Abstracts - Oral Presentations

Sturgeon Genetic Structure and Stocking Considerations Presentations:

Welsh, Amy - Spatial Population Genetic Structure throughout the Great Lakes [full presentation (845 KB pdf)]

Description: Understanding lake sturgeon population genetic structure can help guide management decisions, by taking into account genetic relationships between spawning populations. Genetic analysis has been completed for numerous populations throughout the Great Lakes basin, using standardized microsatellite and mitochondrial DNA markers. Levels of genetic variation within and between populations will be summarized. A high degree of population structure has been observed, as evidenced by significant differences in the frequency of alleles at each genetic marker. Results indicate that populations are reproductively isolated, likely due to spawning site fidelity. Differences among populations are not believed to be recent artifacts resulting from reductions in numerical abundance. Substantial population genetic structure, even among populations in close proximity within a lake basin, highlights the need for recognizing population autonomy when devising management plans. Lake basins should not be managed as single units.

Scribner, Kim - Linking Lake Sturgeon Demographics and Genetics [full presentation (340 KB pdf)]

Description: The restoration of small populations of lake sturgeon focuses attention on tradeoffs between demographic growth and maintenance of genetic diversity. Here we report on simulations that incorporate aspects of both lake sturgeon population dynamics and genetics. Starting populations comprised of only adults with less than 50 individuals face substantial risk of extinction due to demographic stochasticity. These simulations also indicate that the loss rate of unique alleles is primarily dependent on the growth rate of the population, and with little dependency on initial population size. Rates of inbreeding, however, are strongly dependent on initial population size, and accumulate rapidly for initial populations of less than 50 adults. These simulations provide a baseline for future work exploring the implications that different supplementation or reintroduction strategies have on the population dynamics and genetics of lake sturgeon.

Bott, Kristin - Relative contributions of spawning stocks of lake sturgeon to populations in Lake Michigan

Description: Historically, lake sturgeon were abundant throughout the Great Lakes, but populations have declined in both abundance and distribution due to habitat loss, water quality degradation, barriers to migration, and overexploitation. The lack of knowledge regarding their abundance, population structure, reproductive status and genetic diversity hinders rehabilitation efforts. An important issue facing managers is identifying the size and stock characteristics of remnant populations, as well as movement and habitat use of different stocks in open waters of the Great Lakes during non-reproductive periods. Spawning populations of lake sturgeon still remain in four tributaries to Green Bay in northeastern Lake Michigan. Previous genetic analysis revealed that populations are genetically distinct, likely due to a high degree of philopatry. This genetic structuring allows individuals sampled from open-water habitats to be assigned to breeding populations of origin with a high degree of confidence. Using mixed stock analyses, we determined the most likely population of origin for individuals captured throughout Green Bay, as well as a fall harvest on the Menominee River. These results will be discussed with a focus on habitat use and movements that may be affecting these populations. This information can be of great use to managers interested in furthering restoration and conservation efforts for lake sturgeon, as it can provide information on relative recruitment rates from all lake sturgeon stocks contributing to the Green Bay mixed population, and of potential stock-specific differences in risk of mortality.

Forsythe, Patrick - Fertilization success, egg predation, deposition and post emergent survival in the lake sturgeon (Acipenser fulvescens): The relative importance of potential barriers to recruitment
[full presentation (1.2 MB pdf)]

Description: Lake sturgeon were once historically abundant throughout their range but have experienced dramatic declines in population numbers and abundance due to overharvest, destruction of spawning habitats and barriers to migration. Management activities have resulted in some improvements to spawning habitats and restoring natural flow regimes. However, many extant populations continue to show little evidence of natural recruitment. High rates of predation on eggs could be one explanation for the low rates of recruitment. Lake sturgeon may also be subject to an Allee effect, where low recruitment is attributed to low fertilization rates due low spawner numbers. We currently lack quantitative information on factors that may be barriers to natural recruitment in lake sturgeon. The objectives of this study were to 1) estimate fertilization rate as a function of spawner number and sex ratio, 2) characterize the water velocity, depth and substrate size where lake sturgeon eggs are naturally deposited and 3) determine the sources and magnitude of egg predation prior to larval emergence at several different spawning sites and stream habitats. Results over two field seasons revealed a large amount of heterogeneity in egg deposition, high invertebrate predation, and inter-annual variability in post-emergent recruitment to the larval stage. Quantification of the relative importance of factors affecting recruitment is vital to the recovery of this species.

Elliott, Rob (Ed Baker, Brad Eggold, and Marty Holtgren) – Overview of the Lake Michigan lake sturgeon rehabilitation plan conservation genetics and rehabilitation stocking section

Description: As part of the development of a lake sturgeon rehabilitation plan for Lake Michigan, the Lake Michigan Lake Sturgeon Task Group has developed a draft document providing guidelines for the introduction of lake sturgeon within the Lake Michigan basin. The intent of these guidelines is to ensure genetic conservation of populations during rehabilitation. While these guidelines are still being reviewed and refined by the Task Group, what is currently described in the document represents a significant level of discussion and eventual agreement among the Lake Michigan resource management agencies of how introduction of lake sturgeon for purposes of rehabilitation should be implemented.

As a foundation, six guiding genetic principles for lake sturgeon rehabilitation were identified:
1. Maintaining the current level of genetic variability among populations is critically important
2. Management actions that may lead to increased inbreeding or outbreeding are to be avoided
3. Fisheries managers should maintain the genetic characteristics of river-specific locally adapted stocks
4. Fisheries managers should maximize the effective population size, reflected in the offspring of the donor population, in gamete collection operations
5. Management policies, strategies, and actions will seek to maximize homing behavior
6. Fisheries managers should perform a risk/benefit analysis for any proposed stocking

Specific guidelines and rational for when to initiate stocking, for the selection of donor populations, for the collection of gametes, for mating schemes, for numbers to stock, and for rearing and release techniques that build on these guiding principles are then described.

Specifics include the following:
Prior to initiating rehabilitation, explore the underlying reasons why a system is not being populated or why a remnant population is at risk. Stocking should be initiated only when water quality and habitat are capable of supporting stocked fish and will be capable of supporting natural reproduction by the time stocked fish mature and return to spawn.

Donor populations should be selected based on similarity in genetic lineage, life history and ecology of originating environment to the population being rehabilitated. A donor population also needs to be of sufficient size and genetic diversity to support gamete or larval collections. To protect the donor population, gamete collections should be made from no more than 5% of the annual adult spawning stock in any year, or should not exceed 10% of that population’s annual production of eggs or larvae.

Over the period of rehabilitation (25 years) gametes should be collected from a minimum of 250 different females and 250-1250 males. Eggs from individual females should be divided equally among available males and fertilized 1:1. An alternative is to collect naturally deposited eggs or drifting larvae so that as many families as possible contribute. Family contribution should be equalized throughout the rehabilitation or restoration process by rearing and stocking equal numbers from each contributing family.

Fish should be reared and released in a manner that imprints stocked fish to receiving waters. (Streamside rearing, stocking of eggs or early stage larva and within system transfers are examples), and sturgeon should be release at locations where wild fish of that life stage are known or would be expected to occur.

The number of fish stocked should be based on habitat availability and expected survival rates so that a minimum population of 750 mature adults (including males 15 years and older and females 20 years and older) is established that produces a minimum annual spawning run of 250 fish. All stocked fish should be permanently marked, and genetic analysis of parents and progeny should be conducted to document diversity of fish produced.

Evaluation measures capable of documenting the success of rehabilitation actions
need to be planned for and implemented prior to and concurrently with initiating rehabilitation.

Though these guidelines are still in draft form, Lake Michigan resource management agencies have and are taking actions to follow these guidelines for current reintroduction initiatives, though implementation of some actions, such as streamside rearing, will likely take a few years to implement fully as funding becomes available.

Holtgren, Marty – Implementation of a streamside-rearing facility for sturgeon rehabilitation stocking [full presentation (2.5 MB pdf)]

Aloisi, Doug - Developmental Indices to Predict Hatching, First Feeding, and Timing of Migration of early life stages of lake sturgeon

Description: Using previous literature and applying linear regression to specific temperature points, a developmental index can be applied to varying water temperatures to estimate hatch, time of first feeding, and theoretically outmigration in natal rivers. Information may be helpful when attempting larval drift sets for assessment/culture.

Status Assessment Techniques Presentations:

Auer, Nancy - Split-beam hydroacoustics for assessment of lake sturgeon spawning populations

MacKenzie, Chet – Lake Champlain lake sturgeon sampling techniques [full presentation (2.2 MB pdf)]

Habitat Classification, Restoration and Enhancement Presentations:

Sutton, Trent - Habitat Use and Movement Patterns of Age-0 Juvenile Lake Sturgeon in the Lower Peshtigo River, Wisconsin [full presentation (739 KB pdf)]

Description: Restoration of lake sturgeon Acipenser fulvescens in the Great Lakes has been ineffective in part due to limited information on early life history. Characterizing habitat use and movement patterns of age-0 juvenile fish would facilitate these efforts by allowing for the identification of nursery areas. The objectives of this study were to determine the habitat preferences and movement patterns of age-0 juvenile lake sturgeon in the lower Peshtigo River, Wisconsin. Fish were captured from June through October 2002 and 2003 and radio transmitters were attached to individuals > 74 g each year (N = 4 and 11, respectively). At each capture and tracking location, water depth and current velocity were measured, and the dominant substrate type was determined from a dredge sample and preserved for later macroinvertebrate analyses. Lake sturgeon were found over sand substrates, at shallow depths (< 2 m), and low current velocities (< 0.60 m/s). Capture locations were dominated by Dipterans, with sites having a median density of 53 (range, 0 to 907) individuals/m2 in 2002 and 33 (range, 0 to 2,013) individuals/m2 in 2003. All fish were found over substrates with low macroinvertebrate diversity index values (< 0.44). Daily movements showed that fish were nocturnally active, while long-term movements, possibly to deeper waters, were related to declining fall water temperatures. Based on these results, nursery habitats for age-0 juvenile lake sturgeon consisted of low current velocities, shallow depths, and sand substrates dominated by Dipterans and should be protected in tributaries supporting spawning populations of this species.

Friday, Mike - Spawning Habitat Enhancement through Flow Manipulation

Description: From May 14 to June 30, 2004 Ontario Power Generation provided at least 23 m3/sec of spill over Kakabeka Falls to allow adult sturgeon access to traditional spawning grounds and facilitate successful spawning, hatch and larval drift. This area is often dewatered during the period of spawning for power production and scenic flows for Kakabeka Falls Provincial Park. To monitor sturgeon movements into the spawning area radio telemetry was utilized. Fifteen adult sturgeons were tagged in the lower river (with external radio transmitters) when they were known to be migrating upstream to spawn. Their movement into the spawning area and migration back downstream was monitored using an ATS data logger. Larval drift netting was carried out to document spawning success under this flow regime.

Daugherty, Dan - Assessment of potential lake sturgeon habitat availability in Lake Michigan tributaries: Applications to the restoration process [full presentation (632 KB pdf)]

Description: Presentation will introduce and discuss techniques currently being utilized to determine potential availability of suitable habitat types for egg, larval, juvenile, and staging and spawning adult lake sturgeon in historically important northern Lake Michigan spawning tributaries. Information gathered from these habitat assessments will also be discussed as a decision-making tool for restoration efforts

Haxton, Tim and William Johnson - Spatial Application of a habitat suitability index model for lake sturgeon [full presentation (1.5 MB pdf)]

Description: The Threader et al. (1998) HSI model for lake sturgeon was developed into a spatial application in ARCMAP 8.0. This presentation will describe background on the model (suitability indices), the techniques used to collect the pertinent information to populate the model, and model results. I will display example model outputs and, time permitting; a summary of the model field validation will be included.

Geddes, Christine - Classification & Visualization of Lake Sturgeon Habitat Suitability using the Great Lakes GIS [full presentation (1.2 MB pdf)]

Description: Once abundant in the Great Lakes watershed, the lake sturgeon Acipenser fulvescens is now listed as a threatened species under the Michigan Endangered Species Act. It has ling been understood that habitat and nursery loss from dam construction, logging practices, and poor water quality has been an important factor in the lake sturgeon decline. The Great Lakes GIS, a habitat-based aquatic GIS, is a unique tool for the Great Lakes lake sturgeon habitat visualization and decision support. The great Lakes GIS includes map-delineated spatial unites, and associated habitat and biological attributed data for terrestrial, tributary, nearshore, and offshore ecosystems. Additionally, it includes subsets of spatially explicit data from other regional GIS projects, including the National Hydrography Dataset (NHD) and the Digital Water Atlas (DWA), as well as associated tool kits. Together, these datasets allow the assessment of inland water habitat, potentially valuable as lake sturgeon spawning habitat. Using criteria from the Lakes sturgeon Rehabilitation Strategy, published by the Michigan Department of Natural Resources, and the Great Lakes GIS, Michigan inland water habitats (i.e., inland lakes and tributaries) were classified in terms of suitability to sustain lake sturgeon populations. Several digital maps, including historic distributions, historic spawning areas, estimated historic population sizes, estimates of present sizes and distributions of lake sturgeon population in Michigan, and barrier locations, were compared wit the habitat classification. The utility of this application for lake sturgeon habitat classification and management is discussed.

Manny, Bruce – Classification of lake sturgeon spawning habitat in the Detroit River [full presentation (2.6 MB pdf)]

Description: In 1999-2000, we surveyed nine reputed, historic spawning sites of lake sturgeon in the Detroit River using Side Scan Sonar (SSS) and underwater TV (UTV). Video tapes of bottom substrates present at each site were examined to determine theoretical suitability of bottom substrates for successful incubation of sturgeon eggs. Our classification was based on the percentage of the river bottom covered by rocks, plant growth, and silt, estimated interstitial void space among the rocks, and estimated water velocity. We scored each site using a standardized evaluation sheet for each video of that site and subjectively classified substrates at each site as suitable, impaired, or unsuitable for incubation of sturgeon eggs. In 2001-2003, ultrasonic telemetry revealed an active sturgeon spawning site (Zug Island) and several suspected spawning sites in the river. Those and 86 other sites chosen at random in the main channels of the river were evaluated systematically with SSS and UTV. Deployment of egg mats at the known and suspected spawning sites revealed that sturgeon spawned only at Zug Island. That site is now inundated with lethal concentrations of residual chlorine from a large (13,262 cubic feet/sec) combined sewer overflow upstream that was chlorinated in 2002. In June 2004, in partnership with Michigan Sea Grant, we constructed reefs in the headwaters of the river near Belle Isle of broken limestone, gravel/cobble, and coal cinders to provide clean, suitable spawning substrate in the river for lake sturgeon.

Kennedy, Greg – Evaluation of underwater remote sensing technologies to survey potential lake sturgeon spawning habitat in large river systems in the Great Lakes

Description: Lake sturgeon spawning habitats in large rivers are difficult to quantify. To quantify potential lake sturgeon spawning habitat in the St. Clair River, we mapped and classified surficial substrates at eight sites (six reputed and two active spawning sites) using side-scan sonar and underwater video. At each site, the sonar images was used to obtain surficial sediment imagery, then underwater video images were obtained to ground-truth the substrate images visible on sonar records. In all, about 365 ha of river bottom (8.5% of the entire river) were surveyed using sonar and underwater video. Substrate classification maps, produced from the sonar and video data, were used to determine the extent of suitable spawning habitat within each site. Detailed examination of two sites (Point Aux Chenes in the lower river, and Port Huron in the upper river) identified 5 different substrate types, ranging from soft clay to rock/cobble. At Point Aux Chenes, substrates were primarily clay and sand (mostly on the bank and shallower portions of the main channel); gravel occupied deeper portions of the main channel. Substrate composition at Port Huron consisted primarily of rubble/cobble throughout the entire survey area. However, we found hard-pan clay on the west side and sand on the east side of the river. The results of this study increased our understanding of sturgeon spawning habitat within the St. Clair River. In addition, locations of transmittered adult sturgeon could be overlain on the substrate maps to determine which bottom substrate types are being utilized by sturgeon. Continued substrate mapping throughout the river could provide a more accurate picture of spawning habitat within the St. Clair River.

Haxton, Tim - Development of a management plan for Lake Sturgeon in the Lake St. Francis portion of the St. Lawrence River [full presentation (681 KB pdf)]

Description: Lake sturgeon are present in low abundance in the Lake St. Francis portion (below the Moses-Saunders Power Dam and upstream of the Beauharnois Power Dam) of the St. Lawrence River. Lake St. Francis has been identified as an Area of Concern by the International Joint Commission. A workshop to develop a management strategy for lake sturgeon was held on September 22 and 23, 2004. The workshop participants developed a list of the most appropriate management actions for lake sturgeon in Lake St. Francis. This workshop could provide a foundation for workshops on other waterbodies that fall within interprovincial/interstate and/or international jurisdiction. This presentation will provide a summary of the workshop, its effectiveness and an update on the progress to date.

Sturgeon Passage Presentations:

Whelan, Gary - Social, Economic and Biological Considerations Related to Lake Sturgeon Passage in the Great Lakes

Description: Fish passage is critical to the successful rehabilitation of lake sturgeon populations in the Great Lakes. There a number of social, biological, economic and engineering considerations that must be taken into account. From a social perspective a range of constituents will need to be brought into the process ranging from local residents to utilities to resource user groups to “love my dam or fish species” groups. Some of the key biological issues are the effects of fish passage on other “resident” species and fisheries, contaminant transport, aquatic nuisance species and wildlife effects.

Engineering considerations include who is going to do the engineering and what method will be used. The selection of the appropriate method that could include dam removal, fishways, elevators or lifts, natural fishways and trap/transfer methods will depend on the conditions and funds available. It is critical to keep in mind that any fish passage method other than dam removal will require annual maintenance funds that range from 0.1 to 5% of the capital cost. Both upstream and downstream passage must be considered when implementing passage for lake sturgeon. There are a range of regulatory tools to obtain passage and these include state/provincial passage laws and provincial hydropower facility licensing. A number of federal regulatory options exist for use including the Federal Fisheries Act (Canada), Fish and Wildlife Coordination Act (US), Clean Water Act using Section 401 Certification (US) and the Federal Energy Regulatory Commission hydropower licensing proceedings (US). To successfully implement a fish passage strategy a considerable amount of planning, expertise and time will be need to deal with the social, biological, engineering and regulatory issues. Even with these constraints, there is simply no choice but to deal with these issues to be successful in lake sturgeon rehabilitation in the Great Lakes.

Kynard, Boyd – Experimental studies at Conte AFRC on up- and downstream passage of lake and shortnose sturgeon and riverine fishes [full presentation (1.1 MB pdf)]

Description: The presentation will review studies at the Conte AFRC on upstream passage
of sturgeons and riverine fishes in a spiral fish ladder and review ongoing studies to develop a downstream bypass for shortnose sturgeons (yearling to adult life intervals) in the Connecticut Riverupstream sturgeon passage at barriers.

Amaral, Steve – Downstream fish passage for sturgeon: past, present, and future [full presentation (5.3 MB pdf)]

Description: Fish passing downstream through hydro turbines may be subject to mortality rates between 10 and 20%, depending on fish size and turbine design. Turbine passage mortality typically is mitigated through the use of physical screening devices that reduce entrainment and guide fish to alternative downstream passage routes. Behavioral deterrent technologies have also been evaluated as means to minimize turbine entrainment, but very few successful applications have resulted. More recently, new turbine runner designs have been developed to specifically minimize injury and mortality of entrained fish. Biological studies have demonstrated that mortality rates of fish passing through these “fish-friendlier” turbines often are very low (less than 4%) and comparable to mortality rates of fish passing over spillways and through downstream bypasses. Although most downstream fish passage technologies have been evaluated with a wide variety of freshwater and diadromous fishes, relatively few studies have been conducted with sturgeon species. Because sturgeons are very unique with respect to morphology, size, life history, and behavior, results from previous fish passage studies with other species generally are not directly applicable to sturgeon. However, a review of biological, environmental, and engineering parameters that have contributed to effective downstream passage with other species can be assessed for relevance to sturgeon. Additionally, recent laboratory studies have evaluated several species of sturgeon with angled bar racks and louvers and a “fish-friendly” turbine, providing the first evidence that some traditional and experimental technologies hold promise for effectively protecting sturgeon at hydro projects. Based on the results of these studies, and those with other species, fisheries managers and scientists can begin to focus future their research efforts on specific downstream passage technologies that have the greatest potential for successfully protecting sturgeon.

Aadland, Luther - Lake Sturgeon Passage and Habitat Restoration [full presentation (372 MB pdf)]

Description: Lake sturgeon populations have diminished over much of their historic range. While over-fishing and water quality declines have been significant factors in this decline, dam construction may be the most important. Dams have both blocked migratory pathways and inundated critical spawning habitat. Traditional fish ladders were rarely designed to accommodate or effectively pass sturgeon. While dam removal is the best solution to sturgeon passage, nature-like passage may be the next best alternative. This presentation will discuss by-pass fishways and conversion of low-head dams to rapids that both pass fish and provide potential spawning habitat.

Regulations, Status Determination, and Rehabilitation Progress:

Mosindy, Tom - Regulatory Options for Managing the Angling Fishery for Lake Sturgeon in Ontario

Description: A brief overview of options that are being proposed by the Ontario Ministry of Natural Resources to regulate lake sturgeon angling fisheries throughout the province. These include changes to existing seasons, catch and possession limits, size regulations and sanctuaries. This forms part of a much broader exercise to modernize sport fishing regulations in Ontario.

Vandergoot, Chris - Summary of the information collection on Lake Sturgeon in the Western Basin of Lake Erie 1999-2003 [full presentation (5.8 MB pdf)]

Description: The western basin of Lake Erie has been referred to as the black-hole of sturgeon research because little research has been conducted in this area of the Great Lakes. Since 1992 information regarding the capture of lake sturgeon in the western basin of Lake Erie by recreational and commercial fishermen has been collected by the Ohio Department of Natural Resources (ODNR). The information collected by the ODNR suggests that the western basin plays an important role in the life history of lake sturgeon in this locale. It appears that the Bass Island area provides juvenile habitat during the spring and summer months, however, information concerning adult lake sturgeon in the western basin is lacking. Additionally, anecdotal evidence suggests that the Maumee River may be used by lake sturgeon as a spawning ground.

Jackson, Randy - Lake sturgeon restoration in Oneida Lake, New York: stocking, habitat use, and life in the fast lane [full presentation (2.7 MB pdf)]

Description: Oneida Lake is one of several waters in New York State included in a lake sturgeon restoration program initiated in 1995. To date, 7,000 hatchery-reared lake sturgeon have been stocked into Oneida Lake and data from over 400 fish sampled since 1996 indicate a fast-growing and healthy population. Length-at-age data show growth rates of 116 mm/year through age 8, faster than other systems for which data are available. Similarly, length-weight relationships show lake sturgeon in Oneida Lake to be in excellent condition, with the largest individual from our samples weighing 16.9 kg at a length of 131.5 cm. Several age-8 males readily released sperm during spring 2003 sampling, providing further evidence that conditions in Oneida Lake are very favorable. A habitat-specific gill net survey has produced overall catch rates of 0.3 sturgeon/hour over 2 years, with highest catches observed over sand and shoal substrates as compared to silt and mud bottoms. Diet samples indicate that amphipods, snails and zebra mussels are the most important foods of sturgeon in Oneida Lake and availability of these taxa is highest in sand and shoal habitats. These studies should assist in identification of habitats where sturgeon stocking might be most successful.

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