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Lake Sturgeon is a potamodromous, fluvial-dependent species from the family Acipenseridae, and one of the largest freshwater fishes within its North American range extending to the Great lakes, Mississippi River, and Hudson Bay drainages. Like almost all other sturgeon species, Lake Sturgeon populations throughout its range suffered mass declines or extirpation in the late 1800s into the early 1900s, due to extensive overexploitation and habitat loss and alteration. However, Lake Sturgeon are still present in low to high densities throughout their native range due primarily to factors including: the species long life span and resiliency, the remote location of many northern populations, long-term pro-active management programs effectively controlling exploitation, improved habitat and water-quality conditions, and recovery programs that have been in effect since the late 1970s. Recovery programs initiated in the late 1970s are now just beginning to show signs of natural recruitment from populations re-built with stocked fish. Large sustainable recreational Lake Sturgeon fisheries with annual harvests of up to 45 000 kg and a commercial fishery with an annual harvest of up to 80 000 kg still exist and are maintained for Lake Sturgeon due primarily to rigid regulations, harvest controls, enforcement, and user involvement. The prognosis for the species is generally good, although habitat loss and maintaining public interest in the species management and recovery continue to be the greatest threats to local and regional populations. Hydropower development, especially in the northern part of the species' range, is especially challenging due to the potential negative impact this type of development can have on a long migrating fish like Lake Sturgeon. Advances in understanding Lake Sturgeon life history, habitat requirements, and distribution within and among water systems has strongly indicated that dams and Lake Sturgeon can co-exist, if the correct planning and necessary mitigative techniques are employed at each site on a case-by-case basis. [ABSTRACT FROM AUTHOR]

The primary goal of this study was to obtain accurate data of previously undocumented lake sturgeon ( Acipenser fulvescens Rafinesque, 1817) spawning sounds, generated during wild sturgeon reproduction. Biologists have long known that lake sturgeon produce low-frequency sounds during spawning bouts; energy from these sounds can break the surface of the water occasionally and propagate harmonics in the terrestrial atmosphere, creating a faint drumming popularly known as 'sturgeon thunder'. Understanding the contribution of this sonic behavior in context is essential for gaining a more comprehensive scientific appreciation of the process of sturgeon spawning, and accurate acoustic data should prove useful for fisheries managers seeking to monitor or enhance sturgeon stocks for reproductive activity. Recordings were made at several locations on the Wolf and Embarrass rivers during the 2011-2013 spawning seasons. Drumming sounds ranging from 5 to 8 Hz fundamental frequency were evident. Other characteristic noises associated with spawning lake sturgeon, including low-frequency rumbles and hydrodynamic sounds, were identified. Other high frequency sounds were also discovered. All of these sounds coalesce into a distinctive acoustic signature of lake sturgeon spawning activity. Knowledge of this sonic signature can be used to accurately document reproductive activity at multiple locations over extended periods using remote recording tools and techniques. [ABSTRACT FROM AUTHOR]

Historical abundance and biomasss of lake sturgeon ( Acipenser fulvescens Rafinesque, 1817) in the Great Lakes were estimated from historical commercial harvest data from 1879 to 1920 using two modeling techniques: a surplus production model with a Bayesian approach, and a depletion model. In addition, theoretical sustainable levels of exploitation and temporal recovery periods were estimated based on the surplus production model. The historical biomass of Lake Sturgeon in the Great Lakes during the period from 1879 to 1885 varied for each model and ranged from 313 900 to 6 473 000 kg (0.5-16.7 kg ha−1) using the surplus production model to 968 000 to 25 414 000 kg (2.4-31.7 kg ha−1) using the depletion model. The intrinsic population growth rate as determined from the surplus production model ranged from 0.079 to 0.123, and the theoretical sustainable exploitation rate ranged from 2.0 to 3.1%. The predicted recovery period for the overexploited populations was in excess of 60 years given recruitment assuming all other impediments to population recovery were removed. [ABSTRACT FROM AUTHOR]

Summary In fisheries management it is often useful to compare length and weight relationships or condition among populations across a species' range. Currently, the most commonly used metric for this is relative weight ( Wr), although some problems have arisen with the use of Wr including the impact of seasonal changes in body condition due to reproduction, and length-related biases in standard weight equations. We propose the use of a modified form factor (mFF) based on the regression of log10 α vs β (weight-length model parameters) within a species, to provide a quick and meaningful comparison of mean condition among North American lake sturgeon populations. We used the α and β parameters from 63 lake sturgeon weight-length models from 43 lake sturgeon populations from throughout their range in the equation to calculate the mFF for the 63 samples. Modified form factor values of juvenile, adult male, and female lake sturgeon from the Winnebago System, Wisconsin, in various stages of reproductive development had a 98.0% correlation with their respective relative condition values over a wide range of mFF values. Simple t-tests on sets of mFF values can be used to test the condition differences between populations or sub-samples within populations. Lake sturgeon from the Winnebago System, Wisconsin, USA were found to show W- L relationships best described in two stanzas: all juveniles <71.1 cm, and juveniles and adults combined, but separate by sex, ≥71.1 cm. Likelihood ratio tests found significant differences between male and female (>71 cm) W- L models; juvenile (≤71 cm) and male (>71 cm) models; and juvenile (≤71 cm) and female (>71 cm) models. [ABSTRACT FROM AUTHOR]

No abstract available. [ABSTRACT FROM AUTHOR]

Summary The spawning behavior of lake sturgeon, Acipenser fulvescens , was observed and characterized over a 16-year period on the Wolf and upper Fox rivers of the Winnebago system in East Central Wisconsin. Lake sturgeon display an intricate set of sexual behavior responses to water temperature during their spawning period. When water temperatures rise to 6.6–16.0°C, sturgeon begin exhibiting a porpoising behavior in the vicinity of the spawning grounds. As the water continues to warm, this behavior increases in intensity and continues until slightly past the peak of spawning activity. In the range of 8.8–16.0°C, males move onto the spawning grounds and begin cruising, apparently searching for signs of ovulating females. Individual females will move onto a site at water temperatures of 8.8–19.1°C, with the maximum number of females and heaviest spawning activity on a site occurring generally within 11.5–16.0°C. Lake sturgeon were observed spawning both during the day and night at wide temperature ranges, 8.8–21.1°C. Whereas males arrive first at the spawning site, females ultimately determine the duration of spawning through the timing and intensity of their use of that site. During the spawning act, activity also keys off the females, with the males responding to cues from the female to participate in 2–4 s spawning bouts during which a relatively small number of eggs (estimated 947–1444 eggs per bout) are released by the female into a cloud of sperm (estimated 200–800 billion sperm) from two to eight males. The males beat the abdomen of the female with their tails and caudal peduncles while ejaculating. While ejaculating, males emit a dull, thunderous vibrating sound which attracts other males to the area. The female initiates a spawning bout at approximately 1.5 min intervals and will continue oviposition for 8–12 h, even if the water temperature decreases or increases... [ABSTRACT FROM AUTHOR]

Summary The lake sturgeon (Acipenser fulvescens ) is a species of cultural significance to the Menominee Nation, a Native American tribe indigenous to northeast Wisconsin. Lake sturgeon in the Lake Winnebago system historically migrated up the Wolf River to spawn at Keshena Falls, within the current boundaries of the Menominee Reservation where, each spring, the Menominee people gathered at Keshena Falls to harvest lake sturgeon. The construction of two dams on the Wolf River downstream of Keshena Falls in the late nineteenth and early twentieth centuries contributed to extirpation of this species on the Menominee Reservation. The general public has had the opportunity to harvest lake sturgeon from Lake Winnebago during a winter spear fishery since 1932. Those who participate in this fishery feel as strongly about the lake sturgeon resource as do the Menominee people. Cooperation among multiple resource management agencies and the public was necessary to address the interests of both groups and at the same time ensure protection of the Winnebago system lake sturgeon population. In 1993, tribal, state, and federal representatives developed a plan to reintroduce lake sturgeon to the Menominee Reservation. The planning process was designed to involve all the various, often competing, tribal and non-tribal interests in a constructive effort to develop and implement a Menominee Reservation sturgeon rehabilitation plan that all parties could accept and endorse. The core planning group was the Menominee Reservation Lake Sturgeon Enhancement Committee which worked with the various sturgeon ‘publics’ to identify common sturgeon restoration goals, objectives and management strategies, and which has worked together since that time in the effort to re-establish viable lake sturgeon populations in Menominee Reservation waters. Since 1994, over 30 000 hatchery-raised lake sturgeon have been stocked in reservation lakes, and 87 Wolf River lake sturgeon have been... [ABSTRACT FROM AUTHOR]