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Summary: Lake Sturgeon, Acipenser fulvescens, was assessed in a large, pristine river in northern Canada using a standardized protocol. Gill netting (38‐127 mm and 204‐306 mm stretched mesh) was conducted at five sites averaging 37 rkm in the Attawapiskat River in Ontario. The objectives were to ascertain relative abundance of Lake Sturgeon within a northern river; determine if Lake Sturgeon are randomly distributed within a ‘pristine’ river; assess if there is evidence of spatial structuring; and determine if there is genetic structuring within the river. Over the two years (2015 and 2016), 176 Lake Sturgeon were sampled with a mean total length of 851.1 mm (323.4 SD) and mean age of 21 years (12.2 SD). There was a significant difference in the mean total length of the Lake Sturgeon caught, with larger sturgeon in the upstream sites and smaller sturgeon in the downstream sites, signifying a spatial segregation of life stages within the Attawapiskat River. One hundred and fifty‐four Lake Sturgeon were genotyped at 10 or more loci. There was no evidence of genetic divergence among sites or population structuring. In fact, parent‐offspring relationships were determined using COLONY between upstream and downstream sites, a minimum distance of approximately 190 rkm. This study represents the first to assess a Lake Sturgeon population systematically using a standardized index approach at multiple sites in a ‘pristine’ river. It demonstrated the importance of a holistic approach to the river at a larger scale and a better understanding of life history requirements for conservation. For example, if only one of the upper sites were assessed, it might have been interpreted as the idyllic ‘old growth’ population with limited or no recruitment. The corollary from sampling only lower sites would be identifying a lack of adults and potentially erroneously declaring an overexploitation concern. This stresses the importance of a larger scale approach for assessing ‘pristine’ rivers and not using a small scale approach to make large scale inferences. [ABSTRACT FROM AUTHOR]

In response to a contamination incident in water distribution networks, disinfectant booster stations can be used to neutralize the contaminant and protect the public. In this paper, two mixed-integer linear programming formulations are proposed for optimal placement of disinfectant booster stations. The first formulation minimizes the contaminant mass consumed by the public, while the second formulation minimizes the number of people who ingest the contaminant above a mass threshold. The proposed formulations consider uncertainty in both the location and time of the contamination incident, resulting in an intractably large stochastic programming problem. This manuscript proposes a series of reductions that decrease the size of the problem by up to five orders of magnitude. The results show that the use of a small number of disinfectant booster stations can be very effective as a response strategy. [ABSTRACT FROM PUBLISHER]

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]

Hydroelectric facilities can dramatically alter the quantity and quality of fish habitat; however it is not well known how these habitat changes affect the growth and life history of fish. We examine the growth and life history of slimy sculpin ( Cottus cognatus), a small-bodied sedentary, benthic stream fish, in two regulated and eight unregulated tributaries of Lake Superior, Canada. Among rivers, we found that slimy sculpin grew faster in the regulated Magpie River than in nearby unregulated systems, whereas growth in the Michipicoten River was intermediate. Sculpin were also in better condition in the regulated Magpie and Michipicoten than in nearby natural rivers. Faster growth of sculpin, however, potentially led to their rapid maturity and higher instantaneous mortality in regulated rivers. Within the regulated rivers, there are strong longitudinal gradients in growth, with sculpin at sampling sites near the dams growing more rapidly, maturing earlier and attaining a larger size-at-age than sculpin at sites farther downstream or in natural systems. Differences in sculpin life history traits within rivers closely followed spatial patterns in food availability. We caution future researchers and managers to acknowledge the longitudinal gradients in abiotic and biotic conditions below dams early in experimental designs and monitoring programmes and how this may impact the measures of central tendency and statistical power when comparing rivers. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The objectives of this study were to (i) assess the variation in relative abundance of lake sturgeon ( Acipenser fulvescens Rafinesque, 1817) subjected to various man-induced stresses and physical characteristics at a landscape scale across Ontario; and (ii) ascertain the factors that explain the variability observed among rivers using a multivariate approach. A standardized index netting program targeting juvenile and adult Lake Sturgeon was conducted over two field seasons at 22 river sites across Ontario. Each river had unique or different human-induced stresses and physical characteristics. Relative abundance of Lake Sturgeon varied in river across the Ontario landscape. A principal component analysis was conducted using site physical characteristics with the associated anthropogenic stressors. The catch-per-unit-effort ( CPUE) for juvenile and adult Lake Sturgeon were then regressed with the scores of principal components having eigenvalues >1. The variation observed was best explained by the negative relationship observed between CPUE and the presence of hydroelectric generating stations. Historical commercial fisheries also had an effect on Lake Sturgeon abundance whereas subsistence fisheries seemed to focus on rivers that were not regulated and where Lake Sturgeon numbers were greater. Research and recovery efforts should focus on minimizing the impact of hydroelectric generation on Lake Sturgeon while achieving socioeconomic goals. [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]

The potential of sturgeon species and populations to adapt to current challenges and changing conditions will depend on their adaptive resources and capacity, which can be inferred from their genetic effective population size ( Ne). Existing microsatellite genetic data from published studies were used to estimate Ne of lake sturgeon ( Acipenser fulvescens) across hierarchical spatial and temporal scales. Previous analysis of mitochondrial DNA data suggested that the species has an evolutionary female effective population size ( Nef) of ~8000, substantially lower than other North American freshwater fish species with similar distributions. Phylogeographic data were used to reconstruct the genetic makeup and diversity of phylogeographic lineages, and compare the genetic diversity and Ne of contemporary Canadian populations to their ancestral founding populations. A similar approach was used to estimate ancestral Ne for fragmented populations in formerly continuous habitats. On the finest spatiotemporal scale, point estimates of Ne for sturgeon populations in contiguous river fragments were compared against Ne values from reconstructed ancestral (pre-fragmentation historical) populations to assess changes in Ne since fragmentation occurred. These results illustrate the versatility of genetic data for estimating historical demographics of sturgeon, as well as providing information on their adaptive potential and long-term sustainability if given the ecological opportunity. [ABSTRACT FROM AUTHOR]

The article presents several charts and tables which features various group of daily river flows and monthly groundwater levels that can be use for climate change impact assessment in Great Britain.

Although bycatch is well known and well studied in marine fisheries, comparatively little is known about bycatch in freshwater fisheries. Even basic information on bycatch composition and mortality in freshwater is unavailable, given that few inland jurisdictions require reporting of bycatch. A small-scale inland hoop net fishery that targets pan fish (e.g. sunfish, L epomis spp.) and operates primarily in the spring and fall was simulated in two lakes in south-eastern Ontario to characterize both bycatch composition and mortality. We fished one lake in both spring and fall to compare catch rates, while in the other lake we set nets for 2 or 6 days during the spring to assess fish mortality associated with different net tending frequencies. In both lakes, bycatch consisted of gamefish, turtles (including several species at risk), and mammals. For fish, there was no difference in spring and fall catches. Turtles, however, were captured more often in spring. Fish mortality of both target and non-target species increased from 0.3-0.9% to 3.0-3.7% (4-10 times) when set net duration increased from 2 to 6 days. Despite the provision of an air breathing space in our nets, we documented severe turtle mortality (33% in one lake) and all mammals died, suggesting that provision of air spaces is not always effective. Although all bycatch mortality is a concern, turtles are prone to population declines even with low levels of non-natural mortality. As such, regulators may consider limiting commercial fishing to the fall in this region to reduce turtle captures. Seasonal restrictions on fishing or use of frequent net tending (e.g. < 2 days) will not prevent all turtle bycatch and therefore gear modifications should be investigated to further reduce turtle captures and mortality associated with hoop nets. [ABSTRACT FROM AUTHOR]

Brook trout (Salvelinus fontinalis) are a highly prized species found in lakes and streams throughout Ontario. A broadscale monitoring program (BsM) has been conducted in lakes throughout the province, in 5-year cycles, which targets Salvelinus fontinalis populations. The objective of this study was to use the data gained from the BsM and establish a contemporary baseline on the variation of relative abundance and demographics of natural lake populations of S. fontinalis in Ontario. Additionally, given the variability in environmental conditions across the landscape, an objective was to assess the factors, abiotic and biotic, that influence relative abundance among waterbodies. Over the three BsM cycles (2008-2022), 273 S. fontinalis waterbodies were assessed, some multiple times, and 124 were unique populations. S. fontinalis were sampled in 112 of these unique lakes. In total, 7487 S. fontinalis were caught and 5372 were fully sampled (length, weight, and age assessed). The mean catch-per-unit-effort (CPUE) in all waterbodies was 1.4 (0.12 standard error) S. fontinalis per net gang. There was not a significant trend in CPUE over the three BsM cycles nor did CPUE vary significantly among BsM cycles at the provincial scale, but CPUE varied significantly among fisheries management zones (FMZs). Multiple variables were examined to explain the variation in CPUE across the province; a negative association with species diversity was the only variable considered significant. Furthermore, S. fontinalis were more associated with the relative abundance of small cyprinids (i.e., chubs and shiners) and negatively associated with centrarchids, smelt, and other game species. Mean growth potential was greater for males than females but not significantly, whereas longevity favored females. Growth potential and parameters were similar between sexes within FMZs but varied among FMZs. Mean survival among these populations was 25.7%, ranging from 15.2% to 45.6%, with a mean instantaneous mortality of 1.41. This study provided a contemporary assessment of the current range and variability in relative abundance population dynamics of S. fontinalis in lakes within Ontario. This provides a benchmark to assess changes with the pending stressors of climate change and human expansion across the landscape., (© 2024 His Majesty the King in Right of Canada. Journal of Fish Biology © 2024 Fisheries Society of the British Isles. Reproduced with the permission of the Minister of Natural Resources and Forestry.)

Drinking water utilities are vulnerable to both human-caused and natural disasters that can impact the system infrastructure and the delivery of potable water to consumers. Analyzing system performance and resilience can help utilities identify areas of high risk or concern, understand the impacts on consumers, and evaluate response actions during disasters. In this case study, the Water Network Tool for Resilience (WNTR) was used to investigate the performance and resilience of a drinking water system in New York during increased demands due to firefighting, pipe damage, and loss of the source water emergencies. This case study introduced a new combined performance index (CPI) resilience metric, which served to quantify system resilience as a ratio of system performance during an emergency to normal operations. The results revealed that this drinking water system was able to maintain service to most of the consumers during these emergencies due to high redundancy within the system, and conservation efforts extended water service for an additional 20 h. The analysis in this paper can be used by other drinking water utilities to understand their vulnerabilities and evaluate resilience-improving actions in similar disaster scenarios.

The two Category-5 hurricanes that impacted the United States Virgin Islands in 2017 exposed critical infrastructure vulnerabilities that must be addressed. While the drinking water utility has first-hand knowledge about how the hurricanes affected their systems, the use of modeling and simulation tools can provide additional insight to aid investment planning and preparedness. This paper provides a case study on resilience analysis for the island's potable water systems subject to long term power outages. Power outage scenarios help quantify differences in water delivery, water quality, and water quantity during and after the disruption. The analysis helps illustrate important differences in system operations and recovery time across the islands. Results from this case study can be used to better understand how the system might behave during future disruptions, provide justification for investment, and provide recommendations to increase resilience of the system. The analysis framework can also be used by other utilities to explore vulnerability to long term power outages.

Illicit discharges in surface waters are a major concern in urban environments and can impact ecosystem and human health by introducing pollutants ( e.g. , petroleum-based chemicals, metals, nutrients) into natural water bodies. Early detection of pollutants, especially those with regulatory limits, could aid in timely management of sources or other responses. Various monitoring techniques ( e.g. , sensor-based, automated sampling) could help alert decision makers about illicit discharges. In this study, a multi-parameter sensor-driven environmental monitoring effort to detect or identify suspected illicit spills or dumping events in an urban watershed was supported with a real-time event detection software, CANARY. CANARY was selected because it is able to automatically analyze data and detect events from a range of sensors and sensor types. The objective of the monitoring project was to detect illicit events in baseline flow. CANARY was compared to a manual illicit event identification method, where CANARY found > 90% of the manually identified illicit events but also found additional unidentified events that matched manual event identification criteria. Rainfall events were automatically filtered out to reduce false alarms. Further, CANARY results were used to trigger an automatic sampler for more thorough analyses. CANARY was found to reduce the burden of manually monitoring these watersheds and offer near real-time event detection data that could support automated sampling, making it a valuable component of the monitoring effort., Competing Interests: Conflicts of interest There are no conflicts to declare.