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Sea lamprey (Petromyzon marinus) control on a lake-wide basis was initiated in 1970 and eventually reduced the original population of sea lampreys in Lake Huron by nearly 85%. Although some fish populations started to rebound after the first round of lampricide treatments, the recovery was short-lived and the population of parasitic-phase sea lampreys in the lake again began to increase largely because of the uncontrolled population in the St. Marys River. By 1994, the population of parasitic-phase sea lampreys in Lake Huron exceeded the combined populations in the four other Great Lakes. Lamprey-induced mortality rates on lake trout were greater than that recommended for recovering populations of lake trout. In response to the high lamprey-induced mortality rates, lake trout (Salvelinus naymaycush) were not stocked in the northern part of the lake from 1994 until 1997, when an integrated plan for sea lamprey control was implemented in the St. Marys River. Fish community objectives for sea lampreys in Lake Huron call for a 75% reduction in parasitic sea lampreys by the year 2000 and a 90% reduction by the year 2010. The integrated approach to the control of sea lampreys in the St. Marys River is projected to reduce the number of sea lampreys in Lake Huron by 85%. This exceeds the objective for 2000 and nears the objective for 2010. [ABSTRACT FROM AUTHOR]

For successful control of the St. Marys River sea lamprey (Petromyzon marinus) population, one critical uncertainty that needs to be characterized is uncertainty in the stock-recruitment relationship. A statistically-based, age-structured population model was developed to estimate the parameters of a Ricker stock-recruitment relationship for St. Marys River sea lampreys and the associated uncertainty in these parameters. This analysis indicated considerable stock-independent variability in recruitment across a range of stock sizes, potentially limiting the effectiveness of control options that reduce the spawning population in comparison to those that reduce the larval population. Point estimates of the stock-recruitment parameters suggest moderate compensation, but the uncertainty in these point estimates is large, spanning a range from negligible to high compensation. By characterizing these uncertainties and incorporating the results into a decision analytic framework, it is then possible to evaluate the effects of compensation and stock-recruitment uncertainty on management options available for St. Marys River sea lamprey control. [ABSTRACT FROM AUTHOR]

This paper describes use of an integrated chemical/oil spill computer model to study lampricide transport in the St. Marys River. The model is developed based on a depth-averaged two-dimensional advection-diffusion equation using a Lagrangian discrete parcel method. The hydrodynamics in the model is computed using a depth-averaged two-dimensional finite element model. The model is used to analyze the effectiveness of alternative lampricide application strategies. This analysis showed that releasing TFM from both the Great Lakes Power Plant and the Edison Sault Power Station is more effective than releasing from the Great Lakes Power Plant only, in terms of kill-per-dollar. However, the total cost for two-site releases are higher than single-site releases. The simulations also showed that the optimum duration of TFM release is between 14 and 16 hours. Simulations of bottom velocity distribution showed that the area over which the granular Bayluscide application could cover 70 to 90% of the sea lamprey (Petromyzon marinus) population in the St. Marys River, depending on the total river discharge. [ABSTRACT FROM AUTHOR]

Sea lampreys (Petromyzon marinus), first reported in Lake Erie in 1921, emigrated from Lake Ontario via the Welland Canal. It was not until the advent of pollution abatement, stream rehabilitation, and salmonid enhancement programs that sea lampreys proliferated. The Great Lakes Fishery Commission (GLFC), in co-operation with state, provincial, and federal fisheries agencies, implemented an integrated sea lamprey management (IMSL) plan for Lake Erie in 1986. Suppression of sea lampreys was nearly immediate, as indicated by declining larval-, parasitic-, and spawning-phase abundance, while survival of lake trout (Salvelinus namaycush) was markedly improved. Consistent with their vision statement, the GLFC began reducing lampricide use by the mid-1990s, while increasing reliance on alternative control methodologies. Reduction of treatment effort coincided with the development of new lampricide application techniques and treatment selection criteria, in addition to heightened regional concern for the impact of lampricide on non-target species. Subsequently, Lake Erie's sea lamprey numbers have rebounded, and marking rates on lake trout have approached pre-control levels. It is hypothesized that Lake Erie's rising abundance is primarily fuelled by untreated and residual larval populations, although some migration of parasitic-phase sea lampreys from Lake Huron is suspected. Model simulations infer that treatment effort on Lake Erie was sub-optimal from 1995 to 1998. Beginning in 1999, the GLFC enhanced measures to identify and control sources of sea lampreys. Based on historical abundance patterns and model results, it is anticipated that intensified management in Lake Erie will reduce sea lamprey numbers and provide an opportunity for lake trout restoration. [ABSTRACT FROM AUTHOR]

The Great Lakes Fishery Commission successfully coordinated fishery management and delivered an international program of sea lamprey (Petromyzon marinus) control and assessment that facilitated the rehabilitation of lake trout (Salvelinus namaycush) and development of a salmonid fishery in Lake Ontario during 1971 to 1999. During the 1980s and 1990s, the integrated management of sea lampreys (IMSL) strategy optimized control and assessment techniques and refined the stream selection process. The program focused primarily on the juvenile life stage (larval phase) through the application of the selective lampricide 3-trifluoromethyl-4-nitrophenol (TFM) to tributaries of the lake, although the addition of barriers to Lake Ontario tributaries appears to have reduced the reliance on TFM. By 1999, IMSL had eliminated sea lampreys in 20 of the 57 tributaries with historical records of production. Accordingly, the abundance of spawning phase sea lampreys showed a significant downward trend, and substantial declines in marking rates for large lake trout were observed. Targets for control were established through the lake trout rehabilitation plan, fish community objectives, and simulation models incorporating an economic injury level (ELL) approach. The EIL for sea lamprey control is the point in which more treatment is not economically justified. The updated IMSL model developed for Lake Ontario provided a tool to support trade-off analysis to estimate target levels of sea lamprey abundance relative to lake trout harvest. Comparison of model predictions and trends in spawning phase abundance revealed general agreement, but also pointed to inconsistencies that merit further investigation. The EIL of control based on the entire treatment history is 8,100 kg TFM per year, which produces a treatment residual of 4,100 adult sea lampreys. Given recent estimates of transformer production from the Niagara River, the annual contribution from untreated sources... [ABSTRACT FROM AUTHOR]

The sea lamprey (Petromyzon marinus) control program, along with the stocking of native fish species, the introduction of Pacific salmon, and the application of regulations controlling harvest, has allowed the socioeconomic and biological recovery of the Lake Michigan fishery which has been described as "spectacular." The program is now instrumental in maintaining today's fish community structure. Initial treatment of Lake Michigan tributaries with the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) reduced the number of spawning-phase sea lampreys by 85% and resulted in a noticeable recovery of the Lake Michigan fishery by 1979. Prior to 1979, sea lampreys were present in 115 of the 511 tributaries of Lake Michigan. Sea lampreys were found in four additional streams between 1978 and 1999. The greatest number of parasitic-phase sea lampreys are produced in 34 streams tributary to Lake Michigan. Between 1960 and 1999, 730 treatments were conducted in 113 Lake Michigan tributaries. The six remaining streams were not treated because few sea lampreys were present. The average number of streams treated annually declined from 21 during 1970-1979 to 12 during 1990-1999. Thirty eight percent less TFM (active ingredient) was applied annually, on average, in 1990 to 1999 (192 kg/m³ of stream discharge) than in 1960 to 1969 (310 kg/m³ of stream discharge). Barriers specifically constructed or modified to block migrating sea lampreys are currently found on 12 Lake Michigan streams. An additional 27 potential barrier sites have been identified on Lake Michigan streams. The estimated numbers of parasitic-phase sea lampreys in Lake Michigan between 1977 and 1999 ranged from 32,000 (1979) to 105,900 (1998). The incidence of fresh sea lamprey wounds on lake trout (Salvelinus namaycush) in Lake Michigan was generally less than five per 100 fish in most years since 1971. Sea lamprey-induced mortality increased steadily in the 1990s, especially among... [ABSTRACT FROM AUTHOR]

The efficacy of 2′, 5-dichloro-4′-nitrosalicylanilide (niclosamide) at various concentrations and exposure times was tested against free-swimming larval sea lampreys (Petromyzon marinus) at 12°C and 17°C in Lake Huron water. Concentrations of niclosamide in test solutions ranged from 0.46 to 4.7 mg/L with pH 7.8 to 8.3, total alkalinity 78 to 88 mg/L as CaCO3, and total hardness 95 to 105 mg/L as CaCO3. In each test, six groups of larvae were exposed to a single concentration of niclosamide for times ranging from 30 s to 30 mm. Exposure time was treated as the dose and, for each concentration tested, the exposure time necessary to kill 50 and 99.9% of larvae (ET50 and ET99.9) was determined. Linear regressions of the log 10-transformed ET50 and ET99.9 on the Log 10-transformed niclosamide concentrations were significant at both temperatures with r² ranging from 0.94 to 0.98. The predicted ET50 ranged from 58 sec to 21.7 mm and the ET99.9 ranged from 2.5 to 43.5 mm across the concentrations and temperatures tested. Niclosamide required a significantly longer time to kill larvae at 12°C than at 17°C. [ABSTRACT FROM AUTHOR]

The Empiric Stream Treatment Ranking (ESTR) system is a data-driven, model-based, decision tool for selecting Great Lakes streams for treatment with lampricide, based on estimates from larval sea lamprey (Petromyzon marinus) surveys conducted throughout the basin. The 2000 ESTR system was described and applied to larval assessment surveys conducted from 1996 to 1999. A comparative analysis of stream survey and selection data was conducted and improvements to the stream selection process were recommended. Streams were selected for treatment based on treatment cost, predicted treatment effectiveness, and the projected number of juvenile sea lampreys produced. On average, lampricide treatments were applied annually to 49 streams with 1,075 ha of larval habitat, killing 15 million larval and 514,000 juvenile sea lampreys at a total cost of $5.3 million, and marginal and mean costs of $85 and $10 per juvenile killed. The numbers of juvenile sea lampreys killed for given treatment costs showed a pattern of diminishing returns with increasing investment. Of the streams selected for treatment, those with > 14 ha of larval habitat targeted 73% of the juvenile sea lampreys for 60% of the treatment cost. Suggested improvements to the ESTR system were to improve accuracy and precision of model estimates, account for uncertainty in estimates, include all potentially productive streams in the process (not just those surveyed in the current year), consider the value of all larvae killed during treatment (not just those predicted to metamorphose the following year), use lake-specific estimates of damage, and establish formal suppression targets. [ABSTRACT FROM AUTHOR]