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Jory L. Jonas

Publications and source records attributed to Jory L. Jonas.

8 recordsLinked to original sources
USGS2024

Synthesizing professional opinion of Lake Whitefish and Cisco recruitment drivers across the Great Lakes

Disentangling the suite of ecological drivers that explain recruitment variability for Lake Whitefish Coregonus clupeaformis and Cisco C. artedi is of critical importance for their conservation, management, and stewardship in the Laurentian Great Lakes. However, recruitment is inherently variable and can be regulated by many interacting processes, the relative importance of which can vary spatially, temporally, and ontogenetically. Given this complexity, comparisons across lakes and species that identify overarching hypotheses could efficiently guide future research. Using facilitated deliberations among fishery professionals (n = 57) with expertise in Great Lakes Coregonus spp., we synthesized current knowledge regarding (1) which biophysical processes are most important for driving contemporary recruitment between species, among lakes, and across life stages and (2) mechanisms by which those drivers regulate recruitment at key life stages. Participants affirmed the hypothesis that many drivers interact in complex ways to regulate Lake Whitefish and Cisco recruitment. Large-scale climatic processes affecting early life-stage growth and survival were consistently considered important. Other drivers were only deemed influential in certain lakes, highlighting perceived context-dependent recruitment dynamics. Notably, recruitment in Lakes Superior, Michigan, and Huron was considered limited during larval and early juvenile life stages by low productivity, whereas spawning-habitat degradation and reduced metapopulation diversity were hypothesized to limit recruitment during embryonic and larval stages in Lakes Erie and Ontario. Several drivers were hypothesized to similarly impact Lake Whitefish and Cisco during early life stages, while drivers acting on post-larval life stages were typically distinct between species. The hypotheses synthesized herein can guide future research on Lake Whitefish and Cisco recruitment dynamics in the Great Lakes.

Great Lakes↗
USGS2024

Spatial distribution and diet of Lake Michigan juvenile lake trout

Most studies of Lake Michigan lake trout ( Salvelinus namaycush ) have focused on adults, with scant attention to juveniles (<400 mm). We explored the spatial distribution and diet of juvenile lake trout using U.S. Geological Survey September bottom trawl data (2015–2022) and stomach content information opportunistically collected since 2012 by various agencies using multiple gear types. Most juvenile lake trout in the September bottom trawl survey were caught at 37–64 m bottom depths. Length frequency data from the bottom trawl survey identified three size classes likely associated with wild juvenile lake trout age: < 85 mm (∼age-0), 85–170 mm (∼age-1) and > 170 mm (∼age-2+). Largest catches of wild lake trout < 170 mm occurred along a northeastern transect (near Frankfort, Michigan), whereas most > 170 mm were collected along southern transects. Mysis diluviana was the dominant prey for juvenile lake trout < 170 mm, and > 250 mm were primarily piscivorous, while 170–250 mm appeared to be a transitional period of switching from Mysis to fish. Species composition of prey fishes consumed by lake trout varied spatially and we found evidence of seasonal and annual diet variation within Grand Traverse Bay. Diporeia , once an important component of juvenile lake trout diet, appears to no longer be consumed by juvenile lake trout in Lake Michigan to any measurable degree. Continued research on the ecology of juvenile lake trout may provide insight into the effects of a changing ecosystem on juvenile lake trout diet and growth, thereby contributing to the effort to rehabilitate the Lake Michigan lake trout population.

Lake Michigan↗
USGS2023

Estimates of adult Lake Trout mortality from coded wire tags in a population with developing natural reproduction in southern Lake Michigan

Objective Overfishing and Sea Lamprey Petromyzon marinus predation led to extirpation of Lake Trout Salvelinus namaycush from Lake Michigan in the 1950s. Large populations of hatchery‐reared fish were developed by the 1970s, but natural reproduction was limited until the early 2000s when it began to increase in the southern main basin. Hypothesizing that the relatively low mortality of spawning‐aged fish contributed to this reproductive success, we estimated the total annual mortality rate for this population. Methods We used catch curves to estimate the total instantaneous mortality rate Z using coded wire tags, which provided definitive ages. We made separate estimates from fish collected in three on‐going surveys: a spring gill‐net survey, a fall gill‐net spawning survey, and a sport fishery survey. Result Our estimates of Z ± SE were 0.297 ± 0.019, 0.239 ± 0.009, and 0.205 ± 0.007 for the spring, spawning, and sport fishery surveys, respectively. We suggest that the mean Z ± SE of all survey estimates of 0.247 ± 0.027 would be a reasonable estimate for this population, which equates to a total annual mortality of 22 ± 3%. This estimate is in the low range of rates reported for the species and is in the same range as other populations in the Great Lakes with well‐established natural reproduction. Conclusion We concluded that these low total mortality rates contributed to the reproductive success in southern Lake Michigan through increasing spawning stock density and age structure and that previous estimates of another important population parameter, the instantaneous natural mortality rate M , were too high. Estimates of M ranged from 0.210 to 0.240 and were based on the Pauly equation, a growth‐ and temperature‐based estimator. We suggest maximum‐age‐based estimators of M are more appropriate for Lake Trout. Several alternative maximum‐age‐based estimators produced estimates for M of 0.132–0.058, all of which are more compatible with our estimate of Z .

Lake Michigan↗
USGS2021

Diversity in spawning habitat use among Great Lakes Cisco populations

Cisco ( Coregonus artedi ) once dominated fish communities in the Laurentian Great Lakes. Restoring the abundance and distribution of this species has emerged as a management priority, yet our understanding of Cisco spawning habitat use is insufficient to characterise habitat needs for these populations and assess whether availability of suitable spawning habitat could be a constraint to recovery. We characterised the distribution of incubating Cisco eggs in situ across gradients of depth and substrate types to describe the spawning habitat used by three Great Lakes populations. In Chaumont Bay, Lake Ontario, eggs were concentrated on shallow bedrock shoals and not found on deeper silt or sand substrate. In contrast, eggs in Thunder Bay, Lake Superior, and Elk Rapids, Lake Michigan, were found on deeper fine grain sediments with low utilisation of shallow rocky and cobble habitats. These patterns of egg incubation habitat use suggest a broad spawning habitat niche at the species level but distinct spawning habitat preferences at the population level. While our results indicate some historical diversity in spawning habitat use has been maintained across the species’ range in the Great Lakes, comparisons of contemporary spawning habitat utilisation against historical accounts raise questions as to whether some spawning habitat use behaviours may no longer be prevalent within specific lakes. Thus, characterising the portfolio of spawning strategies remaining within lakes may improve our understanding of habitat needs and identify opportunities to maintain population diversity while supporting Cisco rehabilitation.

Michigan, New York↗
USGS2020

Piscivory in recovering Lake Michigan Cisco (Coregonus artedi): The role of invasive species

Contemporary conditions in Lake Michigan where cisco ( Coregonus artedi ) populations are expanding are vastly different from those encountered by the historic fish community. Invasive species introductions have substantially altered the Lake Michigan ecosystem in the last half century. Successful management efforts for cisco in Lake Michigan hinge on our ability to understand their contemporary ecology, especially diet. We collected 725 cisco stomachs opportunistically from commercial fisheries (2%) and in agency surveys (98%) over six years (2014–2019). The majority (70%) of stomachs were from East Grand Traverse Bay and 96% of these were collected at Elk Rapids. Additional samples were collected from Charlevoix (8%), Little Traverse Bay (11%), other sites in northern Lake Michigan (4%), Central Lake Michigan (6%), and Green Bay (1%). Our results indicated a high degree of piscivory, in contrast to historical and contemporary accounts of planktivory for cisco in the other Laurentian Great Lakes. The top three prey items by mass were not native to the Great Lakes and these accounted for 87% of all observed prey mass consumed: round goby ( Neogobius melanostomus) (58%), Bythotrephes longimanus (15%), and alewife ( Alosa pseudoharengus) (14%). Round goby dominated the prey in the spring and summer, while B. longimanus and alewife occurred more in summer and fall diets. The contemporary population of cisco in Lake Michigan has been able to uniquely capitalize on abundant invasive prey resources, which may be less limiting and more energy-rich than a more typical planktivorous cisco diet.

Lake Michigan↗
USGS2019

Factors affecting post-release survival of coded-wire tagged Lake Trout Salvelinus namaycush in Lake Michigan at four historical spawning locations

Since the 1950s, fishery agencies on Lake Michigan have pursued Lake Trout Salvelinus namaycush rehabilitation through Sea Lamprey Petromyzon marinus control, harvest regulations, and by stocking millions of fish annually. Stocking was prioritized at four historically important spawning locations beginning in 1985, and coded wire tags (CWTs) were used to help evaluate performance. We used data from CWT fish captured in fishery-independent surveys from 1998 – 2014 to evaluate relative post-release survival of Lake Trout, estimated by catch-per-unit-effort and corrected for the number of fish stocked (CPUE), across 173 CWT tag lots of the 1994 – 2003 year classes stocked at these four locations. Boosted regression tree (BRT) models were used to assess the relative influence of four variables on Lake Trout CPUE in two age groups (age 4-5 years and 6-10 years) and paired with analyses of variance to test for statistical significance. Genetic strain (29.1%), stocking location (27.8%), mortality at release (23.1%) and predator density (19.9%) had similar influence on the relative survival of younger fish, whereas relative survival of older fish was heavily influenced by stocking location (79.8%). Survival of both age groups was lowest for fish stocked in the Northern Refuge, where the age structure was truncated due to fishery harvest and Sea Lamprey predation. Survival of stocked fish was higher at the Southern Refuge, Clay Banks, and Julian’s Reef, where mortality from sea lamprey and harvest was lower, and where increases in wild Lake Trout have been observed in recent years. Stocked Lake Michigan remnant genetic strains also appeared to survive better than strains from other lakes at these three locations, but strain effects could not be fully disentangled from effects of stocking location, and continued stocking of multiple genetic strains may provide resiliency toward future selection pressures. Continued progress toward rehabilitation will require reducing fishing and lamprey-induced mortality in northern Lake Michigan to build parental stocks of advanced ages as well as balancing efforts among competing management goals.

Lake Michigan↗
USGS2019

Resurgence of cisco (Coregonus artedi) population levels in Lake Michigan

In recent decades, many factors that were linked with the decline of Great Lakes cisco ( Coregonus artedi ) populations have subsided. The goal of this study was to investigate where cisco exist in Lake Michigan and evaluate evidence for recovery including when, where, and to what extent it is occurring. We evaluated datasets from several independent monitoring efforts that did and did not target cisco. We also evaluated trends in commercial and recreational catches of cisco. Across these datasets, there was strong evidence of a sustained recovery of cisco stocks that began in Lake Michigan in the mid-2000s. Fall gill net surveys and commercial fisheries provided reasonable indications of a population recovery in the northeast by 2011. Further south, Ludington Pump Storage barrier net monitoring also recorded increasing numbers of cisco starting in 2011. Recreational harvest estimates were valuable in evaluating spatial distributions but were less valuable as an early signal of abundance shifts. Measures of the recreational harvest of cisco most notably increased in 2014. The highest catch rates and harvest occurred in Grand Traverse Bay and northern Lake Michigan as evidenced by recreational, commercial, and fall netting surveys. Observations of cisco are expanding and have increased in intensity along the eastern shore of Lake Michigan south to Muskegon in both fishery dependent and independent surveys. The similarity in trends from all data sources indicate that cisco abundance has increased, and their range within the basin continues to expand.

Michigan↗