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Jacques Rinchard - One of the best experts on this subject based on the ideXlab platform.
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thiamine concentrations in Lake Trout and atlantic salmon eggs during 14 years following the invasion of alewife in Lake champlain
Journal of Great Lakes Research, 2020Co-Authors: Bret J Ladago, Jacques Rinchard, Stephen C Riley, Dale C Honeyfield, Matthew H Futia, William R Ardren, Kevin P Kelsey, Carrie L Kozel, Donald E Tillitt, James L ZajicekAbstract:Abstract Thiamine (vitamin B1) deficiency in Great Lakes salmonines has been linked to consumption of alewife Alosa pseudoharengus. Thiamine deficiency has been recognized as a possible impediment to Lake Trout Salvelinus namaycush recruitment in the Great Lakes and Atlantic salmon Salmo salar recruitment in the Finger Lakes and Baltic Sea. Alewife invaded Lake Champlain in 2003 which provided an opportunity to investigate changes in thiamine concentrations in salmonine predators during an alewife invasion. We monitored egg unphosphorylated and total thiamine concentrations in Lake Trout and Atlantic salmon in 2004 and 2007–2019, assessed whether concentrations were associated with mortality, and examined thiaminase activity in alewife. Total thiamine concentrations in Lake Trout and Atlantic salmon were significantly lower than in 2004 for seven of the ten collection years for Lake Trout and for nine of the 12 collection years for Atlantic salmon. Mortality and signs of thiamine deficiency were observed in laboratory-reared Atlantic salmon free embryos but not in Lake Trout. Average thiaminase activity in adult alewife declined from 5200 pmol/g/min in 2006 to 1500 pmol/g/min in 2012. Our results provide further evidence that a diet that includes alewife reduces egg thiamine concentrations in salmonines. This effect was observed within four years of the invasion of alewife.
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spatial variability of Lake Trout diets in Lakes huron and michigan revealed by stomach content and fatty acid profiles
Canadian Journal of Fisheries and Aquatic Sciences, 2018Co-Authors: Austin Happel, Jacques Rinchard, Jory L Jonas, Paul R Mckenna, Ji Xiang He, Sergiusz CzesnyAbstract:Despite long-term efforts to restore Lake Trout (Salvelinus namaycush) populations in the Great Lakes, they continue to experience insufficient recruitment and rely on hatchery programs to sustain stocks. As Lake Trout reproductive success has been linked to diets, spatial heterogeneity in diet compositions is of interest. To assess spatial components of adult Lake Trout diets, we analyzed stomach contents and fatty acid profiles of dorsal muscle collected throughout Lake Michigan and along Lake Huron’s Michigan shoreline. Lake Trout from Lake Huron were generally larger in both length and mass than those from Lake Michigan. However, Lake Trout from Lake Michigan varied more in size based on depth of capture with smaller fish being caught more in deeper set nets. Fatty acids and stomach contents indicated that alewife (Alosa pseudoharengus) were consumed more in western Lake Michigan in contrast with round goby (Neogobius melanostomus) along the eastern shoreline. Conversely, in Lake Huron, Lake Trout pri...
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Linking egg thiamine and fatty acid concentrations of Lake michigan Lake Trout with early life stage mortality
2016Co-Authors: Sergiusz Czesny, John M. Dettmers, Jacques Rinchard, Konrad Dabrowski, M. DettmersAbstract:Abstract.—The natural reproduction of Lake Trout Salvelinus namaycush in Lake Michigan is thought to be compromised by nutritional deficiency associated with inadequate levels of thiamine (vitamin B 1) in their eggs. However, mortality driven by thiamine deficiency (commonly referred to as early mortality syndrome [EMS]) is not the only significant cause of low Lake Trout survival at early life stages. In this study, we sought to better understand the combined effects of variable levels of thiamine and fatty acids in Lake Trout eggs on prehatch, posthatch, and swim-up-stage mortality. We sampled the eggs of 29 Lake Trout females from southwestern Lake Michigan. The concentrations of free thiamine and its vitamers (e.g., thiamin
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fatty acid profiles of juvenile Lake Trout reflect experimental diets consisting of natural prey
Freshwater Biology, 2016Co-Authors: Austin Happel, Jacques Rinchard, Logan Stratton, Robert Pattridge, Sergiusz CzesnyAbstract:Summary It is relatively well-known that fatty-acid profiles of consumers reflect their diets. However, with fish, controlled studies that trace fatty-acid profiles of natural prey into consumers are lacking. We asked whether Lake Trout (Salmonidae: Salvelinus namaycush) fatty-acid profiles reflect diets at 4, 8 or 14 weeks after feeding began. We also evaluated if calibration coefficients were similar for each diet, a key assumption of quantitative fatty-acid signature analysis (QFASA). In this study, juvenile Lake Trout were fed commercially available frozen diets of chironomids (Chironomidae: Chironomus spp.), copepods (Cyclopoida spp.), or Mysis (Mysidae: Mysis relicta) over a 14-week period. Accurate classification of Lake Trout into a priori diet groups was attained after 8 weeks of feeding. Calibration coefficients were significantly different among diet groups, especially for Lake Trout that were fed chironomids, suggesting that diet-specific modifications to fatty acids occurred. Chironomid-fed Lake Trout grew significantly larger than others despite consuming prey that lacked long-chain essential fatty acids. Furthermore, chironomid-fed Lake Trout provide evidence for the conversion of 18:3n-3 into longer chain n-3 fatty acids. Our results call for additional studies to better understand how fatty acids reflect dietary origins prior to employing QFASA on wild freshwater fishes. QFASA could provide accurate diet estimates for freshwater fishes with low-diversity diet compositions, if calibration coefficients for each predator–prey relationship are incorporated.
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increasing thiamine concentrations in Lake Trout eggs from Lakes huron and michigan coincide with low alewife abundance
North American Journal of Fisheries Management, 2011Co-Authors: Stephen C Riley, Jacques Rinchard, Dale C Honeyfield, Allison N Evans, Linda J BegnocheAbstract:Abstract Lake Trout Salvelinus namaycush in the Laurentian Great Lakes suffer from thiamine deficiency as a result of adult Lake Trout consuming prey containing thiaminase, a thiamine-degrading enzyme. Sufficiently low egg thiamine concentrations result in direct mortality of or sublethal effects on newly hatched Lake Trout fry. To determine the prevalence and severity of low thiamine in Lake Trout eggs, we monitored thiamine concentrations in Lake Trout eggs from 15 sites in Lakes Huron and Michigan from 2001 to 2009. Lake Trout egg thiamine concentrations at most sites in both Lakes were initially low and increased over time at 11 of 15 sites, and the proportion of females with egg thiamine concentrations lower than the recommended management objective of 4 nmol/g decreased over time at eight sites. Egg thiamine concentrations at five of six sites in Lakes Huron and Michigan were significantly inversely related to site-specific estimates of mean abundance of alewives Alosa pseudoharengus, and successful...
Sergiusz Czesny - One of the best experts on this subject based on the ideXlab platform.
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spatial variability of Lake Trout diets in Lakes huron and michigan revealed by stomach content and fatty acid profiles
Canadian Journal of Fisheries and Aquatic Sciences, 2018Co-Authors: Austin Happel, Jacques Rinchard, Jory L Jonas, Paul R Mckenna, Ji Xiang He, Sergiusz CzesnyAbstract:Despite long-term efforts to restore Lake Trout (Salvelinus namaycush) populations in the Great Lakes, they continue to experience insufficient recruitment and rely on hatchery programs to sustain stocks. As Lake Trout reproductive success has been linked to diets, spatial heterogeneity in diet compositions is of interest. To assess spatial components of adult Lake Trout diets, we analyzed stomach contents and fatty acid profiles of dorsal muscle collected throughout Lake Michigan and along Lake Huron’s Michigan shoreline. Lake Trout from Lake Huron were generally larger in both length and mass than those from Lake Michigan. However, Lake Trout from Lake Michigan varied more in size based on depth of capture with smaller fish being caught more in deeper set nets. Fatty acids and stomach contents indicated that alewife (Alosa pseudoharengus) were consumed more in western Lake Michigan in contrast with round goby (Neogobius melanostomus) along the eastern shoreline. Conversely, in Lake Huron, Lake Trout pri...
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Linking egg thiamine and fatty acid concentrations of Lake michigan Lake Trout with early life stage mortality
2016Co-Authors: Sergiusz Czesny, John M. Dettmers, Jacques Rinchard, Konrad Dabrowski, M. DettmersAbstract:Abstract.—The natural reproduction of Lake Trout Salvelinus namaycush in Lake Michigan is thought to be compromised by nutritional deficiency associated with inadequate levels of thiamine (vitamin B 1) in their eggs. However, mortality driven by thiamine deficiency (commonly referred to as early mortality syndrome [EMS]) is not the only significant cause of low Lake Trout survival at early life stages. In this study, we sought to better understand the combined effects of variable levels of thiamine and fatty acids in Lake Trout eggs on prehatch, posthatch, and swim-up-stage mortality. We sampled the eggs of 29 Lake Trout females from southwestern Lake Michigan. The concentrations of free thiamine and its vitamers (e.g., thiamin
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fatty acid profiles of juvenile Lake Trout reflect experimental diets consisting of natural prey
Freshwater Biology, 2016Co-Authors: Austin Happel, Jacques Rinchard, Logan Stratton, Robert Pattridge, Sergiusz CzesnyAbstract:Summary It is relatively well-known that fatty-acid profiles of consumers reflect their diets. However, with fish, controlled studies that trace fatty-acid profiles of natural prey into consumers are lacking. We asked whether Lake Trout (Salmonidae: Salvelinus namaycush) fatty-acid profiles reflect diets at 4, 8 or 14 weeks after feeding began. We also evaluated if calibration coefficients were similar for each diet, a key assumption of quantitative fatty-acid signature analysis (QFASA). In this study, juvenile Lake Trout were fed commercially available frozen diets of chironomids (Chironomidae: Chironomus spp.), copepods (Cyclopoida spp.), or Mysis (Mysidae: Mysis relicta) over a 14-week period. Accurate classification of Lake Trout into a priori diet groups was attained after 8 weeks of feeding. Calibration coefficients were significantly different among diet groups, especially for Lake Trout that were fed chironomids, suggesting that diet-specific modifications to fatty acids occurred. Chironomid-fed Lake Trout grew significantly larger than others despite consuming prey that lacked long-chain essential fatty acids. Furthermore, chironomid-fed Lake Trout provide evidence for the conversion of 18:3n-3 into longer chain n-3 fatty acids. Our results call for additional studies to better understand how fatty acids reflect dietary origins prior to employing QFASA on wild freshwater fishes. QFASA could provide accurate diet estimates for freshwater fishes with low-diversity diet compositions, if calibration coefficients for each predator–prey relationship are incorporated.
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Effects of vitamin B1 (thiamine) deficiency in Lake Trout (Salvelinus namaycush) alevins at hatching stage.
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2009Co-Authors: Marta Jaroszewska, Sergiusz Czesny, Jacques Rinchard, Konrad Dabrowski, Bong Joo Lee, P. Trzeciak, B. WilczynskaAbstract:The objectives of this study were to examine the relationship between thiamine concentrations in unfertilized eggs and yolksac individuals of Lake Trout (Salvelinus namaycush), along with any associated histopathological changes in the tissues of alevins at the hatching stage. We address these questions in a Lake Trout population from different spawning grounds of Lake Michigan (North and South), known for compromised survival due to early mortality syndrome (EMS). However, a dichotomous forage base of Lake Trout spawning stocks, with a dietary thiaminase-rich alewife in the North, and dietary low-thiaminase round goby in the South, provides the basis for the assumption that different diets may lead to differences in severity of EMS between different stocks. Lake Trout eggs of 18 females were collected and fertilized individually with the sperm of several males. The eggs, eyed embryos and newly-hatched alevins were sampled to examine thiamine utilization during embryogenesis. Progenies of females with low ( 0.85 nmol/g) levels of thiamine were chosen for histological studies. The obtained results showed that total thiamine levels in the body and yolk of eyed embryos and alevins at hatching were influenced by thiamine levels of unfertilized eggs and it decreased during embryogenesis (to 51% in eyed embryos and 28% in newly-hatched alevins in comparison to unfertilized eggs). The survival of Lake Trout until hatching stage does not correlate with the thiamine level, however it was affected by collection site and was significantly higher in fish from the South site (Julian's Reef). At the hatching stage, no pathological changes were observed in the brain, olfactory lobe, retina or liver in embryos regardless of thiamine concentrations in unfertilized eggs. It has been concluded that an enhanced thiamine requirement for the fast muscle mass growth near the swim-up stage is responsible for overt and histopathological signs of EMS. Current study confirms earlier findings that Lake Trout suffering from EMS can be successfully treated by immersion in thiamine solution as late as at the swim-up stage.
Charles C. Krueger - One of the best experts on this subject based on the ideXlab platform.
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Evidence of sound production by spawning Lake Trout (Salvelinus namaycush) in Lakes Huron and Champlain
Canadian Journal of Fisheries and Aquatic Sciences, 2018Co-Authors: Nicholas S. Johnson, Dennis M. Higgs, Thomas R. Binder, J. Ellen Marsden, Tyler J. Buchinger, Linnea Brege, Tyler Bruning, Steve A. Farha, Charles C. KruegerAbstract:Two sounds associated with spawning Lake Trout (Salvelinus namaycush) in Lakes Huron and Champlain were characterized by comparing sound recordings with behavioral data collected using acoustic telemetry and video. These sounds were named “growls” and “snaps” and were heard on Lake Trout spawning reefs, but not on a nonspawning reef, and were more common at night than during the day. Growls also occurred more often during the spawning period than the prespawning period, while the trend for snaps was reversed. In a laboratory flume, sounds occurred when male Lake Trout were displaying spawning behaviors: growls when males were quivering and parallel swimming and snaps when males moved their jaw. Combining our results with the observation of possible sound production by spawning spLake (Salvelinus fontinalis × Salvelinus namaycush hybrid) provides rare evidence for spawning-related sound production by a salmonid or any other fish in the superorder Protacanthopterygii. Further characterization of these sound...
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use of electricity to sedate Lake Trout for intracoelomic implantation of electronic transmitters
North American Journal of Fisheries Management, 2017Co-Authors: Matthew D Faust, Thomas R. Binder, Christopher S Vandergoot, Eric T Hostnik, Julia Mida L Hinderer, Jessica T Ives, Charles C. KruegerAbstract:AbstractUse of telemetry data to inform fisheries conservation and management is becoming increasingly common; as such, fish typically must be sedated before surgical implantation of transmitters into the coelom. Given that no widely available, immediate-release chemical sedative currently exists in North America, we investigated the feasibility of using electricity to sedate Lake Trout Salvelinus namaycush long enough for an experienced surgeon to implant an electronic transmitter (i.e., 180 s). Specifically, our study objectives were to determine (1) whether some combination of electrical waveform characteristics (i.e., duty cycle, frequency, voltage, and pulse type) could sedate Lake Trout for at least 180 s; and (2) whether Lake Trout that were sequentially exposed to continuous DC and pulsed DC had greater rates of spinal injury and short-term mortality than control fish. A Portable Electrosedation System unit was used to sedate hatchery and wild Lake Trout. Dual-frequency pulsed-DC and two-stage app...
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five year evaluation of habitat remediation in thunder bay Lake huron comparison of constructed reef characteristics that attract spawning Lake Trout
Fisheries Research, 2016Co-Authors: Ellen J Marsden, Nicholas S. Johnson, Thomas R. Binder, Tyler J. Buchinger, James E Johnson, Natalie Dingledine, Janice Adams, Charles C. KruegerAbstract:Abstract Degradation of aquatic habitats has motivated construction and research on the use of artificial reefs to enhance production of fish populations. However, reefs are often poorly planned, reef design characteristics are not evaluated, and reef assessments are short-term. We constructed 29 reefs in Thunder Bay, Lake Huron, in 2010 and 2011 to mitigate for degradation of a putative Lake Trout spawning reef. Reefs were designed to evaluate Lake Trout preferences for height, orientation, and size, and were compared with two degraded natural reefs and a high-quality natural reef (East Reef). Eggs and fry were sampled on each reef for five years post-construction, and movements of 40 tagged Lake Trout were tracked during three spawning seasons using acoustic telemetry. Numbers of adults and spawning on the constructed reefs were initially low, but increased significantly over the five years, while remaining consistent on East Reef. Adult density, egg deposition, and fry catch were not related to reef height or orientation of the constructed reefs, but were related to reef size and adjacency to East Reef. Adult Lake Trout visited and spawned on all except the smallest constructed reefs. Of the metrics used to evaluate the reefs, acoustic telemetry produced the most valuable and consistent data, including fine-scale examination of Lake Trout movements relative to individual reefs. Telemetry data, supplemented with diver observations, identified several previously unknown natural spawning sites, including the high-use portions of East Reef. Reef construction has increased the capacity for fry production in Thunder Bay without apparently decreasing the use of the natural reef. Results of this project emphasize the importance of multi-year reef assessment, use of multiple assessment methods, and comparison of reef characteristics when developing artificial reef projects. Specific guidelines for construction of reefs focused on enhancing Lake Trout spawning are suggested.
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Ontogenetic niche shifts and resource partitioning of Lake Trout morphotypes
2016Co-Authors: Mara S Zimmerman, Charles C. Krueger, Stephanie N. Schmidt, M. Jake, Er Z, Y L. EshenroderAbstract:Abstract: Resource polymorphisms are widely observed in fishes; however, ontogenetic contributions to morphological and ecological differences are poorly understood. This study examined whether ontogenetic changes in niche partitioning could explain morphological and buoyancy differences between Lake Trout (Salvelinus namaycush) morphotypes in Great Slave Lake (Northwest Territories, Canada). Morphometric analysis, buoyancy, capture depth, diet, and stable isotope data were used in concert to determine whether (i) differences occur in small, as well as large, Lake Trout, (ii) ontogenetic changes in morphology and buoyancy correlate with shifts in depth or diet, and (iii) a subset of small Trout, putatively identified as ‘‘humpers’’, are distinct from other morphotypes. Ontogenetic changes in Lake Trout morphology were associ-ated with an ecological shift between benthic and pelagic feeding. Resource partitioning between lean and siscowet-like Trout occurred within benthic (small Trout) and pelagic (large Trout) habitats. The humper subset did not differ from small siscowet-like Trout. By combining multiple methods and an ontogenetic perspective, our study provides novel perspectives on resource polymorphisms in large, deep Lakes and on existing interpretations of stable isotope data from large Lakes in general. Résume ́ : Le polymorphisme des ressources est un phénomène fréquemment observe ́ chez les poissons; cependant, les contributions ontogéniques aux différences morphologiques et écologiques restent mal comprises. Notre étude examine si les changements ontogéniques de partition de niche peuvent expliquer les différences de morphologie et de flottabilite ́ en
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life history variation among four Lake Trout morphs at isle royale Lake superior
Journal of Great Lakes Research, 2016Co-Authors: Michael J Hansen, Charles R Bronte, Mara S Zimmerman, Andrew M Muir, Nancy A Nate, Charles C. KruegerAbstract:Abstract Life history traits were compared among four morphs of Lake Trout at Isle Royale, Lake Superior. Of 738 Lake Trout caught at Isle Royale, 701 were assigned to a morph (119 humpers, 160 leans, 85 redfins, and 337 siscowets) using a combination of statistical analysis of head and body shape and visual assignment. On average, redfins were longer (544 mm), heavier (1481 g), heavier at length, more buoyant, and older (22 years) than siscowets (519 mm; 1221 g; 19 years), leans (479 mm; 854 g; 13 years), and humpers (443 mm; 697 g; 17 years). On average, leans grew from a younger age at length = 0 and shorter length at age = 0, at a faster early growth rate to a longer asymptotic length than the other three morphs, while redfins grew at a slower instantaneous rate and humpers grew to a shorter asymptotic length than other morphs. On average, leans were longer (562 mm) and older (15 years) at 50% maturity than redfins (427 mm, 12 years), siscowets (401 mm, 11 years), or humpers (394 mm, 13 years). Life history parameters did not differ between males and females within each morph. We conclude that differences in life history attributes of lean, humper, redfin, and siscowet morphs of Lake Trout are consistent with differential habitat use in waters around Isle Royale, Lake Superior.
Ellen J Marsden - One of the best experts on this subject based on the ideXlab platform.
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differences in seasonal distribution of wild and stocked juvenile Lake Trout by depth and temperature in Lake champlain
Journal of Great Lakes Research, 2021Co-Authors: Pascal D Wilkins, Ellen J MarsdenAbstract:Abstract Lake Trout (Salvelinus namaycush) reared in hatcheries are exposed to an environment and feeding regime that is different from wild Lake Trout, and are stocked at substantially larger sizes with higher lipid reserves. In addition to differences in diet and growth, this early experience may alter habitat use compared to the wild cohort. We used seasonal data on the depth and temperature distribution of wild and stocked juvenile Lake Trout to test for differences in habitat use and inform sampling strategies to evaluate annual recruitment. Bottom trawling was conducted from 2015 to 2019 in the central basin of Lake Champlain every two to four weeks during the ice-free season. Differences in distribution of wild and stocked Lake Trout were most pronounced during thermal stratification, when wild juveniles were more abundant than stocked juveniles at shallower depths and warmer temperatures and stocked juveniles were more abundant at deeper depths and colder temperatures. Temperature preferences may be a consequence of different early rearing environments; wild Lake Trout are acclimated to Lake temperatures and forage, whereas stocked fish entered the Lake with high lipid content and little foraging experience. Unbiased assessment of the proportion of wild Lake Trout and growth and survival of the entire juvenile Lake Trout population using bottom trawl sampling should either take place in the pre- and post-stratification seasons when wild and stocked fish are at the same depths, or include the full range of depths and temperatures that wild and stocked fish occupy during the stratified period.
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spatial and seasonal comparisons of growth of wild and stocked juvenile Lake Trout in Lake champlain
Journal of Great Lakes Research, 2021Co-Authors: Pascal D Wilkins, Ellen J MarsdenAbstract:Abstract After 42 years of stocking in Lake Champlain, recruitment of wild juvenile Lake Trout (Salvelinus namaycush) was first observed in 2015. Abundance of wild Lake Trout juveniles was spatially heterogeneous. Recruitment of wild fish to age-1 and subsequent survival are likely related to growth including overwinter growth. We hypothesized that growth potential or growth-related mortality of wild and stocked fish may explain spatial differences in abundance. We collected juvenile (age-0 to 3) Lake Trout by bottom trawling in the central, north, and south Main Lake every 2–4 weeks during the ice-free season, 2015–2018. The percentage of wild juveniles increased from 27.8% of the total catch in 2015 to 65.7% in 2018. Rates of growth in length and change in condition were compared in wild versus stocked Lake Trout, among sampling areas, and between seasons (sampling season relative to winter). Wild juveniles grew equally or faster in length than stocked juveniles at the same age, but changed more slowly in condition. There was a higher percentage of wild juveniles in the central sampling area than the north and south, but no differences in growth among sampling areas. Wild and stocked fish grew in length over winter, but most cohorts (6 of 7) maintained or increased condition. Results indicate high growth potential of wild juvenile Lake Trout and progress toward population restoration.
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five year evaluation of habitat remediation in thunder bay Lake huron comparison of constructed reef characteristics that attract spawning Lake Trout
Fisheries Research, 2016Co-Authors: Ellen J Marsden, Nicholas S. Johnson, Thomas R. Binder, Tyler J. Buchinger, James E Johnson, Natalie Dingledine, Janice Adams, Charles C. KruegerAbstract:Abstract Degradation of aquatic habitats has motivated construction and research on the use of artificial reefs to enhance production of fish populations. However, reefs are often poorly planned, reef design characteristics are not evaluated, and reef assessments are short-term. We constructed 29 reefs in Thunder Bay, Lake Huron, in 2010 and 2011 to mitigate for degradation of a putative Lake Trout spawning reef. Reefs were designed to evaluate Lake Trout preferences for height, orientation, and size, and were compared with two degraded natural reefs and a high-quality natural reef (East Reef). Eggs and fry were sampled on each reef for five years post-construction, and movements of 40 tagged Lake Trout were tracked during three spawning seasons using acoustic telemetry. Numbers of adults and spawning on the constructed reefs were initially low, but increased significantly over the five years, while remaining consistent on East Reef. Adult density, egg deposition, and fry catch were not related to reef height or orientation of the constructed reefs, but were related to reef size and adjacency to East Reef. Adult Lake Trout visited and spawned on all except the smallest constructed reefs. Of the metrics used to evaluate the reefs, acoustic telemetry produced the most valuable and consistent data, including fine-scale examination of Lake Trout movements relative to individual reefs. Telemetry data, supplemented with diver observations, identified several previously unknown natural spawning sites, including the high-use portions of East Reef. Reef construction has increased the capacity for fry production in Thunder Bay without apparently decreasing the use of the natural reef. Results of this project emphasize the importance of multi-year reef assessment, use of multiple assessment methods, and comparison of reef characteristics when developing artificial reef projects. Specific guidelines for construction of reefs focused on enhancing Lake Trout spawning are suggested.
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Lake Trout in northern Lake huron spawn on submerged drumlins
Journal of Great Lakes Research, 2014Co-Authors: Stephen C Riley, Thomas R. Binder, Ellen J Marsden, Charles R Bronte, Mark P Ebener, Nigel J Wattrus, Matthew D Faust, John Janssen, John Menzies, Taaja R TuckerAbstract:article i nfo Recentobservationsof spawning LakeTroutSalvelinusnamaycushnearDrummond IslandinnorthernLakeHuron indicate that Lake Trout use drumlins, landforms created in subglacial environments by the action of ice sheets, as a primary spawning habitat. From these observations, we generated a hypothesis that may in part explain loca- tions chosen by Lake Trout for spawning. Most salmonines spawn in streams where they rely on streamflows to sort and clean sediments to create good spawning habitat. Flows sufficient to sort larger sediment sizes are generally lacking in Lakes, but some glacial bedforms contain large pockets of sorted sediments that can provide the interstitial spacesnecessary for LakeTroutegg incubation,particularlyifthesebedforms are situatedsuch that Lake currents can penetrate these sediments. We hypothesize that sediment inclusions from glacial scavenging and sediment sorting that occurred during the creation of bedforms such as drumlins, end moraines, and eskers create suitableconditionsfor LakeTroutegg incubation, particularlywherethesebedforms interactwith Lakecur- rents toremove finesediments. Further,these bedforms may provide high-quality LakeTrout spawninghabitatat many locations in the Great Lakes and may be especially important along the southern edge of the range of the species. A better understanding of the role of glacially-derived bedforms in the creation of Lake Trout spawning habitatmay helpdeveloppowerful predictorsofLakeTroutspawninglocations,provide insightintothe evolution of unique spawning behaviors by Lake Trout, and aid in Lake Trout restoration in the Great Lakes. Published by Elsevier B.V. on behalf of International Association for Great Lakes Research.
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influences of spawning habitat characteristics and interstitial predators on Lake Trout egg deposition and mortality
Transactions of The American Fisheries Society, 2005Co-Authors: Randall M Claramunt, Jory L Jonas, John D Fitzsimons, Ellen J MarsdenAbstract:Abstract To understand the factors affecting natural recruitment of Lake Trout Salvelinus namaycush, we evaluated natural egg deposition, the rate of egg loss of seeded eggs, and the relationship of interstitial predators to egg mortality at a protected nearshore Lake Trout spawning area in Lake Michigan. Egg mortality and predator densities were evaluated with collection bags that were buried above the drop-off on spawning substrate at 1-, 3-, and 9-m depths. Habitat selection by spawning Lake Trout was probably related to the coverage by periphyton and zebra mussels Dreissena polymorpha given that abiotic characteristics of the spawning habitat such as slope (55– 65°), interstitial depth (30–50 cm), and substrate type did not differ across depths. The results of seeding eggs during spawning and recovering them throughout the incubation period (2–177 d) indicated that egg mortality was extremely high early in the spawning period: Over 40% of seeded eggs were lost by 2 d and over 80% of the eggs were lost...
Joseph B. Rasmussen - One of the best experts on this subject based on the ideXlab platform.
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Influence of food web structure on the growth and bioenergetics of Lake Trout (Salvelinus namaycush)
Canadian Journal of Fisheries and Aquatic Sciences, 2002Co-Authors: Ivano Pazzia, Marc Trudel, Mark S. Ridgway, Joseph B. RasmussenAbstract:In this study, we compared energy budgets of Lake Trout (Salvelinus namaycush) populations in contrasting food webs. Nonpiscivorous Lake Trout (NPLT) reached a much smaller size and grew at a much slower rate than piscivorous Lake Trout (PLT) populations. Food consumption rates were, on average, 23 times higher in NPLT when they were expressed on a wet weight basis. However, only a slight (less than 10%) difference in their energy intake was detected once consumption rates were corrected for differences in prey caloric content. Growth efficiency was approximately two times lower in NPLT compared with PLT, while their metabolic costs were higher and their assimilation efficiency was lower. It is most likely that the increased metabolic costs were associated with higher foraging costs, since more feeding attempts must be made to acquire a given quantity of food when fish are feeding on smaller prey. Furthermore, the portion of indigestible matter is likely to be higher in the diet of NPLT than in PLT (i.e....
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within and among population variation in the trophic position of a pelagic predator Lake Trout salvelinus namaycush
Canadian Journal of Fisheries and Aquatic Sciences, 2000Co-Authors: Jake Vander M Zanden, Brian J Shuter, Nigel P Lester, Joseph B. RasmussenAbstract:Many aquatic consumers have flexible feeding habits, and the diet and trophic position of a species can be expected to vary both within and among populations. In this study, we quantify the importance of both within- and among-population trophic variation for Lake Trout (Salvelinus namaycush) using stable isotope designations of trophic position from 13 Ontario and Quebec Lakes. Lake-to-Lake differences explained 78% of the total variation in Lake Trout trophic position. Analysis using both stable isotopes and published dietary data demonstrated that the trophic position of Lake Trout failed to increase appreciably as a function of animal body size. This finding was attributed to weak pred - ator size - prey size relationships as well as to there being no relationship between prey fish trophic position and body size. The variance in trophic position of a population reflects the extent to which individuals forage as trophic special - ists; however, we did not identify any one factor that was correlated with within-population trophic variation. Our find - ing that much of the total variation in trophic position represents among-population differences indicates that
