) and purple martins use the Franz Lake area, where they feed extensively on aerial insects (A. Poole and F. Gill, eds. 2002). These birds' primary food source is larger insects like dragonflies and damselflies, which feed on mosquitos (Higgins 2002, pers. comm.). These birds fly in groups of up to 25-50 over open water and wetland areas.
Breeding ducks and their young (mallards, cinnamon and blue-winged teals, gadwalls, northern shovelers, hooded mergansers, and wood ducks) and Canada geese are summer users of the lakes and wetlands, feeding in shallow waters along the shorelines. These species feed by filtering aquatic invertebrates (including mosquito larvae) from the water column, substrate, and vegetation.
It has been generally acknowledged that aquatic invertebrates comprise a significant portion of the diet of breeding waterfowl, but contributed little to the overall diet of non-breeding waterfowl. Recent studies, however, have shown that invertebrate foods have been found to be the dominant food of even non-breeding waterfowl when molting during the summer, fall, and winter (Heitmeyer 1988), egg production during the spring (Swanson et al. 1979), and duckling growth during the summer rearing period (Krapu and Swanson 1978).
Other wetland birds, such as great blue herons, great egrets, bitterns, sora, and Virginia rails are summer residents of the Franz Lake NWR, using vegetation in shallow waters along the shoreline for nesting and cover. The rails feed directly on selected invertebrates, while the larger wetland birds (i.e., great blue herons, great egrets, etc.) feed on small fish, reptiles, and amphibians, which themselves depend upon wetland invertebrates as their food supply. Midges of the family Chironomidae and others are important components of the diets of many of these wetland-using birds. These invertebrates, which are biologically, morphologically, and behaviorally similar to mosquitoes, are adversely impacted by most mosquito control treatments, including B.t.i.
It has been very difficult to develop any chemical pesticide which is entirely target specific, as most pesticides have some degree of impact on various non-target organisms. In recent years, the larvicide Bacillus thuringiensis israelensis (B.t.i.) has been viewed by some people as a "preferred" mosquito control material because of its status as a biological control.
Recent literature regarding the effects of B.t.i. on non-target organisms have highlighted and verified a number of concerns about mosquito control on wildlife refuges. The majority of initial studies have been accomplished in the lab or during one-season field studies. The first long-term research was a 3-year study (1998-1990) completed in Minnesota (Charbonneau et al. 1994). The first two years showed no reduction of the major aquatic invertebrates in the ponds, but the third year indicated significant adverse impacts to chironomids and several other taxa that are important dietary components of vertebrates such as waterfowl, fish, and amphibians. Further toxicity tests indicated that various environmental factors, such as temperature, larval instar development, water depth, water flow, tidal flow, substrate type, and the amount of organic material in the water column reduced the efficacy of the larvicide in the field.
A six-year study on 27 wetlands in Minnesota consisted of three years (1988-1990) of pre-treatment sampling of aquatic invertebrates and other parameters, followed by three years (1991-1993) of treatment with B.t.i. and subsequent sampling (Hershey et al. 1998). Insect densities and diversity were reduced by 57 to 83 percent in the second and third years of treatment. During this study, 179 genera of aquatic insects were examined, with chironomids (primarily midges) representing about half of the insect genera present at the beginning of the study. By the end of the study, however, only one to six genera dominated the treatment sites. Adverse impacts were primarily observed in the invertebrate tribes, primarily in the Chironomini and Tantarsini. These tribes are ubiquitous and are represented in almost every wetland with chironomids. There are over 300 species of midges within these two groups and not necessarily all of them would be adversely impacted by B.t.i,, but since it is likely that less than 10 species were examined, impacts of B.t.i. on individual species are unknown. This suggested the potential for indirect impacts on non-target species, creating a negative food web effect, and highlighted the need for further study, especially on a long-term basis. Without knowledge of what midge species are present in Franz and Arthur Lakes and what the impact to those species would be from B.t.i., the conservative approach based on the best available science would be to avoid application of B.t.i. (Higgins 2002, pers. comm.).
The potential negative impacts of B.t.i. treatments with respect to wildlife refuges center on direct impacts to chironomids and a general disruption of the aquatic food chain, both anticipated to be short-term, but depending on severity, may persist over the long-term. As stated earlier, chironomids are one of the more important food web components in wetlands. A single, highly-effective treatment (with accompanying side effects) can negate the important ecosystem values of individual wetlands and significantly reduce the value of these wetlands to wildlife species, which are the focus of refuge goals. Impacts of B.t.i. on non-target invertebrates may be highly variable and there are many unknowns.
Fisheries Impacts from Mosquito Control
The waters and wetlands of Franz Lake NWR provide habitat for several species of anadromous salmonids including chinook salmon, coho salmon, chum salmon, steelhead, and sea-run coastal cutthroat trout. Steelhead and fall chinook are listed under the Endangered Species Act as threatened, cutthroat trout are proposed for listing, and coho salmon are candidates for listing.
Coho salmon, steelhead, and cutthroat trout spawn in tributary streams, and chum salmon spawn in the outlet of Franz Lake. These species, as well as chinook salmon, rear in Franz and Arthur Lakes. Juvenile anadromous salmonids that originate from nearby tributaries, the mainstem Columbia River, and other streams throughout the Columbia River system also enter the Franz/Arthur Lake backwater to rear and to seek refuge from high flows in the Columbia River during the spring freshet. Shallow waters in these areas are especially important rearing areas for subyearling chinook salmon during their seaward migrations. Salmonids are moving through the Franz Lake NWR throughout the year. Other native and introduced fish species are also present throughout the year (see Appendix 3, Table 1, for list of species collected at Franz Lake NWR).
Bioassays have shown that B.t.i. is of low direct toxicity to various fish species. Therefore, salmonids and other fishes are not expected to suffer direct adverse effects from applications of B.t.i. for mosquito control. There is greater potential for indirect adverse effects to fish from disruption of the food web. B.t.i. is specific to mosquitoes, blackflies, and midges (chironomids). All three groups of insects are important food items for salmonids and other fishes, with midges (chironomids) having been documented as one of the most important food items for subyearling chinook salmon throughout the Columbia River and the Pacific Northwest. Subyearling chinook salmon inhabit the shallow backwater areas of Franz and Arthur Lakes from March through August (see Appendix 2, Graph 1), and during this time they feed extensively on chironomids. As noted earlier, studies have shown B.t.i. to have adverse effects on various species of chironomids. Lowered chironomid populations would reduce an important food source for rearing juvenile salmonids during the critical rearing period before seaward migration.
Mosquito control operations at Franz Lake NWR would be likely to coincide with the period of highest use of this area by subyearling fall chinook and other juvenile salmonids (March through August) (see Appendix 2, Graphs 2-4). Mosquito populations likely would be higher during years when Columbia River flows are high and water levels are fluctuating. These are also the years when more juvenile salmonids would be expected to enter backwaters and side channels to seek refuge from high-water velocities in the mainstem Columbia River. These fish would typically move along the shoreline of the Columbia River where velocities are slower, and enter into backwaters, where they would continue to move along the shorelines in search of food. This would lead them to the shallow waters vegetated with reed canary grass along the shorelines and the east end of Franz Lake. Mosquito control operations in these areas and during these years would likely adversely affect many juvenile salmonids.
Wildlife and Fisheries Impacts from Mosquito Monitoring and Research
The impacts anticipated from the proposed monitoring and research activities would be minimal. Foot traffic would be minimized; a single, all-terrain vehicle would be allowed for these activities and would be restricted to refuge service roads and a maximum speed limit of 5 miles per hour; and the number of mosquito larvae and adults anticipated to be taken would not be large enough to adversely impact any species or habitat. These activities would likely pose only minor, short-term disturbances. In the event of a health-related emergency, the data from these monitoring and research efforts would be invaluable to the refuge for determining an appropriate course of action.
Public Review and Comment: Public review of and comment on this Compatibility Determination will be conducted via a 30-day comment period, with notices placed at: the refuge headquarters; the Ridgefield NWR Complex headquarters; U.S. Fish and Wildlife Service, Lower Columbia River Fisheries Program Office, Washington State Office; National Marine Fisheries Service; Washington Department of Fish and Wildlife (Vancouver); Skamania County District 1 Commissioner; mosquito control districts (Skamania County, Clark County, Multnomah County, Columbia County); Stevenson, Camas, and Washougal post offices and libraries; the Skamania General Store; and in local newspapers (Vancouver Columbian, Skamania County Pioneer, Camas-Washougal Post Record, and Oregonian). Copies would also be sent to federal, state, and local legislative representatives. The proposed refuge uses evaluated herein will be re-evaluated during the CCP process and a new Compatibility Determination may be prepared at that time.
Determination for Mosquito Control (Non-emergency) (Check one below):
X Use is Not Compatible
Use is Compatible With Following Stipulations
Stipulations for Mosquito Control (Non-emergency):
Justification for Mosquito Control (Non-emergency):
Based on the information available, the scale of impacts to chironomids and other non-target aquatic invertebrates from B.t.i. application depends on the species presence, abundance and distribution; substrate type; water depth during treatment periods; and the density of aquatic invertebrates at the treatment sites. Information about these parameters is largely unknown for the Franz Lake NWR. However, initial research in Minnesota indicates negative impacts on several non-target aquatic invertebrates, including chironomids.
Specifically, additional information is needed to properly assess the impacts of B.t.i. application on chironomids, wetland birds, and salmonids. These information needs include the habitat characteristics of areas to be treated, species of invertebrates (particularly chironomids) present, densities of invertebrate populations (particularly chironomid) in proposed treatment areas, and wildlife and fish use of these areas (see Appendix 3 for a discussion of research needs). Additionally, bioassays have not been conducted to examine the effect of B.t.i. on the chironomid species present. This should be done. The results would aid in predicting whether or not large-scale and repeated application of these insecticides would detrimentally impact the food web at Franz Lake NWR.
Subyearling chinook salmon are the species of salmon most likely to be using shallow water habitat in Franz Lake NWR and are also the species and life stage of salmonid that relies most heavily on chironomids. Mosquito treatment is likely to occur during the time when subyearling chinook salmon would be rearing in shallow waters of Franz Lake NWR, as these are also the times when mosquito populations in these areas are high. Subyearling chinook salmon use of Franz Lake NWR may also be highest in years of higher river flow when these fish seek refuge from strong river currents in backwaters.
Recent research into the effects of Bacillus thuringiensis israelensis (B.t.i.) on non-target invertebrate populations important to wildlife and fish species using the refuge, especially endangered/threatened species of salmon, have shown that treatment with B.t.i. may adversely affect listed fish species because of short-term food chain disruption, with unknown impacts in the long-term. This information, when combined with the absence of vital refuge-specific invertebrate information, has led to the conclusion that mosquito control using this product, which currently is considered to have the least negative consequences on invertebrate populations important to fish and wildlife, cannot be determined to be compatible at this time, as it is anticipated that this use would materially interfere with and detract from refuge purposes, Refuge System mission, and our legal mandate to ensure the biological integrity, diversity, and environmental health of the NWR System.
Determination for Mosquito Control (Emergency):
Use is Not Compatible
X Use is Compatible With Following Stipulations
Stipulations Necessary to Ensure Compatibility of Mosquito Control (Emergency):
1. Mosquito control measures will only be taken in the case of an emergency when there is real and imminent threat to the health of human, fish, or wildlife populations. For the purpose of treatment of refuge lands for disease-carrying mosquitoes, a public health emergency will be determined by the Regional Director of the U.S. Fish and Wildlife Service. The Regional Director will make this determination after consultation with the U.S. Centers for Disease Control and Prevention, the Washington State Department of Health, the Southwest Washington Department of Health (Clark County), and/or the Skamania County Department of Health. Once the Regional Director has determined the existence of a human health emergency, designated Service representatives will prescribe, following consultation with State and County health district personnel, and recognized biologists and entomologists, the type and duration of treatment for mosquitoes on refuge lands.
2. For the purpose of allowing the use of certain chemical pesticides or biological control pesticides to control mosquitoes, a mosquito-borne public health emergency is defined as:
Actual or threatened, imminent outbreak of western equine encephalitis, St. Louis encephalitis, West Nile encephalitis, malaria, or other mosquito vector-borne public health disease. The presence of western equine encephalitis, St. Louis encephalitis, West Nile encephalitis, or malaria viral titers or mosquito pool titers in the mosquito population, wild birds, or in sentinel chickens (in accordance with test protocols developed by the Washington State Department of Health and the U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (CDC 2001)) will confirm that a public health emergency exists or is imminent. The West Nile Virus will also be monitored due to the discovery of its presence on the east coast in the vicinity of New York City and other locations in September 1999, and the January 2002 discovery in Seattle, Washington of a mosquito species found in the eastern United States capable of carrying the West Nile Virus.
3. Once a mosquito abatement district notifies the Refuge Manager of a laboratory test that is positive for any of the above viruses in mosquitoes documented to be on the refuge, the Refuge Manager will immediately inform the Regional Director of the U.S. Fish and Wildlife Service to make the ultimate determination of whether an emergency exists relative to the refuge.
4. The Service may allow mosquito control on System lands when all of the following exist:
A. There is documented incidence of mosquito-borne disease activity in those mosquito species that have been documented to breed on the refuge. The disease may be identified in birds, mosquitoes, humans, and/or other mammals.
B. Current monitoring data indicate that refuge-based mosquitoes pose an imminent threat to human health. The term "imminent threat" used here would mean high larval and/or adult populations of a mosquito species known to be present on the refuge.
C. The Regional Director, in consultation with appropriate health care professionals, determines there is a high probability that disease-carrying mosquitoes originating from the refuge may infect humans.
5. After receiving the determination of an emergency from the Regional Director, the Refuge Manager, in consultation with recognized experts (i.e., biologists/entomologists) and human health care authorities, will respond appropriately to a mosquito-borne disease threat when the above conditions have been met. The term "appropriately" means using the most effective agents practicable to address the specific human health risk, and would include larviciding or, in cases where infected mosquitoes have been found on System lands, adulticiding.
6. The use of pesticides on the refuge will only occur when:
A. there is evidence of an increasing risk for human infection;
B. this risk will be substantially lowered by the pesticide(s); and
C. the application of pesticides to the refuge is superior to other available approaches to manage disease risk.
7. Any emergency treatment lasting beyond 30 days will require a separate Compatibility Determination.
Justification for Mosquito Control (Emergency):
The National Wildlife Refuge System Improvement Act of 1997 authorizes the Secretary of the Interior to temporarily suspend, allow, or initiate any activity on a refuge necessary to protect the health and safety of the public or any fish and wildlife population on the National Wildlife Refuge System.
Determination for Mosquito Monitoring (Check one below):
Use is Not Compatible
X Use is Compatible With Following Stipulations
Stipulations Necessary to Ensure Compatibility of Mosquito Monitoring
Dates and specific locations of sampling efforts
Data sheets and accompanying maps for each dipsite
b. December 30, 2002
Information regarding mosquito trapping/testing for mosquito-borne diseases.
c. March 31, 2003
A final report will be submitted that will include a total wrap-up of the information requested. This will include information on mosquito-borne disease sampling/testing results.
Peer review of the above reports will be conducted by one or more specialists of the Service's choosing.
Justification for Mosquito Monitoring:
The effects of mosquito monitoring and research activities, as authorized with stipulations to ensure continued compatibility, would be expected to be negligible. Excessive and uncontrolled foot traffic in areas of wildlife resources have long been considered to be detrimental, but when regulated, they can be made to be significantly less disruptive. All-terrain vehicle use can be minimized and regulated the same way, to minimize the duration of the monitoring/research activities and damage to the resources, by restricting the vehicles to refuge service roads. Because there would be no application of a control agent, there would be minimal disturbance to the aquatic invertebrate populations providing food for wetland birds and juvenile salmon feeding in the shallow water areas where activities might occur, with the opportunity for the wildlife and fish to return to the area after the personnel have departed the particular monitoring site.
Monitoring activities will generate valuable information regarding the mosquito populations using the waters and associated wetlands of the Franz Lake NWR. These activities are not expected to materially interfere with or detract from the purposes of the Franz Lake National Wildlife Refuge, the mission of the Refuge System, or our legal mandate to ensure the biological integrity, diversity, and environmental health of the NWR System. These uses are not anticipated to have significant adverse impacts on fish, wildlife, plants, or their habitats There are no authorized public uses at Franz Lake NWR, so there will be no conflict between the proposed uses and public uses. For these reasons, mosquito monitoring, as proposed herein, has been determined to be a compatible use of the Franz Lake NWR.
Determination for Mosquito Research:
Use is Not Compatible
X Use is Compatible With Following Stipulations
Stipulations Necessary to Ensure Compatibility of Mosquito Research:
1. A Special Use Permit from the Refuge Manager must be obtained by mosquito control districts that propose to carry out these activities on the Franz Lake NWR.
2. Mosquito control district personnel will be required to conduct the following activities of a mark-recapture study as funding and personnel permit:
Collect and transport mosquito larvae to a rearing facility
Rear larvae to adult stage
Mark adult mosquitos with a flourescent dye
Return and release marked mosquitos to Franz Lake NWR as near to point of capture as possible
Hire a qualified entomologist to conduct this portion of the study
Set up light traps around the Skamania area, with maps identifying locations
Return captured adult mosquitos to the lab for identification as to species and presence of marking dye
Determine proportion of marked adult mosquitos as a percentage of total mosquitos captured at each capture site
3. Research activities are permitted only in low-slope, shallow wetland edges, and periodically flooded shorelines suitable for mosquito breeding. The east and south shores of Franz Lake have currently been identified as probable breeding areas. Other areas that district personnel wish to investigate must be approved in advance by the Refuge Manager.
4. District personnel may use one all-terrain vehicle at slow speeds, not to exceed 5 miles per hour, on the service road along the south shoreline of Franz Lake. This will minimize the time it takes to complete the surveys and disturbance to wildlife resources.
5. Actual research activities will be done on foot only along the Franz Lake shorelines as described above to avoid and/or minimize damage/disturbance to the vegetation, wildlife, and fisheries resources using the area.
6. District personnel will be required to notify the Refuge Manager on the Monday of each week they schedule for research activities.
7. No research activities will take place within 100 meters of any active bald eagle nest.
8. This Compatibility Determination is only valid for one year, the uses will be re-assessed during the CCP process, and a new Compatibility Determination may be prepared at that time.
9. District personnel will be required to comply with the terms and conditions detailed in the Special Use Permit.
10. Refuge staff will monitor district compliance with these stipulations and the terms and conditions specified in the Special Use Permit.
11. District personnel will provide the Refuge Manager with annual, written reports of mosquito research activities. Because the Clark County Mosquito Control District does not work between October 1 and mid-March, a report of Phase 1 activities will be submitted by September 30, 2002. If Phase 2 activities are completed, a professionally written report will be submitted by December 30, 2002. Peer review of these reports will be conducted by one or more specialists of the Service's choosing. The final report will be provided to the Refuge Manager as soon as it is available.
Justification for Mosquito Research:
Research activities will generate valuable information regarding the mosquito populations using the waters and associated wetlands of the Franz Lake NWR (mark/recapture study). These activities are not expected to materially interfere with or detract from the purposes of the Franz Lake National Wildlife Refuge, the mission of the Refuge System, or our legal mandate to ensure the biological integrity, diversity, and environmental health of the NWR System. These uses are not anticipated to have significant adverse impacts on fish, wildlife, plants, or their habitats. We do not anticipate these uses will conflict with other priority public uses of Franz Lake NWR. For these reasons, mosquito research, as proposed herein, has been determined to be a compatible use of the Franz Lake NWR.
The effects of mosquito monitoring and research activities, as authorized with stipulations to ensure continued compatibility, would be expected to be negligible.
Mandatory Re-Evaluation Date (provide month and year for "allowed" uses only):
_________ Mandatory 15-year Re-Evaluation Date (for priority public uses)
X Mandatory 10-year Re-Evaluation Date (for all uses other than priority public uses)
NEPA Compliance for Refuge Use Decision (check one below):
X Categorical Exclusion without Environmental Action Statement
___ Categorical Exclusion and Environmental Action Statement
Environmental Assessment and Finding of No Significant Impact
___ Environmental Impact Statement and Record of Decision
Centers for Disease Control and Prevention (CDC). 2001. Epidemic/Epizootic West Nile Virus in the United States: Revised Guidelines for Surveillance, Prevention, and Control. Report from a workshop held in Charlotte, North Carolina, January 31-February 4, 2001.
Charbonneau, C.S., R.D. Drobney, and C. F. Rabeni. 1994. Effects of Bacillus thuringiensis var. israelensis on nontarget benthic organisms in a lentic habitat and factors affecting the efficacy of the larvicide. Env. Toxic. and Chem. 13(2):267-279.
Grendon, J. 2000. The history of vector borne disease in Washington. Northwest Mosquito Vector Control Association Disease Surveillance Workshop. Unpublished.
Heitmeyer, M.E. 1988. Protein costs of the prebasic molt of female mallards. The Condor 90:263-266.
Hershey, A.E., A.R. Lima, G.J. Niemi, and R.R. Regal. 1998. Effects of Bacillus thuringiensis israelensis (Bti) and methoprene on nontarget macroinvertebrates in Minnesota wetlands. Ecol. Applic. 8(1):41-60.
Higgins, M. 2002. U.S. Fish and Wildlife Service, National Mosquito Control Coordinator. Personal communication with Jim Clapp, March 2002.
Holm, Jeff. 2002. U.S. Fish and Wildlife Service, former Franz Lake NWR Manager, current Chief of Branch of Refuge Operations and Administration. Personal communication with Jim Clapp, February 2002.
Krapu, G.L., and G.A. Swanson. 1978. Foods of juvenile, brood hen, and post-breed in pintails in North Dakota. Condor 79:504-507.
A. Poole and F. Gill, eds. 2002. The birds of North America, Inc., Philadelphia, Pennsylvania.
Price, John. 2002. Long-time resident adjacent to Franz Lake NWR. Personal communication with Jim Clapp, February 2002.
Swanson, G.A., G.L. Krapu, and J.R. Serie. 1979. Foods of laying female dabbling ducks on the breeding grounds. Pages 47-57 in T.A. Bookhout, ed., Waterfowl and wetlands-An integrated review. Proc. Symp. North Cent. Sect., The Wildl. Soc.
U.S. Geological Survey - Center for Integration of Natural Disaster Information. May 2002. National and State West Nile Virus Maps . Website address: http://cindi.usgs.gov/hazard/event/west_nile/west_nile.html.
University of Washington. May 2002. Columbia River Data Access in Real Time (DART), Smolt Index. Website Address: http://www.cqs.washington.edu/dart/dart.html.
Prepared by: ____________________________________ ____________
Approval: ____________________________________ ____________
Refuge Supervisor: ____________________________________ ____________
Refuge System: ____________________________________ ____________
Appendix 1. Franz Lake National Wildlife Refuge
Appendix 2. Graphs showing presence of specific species of salmon at the nearby Bonneville Dam. Note that Chinook-0 are young-of-the-year fall chinook.
Source: University of Washington's Columbia River Data Access in Real Time (DART), Smolt Index. May 2002. Website Address: http://www.cqs.washington.edu/dart/dart.html
Appendix 3. Potential Effects of Mosquito Control on Salmonids and other Fishes at Franz Lake National Wildlife Refuge. M. Yoshinaka, 2002. U.S. Fish and Wildlife Service, Columbia River Fisheries Program, Vancouver, Washington
Skamania County has proposed a mosquito control program at Franz Lake National Wildlife Refuge (NWR). This mosquito abatement program would use the bacterial larvicide Bacillus thuringiensis var israelensis (B.t.i.) to control mosquitoes. As proposed, this insecticide would be applied once every two to three weeks as needed at an application rate of 10 pounds per acre to wetlands and waters along Franz Lake and the Columbia River. The following discussion describes the potential direct and indirect effects of mosquito abatement programs using B.t.i., on salmonids that use the waters of Franz Lake NWR.
Fish Species Occurring in Waters of Franz Lake NWR
Anadromous and resident fish are present in the waters of Franz Lake NWR throughout the year. These include anadromous and resident salmonids, anadromous nonsalmonid fish, and native and introduced resident fishes. Staff from the Columbia River Fishery Program Office (CRFPO) conducted limited sampling of waters at Franz Lake NWR from August, 1996 to June, 1997 and collected 22 species of fish. Waters which were sampled included Franz and Arthur lakes, Prices Pond, Indian Mary and Good Bear creeks, Poacher Springs, and the channels connecting these bodies of water. Table 1 lists fish species collected during this sampling period. This list may not include all of the species that may occur in Franz Lake NWR waters because of the limited number of samples collected and the types of sampling gear used. For example, Pacific lamprey (Lampetra tridentata) and western brook lamprey (Lampetra richardsoni) occur in nearby streams and are likely inhabitants of Franz Lake NWR waters, but were not collected.
Four species of native salmonids: coho salmon (Onchorhynchus kisutch); fall chinook salmon (O. tshawytscha); cutthroat trout (O. clarki); and steelhead (O. mykiss) were found to be using these waters during the CRFPO sampling. Chum salmon (Oncorhynchus keta) were not reported from the 1996-1997 sampling but were observed spawning at the outlet of Franz Lake in 2001 (K. Keller, PSMFC, personal communication). Of these species, steelhead, chum, and fall chinook are listed under the Endangered Species Act as threatened. Cutthroat trout are proposed for listing and coho salmon are candidates for listing.
Cutthroat, steelhead, and coho were captured at all times of the year in both Poacher Springs and in Indian Mary Creek upstream of Franz Lake. Smolts of all species were captured, indicating that these fish are migratory. These data, along with our habitat observations, indicate that cutthroat spawn in both Indian Mary Creek and Poacher Springs. Whereas both steelhead and coho salmon may spawn in these streams, they also appear to move into these waters for rearing purposes from adjacent drainages, such as Good Bear and Duncan Creeks. Juvenile fall chinook salmon were captured in Franz Lake in the spring and early summer. These fish were rearing in Franz Lake in high densities.
The immigration periods for adults of these species are August to November for cutthroat, November to April for steelhead, October to January for coho, and November to January for chum. The main emigration period for cutthroat, steelhead, and coho juveniles and smolts is from March to June. Chum salmon emigrate from February to April. Fall chinook juveniles immigrate to Franz Lake from March to May, rear there, and emigrate from July to August.
Direct Effects of B.t.i. on Fish
In general, available information indicates that B.t.i. is relatively nontoxic to fish. However, there have been relatively few studies on the effects of either insecticide on fish. Data on the direct effects of B.t.i. on salmonids and other fish species occurring in the Franz/Arthur lakes system are lacking. However, some studies have been conducted on salmonids in other geographical areas. Wipfli et al. (1994) found direct and indirect exposure to B.t.i. did not measurably affect the growth and survival of brook, brown, or steelhead trout when the pesticide was applied at concentration recommended for blackfly control (15 ppm for 15 minutes) in Michigan laboratory tests. Fish mortality was observed when concentrations were 70 times greater and at exposure periods 192 times longer than those recommended for blackfly control.
Merritt, et al. (1989) found no detectable differences in mortality or weight change of rock bass (Ambloplites rupestris) in the Betsie River, Michigan, when that stream was treated with Bti to control black flies.
Solvents present in the formulation of B.t.i. may have a greater effect on fish than B.t.i. spores or crystals. Fortin et al.(1986) noted that brook trout fry exposed to Teknar, a water-based formulation of B.t.i., showed signs of stress or died at concentrations greater than 3000 mg/l. They suspected that xylene present in the formulation was responsible for stress and mortality. Tests using Teknar with xylene removed by freeze drying showed no effect on fish exposed to concentrations of 6000 mg/l. Fish tested with 6000 mg/l of freeze dried Teknar with 2% xylene added showed immediate immobilization and 100% mortality.
Direct Effects on Aquatic Invertebrates
Bacillus thuringiensis var israelensis is narrowly specific to certain Dipterans including mosquitoes, blackflies and midges and appear to have little impact on other species of other aquatic invertebrates (Mike Higgins, FWS, personal communication).
Wipfli and Merritt (1994) observed no lethal or sublethal effects on most of 16 taxa of mayflies, stoneflies, caddisflies, and true flies exposed both directly and indirectly to B.t.i.. They concluded that B.t.i. appeared to be harmless to nontarget benthic insects even when exposed to higher than recommended dosages and when they consumed Bti-killed blackfly larvae.
Brown (W. Brown, USFWS, Maryland Cooperative Research Unit, unpublished) reviewed the existing literature concerning the effects of B.t.i. on various organisms and indicated that it had no effect on certain crustaceans that were studied (cladocerans, conchostracans, copepods, isopods, and ostracods). She also reported that B.t.i. had no effect on beetles (Coleoptera), some mayflies (Ephemeroptera), true bugs (Hemiptera), damselflies and dragonflies (Odonata), stoneflies (Plecoptera), and caddisflies (Trichoptera).
Chironomids (midges) are the other major group of Dipterans adversely affected by B.t.i.. The effect of B.t.i. on Chironomidae varies depending on genus or species. Brown's review of studies that addressed B.t.i. effects on chironomids found effects ranging from adverse impacts to no effects. The effects varied depending on the species of chironomid tested.
The toxicity of B.t.i. to chironomids also appears to be affected by environmental factors such as water temperature, water depth, and the water surface area covered by macrophytes. Charbonneau et al. (1994) reported that the efficacy of B.t.i. (Vectobac-G®) was temperature dependent at 6 ppm. Mortality of chironomids was significantly higher at 27 C. than at 11 or 19 C. They also reported that Vectobac-G did not adversely affect chironomids when applied to deep freshwater marsh and deep open water habitats. They attributed lowered toxicity to the rapid denaturing of the B.t.i. crystals as they sank. They also indicated that other researchers have reported greater macrophyte coverage of sediments reduced the efficacy of Vectobac-G to chironomid larvae. This was thought to be due to the adhesion of settling B.t.i. pellets and crystals to the leaves of submerged vegetation or to the removal of B.t.i. by snails or other organisms.
Indirect Effects of B.t.i. on Fish
Indirect effects such as food web changes caused by the loss or reduction of prey organisms for fish may have a greater adverse impact. Wipfli et al. (1994) stated that the greatest harm from Bti to fish and other predators may result from food resource losses when organisms such as blackfly larvae are removed from the food web. They concluded by stating that food resource loss for predators and its effect on the overall stream ecology is an important area for future research.
Indirect effects of B.t.i. on nontarget organisms that affect the food web of Franz Lake NWR's waters and may be of greater concern than their direct effects on fish. Bacillus thuringiensis var israelensis appears to be narrowly specific to mosquitoes, blackflies, and certain midges (Chironomidae) and have little impact on other species of aquatic invertebrates. Indirect effects of mosquito control through use of B.t.i. on fish may occur when non-target species such as Chironomidae or blackflies (Simuliidae) are killed. These groups as well as mosquitoes are major food sources for juvenile fishes, especially chinook salmon, found in the Franz Lake system.
Chironomidae are known to be a major component of the diet of juvenile chinook salmon throughout the Columbia River system and elsewhere in the Pacific Northwest. Becker (1973) reported that Chironomidae dominated the diets of juvenile chinook salmon in the Hanford Reach of the Columbia River. He found that adult midges provided between 58 and 64% of the diets of young-of-the-year chinook salmon and that larval midges provided 17 to 18% of their diets. The chinook salmon that use Franz Lake are young-of-the-year fish.
Muir and Emmett (1988) found that adult chironomids were the most important food item during August for subyearling chinook salmon that were collected at Bonneville Dam. Muir and Coley (1996) examined the stomachs of yearling chinook salmon at Lower Granite Dam on the Snake River as well as at McNary and Bonneville dams and found chironomids were a major diet component of these fish.
Rondorf et al. (1990) reported that adult and pupal Chironomidae comprised a major portion of the diet of subyearling chinook salmon (42% by number and 27% by weight) in the McNary Dam pool reach of the Columbia River. Chironomids were major food items in all habitat types (riverine, mid-reservoir, and forebay) that were sampled in McNary pool.
Garland et al. (In review) examined the stomach contents of subyearling fall chinook salmon from both the Hanford Reach of the Columbia River and the Hells Canyon Reach of the Snake River during 1996 and 1997. Their study indicates that larval and adult Dipterans were important food items for subyearling fall chinook. In both years both larval and adult Dipterans were mostly from the family Chironomidae. The insect order Diptera includes both mosquitoes and midges.
Cordell et al. (1999) found that chironomids dominated the diet of juvenile chinook salmon in restored intertidal freshwater wetlands of the Snohomish River Estuary. They noted that their findings were similar to observations of juvenile chinook salmon diets elsewhere in the Pacific Northwest.
Juvenile cutthroat and rainbow trout and coho salmon feed on Diptera to varying degrees. Wydoski and Whitney (1979) state that juvenile coho in streams feed primarily on aquatic insects such as Diptera, mayflies, and stoneflies. They also indicate that rainbow trout feed primarily on foods, such as Diptera, that are associated with the bottom. Cutthroat trout are reported to feed primarily on aquatic insects.
Regular applications of Bti according to standard protocols for mosquito control may have a long term effect on nontarget species of insects. Hershey, et al. (1998) found a long term negative impact on the nontarget insect community in wetland areas that were treated with Bti compared to non-treated control sites. Their study found that chironomid population densities in Bti treated sites were from 66 to 84% lower than those in untreated sites.
There are few published reports on the direct effects of B.t.i. on fish species that occur in waters of Franz Lake NWR. Studies that have been conducted on the direct effects of B.t.i. have generally shown both insecticides to be of low toxicity to fish at the application rates recommended for mosquito control.
Fish sampling conducted by the CRFPO has shown that waters on Franz Lake NWR are inhabited by migratory salmonids including steelhead and cutthroat trout and chinook and coho salmon. Chinook salmon and steelhead are listed as threatened under the Endangered Species Act. Coho salmon are candidates for listing and cutthroat are proposed for listing. Any activities that would adversely impact species under jurisdiction of the Endangered Species Act would be of particular concern.
There is greater potential for indirect adverse impacts to fish from disruption of the food web. Bacillus thuringiensis var israelensis is specific to mosquitoes, blackflies and midges. All three groups of insects are important food items for salmonids and other fishes.
Juvenile salmonids, especially rearing subyearling chinook salmon, feed heavily on midges in shallow backwaters and lakes adjoining the Columbia River. Midges (chironomids) have been documented as one of the most important food items for subyearling chinook salmon throughout the Columbia River and the Pacific Northwest. Subyearling chinook salmon inhabit the shallow backwater areas of Franz Lake NWR in high densities from March to August. During this time they feed extensively on chironomids. Numerous studies have shown Bti and B. sphaericus to have adverse effects on various species of chironomids. Lowered chironomid populations would reduce an important food source for rearing juvenile salmonids during the critical rearing period before seaward migration.
Mosquito control operations at Franz Lake NWR are likely to coincide with the period of highest use of this area by subyearling fall chinook and other juvenile salmonids (March-August). Mosquito populations are likely to be higher during years when Columbia River flows are high. These are also the years when more juvenile salmonids are expected to enter backwaters and side channels to seek refuge from high water velocities in the mainstem Columbia River. Mosquito control operations during these years are likely to adversely affect greater numbers of juvenile salmonids over a longer period of time.
Regular applications of B.t.i. to control mosquitos may repeatedly reduce the population of midges at Franz Lake NWR thereby reducing the long term supply of food for rearing salmonids. This could reduce the growth rate and survival of rearing salmonids.
Information and Monitoring Needs
Presently, knowledge regarding chironomids present at Franz Lake NWR does not exist. Additional information would be needed to properly assess the impact of B.t.i. application on chironomids and juvenile salmonids if it were used. These information needs include the habitat characteristics of areas to treated, species of chironomids present, densities of chironomid populations in proposed treatment areas, and fish use of these areas.
The efficacy of B.t.i. on chironomids would be affected by factors such as substrate type, water depth during treatment periods, and the density of aquatic macrophytes at the treatment sites. Therefore, data for these habitat characteristics need to be collected to estimate the potential for adverse effects on non-target chironomids.
There would be a need to know the species of Chironomidae present in waters of Franz Lake NWR to determine their susceptibility to the effects of B.t.i. The available information indicates that B.t.i. differs in its effects on different species of chironomids. The effects of a B.t.i. application on chironomids at Franz Lake NWR would depend on the susceptibility of the species present. At this time the species of chironomids inhabiting Franz Lake NWR waters have not been identified. Samples of insects, especially chironomids, should be collected from potential treatment areas to determine the species present.
It is also unlikely that bioassays have been conducted to examine the effect of either B.t.i. on the chironomid species present. Bioassays should also be conducted to evaluate the effect of B.t.i. on these species. This would aid in predicting whether or not large scale and repeated application of these insecticides would detrimentally impact the food web at Franz Lake NWR.
If a mosquito abatement program would be approved, then the densities of Chironomidae and other Diptera in Franz Lake NWR waters before and after application with B.t.i. should be determined so that population densities and species diversity can be compared before and after treatment. Monitoring of Dipteran population densities should continue if repeated applications of B.t.i. is planned in the future.
Fish use before and after any treatment for mosquito control should be documented at treatment sites. Fish use of Franz Lake NWR waters, especially by subyearling chinook salmon, may be impacted if chironomid populations are reduced. Subyearling chinook salmon are the species of salmon most likely to be using shallow water habitat in Franz Lake NWR and are also the species and life stage of salmonid that relies most heavily on chironomids. Mosquito treatment is likely to occur during the time when subyearling chinook salmon would be rearing in shallow waters of Franz Lake NWR. Subyearling chinook salmon use of Franz Lake may also be highest in years of higher river flow when these fish seek refuge from strong river currents in backwaters. These are also the times when mosquito populations of these areas are high. Fish use of these waters must be examined before and after treatment for mosquitoes to determine if it is being affected.
Table 1. List of Fish Species Collected at Franz Lake NWR
|Common Name||Scientific Name|
Northern Pike Minnow
Becker, C.D. 1973. Food and growth parameters of juvenile chinook salmon, Oncorhynchus tshawytscha, in the central Columbia River. Fish. Bull. 71(2): 387-400.
Cordell, J.R., C. Tanner, and J.K. Aitkin. 1999. Fish assemblages and juvenile salmon diets at a breached-dike wetland, Spencer Island, Washington 1997-98. FRI-UW-9905, June 1999. Fisheries Research Institute, School of Fisheries, University of Washington, Seattle. 15p.
Fortin, C., D. Lapointe, and G. Charpentier. 1986. Susceptibility of brook trout (Salvelinus fontinalis) fry to a liquid formulation of Bacillus thuringiensis serovar. israelensis (Teknar®) used for blackfly control. Can. J. Fish. Aquat. Sci. 43: 1667-1670.
Garland, R.D., K.F. Tiffan, and D.W. Rondorf. In preparation. Food habits of naturally and hatchery produced subyearling fall chinook salmon in the Snake and Columbia Rivers. U.S. Geological Survey Columbia River Research Laboratory, Cook, Washington.
Hershey, A.E., A.R. Lima, G.J. Niemi, and R.R. Regal. 1998. Effects of Bacillus thuringiensis israelensis (Bti) and methoprene on nontarget macroinvertebrates in Minnesota wetlands. Ecological Applications 3(1): 41-60.
Key, P.B. and G.I. Scott. 1992. Acute Toxicity of the Mosquito Larvicide, Bacillus sphaericus, to the Grass Shrimp, Palaemonetes pugio, and Mummichog, Fundulus heteroclitus. Bulletin of Environmental Contamination and Toxicology BECTA6, 49(3): 425-430. Abstract only.
Mittal, P.K., T. Adak, and V.P. Sharma. 1991. Acute toxicity of certain organochlorine, organophosphorus, synthetic pyrethroid and microbial insecticides to the mosquito fish Gambusia affinis (Baird and Girard). Indian J. Malariol., 28(3): 167-70. Abstract only.
Muir, W.D. and T.C. Coley. 1996. Diet of yearling chinook salmon and feeding success during downstream migration in the Snake and Columbia rivers. Northwest Science 70(4):298-305. Nov, 1996.
Muir, W.D. and R.L. Emmett. 1988. Food habits of migrating salmonid smolts passing Bonneville Dam in the Columbia River, 1984. Regulated Rivers 2:1-10.
Rondorf, D.W., G.A. Gray, and R. B. Fairley. 1990. Feeding ecology of subyearling chinook salmon in riverine and reservoir habitats of the Columbia River. Trans. Am. Fish. Soc. 119:16-24.
Wipfli, M.S. and R.W. Merritt. 1994. Effects of Bacillus thuringiensis var. israelensis on nontarget benthic insects through direct and indirect exposure. J. N. Am. Benthol. Soc.13(2): 190-205.
Wipfli, M.S., R.W. Merritt, and W.W. Taylor. 1994. Low toxicity of black fly larvicide Bacillus thuringiensis var. israelensis to early stages of brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and steelhead trout (Oncorhynchus mykiss) following direct and indirect exposure. Can. J. Fish. Aquat. Sci.. 51:1451-1458.
Wydoski, R.S. and R.R. Whitney. 1979. Inland fishes of Washington. University of Washington Press, Seattle. 220 p.