Abstracts - Poster Presentations

Edward A. Baker (Michigan DNR), Patrick Forsythe (Michigan State University), James Crossman (Michigan State University), Kim T. Scribner (Michigan State University) and Kregg M. Smith (Michigan DNR) - Characteristics of spawning lake sturgeon in the Black River, 2001-06

Description: Data on lake sturgeon spawner abundance and demographic characteristics are critical to forecasting recruitment and for prioritizing populations for management action. Great Lakes populations are exceedingly difficult to study because of extremely low abundance and because the fish spawn in large rivers that are difficult to sample. The lake sturgeon population in Black Lake, Michigan is uniquely suited to provide critical background on adult ecology and demographics because of its large size, degree of reproductive isolation, and vulnerability of spawning fish to capture. We have intensively sampled spawning lake sturgeon over 6 consecutive years (2001-2006) in the upper Black River. The number of fish sampled annually has varied from 101 in 2004 to 234 in 2006; the male to female sex ratio has varied annually from 1.6:1 to 2.9:1. The length range of lake sturgeon has been similar among years and ranged from 111-192 cm. Estimates of spawning periodicity ranged from 1-5 years for males and 2-5 years for females with average periodicity of 2 and 3 years, respectively. Date of first spawning has varied from 20 April to 7 May among years, the end of spawning activity has ranged from 19 to 26 May, and the duration of the spawning run has ranged from 18 to 36 days. Based on adult capture dates and observed spawning activity there have been multiple spawning events within each year and males were observed to spawn during multiple periods within a single year. There was no clear pattern in the timing of spawning for individual fish recaptured among years.

David Bos (Purdue University) - Genetic determination of lake sturgeon sex

Philip Cochran (Saint Mary’s University of Minnesota), Robert Elliott (USFWS Green Bay), Kevin Olson (Saint Mary’s University of Minnesota) and Terrance Martin (Illinois State Museum) - Historical distribution of lake sturgeon (Acipenser fulvescens) in the Lake Michigan Basin [view poster (2.59 MB pdf)]

Description: As part of an attempt to reconstruct the original distribution and relative abundance of lake sturgeon in tributaries to Lake Michigan, we surveyed old newspapers (mid-1800s to early 1900s) and other documents for accounts of sturgeon captured by sport and commercial fishers. We also reviewed the zooarcheological literature for records of sturgeon remains from prehistoric sites. We are especially interested in reports of sturgeon from sites to which they no longer have access because of the construction of dams that have blocked upstream spawning migrations. Over 200 records that can be plotted with some degree of accuracy were obtained. Resulting maps reveal a somewhat broader distribution than previously published maps based on museum specimens, but there were few unequivocal reports of sturgeon from reaches above dams in cases where they were not already known to have occurred in those reaches. This may be due in part to the fact that dams were constructed in many regions prior to the first printing of newspapers. Based on what has been published, the zooarcheological record seems more complete for the Michigan portion of the basin.

Dawn Dittman (USGS Great Lakes Science Center) - Assessment of lake sturgeon habitat in Lake Ontario and St. Lawrence River tributaries [view poster (171 KB pdf)]

Description: One of the top priorities in restoration of native fish communities is the assessment of the current available habitat quality in the target ecosystem. In response to the imperiled status of one key native species, the lake sturgeon (Acipenser fulvescens), the New York Department of Environmental Conservation formulated a recovery plan to maintain and establish lake sturgeon populations in at least eight separate locations. As part of the implementation of the recovery plan, pre and post stocking assessments of sturgeon habitat quality and use have been conducted in two very different rivers. These rivers were the Genesee River - a tributary to Lake Ontario (9 km of accessible habitat - low gradient), and the St. Regis River – a tributary to the St. Lawrence River (32 km of accessible habitat – higher gradient). A habitat suitability index (HSI) for lake sturgeon and an index of biotic integrity (IBI) were applied to each river. Released juvenile sturgeon are successfully using both rivers in habitat that is predominantly consistent with the HSI and IBI evaluations. Contrasts in sturgeon habitat use and the HSI and IBI values for these rivers give insights into the status, process, and next steps in the recovery plan for lake sturgeon and the native fish community of Lake Ontario and St. Lawrence River tributaries.

Dawn Dittman (USGS Great Lakes Science Center) – New York Lake Sturgeon Projects [view poster (231 KB pdf)]

Barbara Evans (Lake Superior State University) - Retinal development and light response in larval lake sturgeon [view poster (2.95 MB pdf)]

Description: Little is known about the role of vision during the early development of lake sturgeon. Fertilized lake sturgeon eggs from Black Lake MI were maintained in the laboratory at 13 degrees C and a 15:9 hour light dark cycle. At daily intervals after hatching, larvae were tested for their phototactic response and also sampled for histological examination. The light source was a series of narrow bandwidth light emitting diodes (UV, visible, IR). At hatching, the larvae elicited negative phototaxis; however, the retina was undifferentiated. The pineal organ does appear to be differentiated at time of hatching and likely facilitates the observed response to light. At 5 days post hatch (dph), cone photoreceptors were beginning to differentiate in the central retina, and the larvae appeared less photonegative, instead they froze when the light source was turned on. By 10 dph, both large rods and small cones with oil droplets were present, and the retina showed clear lamination. Coordinated eye movements were observed at 15 dph, but the fish did not respond to moving grating patterns. The retina develops relatively slowly, but once complete has both rods and cones with low numbers of ganglion cells. Histological and behavioral results indicate that the larval lake sturgeon eye is sensitive to low light, but also has low visual acuity. Under natural rearing temperatures, vision is not likely functional prior to 1 week of age, but the light environment is clearly important.

Jeannette Krieger-Kanefsky (Ohio State University) and Paul A. Fuerst (Ohio State University) - Investigation of 18S rRNA gene variant expression in lake sturgeon tissues

Description: Previous studies of the nuclear 18S ribosomal RNA (rRNA) gene of sturgeons discovered intraindividual variation in every species of sturgeon examined (23 species of Acipenser, Huso, Scaphirhynchus or Pseudoscaphirhynchus). This finding (the first in a vertebrate) was highly unusual. We have previously reported that at least 17 sequence variants of 18S rDNA are found in the genome of the lake sturgeon. A process termed concerted evolution ordinarily homogenizes the many copies of the rRNA genes occurring within an individual. Why do sturgeon possess large numbers of 18S rRNA gene sequence variants when very few other species show this characteristic? Possibly, different sequence variants are active in different tissues of the sturgeon. We examined the expression of rRNAs in the liver and found that a single sequence variant is primarily (if not solely) expressed. To test whether tissue specific expression of variant forms occurs, we amplified and sequenced 18S rDNA sequences from a lake sturgeon, and then reverse-transcribed the 18S rRNA from eight different tissues and sequenced the expressed transcripts to determine if there are differences among variants for the tissues in which they are expressed. The same single sequence variant was found to be expressed among all tissue types.

Heidi Keuler (University of Wisconsin La Crosse) - Growth and condition of lake sturgeon (Acipenser fulvescens) in Legend Lake and the Wolf River – Lake Winnebago System of northeastern Wisconsin

Description: Age, growth, and body condition of feral lake sturgeon (Acipenser fulvescens) have been studied in numerous waterbodies; however, comparison of growth and body condition of feral sturgeon to stocked fish is lacking. The objective of this study was to determine if there was a significant difference between a feral population of sturgeon in the Lake Winnebago system, and a stocked population in Legend Lake on the Menominee Reservation. Length and weight of sturgeon were measured and approximately 250 pectoral fin rays were collected from sturgeon in both populations. Fin rays were sectioned with a low-speed saw, aged, and length-at-age was back-calculated from annuli. Sturgeon from Legend Lake showed greater growth than the sturgeon from the Lake Winnebago system in years one (F = 19.12, P = 0.0002), four (F = 7.92, P = 0.0090), six (F = 6.62, P = 0.0167), and eleven (F = 14.53, P = 0.0029). However, the younger lake sturgeon from Legend Lake had slightly poorer growth and condition than sturgeon from Lake Winnebago, while older sturgeon from Legend Lake had superior growth and condition. This may reflect a diet shift or stocking too many fish of certain year classes. Stocking fewer fish in the future may decrease competition and increase growth and condition of lake sturgeon.

Tracy Kolb (Michigan State University), William Taylor (Michigan State University), Doug Beard (USGS Reston) and Andrew Loftus (Loftus Consulting Annapolis) - Developing an Information Infrastructure for North American Sturgeon

In 2004, the Michigan State University Department of Fisheries and Wildlife began working with the U.S. Geological Survey’s National Biological Information Infrastructure (NBII) to develop an information framework for North American fisheries and aquatic resources. The objective is to create an information system that can be overlaid with existing watershed databases to aid managers and researchers in assessing landscape effects on aquatic populations.

In order to meet this objective we are creating a data system to assess fisheries status and trends across state boundaries using sturgeon as a pilot species. Sturgeon are an especially appropriate species complex because of their ubiquitous nature and vulnerability to habitat disturbances. The guiding principles of this project include:

• Creating a system that is useful to managers and researchers for a variety of purposes associated with status and trends
• Utilizing the expertise of managers and researchers in the sturgeon community throughout design and development
• Creating a system adaptable enough to incorporate information from multiple existing management programs, as well as new information as it develops

The result will be a dynamic system that can change to meet the emerging needs of researchers and managers.

Scott Koproski (USFWS Alpena), Meghan Kline (Lake Superior State University), Ashley Moerke (Lake Superior State University) and Roger Greil (Lake Superior State University) - Lake sturgeon telemetry study in the St. Marys River, Michigan [view poster (202 KB pdf)]

Habitat loss and fragmentation have been identified as major factors contributing to the decline of lake sturgeon in the Great Lakes. Lake sturgeon currently utilize the St Marys River system, but little is known about the locations and timing of use of habitats by lake sturgeon. The main objective of this study is to identify critical habitat used by lake sturgeon in the St. Marys River by tracking fish implanted with sonic telemetry tags. During the summer of 2006, 75 lake sturgeon were captured using setlines. All of the lake sturgeon that were captured for the first time received an external cinch tag along with an internal PIT tag. All sturgeon were measured and weighed, and a small section of the left pectoral fin ray was removed for aging and genetic purposes. Sonic telemetry tags were implanted in 12 of the lake sturgeon that exceeded 50 inches in length. Tracking began immediately after the first fish was implanted with a sonic tag. Preliminary results illustrate that the tagged lake sturgeon remained mostly throughout the northern channel of Sugar Island during the summer. However, a couple individuals were located along East Neebish Island, demonstrating movements up to five miles within a three day period. Lake sturgeon tracking will continue through 2007 to identify patterns of seasonal movement and habitat use.

Travis Moore (Missouri DOC), Greg Snellen (Western Illinois University), Mark Miller (Western Illinois University), and Dr. Timothy Spier (Western Illinois University) - Lake sturgeon capture methods and habitat use in the lower pooled portion of the Upper Mississippi River, Missouri

Description: The Missouri Department of Conservation has stocked nearly 300,000 fingerling lake sturgeon into the Mississippi and Missouri Rivers since the mid-1980’s. Two projects (capture techniques, habitat use) were initiated in 2004 to help answer questions about this developing population.

Capture Techniques: While there are scattered reports of large fish being caught in hoopnets by commercial fishermen, hoopnets are labor intensive and yield smaller total numbers of fish. Trotlines baited with nightcrawlers have proven effective at catching various-sized fish when water temperatures are less than 75 degrees. Gillnets have also proven to be an effective method if placed in locations where fish congregate. Larger meshes yield larger fish. Three-inch bar mesh gillnets captured a wider size range of lake sturgeon than other meshes.

Habitat Use: Radio and ultrasonic telemetry was used to track movements of adult and sub-adult lake sturgeon. Radio transmitters were useful the first year but it was difficult to find fish when they used deeper water habitats. Ultrasonic transmitters have proven more effective with much higher location rates. Tagged fish preferred deep water habitats (20+ feet) with moderate flow. Main channel and channel border habitats, either diked or undiked, have been the most used habitats. There are also seasonal movements that appear to be related to flow rates. Fish moved upstream during high spring flows and into the dam tailwaters in late summer. Fish dispersed throughout the lower half of the pool in winter. While all fish were captured, tagged, and re-released in Pool 24, some fish have relocated to other pools.

Holly Patrick (Purdue University) - Host-size selection and lethality of lake sturgeon on sea lamprey [full presentation (556 KB pdf)]

Description: Populations of lake sturgeon Acipenser fulvescens remain imperiled in the Great Lakes, despite conservation and restoration efforts. Parasitism by sea lampreys Petromyzon marinus may contribute to the failure of sturgeon rehabilitation. The objectives of this research were to examine the short- and long-term growth and survival and rate of wound healing and scar retention of lake sturgeon following a sea lamprey attack. A series of 80 experimental trials each allowed one sea lamprey to feed on one lake sturgeon in the laboratory. Lake sturgeon were from one of four size groups; 400-600 mm fork length (FL), 600-800 mm FL, 800-1,000 mm FL, and 1,000-1,500 mm FL. Each trial was terminated upon sea lamprey detachment or lake sturgeon mortality. Surviving sturgeon were allowed a two-week short-term recovery period to assess survival, and a longer-term recovery period to assess growth and wound healing. Estimated growth rates of lake sturgeon decreased following sea lamprey attack, pronouncedly for the smaller fish. Lake sturgeon mortality was greater for the smaller fish. Sea lamprey marks on lake sturgeon differed from those seen on teleosts with scales, with lampreys attaching most frequently on the axils of the pectoral fins. Results from this study will aid fisheries managers in making appropriate decisions for concurrent sea lamprey control and successful rehabilitation of lake sturgeon populations in the Great Lakes.

Mike Thomas (MDNR Lake St. Clair Research Station) - Does hook size matter?: Evaluation of two hook sizes for survey setlines in the St. Clair River

Since 1996, the Michigan Department of Natural Resources (MDNR) has assessed the status of the lake sturgeon (Acipenser fulvescens) population in the lower St. Clair River with setlines. From 1996 through 2004, setlines were constructed and fished using stainless steel size 4 Mustad Kirby Sea Hooks. During this time period, lake sturgeon less than 30 inches total length (TL) were rarely caught. Over time, cohorts that initially appeared weak based on setline catches, appeared in higher numbers in subsequent years. In 2005 and 2006, we investigated the effect of hook size on the catch of lake sturgeon by alternating small and large hooks on each individual setline. The objective of this study was to determine the effect of hook size on the catch of lake sturgeon for assessment setlines in the North Channel of the St. Clair River. Two different sizes of hooks were fished in an alternating pattern on each individual setline. Large hooks were baited with round gobies (Neogobius melanostomus) larger than approximately 2.5 inches TL, while small hooks were baited with round gobies less than 3 inches TL. Upon retrieval of the setline, the size of the hook and size of each sturgeon caught was recorded. For fish captured in 2005, ages were estimated from pectoral fin ray sections. The mean TL of lake sturgeon caught on small hooks in 2005 and 2006 was nearly identical, but significantly smaller than the mean TL of lake sturgeon captured on large hooks in both years. Over a two year period, small hooks consistently caught much higher numbers of lake sturgeon under 35 inches TL or 7 years old, compared with larger hooks alternated on the same setlines. Small hooks were much less effective than large hooks for catching lake sturgeon over 40 inches TL or 10 years old. These results suggest that length frequency and age composition data collected by setlines fished with at least two hook sizes are more representative of the sturgeon population. Assessment setline surveys using only one hook size would likely provide a biased sample of lake sturgeon populations, possibly misleading researchers or managers into ineffective management actions. Sampling with setlines incorporating both small and large hooks has improved MDNR efforts to monitor recruitment and investigate juvenile lake sturgeon habitat utilization in the St. Clair River.

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