Geology topics

Scott P. Minihkeim

Publications and source records attributed to Scott P. Minihkeim.

14 recordsLinked to original sources

USGS2025

Lake Ontario August gillnet survey and Lake Trout assessment, 2024

Lake Ontario Lake Trout ( Salvelinus namaycush ) rehabilitation has been assessed with fishery independent surveys to evaluate program benchmarks and compare observations with management objectives since 1983. These surveys provide information on the abundance, strain composition, and performance of stocked Lake Trout, as well as information on levels of natural recruitment, and Sea Lamprey ( Petromyzon marinus ) wounding rates. In 2024, the gillnet survey occurred in United States (US) and Canadian waters marking the first lake-wide Lake Trout assessment since 2008. Lake Trout catch per unit effort (CPUE) was higher in US than Canadian waters. Recaptures of stocked fish with coded wire tags occurred mostly in US waters, and were composed of the following strains: Lake Champlain, Seneca Lake, Superior Klondike Reef, and Huron Parry Sound. Percentage of naturally produced Lake Trout in US waters continued to be relatively low for mature and immature fish. Interestingly, the percentage of naturally produced Lake Trout was higher in Canadian waters, despite lower total numbers of Lake Trout caught. Sea Lamprey wounding rates on Lake Trout > 432 mm in 2024 were above management targets in US and Canadian waters. Overall, the 2024 survey results suggest that Lake Trout indicators continue to meet some of the management objectives and show spatial differences in overall abundance and the proportion of stocked vs wild fish between the US and Canadian stocks.

Lake Ontario↗

USGS2024

Lake Ontario August gillnet survey and Lake Trout assessment, 2023

Lake Ontario lake trout ( Salvelinus namaycush ) rehabilitation has been annually assessed with fishery independent surveys since 1983, to evaluate program benchmarks and compare observations with management objectives. These surveys provide information on the abundance, strain composition, and condition of the adult lake trout stock, as well as information on levels of natural recruitment, sea lamprey ( Petromyzon marinus ) wounding rates, and abundance indices of other coldwater fish species (burbot Lota lota , cisco C oregonus artedi , and lake whitefish C. clupeaformis ). In 2023, the catch per unit effort (CPUE) of total lake trout in gillnets was notably lower (12.1 fish/net) compared to recent survey years 2018–2022 (average = 17.3 ± 1.0 SD fish/net). CPUE of mature females fell below target levels. Wildproduced mature lake trout remain rare in the adult population (1.0% of adult catch). Strain composition of stocked fish indicated approximately half (51%) of all coded wire tagged lake trout captured in 2023 were from the Superior Klondike strain. Sea lamprey wounding rates decreased in 2023 and were near the target level (2.09 A1 wounds per 100 lake trout). Lake trout condition (predicted weight at length) remains high. Overall, the 2023 survey results suggest that lake trout indicators continue to meet some of the management objectives, however, recruitment of wild-produced offspring to the adult stock continues to be limited, and abundance of stocked fish may be decreasing relative to recent years in response to reduced stocking levels.

Lake Ontario↗

USGS2024

Bottom trawl assessment of Lake Ontario's benthic preyfish community, 2023

Since 1978, surveys of Lake Ontario preyfish communities have provided information on the status and trends of the benthic preyfish community related to Fish Community Objectives that includes understanding preyfish population dynamics and community diversity. Beginning in 2015, the benthic preyfish survey expanded from US-only to incorporate Canadian sites, increasing the survey’s spatial coverage to a lake-wide scale. Additionally, sampling in eastern US embayments (Black River, Chaumont, Guffin, and Henderson Bays), that were historically sampled during a September bottom trawl survey to index Yellow Perch (Perca flavescens; 1978–2007), resumed in 2015. The current survey provides abundance indices for sculpins, Round Goby (Neogobius melanostomus) and Bloater (Coregonus hoyi) with survey techniques, gear and timing comparable to Lake Michigan. This alignment provides a necessary biological reference point for measuring the success of Lake Ontario Bloater reintroduction. In 2023, the collaborative benthic preyfish survey completed 188 bottom trawl tows across main lake and embayment sites at depths from 6 to 249 m. In total, the 2023 survey sampled 85,801 fish from 38 species. Round Goby was the most common species comprising 43% of the total catch, followed by Deepwater Sculpin (Myoxocephalus thompsonii), and Alewife (Alosa pseudoharengus) at 22% and 13%, respectively. Slimy Sculpin (Cottus cognatus) lake-wide biomass density (0.06 kg/ha) remained low relative to historical observations from US waters during the 1980-1990s and was orders of magnitude lower in US than Canadian waters. Lake-wide Deepwater Sculpin biomass density remains high since the population recovery (4.1 kg/ha). Embayment catches continue to have unique species assemblages compared to main lake habitat. Historically common native benthic preyfish species like Trout-perch (Percopsis omiscomaycus), Spottail Shiner (Notropis hudsonius), and darters (Etheostoma spp.), that are now rare at main lake trawl sites, still occur in some embayment trawl sites.

Lake Ontario↗

USGS2024

Lake Ontario April prey fish survey results and Alewife assessment, 2024

The Lake Ontario April bottom trawl survey assesses pelagic prey fish populations, in particular Alewife Alosa pseudoharengus , which are the primary prey supporting the lake’s sport fish populations. The 2024 survey included 234 trawls in the main lake and embayments and sampled depths from 3.9 to 245 m (13 – 809 ft). The survey captured 441,942 fish from 28 species with a total weight of 10,519 kg (23,142 lbs.). Alewife were 89% of the total catch by number while Deepwater Sculpin Myoxocephalus thompsonii , Round Goby Neogobius melanostomus , and Rainbow Smelt Osmerus mordax , comprised 4%, 3%, and 2% of the catch respectively. The estimated Alewife biomass increases slightly from 2023 to 2024 (83.9 to 84.2 kg·ha-1) and was the largest biomass value since whole lake sampling began in 2016. Adult Alewife abundance increased in 2024 as predicted in 2023, and most of the total Alewife biomass was comprised of adult fish (97%), predominantly from the 2020 and 2022 year classes. In contrast, Age-1 Alewife biomass (2.2 kg·ha-1) was the lowest estimated since whole lake sampling began in 2016 (previous range: 2.7 – 26.7 kg·ha-1), indicating reproductive success was poor in 2023. Adult Alewife biomass is predicted to remain relatively high but decline slightly in 2025 and 2026, due to the smaller year classes produced in 2021 and 2023. Alewife condition as measured by the weight of a standard length fish (165 mm; ~6.5 inches), was 32.8 g, which was within of the range of previously observed values (28.0 – 35.9 g, 1997 – 2023). Acoustic-based prey fish densities, in the water above the bottom trawl, were similar to observations from 2021 – 2023 and were orders of magnitude lower than bottom trawl densities. These acoustic results support the seasonal timing of the April survey, when the majority of Alewife and other pelagic prey fishes are near the lake bottom and susceptible to capture with bottom trawls. The trawl survey also provides information on the status of other pelagic prey fishes and native fish restorations. In 2024, biomass indices for Rainbow Smelt, Emerald Shiner Notropis atherinoides , and Threespine Stickleback Gasterosteus aculeatus , were similar to 2023 values while the index for Cisco Coregonus artedi declined. The density index for naturally reproduced, juvenile Lake Trout Salvelinus namaycush declined relative to 2023. Density estimates of Lake Whitefish Coregonus clupeaformis continue to be orders of magnitude lower in U.S. waters relative to Canadian waters. A single purported Bloater Coregonus hoyi (total length = 148 mm, sampling depth = 105 m) was captured near Rochester, NY during the 2024 survey. This is the eighth Bloater recaptured during this survey since restoration stocking began in 2012.

Lake Ontario↗

USGS2023

Bottom trawl assessment of Lake Ontario's benthic preyfish community, 2022

Since 1978, surveys of Lake Ontario preyfish communities have provided information on the status and trends of the benthic preyfish community related to Fish Community Objectives that includes understanding preyfish population dynamics and community diversity. Beginning in 2015, the benthic preyfish survey expanded from US-only to incorporate Canadian sites, increasing the survey’s spatial coverage to a lake-wide scale. Additionally, sampling in eastern US embayments (Black River, Chaumont, Guffin, and Henderson Bays), that were historically sampled during a September bottom trawl survey to index Yellow Perch ( Perca flavescens ; 1978–2007), resumed in 2015. The current survey provides abundance indices for sculpins, Round Goby ( Neogobius melanostomus ) and Bloater ( Coregonus hoyi ) with survey techniques, gear and timing comparable to Lake Michigan. This alignment provides a necessary biological reference point for measuring the success of Lake Ontario Bloater reintroduction. In 2022, the collaborative benthic preyfish survey completed 171 bottom trawl tows across main lake and embayment sites at depths from 6 to 222 m. In total, the 2022 survey sampled 141,552 fish from 34 species. Round Goby was the most numerically abundant species comprising 36% of the total catch, followed by Alewife ( Alosa pseudoharengus ) and Deepwater Sculpin ( Myoxocephalus thompsonii ), at 20% and 16%, respectively. Alewife accounted for most (623 kg) of the fish biomass sampled during the 2022 survey (total=2,197 kg), followed by Deepwater Sculpin (547 kg), and Round Goby (262 kg). Slimy Sculpin ( Cottus cognatus ) lake-wide biomass density (0.03 kg/ha) remained low relative to historical observations from US waters during the 1980-1990s and was similar to the average from the previous three survey years (2019-2021 average 0.04 ± 0.02 kg/ha). Lake-wide Deepwater Sculpin biomass density reached a new high (4.4 kg/ha) in 2022. Embayment catches continue to have unique species assemblages compared to main lake habitat. Historically common native benthic preyfish species like Trout-perch ( Percopsis omiscomaycus ), Spottail Shiner ( Notropis hudsonius ), and darters ( Etheostoma spp.), that are now rare at main lake trawl sites, still occur in some embayment trawl sites.

Lake Ontario↗

USGS2023

Lake Ontario August gillnet survey and Lake Trout assessment, 2022

Lake Ontario Lake Trout (Salvelinus namaycush) rehabilitation has been annually assessed with fishery independent surveys since 1983, in an effort to evaluate program benchmarks and compare observations with management objectives. These surveys provide information on the abundance, strain composition, and condition of the adult Lake Trout stock, as well as information on levels of natural recruitment, Sea Lamprey (Petromyzon marinus) wounding rates, and abundance indices of other coldwater fish species (Burbot Lota lota, Cisco Coregonus artedi, and Lake Whitefish C. clupeaformis). In 2022, the catch per unit effort (CPUE) of total Lake Trout in gillnets remained high (18.9 fish/lift; highest since 1998) compared to lows observed during 2005–2009 (average = 7.5 fish/lift). The CPUE of immature Lake Trout in the 2022 survey was the highest since 1994. Wild-produced mature Lake Trout remain rare in the adult population (2.4% of adult catch). Strain composition of stocked fish indicated more than half (56%) of all coded-wire tagged Lake Trout captured in 2022 were from the Superior Klondike strain. Sea Lamprey wounding rates were above target levels in 2022 (3.15 A1 wounds per 100 Lake Trout) and were nearly double the 2021 rate. Lake Trout condition (predicted weight at length) was the highest since data collection began in 1983. Overall, the 2022 survey results indicate that adult Lake Trout are abundant and of high condition but composed mostly of hatchery-origin strains, suggesting recruitment of wild-produced offspring to the adult stock continues to be limited.

Lake Ontario↗

USGS2023

Lake Ontario April prey fish survey results and Alewife assessment, 2023

The April bottom trawl survey and Alewife Alosa pseudoharengus population assessment provides science to inform Lake Ontario fisheries management. The 2023 survey included 215 trawls in the main lake and embayments, and sampled depths from 6.5 to 252 m (21-833 ft). The survey captured 1,012,178 fish from 32 species with a total weight of 12,136 kg (26,700 lbs.). Alewife were 92% of the catch by number while Rainbow Smelt, Osmerus mordax , Deepwater Sculpin, Myoxocephalus thompsonii , and Round Goby, Neogobius melanostomus , comprised 3%, 3%, and 1% of the catch, respectively. To improve the accuracy of prey fish biomass and density estimates we reanalyzed trawl sensor data from each of three participating survey vessels and created vessel-specific relationships predicting how bottom trawl bottom contact time, wing width, and area-swept varies with depth. Total Alewife biomass increased in 2023 due to growth and survival of the abundant 2020 year class (now age-3) and an abundant 2022 year class (age-1). The 2023 mean Alewife biomass (81.1 kg·ha -1 ) was the largest since whole lake sampling began in 2016 and was the ninth largest value observed in the modern time series (1997-2023, maximum value in 2000 = 91.8 kg·ha -1 ). The 2023 Alewife density (6795 n·ha -1 ) was the greatest density observed in the modern time series. These high biomass and density values are due to above average Alewife reproductive success in 2020 and 2022. Simulation modeling suggests the 2024 and 2025 Alewife biomass index may be substantially higher than the 2023 observations. In 2023, the Rainbow Smelt biomass index increased relative to the 2022 index, as did the biomass index for Cisco, Coregonus artedi . In contrast, Emerald Shiner Notropis atherinoides and Threespine Stickleback Gasterosteus aculeatus , biomass values continue to be low (< 0.01 kg·ha -1 ). Three Bloater Coregonus hoyi , were captured during the 2023 survey. Hydroacoustic sampling conducted during the bottom trawl survey estimated prey fish densities in pelagic habitats not sampled by the bottom trawl (3 m below the surface to 3 m above the lake bottom) and these densities were hundreds to thousands of times lower than bottom trawl-based densities. These results support the idea that, in April, when the warmest water is on the lake bottom, Alewife and most other pelagic prey fish are near the lake bottom and can be effectively sampled with bottom trawling.

Lake Ontario↗

USGS2022

Results of the collaborative Lake Ontario bloater restoration stocking and assessment, 2012–2020

Bloater, Coregonus hoyi , are deepwater planktivores native to the Laurentian Great Lakes and Lake Nipigon. Interpretations of commercial fishery time series suggest they were common in Lake Ontario through the early 1900s but by the 1950s were no longer captured by commercial fishers. Annual bottom trawl surveys that began in 1978 and sampled extensively across putative bloater habitat only yielded one individual (1983), suggesting that the species had been locally extirpated. In 2012, a multiagency restoration program stocked bloater into Lake Ontario from gametes collected in Lake Michigan. From 2012 to 2020, 1,028,191 bloater were stocked into Lake Ontario. Bottom trawl surveys first detected stocked fish in 2015, and through 2020 ten bloater have been caught (total length mean = 129 mm, s.d. = 44 mm, range: 96–240 mm). Hatchery applied marks and genetic analyses confirmed the species identification and identified stocking location for some individuals. Trawl capture locations and acoustic telemetry suggested that stocked fish dispersed throughout the main lake within months or sooner, and the depth distribution of recaptured bloater was similar to historic distributions in Lake Ontario and other Great Lakes. Predicted bloater trawl catches, based on modeled population abundance and trawl survey efficiency, were similar to observed catches, suggesting that post-stocking survival is less than 20% and contemporary bottom trawl surveys can quantify bloater abundance at low densities and track restoration.

Lake Ontario↗

USGS2022

Lake Ontario April prey fish survey results and Alewife assessment, 2022

The annual Lake Ontario April bottom trawl survey and Alewife, Alosa pseudoharengus , population assessment provide science to inform management decisions related to predator-prey balance and fish community dynamics. The 2022 survey was conducted from March 31 to April 26, included 235 trawls in the main lake and embayments, and sampled depths from 5 to 219 m (16 – 723 ft). The survey captured 311,770 fish from 30 species with a total weight of 7,740 kg (17,028 lbs.). Alewife were 85% of the catch by number while Rainbow Smelt, Osmerus mordax , Round Goby, Neogobius melanostomus , and Deepwater Sculpin, Myoxocephalus thompsonii , comprised 6%, 4%, and 4% of the catch, respectively. The 2022 biomass index for Rainbow Smelt decreased 80% relative to the high values observed in 2021 as did the value for Cisco, Coregonus artedi , (46% decline). Emerald Shiner, Notropis atherinoides , biomass index increased in 2021 and Threespine Stickleback, Gasterosteus aculeatus , biomass remained low. No Bloater, Coregonus hoyi , were captured during the 2022 survey. In 2022, Alewife biomass in U.S. waters (58.1 kilograms per hectare, kg·ha-1) was substantially higher than Canadian waters (26.3 kg·ha-1). The 2022 Alewife biomass index (41.6 kg·ha-1) decreased 10% from 2021 while the 2022 density index decreased 62% from 2021. Prediction modeling indicated the growth of the abundant 2020 Alewife year class, sampled as age-1 fish in 2021, would cause the adult Alewife biomass to increase in 2022. Although the adult Alewife biomass did increase relative to 2021 (61%), the increase was lower than predicted. The difference between the predictions and observations was because survival of age-1 fish from 2021 to 2022 was lower than had previously been observed. In the three previous years of observations the proportion of age-1 Alewife surviving to age 2 ranged from 0.33 to 0.53; however, that proportion was only 0.21 from 2021 to 2022. Survival estimates of Alewife age-5 through age-8 were higher than previously observed, possibly because salmonid predation focused on the abundant younger Alewife. The catch of age-1 Alewife in 2022, which is a measure of reproductive success in 2021, was below average and similar to the abundances of the 2018 and 2019 year classes. Simulation modeling results indicated the adult Alewife biomass is likely to increase slightly in 2023, whereas predictions for 2024 are less certain. Hydroacoustic sampling was used to estimate prey fish densities in open-water, pelagic habitats not sampled by the bottom trawl. Bottom trawl-based densities from the lake bottom were at least 25 times greater than densities of prey fish in the water column above the trawl. These results support the idea that, in April, when the warmest, most dense water is on the lake bottom, Alewife and most other pelagic prey fish primarily inhabit deep, near bottom habitats and can be effectively sampled with bottom trawling.

Lake Ontario↗

USGS2022

Lake trout (Salvelinus namaycush) rehabilitation in Lake Ontario, 2021

Each year we report on the progress toward rehabilitation of the Lake Ontario lake trout ( Salvelinus namaycush ) population, including the results of stocking, annual assessment surveys, creel surveys, and evidence of natural reproduction observed from standard surveys performed by U.S. Geological Survey (USGS) and New York State Department of Environmental Conservation (NYSDEC). The catch per unit effort (CPUE) of adult lake trout in gill nets increased each year from 2008-2014, recovering from historic lows recorded during 2005-2007. Adult abundances declined each year from 2015 to 2017; and in 2017 were about 35% below the 2014 peak and 17% below the 1999-2004 mean. Adult abundance increased in 2018 by 51% over the 2017 value and remained nearly stable between 2018 and 2021. The 2020 rate of wounding by sea lamprey ( Petromyzon marinus ) on lake trout caught in gill nets was 1.68 A1 wounds (fresh wound) per 100 lake trout and was near target (2 wounds per 100 lake trout). Condition values for adult lake trout, indexed in September from the predicted weight for a 700 mm lake trout from annual length-weight regressions and Fulton’s K for age-6 males, were among the highest levels observed for the 1983-2021 time series. Reproductive potential for the adult stock indexed from the CPUE of mature females ≥ 4000 g was again above the target in 2021 continuing a trend observed in ten of the last eleven years. The 2021 catch of young wild lake trout marked the 27th observation in the last 28 years, however only two sites off the mouth of the Niagara River were surveyed.

Lake Ontario↗

USGS2021

Lake trout rehabilitation in Lake Ontario, 2020

Each year we report on the progress toward rehabilitation of the Lake Ontario lake trout (Salvelinus namaycush) population, including the results of stocking, annual assessment surveys, creel surveys, and evidence of natural reproduction observed from standard surveys performed by USGS and NYSDEC. Response to the COVID-19 pandemic limited survey effort such that spring and summer bottom trawl surveys and the creel survey were not completed in 2020, and sites sampled during the fall gillnet survey were limited to those east of Rochester, NY. The catch per unit effort of adult lake trout in gill nets increased each year from 2008-2014, recovering from historic lows recorded during 2005-2007. Adult abundances declined each year from 2015 to 2017; and in 2017 were about 35% below the 2014 peak and 17% below the 1999-2004 mean. Adult abundance increased in 2018 by 51% over the 2017 value and remained nearly stable between 2018 and 2020. The 2020 rate of wounding by sea lamprey (Petromyzon marinus) on lake trout caught in gill nets was 2.27 A1 wounds (fresh wound) per 100 lake trout and was near target (2 wounds per 100 lake trout). Condition values for adult lake trout, indexed in September from the predicted weight for a 700 mm lake trout from annual length-weight regressions and Fulton’s K for age-6 males, were among the highest levels observed for the 1983-2020 time series. Reproductive potential for the adult stock indexed from the CPUE of mature females ≥ 4000 g was again above the target in 2020 continuing a trend observed in nine of the last ten years. The 2020 catch of young wild lake trout marked the 26th observation in the last 27 years, however the low numbers of native adults observed during that time period continues to indicate substantial restoration impediments still exist.

Lake Ontario↗

USGS2021

Lake Ontario April prey fish survey and Alewife assessment, 2021

The Lake Ontario April bottom trawl survey and Alewife, Alosa psuedoharengus population assessment are conducted annually to track prey fish community status and aid management decisions related to predator-prey balance. No survey was conducted in 2020 due to the Covid-19 pandemic. The 2021 survey included 248 bottom trawls in both U.S. and Canadian waters, from March 30 - May 7 in the main lake and embayment regions, at depths ranging from 5 – 221 m (16 - 729 ft). The survey captured 947,102 fish, from 30 species with a total weight of 9,191 kg (20,220 lbs). Alewife were 89.2% of the catch by number while Rainbow Smelt, Osmerus mordax , Round Goby Neogobius melanostomus , and Deepwater Sculpin Myoxocephalus thompsonii comprised 5.6, 2.3, and 1.7% of the catch, respectively. Rainbow Smelt biomass in 2021 was among the highest values observed since 1997, especially in U.S. waters. The biomass index for Cisco, Coregonus artedii also increased, primarily due to catches and greater survey effort in the Bay of Quinte. Threespine stickleback, Gasterosteus aculeatus and Emerald Shiner, Notropis atherinoides biomasses remain low. No Bloater, Coregonus hoyi were captured during the 2021 survey. In 2021, the lake-wide Alewife biomass index increased substantially from 2019 due to the presence of an exceptionally high catch of age-1 Alewife (2020 year class). The biomass index of adult Alewife (age-2 and up) declined slightly since 2019, which was expected since Alewife reproduction was generally below average from 2016 to 2019. Expanding the survey spatial extent from U.S. waters to a lake-wide survey in 2016 has improved our ability to estimate Alewife survival and has provided more accurate estimates of Lake Ontario Alewife biomass and density. Simulation modeling based on recent estimates of survival, growth, and reproduction suggests the adult Alewife biomass will likely increase in 2022 and 2023. As part of a continued effort to improve prey fish surveys, we employed hydroacoustic sampling during the 2021 April trawl survey to estimate fish densities in open-water, pelagic habitats not sampled by the bottom trawl. We found fish density, in waters above the trawl headline depth (3m off bottom to surface), were approximately ~100 times lower than pelagic prey fish densities from bottom trawls. These results support the idea that at this time of year, when the warmest water is on the lake bottom, Alewife and most other prey fish primarily inhabit deep, near bottom regions and can be effectively sampled with bottom trawls. We were not able to apportion acoustics targets to species, however the low mean target strength (-43 decibels, dB) suggested these were small fishes (e.g., 100 mm). The greatest hydroacoustics densities were found near the Niagara River confluence and future surveys may use midwater trawls to determine which species these were and continue to improve this multi-agency survey.

Lake Ontario↗

USGS2021

Angler-caught salmonid diets illustrate Lake Ontario Alewife population and predator-prey dynamics

Lake Ontario fisheries decision makers use information about the status and trajectory of prey fish populations, such as alewife, for salmonid sport fish management. In 2020, the April bottom trawl survey, typically used to assess alewife, was canceled the day after it began due to Coronavirus health concerns. This prompted NYSDEC and USGS science teams to initiate a diet study using angler-collected samples to provide information on the alewife population in 2020. Over 800 salmonid diets were collected from across Lake Ontario southern shore from May through September. Past diet studies illustrated alewife size distribution in piscivore diets overlapped April trawl survey-based distributions (proportion overlap = 0.51- 0.81, n = 5). In 2020 few age-1 sized alewife (40 - 140 mm) were observed in salmonid diets, suggesting that 2019 alewife reproduction was below average. Given that alewife reproductive success from 2017 and 2018 were also below average, the 2021 Lake Ontario adult alewife population will likely be at a record low for the 43-year time series. For all years and piscivore species, adult-sized Alewife ( total length > 140 mm) were the predominate size consumed by piscivores greater than 400 mm (~ 16 inches). Sizes of alewife in the diet were positively related to piscivore size. Diet composition, by dry weight, indicated alewife remain the dominant prey supporting salmonids and diets were generally similar to trawl-based estimates of prey fish community composition. The most notable deviation from this pattern included round goby, which comprised substantial portions of brown trout and lake trout diets in 2013 and 2020. These results inform decision making related to Lake Ontario salmonid stocking and predator prey dynamics and highlight the utility of angler-caught piscivore diets for indicating alewife population status.

Lake Ontario↗

USGS2021

Bottom trawl assessment of Lake Ontario's benthic preyfish community, 2021

Since 1978, the Lake Ontario preyfish community survey has provided information on the status and trends of the benthic preyfish community related to Fish Community Objectives that includes understanding preyfish population dynamics and community diversity. Beginning in 2015, the benthic preyfish survey expanded from US-only to incorporate lake-wide sampling sites which increased the survey’s spatial coverage, and resumed sampling in eastern embayments (Black River, Chaumont, Guffin, and Henderson Bays) that were historically sampled during a September bottom trawl survey to index yellow perch from 1978 to 2007. In 2021, the collaborative benthic preyfish survey completed 195 bottom trawl tows across main lake and embayments at depths from 5 to 226 m. New embayment sites at Bay of Quinte, Sodus, and Little Sodus Bay were added to the survey in 2021 to compare fish communities across nearshore sites. In total, the 2021 survey sampled 109,178 fish from 35 species. Round goby ( Neogobius melanostomus ) was the most numerically abundant species comprising 44% of the total catch, followed by deepwater sculpin ( Myoxocephalus thompsonii ), and alewife ( Alosa pseudoharengus ) at 17% and 11%, respectively. Deepwater sculpin accounted for most (406 kg) of the fish biomass sampled during the 2021 survey (total=1,995 kg), followed by round goby (257 kg), and common carp (252 kg). Slimy sculpin ( Cottus cognatus ) biomass was higher in 2021 than in 2020, when spatial coverage was reduced. Deepwater sculpin biomass remained high in 2021 and similar to observations since 2019. White perch biomass ( Morone americana ) in Black River Bay has increased compared to observations from historical surveys. Yellow perch ( Perca flavescens ) accounted for most of the benthic preyfish biomass across the embayments surveyed in 2021 except for the Bay of Quinte and Black River Bay, where white perch accounted for a greater proportion of the fish community biomass.

Lake Ontario↗