Divergence of brown trout (Salmo trutta) within glacial refugia

2000 ◽  
Vol 57 (11) ◽  
pp. 2201-2210 ◽  
Author(s):  
Núria Sanz ◽  
José-Luis García-Marín ◽  
Carles Pla
Keyword(s):  
Population Structure ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Allelic Variation ◽  
Glacial Refugia ◽  
Species Differentiation ◽  
Gene Pools ◽  
Genetic Population ◽  
Geographical Patterns ◽  
Brown Trout Salmo Trutta

The Pleistocene glaciations produced a range of changes that affected the genetic population structure of fish species. Usually, studies focused on the population structure of species in postglacial recolonized areas and less attention was devoted to species differentiation within refuge areas. Allelic frequencies for 21 polymorphic protein-coding loci were compared among 25 collections within a northwestern Iberian glacial refuge of brown trout (Salmo trutta) using adjusted frequencies for nine populations to account for introgressions with exogenous hatchery fish. The high divergence observed (FST = 0.645) and geographical patterns of allelic variation are interpreted to reflect the existence of strong population structuring among native populations of this refuge. Four major geographic groups were defined within the region: (i) in the Tajo River, (ii) in the Duero River, (iii) in the Sil River, and (iv) among Cantabrian Sea flowing rivers including present anadromous populations. These gene pools have diverged genetically and ecologically in response to climatic oscillations. Anthropogenic effects on habitat and fish populations seriously compromise their future.

Exploitation of Self-Sustaining Ontario Stream Populations of Brown Trout (Salmo trutta) and Brook Trout (Salvelinus fontinalis)

1970 ◽  
Vol 27 (6) ◽  
pp. 1087-1102 ◽  
Author(s):  
T. Lawrence Marshall ◽  
Hugh R. MacCrimmon
Keyword(s):  
Population Structure ◽  
Brown Trout ◽  
Brook Trout ◽  
Standing Crop ◽  
Salmo Trutta ◽  
Salvelinus Fontinalis ◽  
Catch Per Unit Effort ◽  
High Quality ◽  
Exploitation Rate ◽  
Brown Trout Salmo Trutta

The August standing crop of harvestable brown trout (Salmo trutta, 90%), and brook trout (Salvelinus fontinalis, 9%) in the upper Sydenham River, Ont., was estimated at 499 trout/ha (63.2 kg/ha) during 1966 and 1967. Brown trout were of age I (68%), age II (23%), and the remainder of ages III, IV, V, and XIII. Brook trout were ages I (95%) and II only.The average annual harvest by 1501 anglers was 1135 fish (64% brown, 35% brook trout) at a rate of 0.34 fish/hr. Exploitation of the preseason standing populations of brown and brook trout was 23 and 59%, respectively. Catch per unit effort from the downriver section (all brown trout of ages II–IV and mean length of 34.0 cm) averaged 0.10 at an angling pressure of 264 hr/ha. An upriver section occupied predominantly (90%) by brown trout of age I–III and mean length of 26.8 cm yielded 0.67 trout/hr at an angling pressure of 251 hr/ha.The population structure, growth, and exploitation rate of naturalized brown trout favours its use in providing continuous angling of creditable quality in heavily fished headwater streams. Coexistence of self-sustaining populations of brown and brook trout provide a sustained, high-quality mixed fishery.

Are Cultured Stocks of Brown Trout (Salmo trutta) and Rainbow Trout (Oncorhynchus mykiss) Genetically Similar to Their Source Populations?

1991 ◽  
Vol 48 (S1) ◽  
pp. 118-123 ◽  
Author(s):  
Moira M. Ferguson ◽  
Peter E. Ihssen ◽  
Julian D. Hynes
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Allelic Variation ◽  
Sampling Error ◽  
Allozyme Variation ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Brown Trout Salmo Trutta ◽  
Source Populations

The Ontario Ministry of Natural Resources (OMNR) implemented a controlled breeding program in the early 1980's with the objective of culturing fish that are genetically representative of the source populations. We describe the OMNR brookstock management plan for brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) and test its effectiveness by comparing the allozyme variation of the source fish collected from the Ganaraska River, Ontario to several descendant hatchery lines. Ancestral and descendant rainbow trout do not show significantly different allele frequencies. However, significant differences were detected in brown trout. The absence of several rare alleles in hatchery fish can be explained by sampling error rather than inappropriate propagation methods. Hatchery stocks of either species do not show reduced enzyme heterozygosity compared to wild fish suggesting that the OMNR hatchery system has been successful in retaining allelic variation during broodstock founding and propagation.

Population and family structure of brown trout, Salmo trutta, in a Mediterranean stream

2010 ◽  
Vol 61 (6) ◽  
pp. 672 ◽  
Author(s):  
Manuel Vera ◽  
Nuria Sanz ◽  
Michael M. Hansen ◽  
Ana Almodóvar ◽  
José-Luis García-Marín
Keyword(s):  
Population Structure ◽  
Brown Trout ◽  
Family Relationships ◽  
Salmo Trutta ◽  
Mediterranean Stream ◽  
Brown Trout Salmo Trutta ◽  
Limited Dispersal ◽  
Related Individuals ◽  
Low Levels ◽  
Mediterranean Trout

The physical arrangement of closely related individuals is expected to significantly influence the pattern of population genetic structure. For example, if related individuals are non-randomly distributed and included in samples, this may lead to exaggerated conclusions about genetic differentiation. In the present study, we compared population structure v. family relationships of brown trout (Salmo trutta L.) along a Mediterranean stream (Pyrenees) by using eight microsatellite loci. Results showed low levels of genetic (FST) differentiation between collections in a 6.5-km transect along the stream, and a significant correlation between genetic and geographical distance matrices, indicating a weak population structure associated with spatial distribution. Our data also indicated that geographical proximity of related individuals in the youngest (0+, 1+) cohorts probably was associated with limited dispersal of younger brown trout from spawning redds. Family relationships provided evidence, however, for movement of adult trout over distances of a few kilometres that probably contributed to the low observed differentiation. Dispersal of adult Mediterranean trout contrasts with the clustering of related older trout observed for some north European rivers and could be related to the reduced productivity in southern stream basins.

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