scholarly journals Population status and demographics of Lake Sturgeon in the Bad and White rivers, Wisconsin

2019 ◽  
Vol 10 (2) ◽  
pp. 442-457 ◽  
Author(s):  
Joshua T. Schloesser ◽  
Henry R. Quinlan
Keyword(s):  
Sex Ratio ◽  
Adult Population ◽  
Lake Superior ◽  
Return Time ◽  
Lake Sturgeon ◽  
River Population ◽  
Mature Adults ◽  
Rehabilitation Plan ◽  
Population Trajectory ◽  
Spawning Run

Abstract Lake Sturgeon Acipenser fulvescens rehabilitation efforts in Lake Superior are guided by a rehabilitation plan that sets goals and criteria for a self-sustaining population, including a minimum of 1,500 mature adults, roughly equal sex ratio, and annual exploitation rates < 5%. The Bad and White rivers, Wisconsin host a genetically unique Lake Sturgeon population that is utilized by state-licensed recreational anglers and tribal subsistence fishers. Our objectives were to 1) determine if the Bad River population meets rehabilitation plan targets for a self-sustaining population, 2) assess harvest of Lake Sturgeon by recreational anglers and tribal subsistence fishers for compatibility with rehabilitation goals, 3) determine population trajectory from annual spawning runs, and 4) describe population demographics given the unique physical features of Lake Superior. We sampled Lake Sturgeon in the Bad and White rivers with gill nets over a 17-y period (2001 to 2017). The observed sex ratio in spawning runs was 2.2:1 (male : female), but calculated at 1.6:1 for the entire adult population on the basis of abundance estimates. Weight–length relationships converted to a standardized modified form factor indicated lower condition and possibly lower female fecundity compared with other large North American populations. Annual spawning run size estimates over time indicated that the population trajectory was stable to slightly increasing, and during 2016 was 739 and 241 individuals in the Bad and White rivers, respectively. Total population size (including nonspawners) exceeded 1,500 individuals, which met Lake Superior rehabilitation criteria for a self-sustaining population. Estimates of 1,426 males and 882 females were considered conservative because 472 unknown-sex fish could not be accounted for in return time and abundance models. Spawning return times were 2 or 3 y for males and 4 to 6 y for females, longer than many other populations. Exploitation by recreational anglers and tribal subsistence fishers was 1.3% or lower and met the rehabilitation plan target of < 5%, but we recommend exploitation not exceed 3.1% to maintain a self-sustaining population. These findings help gauge rehabilitation progress in Lake Superior and better describe the demographics of a remnant self-sustaining Lake Sturgeon population in Lake Superior.

Biology, Management, and Protection of North American Sturgeon

2002 ◽  
Keyword(s):  
Cross Sections ◽  
Lake Michigan ◽  
Habitat Degradation ◽  
Adult Population ◽  
Lake Sturgeon ◽  
Age And Growth ◽  
Current Status ◽  
Population Estimates ◽  
The Status ◽  
Spawning Run

<em>Abstract.</em>—Lake sturgeon <em>Acipenser fulvescens</em> populations in the Great Lakes were drastically reduced in the late 1800s by commercial overfishing and habitat degradation. Although restoration efforts are underway, a lack of current information regarding the status of remaining populations has hindered recent rehabilitation efforts. The Manistee River is believed to support one of the largest remaining lake sturgeon populations in Lake Michigan. However little is known about the current status or population dynamics of this remnant stock. The main objectives of this study were to obtain annual spawning population estimates and to evaluate age and growth of the adult population. From April through June, 1999–2000, lake sturgeon were captured in the Manistee River using large mesh bottom-set gill nets. Population estimates were obtained using the Schnabel population estimator, and age was determined from cross-sections of pectoral fin ray samples. Back-calculations of length-at-age revealed that growth rates of Manistee River lake sturgeon were slightly higher than those obtained in previous studies of lake sturgeon populations inhabiting other similar river systems. Estimates of the spawning run were 106 in 1999 and 57 in 2000. Age analysis of captured fish, however, revealed that approximately one-half of the catch was composed of juveniles, suggesting that the actual number of spawning adults was probably less than 50 individuals in each year.

Evaluation of Organochlorine Pesticides and Sex Steroids in Lower Niagara River Lake Sturgeon

2014 ◽  
Vol 5 (1) ◽  
pp. 109-117 ◽  
Author(s):  
Gregory R. Jacobs ◽  
Deke T. Gundersen ◽  
Molly A. H. Webb ◽  
Dimitry Gorsky ◽  
Kristina Kohl ◽  
...  
Keyword(s):  
Blood Plasma ◽  
Endocrine Disruption ◽  
Sex Steroids ◽  
Polychlorinated Biphenyl ◽  
Nondestructive Method ◽  
Reproductive Physiology ◽  
Lake Sturgeon ◽  
Endocrine Function ◽  
River Population ◽  
Niagara River

Abstract As a long-lived, late-maturing species, lake sturgeon Acipenser fulvescens are vulnerable to the bioaccumulation of contaminants, which may impact reproductive physiology. The purpose of this study was to use a nondestructive method to investigate the relationship between endocrine-disrupting contaminants and sex steroids in lake sturgeon from the lower Niagara River. We screened blood plasma samples from lower Niagara River lake sturgeon (n  =  63) during April and May of 2012 for concentrations of 17 organochlorine (OC) contaminants that may affect endocrine function, as well as for abnormal levels of sex steroids testosterone (T) and 17β-estradiol (E2). We found detectable levels of two OC contaminants in the blood plasma of lake sturgeon, DDE (n  =  21) and γ-BHC (n  =  1). In both cases, plasma contaminant concentration was well below levels known to adversely affect sturgeon reproductive physiology. In addition, qualitative analysis of chromatographs from plasma extracts did not show the presence of other peaks that matched polychlorinated biphenyl standard peaks. Comparisons of plasma steroid levels with those of others from the literature gave no indication of endocrine disruption, though plasma T levels were notably high in the lower Niagara River population. We conclude that plasma OC levels are below threshold levels found in the scientific literature that would affect lake sturgeon reproductive physiology, and that it is unlikely that significant contaminant-mediated endocrine disruption is occurring in this population.

Biology of lake sturgeon (Acipenser fulvescens) spawning below a dam on the Richelieu River, Quebec: behaviour, egg deposition, and endocrinology

2013 ◽  
Vol 91 (3) ◽  
pp. 175-186 ◽  
Author(s):  
J.D. Thiem ◽  
D. Hatin ◽  
P. Dumont ◽  
G. Van Der Kraak ◽  
S.J. Cooke
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Residence Time ◽  
Lake Sturgeon ◽  
Blood Sampling ◽  
Acipenser Fulvescens ◽  
Spawning Ground ◽  
Egg Deposition ◽  
Daily Spawning ◽  
Gill Netting

Knowledge of the reproductive biology of wild sturgeon populations is critical to ensure the survival of this unique group of animals. We combined gill-netting surveys, nonlethal blood sampling, radiotelemetry, and egg collection to examine the reproductive biology of lake sturgeon (Acipenser fulvescens Rafinesque, 1817) at a suspected spawning ground below a dam on the Richelieu River, Quebec. Lake sturgeon were present at the beginning of sampling in early May, and spawning took place from 26 May to 5 June when water temperature averaged 13.4 ± 0.1 °C (range 11.5–15.5 °C). Daily spawning population estimates ranged from 285 to 1282 individuals and the sex ratio of spawners was estimated at 2.1 males per female. The presence of radio-tagged individuals on the spawning grounds peaked from 20 to 28 May, corresponding with known spawning bouts. Residence time of spawners on the spawning ground ranged from 1 to 27 days (median = 5 days) and there were no differences in residence time between sexes. Nonlethal blood sampling enabled the quantification of steroid levels to determine the spawning population sex ratio, and steroid levels were highest before spawning was known to occur and decreased concurrently with, and after, known spawning events.

scholarly journals Adult sex ratios and their implications for cooperative breeding in birds

2017 ◽  
Vol 372 (1729) ◽  
pp. 20160322 ◽  
Author(s):  
Jan Komdeur ◽  
Tamás Székely ◽  
Xiaoyan Long ◽  
Sjouke A. Kingma
Keyword(s):  
Sex Ratio ◽  
Cooperative Breeding ◽  
Adult Population ◽  
Sex Ratios ◽  
Bird Species ◽  
Dispersal Distance ◽  
Sex Bias ◽  
Wide Range ◽  
Cooperatively Breeding ◽  
Using Data

Cooperative breeding is a form of breeding system where in addition to a core breeding pair, one or more usually non-breeding individuals provide offspring care. Cooperative breeding is widespread in birds, but its origin and maintenance in contemporary populations are debated. Although deviations in adult sex ratio (ASR, the proportion of males in the adult population) have been hypothesized to influence the occurrence of cooperative breeding because of the resulting surplus of one sex and limited availability of breeding partners, this hypothesis has not been tested across a wide range of taxa. By using data from 188 bird species and phylogenetically controlled analyses, we show that cooperatively breeding species have more male-biased ASRs than non-cooperative species. Importantly, ASR predicts helper sex ratio: in species with more male-biased ASR, helper sex ratio is also more male biased. We also show that offspring sex ratios do not predict ASRs, so that the skewed ASRs emerge during the period when individuals aim to obtain a breeding position or later during adulthood. In line with this result, we found that ASR (among both cooperatively and non-cooperatively breeding species) is inversely related to sex bias in dispersal distance, suggesting that the cost of dispersal is more severe for the further-dispersing sex. As females usually disperse further in birds, this explains the generally male-biased ASR, and in combination with benefits of philopatry for males, this probably explains why ASR is more biased in cooperatively breeding species. Taken together, our results suggest that a sex bias in helping in cooperatively breeding species relates to biased ASRs. We propose that this relationship is driven by sex-specific costs and benefits of dispersal and helping, as well as other demographic factors. Future phylogenetic comparative and experimental work is needed to establish how this relationship emerges. This article is part of the themed issue ‘Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies’.

Facultative sex allocation in the viviparous lizard Eulamprus tympanum, a species with temperature-dependent sex determination

2003 ◽  
Vol 51 (4) ◽  
pp. 367 ◽  
Author(s):  
Kylie A. Robert ◽  
Michael B. Thompson ◽  
Frank Seebacher
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Breeding Season ◽  
Sex Allocation ◽  
Adult Population ◽  
Selective Advantage ◽  
Adult Males ◽  
Temperature Dependent ◽  
Maternal Manipulation

Females of the Australian scincid lizard Eulamprus tympanum can manipulate the sex of their offspring in response to gender imbalances in the population using temperature-dependent sex determination. Here we show that when adult males are scarce females produced male-biased litters and when adult males were common females produced female-biased litters. The cues used by a female to assess the adult population are not known but presumably depend upon her experience throughout the breeding season. Maternal manipulation of the sex ratio of the offspring in E. tympanum illustrates a selective advantage of temperature-dependent sex determination in a viviparous species.

Combining Fixed-Location Count Data and Movement Data to Estimate Abundance of a Lake Sturgeon Spawning Run: A Framework for Riverine Migratory Species

2021 ◽  
Author(s):  
Lisa K Izzo ◽  
Gayle B. Zydlewski ◽  
Donna L Parrish
Keyword(s):  
Count Data ◽  
Acoustic Telemetry ◽  
Lake Sturgeon ◽  
Dual Frequency ◽  
Movement Data ◽  
Abundance Estimates ◽  
Spatial Coverage ◽  
Frequency Identification ◽  
Spawning Run ◽  
Riverine Systems

Estimating abundance of migrating fishes is challenging. While sonars can be deployed continuously, improper assumptions about unidirectional migration and complete spatial coverage can lead to inaccurate estimates. To address these challenges, we present a framework for combining fixed-location count data from a dual-frequency identification sonar (DIDSON) with movement data from acoustic telemetry to estimate spawning run abundance of lake sturgeon (Acipenser fulvescens). Acoustic telemetry data were used to estimate the probability of observing a lake sturgeon on the DIDSON and to determine the probability that a lake sturgeon passing the DIDSON site had passed the site previously during the season. Combining probabilities with DIDSON counts, using a Bayesian integrated model, we estimated the following abundances: 99 (42–215 CI) in 2017, 131 (82–248 CI) in 2018, and 92 (47–184 CI) in 2019. Adding movement data generated better inferences on count data by incorporating fish behavior (e.g., multiple migrations in a single season) and its uncertainty into abundance estimates. This framework can be applied to count and movement data to estimate abundance of spawning runs of other migratory fishes in riverine systems.

Status, Distribution, and Conservation of Native Freshwater Fishes of Western North America

2007 ◽  
Keyword(s):  
Deterministic Model ◽  
Adult Population ◽  
Fish Passage ◽  
Adult Longevity ◽  
Bull Trout ◽  
Catastrophic Events ◽  
Mature Adults ◽  
Trout Population ◽  
Lake Washington ◽  
Adult Abundance

ABSTRACT A life cycle model was employed to identify the response of an adfluvial bull trout <em>Salvelinus confluentus</em> population to chronic and catastrophic losses of subadults. The model simulates the bull trout population within Rimrock Lake, Washington, a reservoir on the Tieton River impounded by Tieton Dam. Subadult bull trout are entrained during summer water releases for irrigation, and the dam has no fish passage facilities to enable those fish to return upstream. Suitable spawning and rearing habitat is primarily upstream of the dam. Tagging studies of adult bull trout passing weirs in the two major tributaries to the reservoir were used to estimate model parameters for survival, maturity rates, reproductive capacity, and initial abundance. Sampling data and the deterministic model simulations indicated that the population was capable of rebounding quickly from intermittent catastrophic events. Resilience of the bull trout population resulted from high adult longevity and repeat spawning. The accumulation of mature adults across multiple age-classes led to egg deposition that fully seeded rearing capacity of the natal tributaries, even when several consecutive broods of juveniles exhibited poor survival. Catastrophic events simulated to entrain 50% of the subadults every 15 years caused a 40% reduction in adult abundance within 4 years of the event, followed by a full recovery to maximum production within 9 years. Even during the low point of adult abundance, 15 times more eggs were deposited than were needed to fully seed juvenile tributary habitat. Because the population was already producing juveniles at capacity, simulations for opening fish passage over Rimrock Dam showed that the sustained spawner population would increase by only two adults. However, simulations for expanded juvenile habitat by 14% indicated that the sustainable adult population would increase by 14%. Thus, habitat improvements that target juvenile rearing capacity appear to have the greatest potential to increase population size.

Studies with Ostertagia circumcincta in Sheep. I. The epidemiology of mature adults and arrested larvae

1967 ◽  
Vol 41 (2-3) ◽  
pp. 137-150 ◽  
Author(s):  
P. S. James ◽  
I. L. Johnstone
Keyword(s):  
Adult Population ◽  
Post Mortem ◽  
Fourth Stage ◽  
Mature Adults

By means of egg counts, faecal cultures and post-mortem examinations of sheep the course of an infestation of Ostertagia circumcincta was followed from March until the following January in a flock of 100 twelve-months-old wethers at Wellington, N.S.W. The highest adult infestations and egg counts occurred in March and January, while during the winter months there was a continual accumulation of inhibited fourth stage larvae in the abomasal mucosa. The data suggest that the adult population observed in January arose from the inhibited population observed during the previous winter and that one of the factors controlling the development of the inhibited population was larval intake.

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