J. Museth results 8
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Small larvae in large rivers: observations on downstream movement of E uropean grayling T hymallus thymallus during early life stagesNARA Subscribed
Behaviour of early life stages of the salmonid European grayling Thymallus thymallus was investigated by assessing the timing of larval downstream movement from spawning areas, the depth at which larvae moved and the distribution of juvenile fish during summer in two large connected river systems in Norway. Trapping of larvae moving downstream and electrofishing surveys revealed that T. thymallus larvae emerging from the spawn...
Emigration patterns among trout, Salmo trutta (L.), kelts and smolts through spillways in a hydroelectric damNARA Subscribed
The emigration patterns among radio‐tagged trout, Salmo trutta L., kelts ( n = 41, total length: 60–90 cm) and smolts [ n = 27, total body length (BL): 22–30 cm] in the regulated River Gudbrandsdalslågen, south‐east Norway, were studied by investigating the influence of sex (kelts) and BL (kelts and smolts) on the timing of emigration. In total, 49% of the kelts emigrated towards the hydroelectric dam shortly after spawning, w...
The history of the minnow Phoxinus phoxinus (L.) in Norway: from harmless species to pestNARA Subscribed
The causes, effects and extent of minnow Phoxinus phoxinus introductions in Norway are reviewed to assess why the introductions have had severe effects, especially where brown trout Salmo trutta is the only fish species present. The natural distribution of minnow in Norway was mainly restricted to low altitude localities in the south‐eastern part of the country and in some northern areas. The distribution area expanded conside...
Predation by brown trout: a major mortality factor for sexually mature European minnowsNARA Subscribed
Brown trout Salmo trutta in the subalpine lake, Øvre Heimdalsvatn, showed large temporal variation in the rate of predation on the introduced minnow Phoxinus phoxinus population. Minnows were found in the stomachs of brown trout between 16 and 38 cm L T . Significantly greater predation was recorded shortly after ice break at the end of June 1999, with frequencies of 9 and 20% within the L T classes 16–29·9 cm and ≥30 cm, resp...
Introduction of the European minnow into a subalpine lake: habitat use and long‐term changes in population dynamicsNARA Subscribed
Minnows Phoxinus phoxinus , studied 30 years after the first record of the species in the subalpine Lake Øvre Heimdalsvatn, Norway, ≥55 mm L T , were estimated to have densities of c . 4.7 kg ha −1 (120 000 fish) in June 1999 and 2.1 kg ha −1 (63 000 fish) in June 2000. The population was characterized by low individual growth, delayed age of maturity and lived longer when compared to values reported in a previous study in the...
Effects of Ligula intestinalis on habitat use, predation risk and catchability in European minnowsNARA Subscribed
The frequency of infection with Ligula intestinalis (Cestoda) in European minnow Phoxinus phoxinus , in a subalpine lake in Eastern Norway, did not differ between vegetated shoreline, exposed shoreline and non‐vegetated localities >50 m from the shoreline. There was no difference in the vertical distribution of infected and uninfected individuals. The frequency of infection was higher among minnows in brown trout Salmo trutta...
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