Integrated Management of Sea Lampreys in the Great Lakes

1996 Annual Report to the Great Lakes Fishery Commission

ASSESSMENT

Larval

Tributaries of the Great Lakes systematically are assessed for abundance of sea lamprey larvae (quantitative surveys) and distribution (qualitative surveys) to determine when and where lampricide treatments are required and effectiveness of past treatments. Surveys primarily are conducted with backpack electrofishers in waters <1 m deep. Waters of >1 m depth are surveyed with deepwater electrofishers or the granular formulation of Bayluscide. Data collected from these surveys are used to estimate the numbers of transforming larvae that will leave individual tributaries the following year and to recommend where lampricides should be applied.

Streams considered candidates for lampricide treatment in 1997 were surveyed in 1996 to provide statistically reliable estimates (+/- 50 percent of the mean) of larval densities and amounts of habitable substrates. Survey plots randomly were selected in each stream, catches of larvae corrected for gear efficiency, and lengths of larvae standardized to the end of the growing season. Populations of larvae were estimated by multiplying the mean density of larvae in the plots by the estimated total habitat suitable to larvae in the tributary. A curve for probability of transformation derived from historical data was used to estimate the number of larvae that would transform and leave the stream in 1997. The streams scheduled for treatment in 1997 were ranked on an estimated cost per kill of transformers.

The Assessment Task Force was established in 1996 to develop an optimal assessment program through the review of established protocols and the development of new techniques for assessment in the Sea Lamprey Control Program. The report on progress is presented on pages 70 and 71.

Lake Superior

• Larval surveys were conducted in 56 tributaries (38 U.S., 18 Canada, Table 9).
• Quantitative surveys were conducted in 26 tributaries (13 U.S., 13 Canada).
• Qualitative surveys were conducted in 18 tributaries (11 U.S., 7 Canada).
• Surveys were conducted with granular Bayluscide in or offshore of 21 tributaries (12 U.S., 9 Canada). Table 9. Status of Lake Superior tributaries that have been treated for sea lamprey larvae, 1987-96.

Lake Michigan

• Larval surveys were conducted in 64 tributaries.
• Quantitative surveys were conducted in 33 tributaries (Table 10).
• Qualitative surveys were conducted in 36 tributaries.
• Surveys were conducted with granular Bayluscide in or offshore of 7 tributaries. Table 10 . Status of tributaries of Lake Michigan that have been treated for sea lamprey larvae, 1987-96.

Table 10. Status of tributaries of Lake Michigan that have been treated for sea lamprey larvae, 1987-1996.

Lake Huron

• Larval surveys were conducted in 56 tributaries, (24 U.S., 32 Canada).
• Quantitative surveys were conducted in 26 tributaries (13 U.S., 13 Canada, Table 11).
• Qualitative surveys were conducted in 25 tributaries (15 U.S., 10 Canada).
• Surveys were conducted with granular Bayluscide in or offshore of 16 tributaries (10 U.S., 6 Canada).
• The population of larvae in three sections of the Pine River was estimated at the time of lampricide treatment in August with mark/recapture techniques. The population estimate was not significantly different from those made earlier in the year or with Quantitative Assessment Survey (QAS) techniques.
• The efficiency of the 1996 lampricide treatment of the Pine River was estimated at 98.8 percent. Pre- and post-treatment QAS estimates of the population of sea lamprey larvae (excluding young of year) were 580,477 and 7,221 respectively.
• Whole-stream population estimates made at the time of treatment of the Musquash (43,465) and Sauble (14,786) rivers were significantly different from those produced with QAS methodology (299,262 and 7,680 respectively). This supports the need for a deepwater QAS methodology. In both streams less than five percent of the larval habitat can be sampled effectively with backpack electrofishers.
• Mapping of the distribution and density of sea lamprey larvae in the St. Marys River was completed and is described in the report of the St. Marys River Control Task Force.

Table 11. Status of tributaries of Lake Huron that currently support larval sea lamprey populations and/or have been treated for sea lamprey larvae, 1987-1996.

Lake Erie

• Larval surveys were conducted in 10 tributaries (7 U.S., 3 Canada).
• Quantitative surveys were conducted in 4 tributaries (2 U.S., 2 Canada, Table 12).
• Qualitative surveys were conducted in 5 tributaries (3 U.S., 2 Canada).
• Surveys were conducted with granular Bayluscide in one U.S. tributary.
• Estimates of the larval population in Big Creek were produced through quantitative and mark/recapture surveys. The mark/recapture estimate was higher, probably due to immigration from upstream areas.

Table 12. Status of tributaries of Lake Erie that have been treated for sea lamprey larvae, 1987-96.

Lake Ontario

• Larval surveys were conducted in 37 tributaries (19 United States, 18, Canada, Table 13.)
• Quantitative surveys were conducted in 12 tributaries (2 Canada, 10 United States).
• Qualitative surveys were conducted in 38 tributaries (21 Canada, 17 United States).
• A migration study was initiated on Fish Creek, a tributary of Oneida Lake. Transformers marked with coded wire tags were released into Fish Creek and the Little Salmon River (reference stream). Lamprey movements will be monitored through the capture of tagged lampreys in Lake Ontario adult assessment traps in 1998.
• The population of larvae in the Credit River was estimated by several techniques. 1995 and 1996 QAS estimates and a fyke net mark/recapture estimate were not significantly different, but a scap net mark/recapture estimate was significantly higher.

Table 13 . Status of tributaries of Lake Ontario that have been treated for sea lamprey larvae, 1987-96.

Spawning-Phase

Mechanical traps are used to monitor spawning migrations of sea lampreys in spring and early summer. Traps are either portable (rectangular steel mesh, hoop, or fyke nets) or permanent (generally concrete) and usually are associated with a physical or electrical barrier. Trap catch of sea lampreys is a measure of relative abundance.

Stratified multiple mark/recapture studies are conducted in most streams to estimate the spawning population for the year. Lake estimates are computed based on a regression relation (y=ax) where a is the slope of the regression, x is the average stream discharge, and y is the estimated number of adult lampreys that enter tributaries. Biological characteristics (sex, length, weight) are recorded from lampreys removed from each river.

Lake Superior

• 3,216 sea lampreys were trapped in 19 tributaries (Table 14, Fig. 9).
• The estimated population of spawning-phase sea lampreys for the south shore of Lake Superior was 35,707 [29,640 west (y=100.16x; r2=.95, P<0.05) and 6,067 east (y=15.67x; r2=.996, P<0.002) of the Keweenaw Peninsula; Table 15].
• Spawning runs were monitored in eight streams (Amnicon, Middle, Bad, Firesteel, Misery, Traverse, Silver, and Huron rivers) through cooperative agreement with the Great Lakes Indian Fish and Wildlife Commission and in the Brule River through agreement with the Wisconsin Department of Natural Resources.
• Fig. 2 shows a downward trend of spawning populations in U.S. waters of western Lake Superior for 1986-95 with an increase in 1996. Spawning populations in U.S. waters of eastern Lake Superior remained stable during 1987-93, declined in 1994, but increased in 1995 and 1996. Table 14. Stream, number, estimated population, trap efficiency and biological characteristics of adult sea lampreys captured in assessment traps in tributaries of Lake Superior, 1996.

Table 14. Stream, number, estimate population, trap efficiency and biological characteristics of adult sea lampreys captured in assessment traps in tributaries of Lake Superior, 1996. (Number in parentheses corresponds to location of stream in figure 9.)

Lake Michigan

• 16,843 sea lampreys were trapped at 12 sites in 11 tributaries (Table 16 , Fig. 9).
• The estimated population of spawning-phase sea lampreys was 57,615 [37,771 east (y=220.09x; r2=0.96, P<.005) and 19,844 west (y=27.29x; r2=0.78, P<.05]; (Table 17). Streams are grouped west of a line between the Manistique and Betsie rivers, and east (inclusive).
• Spawning runs were monitored in four streams through cooperative agreements with the Grand Traverse Band of Chippewa and Ottawa Indians (Betsie and Boardman rivers), Michigan Department of Natural Resources (Jordan River), and Consumers Power Company (Manistee River).
• Spawning populations in Lake Michigan (1986-96) remained relatively stable during the period (Fig. 3).
• High stream discharge in the St. Joseph River inhibited trapping operations throughout the spawning run.

Table 16. Stream, number, estimated population, trap efficiency and biological characteristics of adult sea lampreys captured in assessment traps in tributaries of Lake Michigan, 1996. (Number in parentheses corresponds to location of stream in Fig. 9.)

Lake Huron

• 35,925 sea lampreys were trapped at 17 sites in 13 tributaries (Table 18, Fig. 9 ).
• The estimated population for Lake Huron is 289,156 [280,621 north (y=970.58; r2=0.84, P<0.002) and 8,535 south (y=56.71; r 2=.93, P<0.05) of a line from Alpena, Michigan to Espanola, Ontario, Table 19]. The estimate is the result of a cooperative effort between the Service and the Department and combines the data of both agencies.
• Spawning runs were monitored through cooperative agreements with the Chippewa/Ottawa Treaty Fishery Management Authority (Albany Creek) and Dow Chemical U.S.A. (Tittabawassee River).
• Spawning populations in Lake Huron increased during 1986-93, followed by an abrupt drop for 1994-96 (Fig. 4).
• A mark/recapture study yielded an estimate of 22,255 adults spawning in the St. Marys River. Analysis of trapping data produced an estimate of the male population (14,123), but trapping removed 3,061 from the population, leaving 11,062 males.

Lake Erie

• 1,191 sea lampreys were trapped in four tributaries (Table 20, Fig. 9).
• The population dropped in 1989-90 following the first round of treatments in 1986-87, stabilized from 1991-95, and increased in 1996 (Fig. 5).

Lake Ontario

• 3,934 sea lampreys were trapped at 14 sites in 13 tributaries (Table 21, Fig. 9).
• The estimated population for Lake Ontario is 28,579 [y=257.65x; r2=.59, P<0.009, (Table 22)]. The estimate is the result of a cooperative effort between the Service and the Department and combines the data of both agencies.
• The numbers of spawning sea lampreys in Lake Ontario have remained relatively stable during 1986-96 (Fig. 6). Table 18. Stream, number, estimated population, trap efficiency, and biological characteristics of adult sea lampreys captured in assessment traps in tributaries of Lake Huron, 1996.

Table 18. Stream, number, estimated population, trap efficiency, and biological characteristics of adult sea lampreys captured in assessment traps in tributaries of Lake Huron, 1996. (Number in parentheses corresponds to location of stream in Fig. 9).

Table 19. Annual mean discharge for U.S. and Canadian streams north and south of a line from Alpena, Michigan to Espanola, Ontario in Lake Huron, ranked as primary1 and secondary2 producers of sea lampreys, and the estimated number of spawning-phase sea lampreys in 1996.

Table 20. Stream, number, estimated population, trap efficiency, and biological characteristics of adult sea lampreys captured in assessment traps in tributaries of Lake Erie, 1996. (Number in parentheses corresponds to location of stream in Fig. 9).

Parasitic-Phase

Lake Superior

The Michigan Department of Natural Resources provided data on the frequency of parasitic-phase sea lampreys attached to fish caught by sport charterboats.

• 54 sea lampreys were collected from seven management districts. All were attached to lake trout and none were attached to chinook salmon.
• Lampreys were attached at a rate of 1.0 per 100 lake trout (n=5,540).

Lake Michigan

The Michigan and Wisconsin Departments of Natural Resources provided data on the frequency of parasitic-phase sea lampreys attached to fish caught by sport charterboats.

• 234 sea lampreys were collected from 14 management districts. 186 of the sea lampreys were attached to lake trout and 48 were attached to chinook salmon.
• Lampreys were attached at a rate of 0.6 per 100 lake trout (n = 32,763) and 0.8 per 100 chinook salmon (n = 61,498).

Lake Huron

The Michigan Department of Natural Resources provided data on the frequency of parasitic-phase sea lampreys attached to fish caught by sport charterboats. Personnel from the Lake Huron Biological Station and Sea Lamprey Control Centre collected parasitic-phase sea lampreys from eight commercial fisheries.

• 2,405 sea lampreys (344 from sport and 2,061 from commercial fisheries) were collected from 12 management districts (6 Canada and 6 United States).
• 96 of the sea lampreys captured in the sport fishery were attached to lake trout and 248 were attached to chinook salmon.
• Lampreys were attached at a rate of 1.9 per 100 lake trout (n=5,107) and 3.9 per 100 chinook salmon (n=6,374).
• The population of parasitic-phase sea lampreys in Lake Huron remains excessively high.

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