Comparative biology and management of Arctic and European grayling (Salmonidae, Thymallus)

Northcote, T. G.

doi:10.1007/bf00179755

Cited by 155 publications

(180 citation statements)

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“…Hence, whitefish seemed to have a restricted trophic niche, likely resulting from competitive interactions with the other two fish species. Grayling usually forage on surface insects and benthic invertebrates along the shallow lake shores (Northcote 1995), but in sympatry with brown trout, they may shift foraging habitat to deeper areas (Haugen & Rygg 1996). In our study lakes, there were no clear signs of competitive constraints on grayling as they appeared to utilise their principal littoral niche.…”

Section: Discussionmentioning

confidence: 59%

“…In some subarctic lakes, Arctic charr and whitefish coexist together with European grayling (Thymallus thymallus). All three species have a generalist feeding behaviour, but in allopatry usually prefer the littoral feeding habitat because of the higher availability of large-sized benthic prey Northcote 1995;Amundsen et al 2004). However, in sympatry, these fish species likely alter their foraging behaviour to diminish niche overlap, which otherwise could lead to competitive exclusion of the inferior species (Hardin 1960;.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal and ontogenetic shifts in the diet of Arctic charr Salvelinus alpinus in a subarctic lake

Eloranta

Kahilainen

Jones

2010

Journal of Fish Biology

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Arctic charr (Salvelinus alpinus (L.)) is a cold-adapted salmonid fish with a wide circumpolar distribution. Due to its wide fundamental trophic niche (i.e. diet and habitat use), Arctic charr can be used to study energy flow as well as competitive and predator-prey interactions in subarctic lakes. The objective of this thesis was to evaluate how the trophic niche of Arctic charr in subarctic lakes is influenced by various biotic (e.g. intra-and interspecific resource competition and predation) and abiotic (e.g. seasonality and lake morphometry) factors. Stomach contents and stable isotope analyses indicated marked between-lake and between-individual differences in Arctic charr diet and habitat use. In Saanajärvi, Arctic charr relied mainly on littoral production regardless of season or individual size, probably due to high primary production and lack of sympatric fish species in the littoral zone. In contrast, Arctic charr showed a reduced littoral reliance when the littoral trophic niche was dominated by brown trout, and an increased prevalence of piscivorous foraging when coexisting with planktivorous whitefish and benthivorous grayling. The final results from a total of 17 subarctic lakes indicated that Arctic charr shifted from littoral to a more pelagic trophic niche with increasing lake area and fish species richness. The shift of Arctic charr to a more pelagic piscivorous niche in large lakes was evidently promoted by the existence of small, planktivorous prey fish species and increased interspecific resource competition and/or predation in the littoral zone. The results demonstrate that littoral and pelagic food-web compartments in subarctic lakes can be integrated by generalist Arctic charr, but the energy flow pathways supporting this top consumer can be strongly influenced by prevailing intra-and interspecific interactions as well as by the morphometric characteristics of the lakes. The findings highlight that a comprehensive view of food-web structures is fundamental for predicting the likely responses of fish communities and subarctic lake ecosystems to potential environmental changes. Keywords: Energy flow; individual specialization; lake morphometry; littoral production; resource competition; stable isotope analysis; trophic niche. LIST OF ORIGINAL PUBLICATIONSThe thesis is based on the following original articles, which will be referred to in the text by their Roman numerals I-IV. I did most of the planning for each study and contributed to field work in I, III and IV, and to laboratory analyses in all the studies. I was responsible for the data analysis and wrote the first draft of all the papers. All co-authors made a significant contribution to planning and preparation of the final papers. IV Eloranta A.P., Kahilainen K.K., Amundsen P.-A., Knudsen R., Harrod C. & Jones R.I. 2013. Lake size and fish species richness determine resource use by top consumers in subarctic lakes. Manuscript. INTRODUCTION Food webs in lakesLakes are complex ecosystems, whose functioning is tightly connecte...

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Section: Discussionmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Seasonal and ontogenetic shifts in the diet of Arctic charr Salvelinus alpinus in a subarctic lake

Eloranta

Kahilainen

Jones

2010

Journal of Fish Biology

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“…This could result in low long-term effective population sizes and, consequently, depauperate levels of within-population T. thymallus microsatellite diversity. Mark-recapture and radio-telemetry studies support this hypothesis, as they have revealed grayling to be far less mobile than autumn spawning salmonids (Peterson, 1968;Northcote, 1995). Limited dispersal of grayling was also suggested by a recent microgeographic study within Lake Saimaa, eastern Finland, where microsatellite-based individual assignment tests were applied to investigate the genetic distinctiveness of three populations .…”

Section: Low Levels Of Genetic Diversity In T Thymallus Populations mentioning

confidence: 88%

“…Heredity (2002) 88, 391-401. DOI: 10.1038/sj/hdy/6800072 populations complete their entire life cycle in rivers or lakes (reviewed in Northcote, 1995), some grayling are adapted to a brackish environment and inhabit parts of the Baltic Sea (Nykänen and Huusko, 1999), and some limited anadromy has been reported (Mü ller and Karlsson, 1983). Although less important for commercial fisheries than many other salmonids, T. thymallus is considered culturally important as a target for sport fisheries.…”

Section: Introductionmentioning

confidence: 99%

Microsatellite data resolve phylogeographic patterns in European grayling, Thymallus thymallus, Salmonidae

et al. 2002

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“…The European grayling has always been a common species throughout Eurasia (Northcote, 1995), but many local populations are currently endangered due to human modifications of river and lake systems (Koskinen, Piironen, & Primmer, 2001). Among important impacts are habitat loss and reduced connectivity between the remaining habitats (Heggenes et al, 2006;Junge, Museth, Hindar, Kraabøl, & Vøllestad, 2014;Van Leeuwen, Museth, Sandlund, Qvenild, & Vøllestad, 2016).…”

mentioning

confidence: 99%

Habitat fragmentation has interactive effects on the population genetic diversity and individual behaviour of a freshwater salmonid fish

Leeuwen

Dalen

Museth

et al. 2017

River Research & Apps

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Sufficient genetic diversity can aid populations to persist in dynamic and fragmented environments. Understanding which mechanisms regulate genetic diversity of riverine fish can therefore advance current conservation strategies. The aim of this study was to investigate how habitat fragmentation interacted with population genetic diversity and individual behaviour of freshwater fish in large river systems. We studied a population of the long-distance migratory, iteroparous freshwater salmonid European grayling (Thymallus thymallus) in south-eastern Norway. Genotyping (n = 527) and radio-tracking (n = 54) of adult fish throughout a 169-km river section revealed three major migration barriers limiting gene flow and depleting genetic diversity upstream. Individuals from upstream areas that had dispersed downstream of barriers showed different movement behaviour than local genotypes. No natal philopatry was found in a large unfragmented river section, in contrast to strong fidelity to spawning tributaries known for individuals overwintering in lakes. We conclude that (a) upstream sub-populations in fragmented rivers show less genetic variation, making it less likely for them to adapt to environmental changes; (b) fish with distinct genotypes in the same habitat can differ in their behaviour; (c) spawning site selection (natal philopatry) can differ between fish of the same species living in different habitats.Together this implies that habitat loss and fragmentation may differently affect individual fish of the same species if they live in different types or sections of habitat. Studying behaviour and genetic diversity of fish can unravel their complex ecology and help minimize human impact.

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Comparative biology and management of Arctic and European grayling (Salmonidae, Thymallus)

Cited by 155 publications

References 85 publications

Seasonal and ontogenetic shifts in the diet of Arctic charr Salvelinus alpinus in a subarctic lake

Seasonal and ontogenetic shifts in the diet of Arctic charr Salvelinus alpinus in a subarctic lake

Microsatellite data resolve phylogeographic patterns in European grayling, Thymallus thymallus, Salmonidae

Habitat fragmentation has interactive effects on the population genetic diversity and individual behaviour of a freshwater salmonid fish

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