An invasive dreissenid mussel given the working name of "quagga" has a present (spring 1993) distribution in the Laurentian Great Lakes from the western basin of Lake Erie to Quebec City. In Lake Erie, quaggas were collected as early as 1989 and now are most common in the eastern basin. In Lakes Erie and Ontario, proportions of quaggas increased with depth and decreasing water temperature. In the eastern basin of Lake Erie, quaggas outnumbered zebra mussel (Dreissena polymorpha) by 14 to 1 in deeper waters (>20 m). In Lake Ontario, quaggas were observed at depths as great as 130 m, and both quagga and zebra mussel were found to survive at depths (>50 m) where temperatures rarely exceed 5 °C. Quaggas were sparse or absent along inland waterways and lakes of New York State. Mean shell size of quagga mussel was larger than that of zebra mussel at sites in the Niagara River, Lake Ontario, and the St. Lawrence River. The largest quaggas (38 mm) were observed in the St. Lawrence River at Cape Vincent.
On a compare le regime alimentaire et la croissance de la perchaude (Perca flavescens) d'âge 0 et de l'alose a gesier (Dorosoma cepedianum) d'âge 0 au cours de la periode juin-aout de 1990 et de 1991. Au cours de ces deux annees, Daphnia dominait la communaute zooplanctonique en juin et au debut juillet, mais disparaissait a la mi-juillet et au debut d'aout. La perchaude d'âge 0 consommait principalement des Daphnia et des copepodes jusqu'a epuisement du stock de Daphnia, puis se nourrissait par la suite de proies benthiques. Les petites aloses a gesier d'âge 0 se nourrissaient surtout de Daphnia et de copepodes, tandis que les aloses plus grosses consommaient moins de zooplancton mais plus de phytoplancton. Selon des donnees obtenues de 1984 a 1993, la competition interspecifique n'a aucun effet direct sur les taux de croissance des autres especes. La baisse des populations de Daphnia au cours des annees caracterisees par une abondance d'aloses a gesier d'âge 0 se produit plus tard dans l'annee que pendant les annees caracterisees par une abondance de perchaudes d'âge 0, ce qui, a notre avis, est tres important pour les resultats des interactions entre les poissons. Lorsque les populations de Daphnia baissent plus tard dans la saison, les grosses perchaudes d'âge 0 peuvent commencer a se nourrir de proies benthiques, tandis que les grosses aloses a gesier d'âge 0 consommeront du phytoplancton; ainsi, les resultats de ces interactions sont differents de la baisse des populations de crapets a oreilles bleues (Lepomis macrochirus) d'âge 0 a la suite de la competition exercee par les aloses a gesier d'âge 0, dont il a ete fait etat dans de nombreux reservoirs.
Rehabilitation efforts for Lake Trout Salvelinus namaycush in Lake Huron have resulted in increased capture of young wild Lake Trout in annual bottom trawl surveys conducted by the U.S. Geological Survey. To better understand the ecology of juvenile (<400 mm) Lake Trout, we summarized the spatial distribution of their capture in bottom trawls at six ports in Lake Huron during October/November 2008–2017 and analyzed diets of wild (n = 306 of 337 total) and hatchery-origin (n = 18 of 30 total) fish captured. Lake Trout ranged in size from 27 to 399 mm, representing at least three age-classes, and 92% were wild origin. Most wild juvenile Lake Trout (83%) were captured at 46–64 m depths at the two northernmost ports, typically below the thermocline. Mysis diluviana was the most prevalent prey type, found in 75% of wild fish with non-empty stomachs, followed by two non-native species: Spiny Water Flea Bythotrephes longimanus (31%) and Round Goby Neogobius melanostomus (12%). Small Lake Trout (<185 mm) consumed invertebrates but transitioned to mostly fish-based diets by >185 mm (∼age 2). The variety of taxa consumed by young Lake Trout increased with length. Further declines in Mysis populations due to increased predation pressure after the loss of Diporeia from the system may hinder the recovery of wild Lake Trout, and although they have been able to utilize invasive species as prey, impacts to Lake Trout growth remain unknown. Additional research on the habitat use and diets of wild juvenile Lake Trout may provide insight into the reasons behind the recent successful natural reproduction and recruitment of Lake Trout in Lake Huron.
FisheriesVolume 48, Issue 2 p. 75-78 AFS NEWS 5th International Percid Fish Symposium: Continuing a Great Trans-Atlantic Tradition Robin DeBruyne, Corresponding Author Robin DeBruyne [email protected] U.S. Geological Survey, Great Lakes Science Center, 1451 Green Rd, Ann Arbor, Michigan, 48105Search for more papers by this authorEdward Roseman, Edward Roseman U.S. Geological Survey Great Lakes Science Center, Ann Arbor, MichiganSearch for more papers by this authorMartin Čech, Martin Čech Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, České Budějovice, South Bohemia, Czech RepublicSearch for more papers by this author Robin DeBruyne, Corresponding Author Robin DeBruyne [email protected] U.S. Geological Survey, Great Lakes Science Center, 1451 Green Rd, Ann Arbor, Michigan, 48105Search for more papers by this authorEdward Roseman, Edward Roseman U.S. Geological Survey Great Lakes Science Center, Ann Arbor, MichiganSearch for more papers by this authorMartin Čech, Martin Čech Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, České Budějovice, South Bohemia, Czech RepublicSearch for more papers by this author First published: 19 December 2022 https://doi.org/10.1002/fsh.10880Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Citing Literature Volume48, Issue2February 2023Pages 75-78 RelatedInformation
Abstract Examination of angler‐caught piscivore stomachs revealed that Lake Trout Salvelinus namaycush , Chinook Salmon Oncorhynchus tshawytscha , and Walleyes Sander vitreus altered their diets in response to unprecedented declines in Lake Huron's main‐basin prey fish community. Diets varied by predator species, season, and location but were nearly always dominated numerically by some combination of Alewife Alosa pseudoharengus , Rainbow Smelt Osmerus mordax , Emerald Shiner Notropis atherinoides , Round Goby Neogobius melanostomus , or terrestrial insects. Rainbow Trout Oncorhynchus mykiss (steelhead), Coho Salmon Oncorhynchus kisutch , and Atlantic Salmon Salmo salar had varied diets that reflected higher contributions of insects. Compared with an earlier (1983–1986) examination of angler‐caught predator fishes from Lake Huron, the contemporary results showed an increase in consumption of nontraditional prey (including conspecifics), use of smaller prey, and an increase in insects in the diet, suggesting that piscivores were faced with chronic prey limitation during this study. The management of all piscivores in Lake Huron will likely require consideration of the pervasive effects of changes in food webs, especially if prey fish remain at low levels. Received December 19, 2013; accepted June 30, 2014
Aquatic habitat has been extensively altered throughout the Laurentian Great Lakes to increase navigation connectivity. In particular, the St. Marys River, a Great Lakes connecting channel, lost >50% of its historic rapids habitat over the past century. In 2016, the natural flow was restored to the Little Rapids area of the St. Marys River. The goal of our study was to evaluate physical and ecological responses to the restoration of the Little Rapids area. Extensive habitat and biological data were collected prior to restoration (2013 and 2014), and after restoration (2017 and 2018). Measured parameters included total suspended solids, current velocity, benthic macroinvertebrates, and larval, juvenile, and adult fishes. Total suspended solids stayed low (<4 mg/L) following restoration, with the exception of a single construction‐related event. Pre‐restoration data indicated that all measured velocities were below the target flow rate of 0.24 m/s, whereas 70% of the measured habitat was above the target flow post‐restoration. Abundance and richness of benthic macroinvertebrates were reduced following restoration (>90% reduction). We observed a 45% increase in richness of larval fish 2 years after restoration and a 131% increase in catch per unit effort. For adult fishes, the proportion of individuals with a preference for fast‐moving waters increased from 1.5 to 45% in the restored area, and from 7 to 15% upstream of the restored area; a similar response was observed for lithophilic spawners. The physical and biological conditions of the Little Rapids improved and resembled conditions typical of rapids habitat extent in other areas of the river and other systems.
