Geology topics

David C. Caroffino

Publications and source records attributed to David C. Caroffino.

4 recordsLinked to original sources

USGS2024

Comparing conventional tagging methods and acoustic telemetry to inform management of Lake Whitefish in Lake Michigan

Objective Studies of fish movement using conventional tags or acoustic telemetry have different benefits and biases that can influence how conclusions are used in a management context. Our objective was to determine whether these two methods provided similar inferences regarding movements and spawning site fidelity of Lake Whitefish Coregonus clupeaformis in Lake Michigan. Additionally, we assessed movement patterns and used telemetry to assess residency time of Lake Whitefish to provide managers with information on which stocks might be exposed to harvest in different regions. Methods Lake Whitefish were tagged during spawning in (1) North and Moonlight bays, (2) Big Bay de Noc, (3) the Menominee River, and (4) the Fox River. Proportions of fish moving between southern Green Bay, northern Green Bay, and Lake Michigan were compared between tag types. Spawning site fidelity was estimated for each tagging site. Seasonal residency indices were calculated using acoustic telemetry detections. Result Estimates differed between the two methods, but overall trends were similar. Fox River fish rarely left southern Green Bay, and fish tagged in North and Moonlight bays rarely entered Green Bay (<10% of individuals). Big Bay de Noc and Menominee River fish moved into other regions more often (>50% of individuals). The residency indices indicated that Big Bay de Noc fish spent most of their time in Lake Michigan while Menominee River fish spent little time in northern Green Bay despite transitioning to the region. Compared to telemetry, conventional tag recoveries underestimated the proportion of individuals moving among regions. Spawning site fidelity estimates (28–100%) varied among tagging groups and between methods. Conclusion Our results suggest that data from conventional tags can inform management at broad geographic scales. However, acoustic telemetry can provide fine-scale information. Information gained from telemetry can be useful in understanding exposure to fishing mortality, which may be valuable for informing management decisions.

Lake Michigan↗

USGS2022

High-density genomic data reveal fine-scale population structure and pronounced islands of adaptive divergence in lake whitefish (Coregonus clupeaformis) from Lake Michigan

Understanding patterns of genetic structure and adaptive variation in natural populations is crucial for informing conservation and management. Past genetic research using 11 microsatellite loci identified six genetic stocks of lake whitefish ( Coregonus clupeaformis ) within Lake Michigan, USA. However, ambiguity in genetic stock assignments suggested those neutral microsatellite markers did not provide adequate power for delineating lake whitefish stocks in this system, prompting calls for a genomics approach to investigate stock structure. Here, we generated a dense genomic dataset to characterize population structure and investigate patterns of neutral and adaptive genetic diversity among lake whitefish populations in Lake Michigan. Using Rapture sequencing, we genotyped 829 individuals collected from 17 baseline populations at 197,588 SNP markers after quality filtering. Although the overall pattern of genetic structure was similar to the previous microsatellite study, our genomic data provided several novel insights. Our results indicated a large genetic break between the northwestern and eastern sides of Lake Michigan, and we found a much greater level of population structure on the eastern side compared to the northwestern side. Collectively, we observed five genomic islands of adaptive divergence on five different chromosomes. Each island displayed a different pattern of population structure, suggesting that combinations of genotypes at these adaptive regions are facilitating local adaptation to spatially heterogenous selection pressures. Additionally, we identified a large linkage disequilibrium block of ~8.5 Mb on chromosome 20 that is suggestive of a putative inversion but with a low frequency of the minor haplotype. Our study provides a comprehensive assessment of population structure and adaptive variation that can help inform the management of Lake Michigan's lake whitefish fishery and highlights the utility of incorporating adaptive loci into fisheries management.

Michigan, Wisconsin↗

USGS2020

Defining the need for genetic stock assignment when describing stock demographics and dynamics: An example using Lake Whitefish in Lake Michigan

Genetic stock assignment is not routinely used when describing the dynamics and demographics of individual stocks supporting mixed-stock fisheries, and capture location and timing are often used as alternative assignment methods. However, variation in stock demographics and dynamics may not be accounted for if stock assignments based on capture location or timing do not accurately reflect genetic assignments. We used Lake Whitefish Coregonus clupeaformis in Lake Michigan as a model fishery to determine whether stock mixing could undermine efforts to describe stock status when using October capture location as a proxy for genetic stock assignment. Accuracy of stock assignments based on October capture location ranged from 54% to 100% among management zones. Metrics describing length and age distributions, weight at length, fecundity, and growth varied among genetic stocks. Stock-specific metrics were typically similar between stock assignment methods (capture location versus genetics) because only one or two genetic stocks were collected in most locations and the majority of those fish were from spatially proximal stocks with similar metrics. However, more extensive mixing of Lake Whitefish stocks has been documented; thus, using capture location for stock assignment could result in incorrect conclusions regarding stock status and harvest management depending on stock composition. Ambiguity in genetic stock assignments was a problem in two management zones, where between 23% and 42% of Lake Whitefish did not assign to a specific stock with a probability of at least 0.70. In the future, using genomic techniques rather than microsatellites may provide different conclusions regarding genetic stock structure; these differences could affect the accuracy of using capture location for stock assignment. Use of capture location as a proxy for genetic stock assignment may not be warranted for all mixed-stock fisheries but may be appropriate when stock mixing is limited or is restricted to stocks with consistently similar characteristics.

Michigan, Wisconsin↗

USGS2017

Asynchrony in the inter-annual recruitment of lake whitefish Coregonus clupeaformis in the Great Lakes region

Spatially separated fish populations may display synchrony in annual recruitment if the factors that drive recruitment success, particularly abiotic factors such as temperature, are synchronised across broad spatial scales. We examined inter-annual variation in recruitment among lake whitefish ( Coregonus clupeaformis ) populations in lakes Huron, Michigan and Superior using fishery-dependent and -independent data from 1971 to 2014. Relative year-class strength (RYCS) was calculated from catch-curve residuals for each year class across multiple sampling years. Pairwise comparison of RYCS among datasets revealed no significant associations either within or between lakes, suggesting that recruitment of lake whitefish is spatially asynchronous. There was no consistent correlation between pairwise agreement and the distance between datasets, and models to estimate the spatial scale of recruitment synchrony did not fit well to these data. This suggests that inter-annual recruitment variation of lake whitefish is asynchronous across broad spatial scales in the Great Lakes. While our method primarily evaluated year-to-year recruitment variation, it is plausible that recruitment of lake whitefish varies at coarser temporal scales (e.g. decadal). Nonetheless, our findings differ from research on some other Coregonus species and suggest that local biotic or density-dependent factors may contribute strongly to lake whitefish recruitment rather than inter-annual variability in broad-scale abiotic factors.

Great Lakes↗