History, Conservation and Management of Adfluvial Brown Trout Stocks in Finland

Syrjänen, Jukka; Vainikka, Anssi; Louhi, Pauliina; Huusko, Ari; Orell, Panu; Vehanen, Teppo

doi:10.1002/9781119268352.ch28

Cited by 9 publications

(11 citation statements)

References 62 publications

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“…The numbers of returning anadromous S. trutta has declined over recent decades in many parts of north‐western Europe (Ferguson et al ., ; Rasmussen et al ., ). Similarly, lacustrine–adfluvial S. trutta have declined in some countries including Finland (Syrjanen et al ., ) and Switzerland (Gafner & Meyer, ). The sustained nature of these declines means that genetic changes have probably occurred in response to changes in fitness and thus natural selection.…”

Section: Direct and Evolutionary Effects Of Environmental Changes On mentioning

confidence: 99%

“…Since outlet rivers have more often been modified by damming, drainage etc ., than inlet ones, allacustrine populations have been adversely affected. For example, in Finland allacustrine populations are mostly extinct or extremely endangered (Syrjänen et al ., ). Anadromous S. trutta are found in western Europe from the Mondego River in central Portugal (Caballero Javierre et al ., ) northwards to Scandinavia and the Cheshkaya Gulf in north‐western Russia, including Iceland and the Baltic Sea (Klemetsen et al ., ), although natural stocks in Finnish and Polish rivers have largely been lost (Dębowski, ; Kallio‐Nyberg et al ., ; Soininen et al ., ).…”

Section: Introductionmentioning

confidence: 97%

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Anadromy, potamodromy and residency in brown trout Salmo trutta: the role of genes and the environment

Ferguson

Reed

Cross

et al. 2019

Journal of Fish Biology

153

176

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Brown trout Salmo trutta is endemic to Europe, western Asia and north‐western Africa; it is a prominent member of freshwater and coastal marine fish faunas. The species shows two resident (river‐resident, lake‐resident) and three main facultative migratory life histories (downstream–upstream within a river system, fluvial–adfluvial potamodromous; to and from a lake, lacustrine–adfluvial (inlet) or allacustrine (outlet) potamodromous; to and from the sea, anadromous). River‐residency v. migration is a balance between enhanced feeding and thus growth advantages of migration to a particular habitat v. the costs of potentially greater mortality and energy expenditure. Fluvial–adfluvial migration usually has less feeding improvement, but less mortality risk, than lacustrine–adfluvial or allacustrine and anadromous, but the latter vary among catchments as to which is favoured. Indirect evidence suggests that around 50% of the variability in S. trutta migration v. residency, among individuals within a population, is due to genetic variance. This dichotomous decision can best be explained by the threshold‐trait model of quantitative genetics. Thus, an individual's physiological condition (e.g., energy status) as regulated by environmental factors, genes and non‐genetic parental effects, acts as the cue. The magnitude of this cue relative to a genetically predetermined individual threshold, governs whether it will migrate or sexually mature as a river‐resident. This decision threshold occurs early in life and, if the choice is to migrate, a second threshold probably follows determining the age and timing of migration. Migration destination (mainstem river, lake, or sea) also appears to be genetically programmed. Decisions to migrate and ultimate destination result in a number of subsequent consequential changes such as parr–smolt transformation, sexual maturity and return migration. Strong associations with one or a few genes have been found for most aspects of the migratory syndrome and indirect evidence supports genetic involvement in all parts. Thus, migratory and resident life histories potentially evolve as a result of natural and anthropogenic environmental changes, which alter relative survival and reproduction. Knowledge of genetic determinants of the various components of migration in S. trutta lags substantially behind that of Oncorhynchus mykiss and other salmonines. Identification of genetic markers linked to migration components and especially to the migration–residency decision, is a prerequisite for facilitating detailed empirical studies. In order to predict effectively, through modelling, the effects of environmental changes, quantification of the relative fitness of different migratory traits and of their heritabilities, across a range of environmental conditions, is also urgently required in the face of the increasing pace of such changes.

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Section: Direct and Evolutionary Effects Of Environmental Changes On mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Anadromy, potamodromy and residency in brown trout Salmo trutta: the role of genes and the environment

Ferguson

Reed

Cross

et al. 2019

Journal of Fish Biology

153

176

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“…This drainage has been particularly intensive in Finland, where 4.7 Mha of peatlands and 1.3 Mha of mineral soil sites have been drained, mostly in the 1960s–1970s (Vaahtera et al, 2018). Thus, waters enriched in organic matter are widespread (Nieminen et al, 2021), and declining water quality is a serious threat to the survival of several fish species, and even to the success of restoration efforts (Marttila et al, 2019; Syrjänen et al, 2017). The results here reveal complex relationships with the detrimental carryover effects of organic matter, but better understanding of the causal links requires both laboratory experiments and field studies in the future (Álvarez & Nicieza, 2005).…”

Section: Discussionmentioning

confidence: 99%

Carryover effects of environmental stressors influence the life performance of brown trout

et al. 2023

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Carryover effects of environmental stressors occur when experiences of the environment in earlier life stages or seasons influence the performance of individuals later in life. These can be especially critical for species that have diverse developmental transition periods in their life cycle, such as salmonid fish. Sublethal changes in metabolism, size, or growth experienced in early life stages may have a long‐lasting effect on the subsequent life performance of these species, but very few studies have formally tested these changes in relation to environmental stressors. Here, we investigated whether different types of fine sediment result in carryover effects that change the life performance of migratory brown trout. First, we manipulated the early habitat conditions of brown trout through the life stages from egg to fry by incubating them in varying substrate treatments (i.e., gravel without added sediment, gravel with added fine sand, and gravel with added organic matter). Exposure to fine sediment during early development had serious effects on the metabolism, size, escape responses, timing of emergence, and potential survival of early life stages. These carryover effects were persistent and remained present over the critical life shift from relying on parentally provided resources as immobile eggs to independent exogenous feeding as parr. Second, fish were relocated as parr to either their original or different treatment environments and their metabolism, size, and growth were reanalyzed. The effects of environmental stress were observed later in their life cycle when fry from the gravel treatment were relocated to sand or organic‐rich treatments. These were found to be significantly smaller in size and had a higher metabolic rate than fry maintained in their original treatment environment. Together, our study experimentally demonstrated that the carryover effects of environmental stressors experienced in early stages may influence the fitness outcomes of migratory fish later in life. We suggest that sublethal environmental stressors should be better considered in restoration schemes and management strategies to reverse the current trend of declining salmonid populations.

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“…However, human actions, such as poorly managed fishing, hydropower developments, and environmental degradation have dramatically affected brown trout populations. Consequently, wild brown trout populations in Eastern Fennoscandia are considered endangered (Kaukoranta et al., 1998; Rassi et al., 2010; Syrjänen et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Ten large lake basins in Eastern Fennoscandia that support adfluvial brown trout populations (Khalturin, 1971; Syrjänen et al., 2017) are located either in Finland or in northwest Russia or shared between the two countries. The Lake Pyaozero Basin is a transborder basin of the latter type that is located south of the Arctic Circle in the Green Belt of Fennoscandia (Ministry of Environment, 2014) (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Fish know no borders—Implications of the genetic structure and mixed‐stock composition to cross‐border management of adfluvial brown trout

Huusko,

Nikula,

Tanhuanpää

et al. 2023

Fisheries Management Eco

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Effective management of migrating fish stocks requires an understanding of population structure and each stock's contribution to the fishery. Water bodies spanning across national borders pose a particular challenge. We investigated the genetic structure of 13 adfluvial brown trout populations from natal rivers and conducted a genetic mixed‐stock analysis of brown trout from the cross‐border Lake Pyaozero Basin in eastern Fennoscandia, using 16 microsatellite loci. Our analysis revealed a clear genetic structure of three distinct geographic groups, consisting of river‐specific populations. The Western and Southern groups, which included 11 rivers, contributed over 90% to the mixed stock in the lacustrine rearing area. This mixed stock of several river‐specific subpopulations renders poorly managed fishing in the area a significant threat to the entire native adfluvial brown trout population complex.

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History, Conservation and Management of Adfluvial Brown Trout Stocks in Finland

Cited by 9 publications

References 62 publications

Anadromy, potamodromy and residency in brown trout Salmo trutta: the role of genes and the environment

Anadromy, potamodromy and residency in brown trout Salmo trutta: the role of genes and the environment

Carryover effects of environmental stressors influence the life performance of brown trout

Fish know no borders—Implications of the genetic structure and mixed‐stock composition to cross‐border management of adfluvial brown trout

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