Lake Sturgeon Research

Characterization of Early Life History Stages
In the Green Bay basin, an insufficient understanding of lake sturgeon early life history and loss of important nursery habitats has been identified as a critical impediment to successful rehabilitation of this species. Because each life stage has unique resource requirements, identifying and preserving critical microhabitats which provide sufficient prey resources and a suitable physico-chemical environment will be important determinants of successful recruitment. This study examined linkages among population abundance and structure, distribution, and movement and usage patterns of larval, juvenile, and subadult lake sturgeon relative to the availability of physical habitat, chemical environmental factors, and benthic macroinvertebrate prey in the lower Peshtigo River and the immediate, nearshore waters of Green Bay. Sampling results from this project will also be used to establish a quantitative sampling protocol for standardizing assessment surveys of early life stages of lake sturgeon in Great Lakes waters. Age-0 lake sturgeon (mean fork length = 239 mm [range, 223 to 249 mm]; mean weight = 83 g [range, 74 to 90 g] were captured from September through October 2002 in the lower section of the Peshtigo River, Wisconsin, using wading surveys with dip nets, haul seines, backpack electrofishing, snorkeling, set lines, bottom trawls, gill nets, and fyke nets. All fish were measured and weighed, and water quality parameters (i.e. water temperature, dissolved oxygen, pH, and conductivity), water depth, and river velocity were measured at each collection location. Radio transmitters were attached to juvenile lake sturgeon larger than 75 g in weight, and were tracked at least twice each day. At each capture site, a bottom dredge sample was also collected. Dominant substrate types were visually estimated and a sample was preserved for later analysis of macroinvertebrate assemblage. Quantitative analysis of habitat types within the Peshtigo River was conducted using dredge samples collected at three points perpendicular to river flow at 50-m intervals. All juvenile lake sturgeon were captured over sand substrates, with particle size ranging from 1.99 to 0.12 mm in diameter, in depths less than 1.0-m, velocities greater than 0.66 m/s, and temperatures ranging from 14.5 to 23.8°C. Eight of thirteen juvenile lake sturgeon were collected over substrate containing macroinvertebrates. Those with transmitters (N = 4) did not leave their capture site until water temperatures within the river declined to 12°C, when the fish moved downstream and into Green Bay within a two- to three-day period. Catch-per-unit-effort (CPUE) was highest with the day seining (CPUE = 2.02 fish/h), followed by day wading surveys and night seining (CPUE = 0.86 and 0.80 fish/h, respectively). No age-0 sturgeon were captured with bottom trawls, set lines, or fyke nets. We recommend the use of day seining or day wading surveys in rivers similar to the Peshtigo River (i.e., shallow and low turbidity) for capturing age-0 lake sturgeon.

Funding Source: Great Lakes Fishery Trust

Personnel: Angela Benson (completed master’s thesis in August 2004)

Publications:
• Benson, A. C., T. M. Sutton, R. F. Elliott, and T. G. Meronek. In revision. Biological attributes of age-0 lake sturgeon in the lower Peshtigo River, Wisconsin. Journal of Applied Ichthyology.
• Benson, A. C., T. M. Sutton, R. F. Elliott, and T. G. Meronek. In revision. Movement patterns and habitat preferences of age-0 juvenile lake sturgeon in the lower Peshtigo River, Wisconsin. North American Journal of Fisheries Management.
• Benson, A. C., T. M. Sutton, R. F. Elliott, and T. G. Meronek. In press. Evaluation of sampling techniques for age-0 juvenile lake sturgeon in the lower Peshtigo River, Wisconsin, and nearshore waters of Green Bay. North American Journal of Fisheries Management.
• Sutton, T. M., and A. C. Benson. 2003. Influence of external radio transmitter size and shape on survival, growth, and tag loss of juvenile lake sturgeon. Transactions of the American Fisheries Society 132:1257-1263.

Collaborators: Robert Elliott, Thomas Meronek, Gregory Kornely, and Kim Scribner

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