Interpopulation variation in male parr maturation of anadromous brown trout (Salmo trutta) in Norway

1990 ◽  
Vol 68 (9) ◽  
pp. 1983-1987 ◽  
Author(s):  
Jan Henning L'Abée-Lund ◽  
Arne Johan Jensen ◽  
Bjørn Ove Johnsen
Keyword(s):  
Fresh Water ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Mature Male ◽  
Good Growth ◽  
Effective Population ◽  
Poor Growth ◽  
Total Length ◽  
Mature Male Parr ◽  
Smolt Age

We studied male parr maturation in anadromous brown trout in nine Norwegian rivers. Mean age at maturity increased from 1.5 years in southern populations to 5.2 years in northern populations, but the latitudinal correlation was not significant. Mean age of male parr at maturity was negatively correlated with mean total length of 0- and 1-year-old parr. The proportion of mature male parr varied between 0.06 and 0.6 among populations, and was positively correlated with mean total length of 0- and 1-year-old parr. The proportion of mature male parr decreased significantly with increasing mean smolt age of males. This indicates that in populations with relatively poor growth in fresh water (i.e., high smolt age) males mainly spawn as sea-run migrants, whereas in populations with relatively good growth in fresh water the mature male parr potentially contribute twice to the genetic makeup of the population, further increasing the effective population size.

Probability of First Sexual Maturation of Male Parr in Wild Sea-run Brown Trout (Salmo trutta) Depends on Condition Factor 1 yr in Advance

1994 ◽  
Vol 51 (9) ◽  
pp. 1920-1926 ◽  
Author(s):  
Torgny Bohlin ◽  
Claes Dellefors ◽  
Ulo Faremo
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Condition Factor ◽  
Mature Male ◽  
Small Stream ◽  
Late Autumn ◽  
Passive Integrated Transponders ◽  
Brown Trout Salmo Trutta ◽  
Mature Male Parr ◽  
Electric Fishing

In three years, in late autumn, underyearling wild sea-run brown trout (Salmo trutta) in a small stream were captured with electric fishing and tagged with microchips (passive integrated transponders). They were recaptured during the following season either as migrating smolts in a trap or by electric fishing in the stream just after the migration period and during spawning (late autumn). At spawning, they were distinguished as sexually mature male parr or immature juveniles. The smolts were longer and heavier at tagging than the mature male parr and the immature parr, which were similar in initial length and weight. The mature male parr had a significantly higher condition factor at tagging than the immature parr. The probability of parr maturation was positively associated with initial condition factor but not with initial body length. Growth of mature male parr and immature parr was similar in the early season but higher for immature parr in the late season. The result indicated that the choice of strategy was made earlier in life than previously recognized.

Significance of Mature Male Parr in a Small Population of Atlantic Salmon (Salmo salar)

1989 ◽  
Vol 46 (6) ◽  
pp. 928-931 ◽  
Author(s):  
Jan Hennsng L'abée-Lund
Keyword(s):  
Atlantic Salmon ◽  
Population Size ◽  
Effective Population Size ◽  
Salmo Salar ◽  
Small Population ◽  
Mature Male ◽  
Effective Population ◽  
Atlantic Salmon Salmo Salar ◽  
Mature Male Parr

The spawning population of Atlantic salmon, Salmo salar, (mature male parr and adults (anadromous salmon)) were assessed in the River Baevra, central Norway, when the river was treated with rotenone in November 1986. The spawning population of adults consisted of 15 males and 19 females. The spawning population of males consisted of 167 mature male parr per adult male. The effective population size of adults was small; Na = 33.5 individuals. The presence of mature male parr theoretically increased the effective population size to Na = 71.7 individuals. This increase indicated that mature male parr brought the effective population size above a recommended minimum (Na = 50) to ensure long term viability.

Prey Fish Dynamics and Salmonine Predator Growth in Lake Ontario, 1978–84

1987 ◽  
Vol 44 (S2) ◽  
pp. s390-s403 ◽  
Author(s):  
Robert O'Gorman ◽  
Roger A. Bergstedt ◽  
Thomas H. Eckert
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Coho Salmon ◽  
Causal Relation ◽  
Lake Ontario ◽  
First Year ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Poor Growth ◽  
Young Of The Year

The size of hatchery-reared brown trout (Salmo trutta) and coho salmon (Oncorhynchus kisutch), 1 yr after release in Lake Ontario, declined when the stocking of salmonines was increased between 1978 and 1984. The principal prey species, alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax), failed to show the expected, predator-induced downturn in abundance. Instead, rainbow smelt remained moderately abundant and alewives very abundant. During this period, alewife year-classes were small, survival of yearling alewives was poor, growth of young-of-the-year of both alewives and rainbow smelt was slow (growth of most older alewives ceased), and rainbow smelt numbers gradually increased (the much larger alewife population presumably buffered older rainbow smelt from predation by large piscivores). When adult alewife numbers were halved by a winter die-off, the subsequent year-class of alewives was large and growth of brown trout during their first year in the lake increased. This suggested a causal relation between abundance of young alewives and brown trout growth. In the first year coho salmon were at liberty, their growth was related to abundance of young-of-the-year alewives; in their second year it was related to the abundance of yearling alewives and the condition of adult alewives. We hypothesize that abundant adult alewives suppressed production of young-of-the-year fish (necessary prey for salmonines during their first year in the lake) through competition for limited zooplankton production, and thus impeded the transfer of energy from the lowest trophic level to young salmonine predators.

Spatial and temporal genetic differentiation and effective population size of brown trout (Salmo trutta, L.) in small Danish rivers

2005 ◽  
Vol 6 (4) ◽  
pp. 615-621 ◽  
Author(s):  
Lasse F. Jensen ◽  
Michael M. Hansen ◽  
Jens Carlsson ◽  
Volker Loeschcke ◽  
Karen-Lise D. Mensberg
Keyword(s):  
Genetic Differentiation ◽  
Population Size ◽  
Effective Population Size ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Effective Population ◽  
Brown Trout Salmo Trutta

Genetic monitoring of supportive breeding in brown trout (Salmo trutta L.), using microsatellite DNA markers

2000 ◽  
Vol 57 (10) ◽  
pp. 2130-2139 ◽  
Author(s):  
Michael M Hansen ◽  
Einar E Nielsen ◽  
Daniel E Ruzzante ◽  
Carmen Bouza ◽  
Karen-Lise D Mensberg
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Allelic Diversity ◽  
Reference Population ◽  
Randomization Test ◽  
Population Bottlenecks ◽  
Effective Population ◽  
Supportive Breeding ◽  
Statistical Procedures ◽  
Brown Trout Salmo Trutta

Stocking with offspring of local wild fish, so-called supportive breeding, is often advocated as an alternative to stocking domesticated fish. However, it is important to ensure that supportive breeding does not result in inbreeding and loss of genetic variability. We analysed eight microsatellite loci in samples of wild and hatchery-reared brown trout (Salmo trutta) from three populations subject to supportive breeding. For calibrating statistical procedures, we included two test samples of reared offspring for which the precise number of parent fish was known and a sample from a further wild reference population. Three different statistical procedures were used to detect population bottlenecks and loss of variability: (i) a randomization test for comparing allelic diversity between samples; (ii) estimates of effective number of breeders from gametic-phase disequilibrium; and (iii) a test for assessing population bottlenecks based on detecting deviations from mutation-drift equilibrium. All three procedures were useful but they also exhibited different strengths and limitations, with the test for population bottlenecks probably being the single most useful procedure for routine monitoring. In two populations subject to supportive breeding, there were strong indications of reduced effective population sizes, and significant genetic differentiation was observed between different samples from the same population.

Sign in / Sign up

Export Citation Format

Share Document