2024 Onward

Permanent URI for this collectionhttps://hdl.handle.net/1807/137423

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Seabird inputs drive changes in Cladocera assemblages in freshwater ponds
(Canadian Science Publishing, 2024-07-13) Kane, Zoe Adria; Duda, Matthew P.; Simmatis, Brigitte; Smol, John P
Seabirds are biovectors that transport large concentrations of nutrients from their marine feeding areas to terrestrial breeding grounds. Here, we used subfossil cladoceran assemblages to assess if, and how, changes in the world’s largest colony of Leach’s Storm Petrels affected the structure of Cladocera assemblages over the past ~1700 years. Using sediment cores from four ponds impacted by Leach’s Storm-Petrel colonies on Baccalieu Island (NL, Canada), we observed a consistent transition in cladoceran assemblages from benthic/littoral to pelagic taxa in association with high seabird presence. This shift aligns with previously published limnological changes that tracked the growth of the colony. Compared to trends in sedimentary chlorophyll-a, pelagic cladoceran taxa lagged behind algal shifts driven by seabird activity. The main drivers of cladoceran assemblage shifts were likely alterations to the physical habitat structure and food availability driven by seabird inputs. Furthermore, deposition of calcium from seabirds may have also contributed to changing the composition of cladoceran communities. Our study provides information on food web shifts associated with seabird-driven eutrophication, which can be compared to future paleoecological studies.
A Modeling Framework for Quantifying Spatial Recruitment Dynamics Using Abundance Estimation and Sibship Analysis
(Canadian Science Publishing, 2024-09-13) Lewandoski, Sean Alois; Brenden, Travis O.
Quantifying recruitment at the sibling group offers a powerful methodology for understanding density-dependent and environmental drivers of recruitment. We propose a modeling framework that combines sibship and abundance estimation datasets to estimate mean sibling group size, sibling group size process error, environmental and density-dependent effects on sibling group size, dispersal, and mortality rate. Geographic states in the model consist of discrete habitat patches connected via dispersal. Simulations were used to investigate the influence of sampling processes and sibling group size on parameter estimation within our modeling framework. Mean sibling-group size, environmental effects on recruitment, and dispersal rate among habitat patches were estimated with high accuracy under a wide range of sampling conditions, including imprecise out-of-model estimates of capture probability and subsampling both within and among habitat patches. Density-dependent effects on recruitment and process error tended to be estimated with lower accuracy, though accuracy improved as sibling group size or sampling intensity increased. The main contribution of this research is a flexible quantitative modeling framework for parameterizing mechanistic models of recruitment dynamics with empirical sibship data.
Assessing the potential responses of ten important fisheries species to a changing climate with machine learning and observational data across the province of Québec
(Canadian Science Publishing, 2024-08-28) Rodríguez, Marco A.; Lemaire, Marine; Fugère, Vincent; Barrette, Marie-France; Gagné, Stéphanie; Leclerc, Véronique; Morissette, Olivier; Pouliot, Rémy; St-Pierre, Annick; Turgeon, Katrine; Velghe, Katherine; Guay, Jean-Christophe; Beisner, Beatrix E
Models are needed to predict changes in game fish abundances with respect to climatic factors undergoing change, but such models are often limited by data availability and the capacity of statistical methods to fit challenging ecological datasets. We use current methods in machine learning to describe the responses of ten fish species to climatic factors across Québec. We assembled a new province-wide, synthetic dataset of fish catches spanning almost 50 years and 6000 sites. Extreme Gradient Boosting (XGBoost) models revealed that climatic factors are more important predictors of trends in game fish catches than nuisance factors (sampling gear, time), lending support to collating other heterogeneous datasets for analyses. Mean annual temperature and precipitation were the most important drivers of species catches. Fish thermal preference guilds predicted primarily species responses to temperature, suggesting that warmer and wetter climates may not favour the same species. Despite the challenging nature of these datasets, XGBoost models provided excellent fit, predictive capacity, and interpretability, thereby illustrating that large, heterogeneous datasets can be used to inform freshwater fisheries management in a changing climate.
Increasing microplastic exposure had minimal effects on fatty acid composition in zooplankton and yellow perch in a large, in-lake mesocosm experiment
(Canadian Science Publishing, 2024-07-24) Covernton, Garth; Metherel, Adam; McMeans, Bailey C.; Bucci, Kennedy; Langenfeld, Desiree; McNamee, Rachel; Veneruzzo, Cody; Hoffman, Matthew Joseph; Orihel, Diane M; Paterson, Michael J.; Provencher, Jennifer; Rennie, Michael D.; Rochman, Chelsea M.
Using 10-m diameter mesocosms in a Canadian boreal lake, we investigated the effects of MP exposure on the body weight and diet of yellow perch (Perca flavescens) and the fatty acid composition of yellow perch and zooplankton. We exposed the aquatic ecosystem within seven mesocosms for 10 weeks to a mixture of polyethylene, polystyrene, and polyethylene terephthalate fragments, ranging in nominal addition concentrations from 6 to 29,240 particles L-1 (although realized water column concentrations were lower), as well as two negative controls. Increasing MP exposure did not affect yellow perch body weight (growth) or diet, or the overall fatty acid composition of yellow perch muscle or zooplankton. Results were highly variable across mesocosms. Despite high levels of MP ingestion by yellow perch, we did not find evidence of MPs leading to food dilution or any other effect where we could anticipate impacts on food web structure.
Confronting transitions in fishery fleet structure and selectivity: Practical recommendations for integrated age-structured stock assessments based on simulation analysis
(Canadian Science Publishing, 2024-07-17) Cheng, Matthew; Goethel, Daniel R.; Hulson, Peter-John F.; Cunningham, Curry James
Dynamic shifts in fleet structure and gear usage lead to complex implications for representing fishery selectivity in stock assessment models. There is generally a lack of consensus on how assessment models should be configured to confront changes in fishery fleet structure or associated selectivity forms, while balancing complexity-parsimony tradeoffs. We conducted a simulation analysis to evaluate the performance of alternative assessment models when confronted with fleet transitions among gear types, which included differences in: 1) rates of transition (i.e., a fast or slow transition among gears), and 2) selectivity forms for each modeled fleet (i.e., asymptotic or dome-shaped). In general, explicitly modelling fleet structure (i.e., multi-fleet models) performed well, but demonstrated bias in biomass estimates and management reference points when selectivity forms were mis-specified. Single-fleet models were only unbiased when time-varying selectivity (e.g., using time blocks or continuous formulations) was estimated to account for changes among gear types. Our results suggest that single-fleet models with time-varying fishery selectivity are adequate for operational management advice, but research oriented multi-fleet models should be used as validation tools to explore model consistency within single-fleet models.
On Increasing Equity and Inclusion of Early-Career Professionals for Conferences and Conference Networking in Canadian Fisheries and Aquatic Science Societies
(Canadian Science Publishing, 2024-06-20) Semeniuk, Christina A.D.; Church, Kathleen D.W.; Eissenhauer, Felix; Grimm, Jaime; Hechler, Robert M; Howell, Bradley E; Ivanova, Silviya V.; Klemet-N'Guessan, Sandra; Madliger, Christine L; Reid, Jessica L; Thompson-Kumar, Kendra; Arismendi, Ivan; Penaluna, Brooke E.; Kirkwood, Andrea E.; Febria, Catherine M.
As early-career professionals (ECPs) navigate their education and professional development in the aquatic sciences, many seek to build a network to help guide their entrance into the field. Scientific societies play a vital role through hosted conferences, where ECPs can meet and share ideas with others and find mentors. However, not all ECPs are the same, and those from marginalized backgrounds face unique challenges. Here, we provide a perspective on ways scientific societies can ensure all members are provided with equitable opportunity to discover, access, and build career-defining networks at conference events, including the critical role of mentors in navigating obstacles to success. Our recommendations originate from an early-career networking workshop in 2022 at a Canadian fisheries and aquatic sciences conference. The day-long hybrid event comprised interactive activities and discussions on how societies and their conferences can foster and promote inclusive networking for all, including online attendees. This perspective serves as a call to action for scientific societies and senior-career professionals to meaningfully engage with early-career professionals and marginalized members to promote transformative science.
Incorporating ecological heterogeneity and intraspecific variation differentiates complex interactions between apex predators and stocked fish
(Canadian Science Publishing, 2024-07-02) Rosinski, Caroline L.; Cavalli, Pete; Neebling, Travis; Skiles, Taylor; Wicks, Samuel; Fetzer, William
Ecological heterogeneity and intraspecific variation can impact energy flow from the base of the food web to top predators. We evaluated the effect of intraspecific variation on estimates of lake trout (Salvelinus namaycush) consumption of stocked kokanee (lacustrine sockeye salmon, Oncorhynchus nerka) in a 390 ha oligotrophic lake with two distinct basins. Lake trout stomach content analyses, stable isotope niche space, and catch rates indicated high intraspecific variation in resource use across habitats and basins. Intraspecific variation and ecological heterogeneity were incorporated into two bioenergetics modeling approaches; one lake-wide model, and one partitioned model that accounted for differences in lake trout diet composition and population size across habitats. The ecologically partitioned model highlighted that lake trout consumption was primarily in the epilimnion of one basin, while the lake-wide, unpartitioned model performed similarly but failed to provide ecological context for where that consumption occurred. Incorporating ecological heterogeneity and intraspecific variation into bioenergetic models can more accurately represent top predators foraging patterns across habitats and inform management actions to mitigate impacts to stocked fish.
Acoustic telemetry and network analysis reveal seasonal spatial overlap between gadid species in a subarctic coastal marine protected area
(Canadian Science Publishing, 2024-07-02) King, Benjamin; Morris, Corey J; Green, John M; Gregory, Robert S; Snelgrove, Paul VR; Cote, David; Pennell, Curtis J.
The Gilbert Bay MPA was established in Labrador, Canada to protect a resident population of Atlantic cod (Gadus morhua) and associated habitat. However, fisheries removals outside MPA boundaries have contributed to population decline and increases in potentially competing species may hinder recovery. Using acoustic telemetry and network analyses, we compared movements of Gilbert Bay cod (n = 23), conspecifics from offshore environments (offshore Atlantic cod, n = 19), and Greenland cod (Gadus ogac, n = 14) within and outside MPA boundaries from August 2014 – June 2017. Similar summer space use resulted in species overlap at seaward MPA boundaries and outside the MPA. In winter, Gilbert Bay and Greenland cod distributions overlapped within some MPA areas, and offshore Atlantic cod were absent. Some Gilbert Bay cod remained within the MPA year-round. Summer vulnerability to fisheries harvest outside MPA boundaries and winter overlap with competing Greenland cod within the MPA, may collectively challenge Gilbert Bay cod population recovery. Our study demonstrates the utility of acoustic telemetry and network analyses in evaluating animal movements for MPA management.
California steelhead populations were regionally buffered and individually resistant to a severe multi-year drought
(Canadian Science Publishing, 2024-06-20) Ohms, Haley; Palkovacs, Eric P; Boughton, David Alan
Weather extremes, such as drought, are predicted to be a strong determinant of species persistence under climate change. Yet predictions often fail to consider that variation in streamflow responses, variation in population dynamics, or adaptations to drought could buffer species against extremes. In this study we examined the responses of eight California (USA) steelhead populations to a severe drought from 2012 to 2016. We observed that streamflows were highly synchronous across the region in all seasons and did not appear to buffer drought impacts. Population dynamics were variable across the region and did appear to buffer the region from drought impacts. Some populations had very low productivity for four years associated with the drought, while others had slightly below-average productivity for only two years. Population synchrony was associated with spring-smolt flow, temperature and drought over time, but was not associated with winter-spawner or summer-juvenile conditions, suggesting populations may be adapted to drought. Our results highlight how regional buffering and adaptation can be important mechanisms against climate extremes both now and into the future.
Enhancing data-limited assessments with random effects: A case study on Korea chub mackerel (Scomber japonicus)
(Canadian Science Publishing, 2024-05-29) Kim, Kyuhan; Sibanda, Nokuthaba; Arnold, Richard; A'mar, Teresa
In a state-space framework, temporal variations in fishery-dependent processes can be modeled as random effects. This modeling flexibility makes state-space models (SSMs) powerful tools for data-limited assessments. Though SSMs enable the model-based inference of the unobserved processes, their flexibility can lead to overfitting and non-identifiability issues. To address these challenges, we developed a suite of state-space length-based age-structured models and applied them to the Korean chub mackerel (Scomber japonicus) stock. Our research demonstrated that incorporating temporal variations in fishery-dependent processes can rectify model mis-specification but may compromise robustness, which can be diagnosed through a series of model checking processes. To tackle non-identifiability, we used a non-degenerate estimator, implementing a gamma distribution as a penalty for the standard deviation parameters of observation errors. This penalty function enabled the simultaneous estimation of both process and observation error variances with minimal bias, a notably challenging task in SSMs. These results highlight the importance of model checking and the effectiveness of the penalized approach in estimating SSMs. Additionally, we discussed novel assessment outcomes for the mackerel stock.
Variation in estuary use patterns of juvenile Chinook salmon in the Fraser River, BC
(Canadian Science Publishing, 2024-05-03) Scott, David Christopher; Chalifour, Lia; MacDuffee, Misty; Baum, Julia K.; Beacham, Terry; Rondeau, Eric B.; Hinch, Scott G
Juvenile Pacific salmon (Oncorhynchus spp.) use estuary habitats to varying degrees with some species and populations thought to rely heavily on these areas for early growth. In the Fraser River, British Columbia, there are 18 distinct Conservation Units of Chinook salmon (O. tshawytscha), and all but one is of conservation concern. Our study compares the outmigration timing, size, and habitat use of juvenile Chinook salmon in the Fraser River estuary. Over five years (2016-2020) we captured 6,493 juvenile Chinook salmon, with 3,318 sampled for stock identification. Fraser River Chinook salmon extensively used estuary habitats, but patterns varied considerably by population. Juvenile Chinook salmon from the Lower Fraser River were most abundant and present the longest, arriving the smallest in late March and early April, and captured until July. South Thompson ocean-type Chinook salmon entered the estuary later, starting to arrive in late May or early June and remaining present until mid-August. Overall, juvenile Chinook salmon varied considerably in their estuary use across populations. Understanding this variation can inform differences in productivity and guide recovery actions.
Declines and shifts in morphological diversity of ciscoes (Coregonus spp.) in lakes Huron and Michigan, 1917-2019
(Canadian Science Publishing, 2024-04-25) Fedorowicz, Paul; Kao, Yu-Chun; Ackiss, Amanda; Anweiler, Katie; Honsey, Andrew E.
Ciscoes (Coregonus spp.) were historically abundant and ecologically important in Laurentian Great Lakes ecosystems. Despite well-documented declines in their abundance and taxonomic diversity, declines in morphological diversity remain understudied. This knowledge gap is especially pertinent for lakes Michigan and Huron, which have each lost six of eight historical species. Improved understanding of historical and contemporary morphological diversity of Great Lakes ciscoes can inform ongoing restoration efforts and further elucidate the factors that contributed to declines. Our goal was to characterize shifts in morphological diversity of ciscoes in lakes Michigan and Huron over a century (1917-2019). We analyzed size-corrected morphometric and meristic measurements from three periods: Early (1917-1923), Middle (1950-1972), and Contemporary (2015-2019). We then identified morphologically distinct clusters while remaining agnostic to species identifications. We found that morphological diversity and the number of distinct clusters declined over time. We then leveraged species identifications to highlight key species losses and examine morphological shifts among extant species. Our findings provide insights into the historical and contemporary morphological diversity of ciscoes and will inform restoration efforts.
A probabilistic foundation for the study of larval fish feeding, growth, and mortality rates
(Canadian Science Publishing, 2024-04-25) Pepin, Pierre
Survival through the larval phase is predicated on the probabilities of successful feeding, which dictates growth rates, and the probabilities of encountering predators. Here I perform a synthesis of feeding, growth, and mortality rates estimated during several studies from coastal Newfoundland, Canada, to provide a description of the probability distribution that can serve as a foundation of the expected distribution of vital rates. The standardized observations clearly follow that of skewed distributions, appropriately fit to a probability gamma distribution, with feeding demonstrating a stronger degree of skewness than either mortality or growth, possibly because each vital rate integrates prey-predator interactions over different time scales. Commonality in the underlying form of the distribution of vital rates in larval fish, along with clear functional relationships between gamma parameters, represents a probabilistic basis of expectations against which observations from prior or new studies can be contrasted. An example of the use of such expectations demonstrates that they can provide useful contextual information about the contrast among observations and our ability to identify their relationship with environmental drivers.
Electronic tags reveal high migratory diversity within largest Atlantic halibut (Hippoglossus hippoglossus) stock
(Canadian Science Publishing, 2024-02-05) Ransier, Krista Tomaselli; Gatti, Paul; Le Bris, Arnault; den Heyer, Cornelia; Claireaux, Guy; Wringe, Brendan F.; Fisher, Jonathan AD
Growing evidence suggests that complex spatial structure occurs within the Scotian Shelf and southern Grand Banks (SSGB) Atlantic halibut stock, yet large knowledge gaps remain about migratory and spawning behaviors. Here, 71 pop-up satellite archival tags were deployed on large Atlantic halibut (FL: 87 - 166 cm) between 2012 and 2020. Migration tracks were successfully reconstructed for 43 fish using a hidden Markov geolocation model, and temperature and depth time series were available for nine fish (total n = 52). Five migratory behaviors were identified: shelf residency, slope residency, shelf-channel migration, shelf-slope migration, and dispersal. The high-resolution data for four of 20 physically recovered tags provided evidence for putative female spawning behavior in deep channels on the continental shelf and along the continental slope between January and February. Additionally, four halibut displayed previously undocumented periods of sustained, oscillatory vertical movement along the continental slope between November and February. The high migratory diversity observed in the SSGB stock supports the existence of multiple resident and migratory contingents in the stock in the apparent absence of significant genetic structure.
Developing management plans for sprat (Sprattus sprattus) in the Celtic Sea consistent with an Ecosystem Approach to Fisheries
(Canadian Science Publishing, 2024-04-25) Kell, Laurence T.; Bentley, Jacob; Feary, David; Egan, Afra; Nolan, Cormac
Sprat are commercially valuable and are an important component of the North-East Atlantic ecosystem as major predators of zooplankton, competitors with herring, and prey for piscivorous fish, marine mammals, and seabirds. Despite this, insufficient information exists for Celtic Seas sprat, one of five North-East Atlantic stocks, to estimate stock status. To ensure the sustainable exploitation of sprat, the health of the Celtic Seas ecosystem and the wider fisheries sector, we conduct a Management Strategy Evaluation to stress test the current single-species advice framework. The aim is to evaluate whether ecosystem objectives can be achieved under single-species maximum sustainable yield and precautionary advice frameworks. An Operating Model was conditioned on life-history theory and strategic information from ecosystem models. We showed that in-year advice using an empirical rule could achieve management objectives and help balance the trade-offs between fishing activities and ecosystem health. The approach allows ecosystem understanding to be incorporated within existing precautionary and maximum sustainable yield frameworks to provide a robust management framework that can meet multiple objectives despite uncertainty.
A systemic approach to analyzing post-collapse adaptations in the Bay of Biscay anchovy fishery
(Canadian Science Publishing, 2024-03-11) Beckensteiner, Jennifer; Villasante, Sebastian; Charles, Anthony; Petitgas, Pierre; Le Grand, Christelle; Thebaud, Olivier
The Bay of Biscay anchovy fishery system has undergone important transformations following a closure from 2005 to 2010. Through a multidisciplinary and systemic approach, combining analyses of fisheries and market data with interviews with key stakeholders, we analyze adaptive responses of the main system components in France and Spain, considering how the fishing sector and fishery management institutions have adapted to changes. Focusing on the question “what has been lost and gained following the collapse?”, we find that while the anchovy stock has recovered, the fishery system has not returned to its pre-collapse status with important socio-economic features having been lost. We highlight the need for holistic consideration of multiple system components and diverse stakeholders’ perspectives. The perceived losses and gains from the anchovy fishery collapse and aftermath are found to vary across the players in the fishery system, depending as well on the management objectives and scales being considered. Such retrospective analysis can serve as a basis for understanding the long-term responses to social-ecological changes in fisheries, and identifying the role of governance mechanisms in supporting adaptations that maintain sustainable fishery systems in the face of future potential shocks.
Effects of temperature, body size, and sex on the standard metabolic rates of a sexually dimorphic freshwater piscivore, walleye (Sander vitreus)
(Canadian Science Publishing, 2024-03-04) Bihun, Christian Joseph; Murphy, Megan K.; Johnson, Timothy B.; Fisk, Aaron T; Guzzo, Matthew M; Madenjian, Charles P; Raby, Graham
Walleye (Sander vitreus) are a sexually dimorphic freshwater piscivore that have long been studied using bioenergetics modeling, yet robust estimates of metabolic rates for use in those models have been lacking. Therefore, we quantified the effects of body mass, water temperature, and sex, on standard metabolic rate (SMR). We estimated SMR across temperatures ranging 0.5-24 °C using intermittent-flow respirometry for male (n = 54) and female (n = 53) walleye raised in hatchery conditions. We found a significant interaction between sex and temperature, whereby males had lower SMR below 16 °C, but increased such that SMR was ~16% higher than females at 22 °C. The mass-scaling coefficient, b, was similar for both sexes at a value around 1. These estimates of metabolic rate are the first to be generated using respirometry for adult walleye and differ slightly from those being used by previous bioenergetics models, which may have underestimated the energetic costs of SMR, and did not include sex-specific estimates for metabolism.
Effects of temperature, body size, and sex on the standard metabolic rates of a sexually dimorphic freshwater piscivore, walleye (Sander vitreus)
(Canadian Science Publishing, 2024-03-04) Bihun, Christian Joseph; Murphy, Megan K.; Johnson, Timothy B.; Fisk, Aaron T; Guzzo, Matthew M; Madenjian, Charles P; Raby, Graham
Walleye (Sander vitreus) are a sexually dimorphic freshwater piscivore that have long been studied using bioenergetics modeling, yet robust estimates of metabolic rates for use in those models have been lacking. Therefore, we quantified the effects of body mass, water temperature, and sex, on standard metabolic rate (SMR). We estimated SMR across temperatures ranging 0.5-24 °C using intermittent-flow respirometry for male (n = 54) and female (n = 53) walleye raised in hatchery conditions. We found a significant interaction between sex and temperature, whereby males had lower SMR below 16 °C, but increased such that SMR was ~16% higher than females at 22 °C. The mass-scaling coefficient, b, was similar for both sexes at a value around 1. These estimates of metabolic rate are the first to be generated using respirometry for adult walleye and differ slightly from those being used by previous bioenergetics models, which may have underestimated the energetic costs of SMR, and did not include sex-specific estimates for metabolism.
Stable isotope analysis provides novel insights for measuring lake ecosystem recovery following acidification
(Canadian Science Publishing, 2024-04-02) Dawson, Jade; Guzzo, Matthew M; Gunn, John M; Emilson, Erik J.S.; McCann, Kevin S.; Edwards, Brie
Unstable and simplified freshwater food webs impair the resilience of Canadian fisheries facing environmental stressors. This study utilizes stable isotope analyses to assess trophic recovery to explore food web resiliency in lakes historically impacted by metal mining in Sudbury, Ontario. Carbon (δ 13C) and nitrogen (δ 15N) stable isotope ratios were quantified in yellow perch (Perca flavescens), smallmouth bass (Micropterus dolomieu), and baseline organisms to develop quantitative population metrics and describe dietary niche partitioning. The most severely damaged lake with a barren watershed had the lowest trophic positioning, smallest body size and niche area, and greatest niche overlap among fish species. Semi-barren and forested watershed lakes were more similar to reference lakes in isotopic metrics; however elevated niche overlap and reduced trophic positioning suggests recovery in these lakes is ongoing. We found that including stable isotope analyses in lake recovery studies provided critical insights not captured by traditional biomonitoring approaches.
Estimating spawning Green Sturgeon (Acipenser medirostris Ayres, 1854) abundance in the Sacramento River using side-scan sonar and N-mixture models
(Canadian Science Publishing, 2024-04-07) Battaile, Brian Charles; Mora, Ethan A.; Lehman, Brendan; Dudley, Peter N
Current estimates of the threatened southern distinct population segment of the North American Green Sturgeon (Acipenser medirostris) combine a plot-sampling density estimator with DIDSON and ARIS sonar data. From 2020 to 2022, we annually collected images of all known Green Sturgeon aggregations and compared the established method to an N-mixture model using side-scan sonar images. We compared 18 different N-mixture model combinations and chose an overdispersed Poisson model that produced estimated abundances of 742, 1286 and 1208 for 2020-2022 respectively. These numbers are ~2 times greater than the previous method and if sustained, would fulfill a key criterion for Green Sturgeon recovery. N-mixture models are known to be sensitive to violations of assumptions, such as the highly dispersed data from our study that caused serious issues, and we recommend practitioners make judicious use of overdispersion and goodness of fit tests and to be able to identify parameter confounding between detectability and abundance estimates. For our Green Sturgeon, we recommend simpler population estimates, and to focus future energy on reducing variability in the data collection process.

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