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.
Back
to Contents | Back to
Home