Lake survival of hatchery and pre-stocked pond brown trout, Salmo trutta L.     

T. HESTHAGEN  B. O. JOHNSEN 《Aquaculture Research》1989,20(1):91-95

Abstract. A comparison was made of lake survival, after 2 years, of hatchery and pre-stocked pond brown trout, Salmo trutta L., (age 0+) in two small mountain lakes in south-central Norway, one which contained a resident population of brown trout. There was a significantly higher recapture of pond fish in both lakes. The mortality rate for the stocked fish was significantly higher in the lake which contained a resident population of brown trout. The competitiveness of the stocked fish is discussed in relation to foraging success, predation and stress.  相似文献   

Recaptures and resource use of native and non-native brown trout, Salmo trutta L., released in a Norwegian lake     

J.H L'ABÉE-LUND  A. LANGELAND 《Fisheries Management and Ecology》1995,2(2):135-145

Abstract Rate of recapture (gill netting), habitat use, and diet of three strains of stocked brown trout, Salmo trutta L., were compared with resident brown trout in a Norwegian lake. The strains originated from an alpine lake, from a boreal lake, and from the native brown trout population in the lake. Overall recapture rate was 5–8% for all strains. The low recapture rate could be due to the relatively small size at stocking; mean fish length varied between 13.1 and 14.5 cm with strain and stocking method. Two years after release, the frequency of the different strains decreased from about 12% in the first year to stabilize at about 1%. The alpine strain showed the highest overall recapture rate, whereas the native strain was recaptured at an intermediate rate. The overall recapture rate of scatter-planted brown trout was higher than that of spot-planted brown trout. Immediately after being stocked, introduced fish ate less and had a less-varied diet than resident trout; however, stocked fish adopted a natural diet within the first summer. The distribution of trout between the pelagic and the upper epibenthic habitat was similar for both the resident and the stocked brown trout. Results indicate that the habitat use of stocked brown trout is adaptive and becomes similar to that of indigenous fish.  相似文献   

Response of resident brown trout, Salmo trutta L., and rainbow trout, Oncorhynchus mykiss (Walbaum), to the stocking of hatchery-reared brown trout     

S. Weiss  & S. Schmutz 《Fisheries Management and Ecology》1999,6(5):365-376

Two strains of hatchery-reared adult brown trout, Salmo trutta L., [208–334 mm total length (TL); n =  591] were individually marked and released into a limestone stream. The estimated survival after one month (86%; n =  508) was comparable to that for resident brown trout and rainbow trout, Oncorhynchus mykiss (Walbaum), (89%; n =  771), but declined to 14% ( n =  83) after 8 months compared with 52% ( n =  451) for resident trout. The movement of resident trout out of stocked stretches was higher (14%) than from control sites (5%), but the population size in both individual sites and the overall study area were unaffected. The growth of resident brown trout was unaffected by stocking, but rainbow trout showed lower growth rates in stocked versus unstocked stretches both one and 8 months after stocking ( P <  0.002).  相似文献   

Competitive exclusion of brown trout Salmo trutta L., by rainbow trout Oncorhynchus mykiss Walbaum, in lake tributaries, New Zealand     

D. Scott  & J. R. Irvine 《Fisheries Management and Ecology》2000,7(3):225-237

Spawning runs of brown trout Salmo trutta L., and rainbow trout, Oncorhynchus mykiss Walbaum, were compared in three tributaries of two lakes for timing, numbers and redd characteristics. Redd characteristics for the two species in four other streams were examined. No significant differences in redd characteristics between the two species were observed, but in all lake tributaries the possibilities of superimposition of spring spawning rainbow trout on redds of brown trout were examined. A common feature was the high ratio of numbers of spawners to the area of preferred spawning gravel, and it was concluded that in the lake tributaries, superimposition resulted in increased mortality of brown trout eggs, and in one case elimination of the brown trout population. Management possibilities for control of the species proportions in comparable situations are discussed.  相似文献   

Factors influencing the yield of brown trout, Salmo trutta m. lacustris L., in northern Finnish lakes     

T. VEHANEN 《Fisheries Management and Ecology》1995,2(2):121-134

Abstract Lake-to-lake variation in brown trout, Salmo trutta m. lacustris L., yield from stocking was examined in 34 lakes in northern Finland. The trout were mainly stocked as 2–3-year-old fish. Catch statistics were compiled with information on water quality, water level fluctuations, fishing effort and lake geomorphology. Absolute brown trout yields (kgha^-1) increased with increasing stocking rate, but there was an indication of non-linearity at higher stocking densities. Relative yields (kg per thousand trout released) were highest at low stocking rates. Stepwise multiple regression analysis was used to determine the best predictive model for lake-to-lake variability in brown trout yields. Seventeen measured regressands were used initially, and then replaced with scores obtained in a principal component analysis of highly correlated water quality variables and species-specific fish yields. Three major determinants of brown trout yields in these lakes were found in both analyses: fish community, stocking rate and fishing effort. Brown trout yields from stocking were higher in lakes with proportionally high yields of vendace or vendace and whitefish and proportionally low yields of pike.  相似文献   

Sea-ranching of brown trout, Salmo trutta L.     

N. JONSSON  B. JONSSON  and L.P. HANSEN 《Fisheries Management and Ecology》1994,1(1):67-76

Abstract  In total, 8211 1-year-old and 14839 2-year-old hatchery-reared brown trout, Salmo trutta L., from 11 stocks were released at the mouth of the River Imsa, southwestern Norway. The recapture rates and total estimated yield were higher for 2- than 1-year-old trout, although recapture rates varied between years of release and stocks. The recapture rate increased with mean individual weight at time of release. Total estimated yield from the individual groups of 1+ trout ranged from 2 to 20 kg per 1000 trout released and for 2+ trout between 11 and 250 kg per 1000 fish released. In all cases, yields were lower than the economic break-even yield. Most fish were recaptured the year of release (89.2% of 2+ and 76.2% of 1+ trout). Almost 31% of the recaptures were caught at sea and 69% in fresh water; 95.8% of the latter were taken in the River Imsa trap.  相似文献   

Brown trout, Salmo trutta L.: a new species for intensive marine aquaculture     

F. KRIEG  E. QUILLET  B. CHEVASSUS 《Aquaculture Research》1992,23(5):557-566

Abstract. Strains of two salmonid species, brown trout, Salmo trutta L., and Atlantic salmon, Salmo salar L., were compared for the purpose of marine aquaculture. Survival rate, growth and sexual maturation rate were investigated. Brown trout performances were good and allowed for intensive production.  相似文献   

Reduction of brown trout, Salmo trutta L., salmon, S. salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), smolt bycatches in eel pound nets     

C. DIEPERINK  & P.C. RASMUSSEN 《Fisheries Management and Ecology》1997,4(3):189-197

Two types of bycatch reduction devices (BRDs) were tested in the Randers Fjord, Denmark, aimed at deflecting the surface-oriented smolts of brown trout, Salmo trutta L., salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), before they became trapped, while retaining the catches of eel, Anguilla anguilla (L.). The methods tested were: a) placing a floating guard net between the wings; and b) submerging the pot net (i.e. last enclosure before fyke net) 55–100 cm below mean sea level. After each haul the pound net-setups were changed from the control to one of the types of BRD, and vice versa. Both methods significantly reduced the bycatch of brown trout smolts, while catches of legal-sized eels were not affected. Submerging the pot net reduced smolt catches of all species; mean reductions were 91.1% for brown trout, 74.5% for rainbow trout, and 86.1% for salmon.  相似文献   

Distribution of genetic variation in brown trout, Salmo trutta L., in Scotland     

A. B. STEPHEN  B. J. McANDREW 《Aquaculture Research》1990,21(1):47-66

Abstract. A total of 1680 brown trout, Salmo trutta L., from 63 different localities in Scotland were sampled and examined for 34 loci. Thirteen loci were polymorphic in one or more populations. The mean observed heterozygosity for wild populations ranged from 0.0 to 8-9% (x=4.5%) in the same range as previous studies on this species. Within drainage studies and gene diversity analysis confirms that a large proportion (33%) of total gene diversity was distributed between populations. The Ldh-5(100) allele was common in Scottish populations and its distribution would fit the hypothesis that this allele was indicative of an ancestral trout population in Scotland before the invasion of trout characterized by the Ldh-5(90) allele. The results have important implications for the management of the brown trout genetic resource.  相似文献   

Feeding by hatchery- and pond-reared brown trout, Salmo trutta L., fingerlings released in a lake and in a small stream     

B. O. JOHNSEN  O. UGEDAL 《Aquaculture Research》1990,21(2):253-258

Abstract. Fingerling (O+) brown trout, Salmo trutta L., pond-reared on natural food or hatchery-reared on artificial food started feeding immediately following their release into a lake or a stream. There was no difference in feeding ability between the hatchery- and the pond-reared fish.  相似文献   

Density-dependence of growth characteristics and maturation in stream-dwelling resident brown trout, Salmo trutta, in Serbia     

P. D. SIMONOVI&#;  & V. P. NIKOLI&#; 《Fisheries Management and Ecology》2007,14(1):1-6

Abstract  Breakpoints in both length and weight that represent the onset of first maturation, revealed that growth and maturation were correlated with density-related parameters in stream-dwelling resident brown trout, Salmo trutta L., from nine different rivers in Serbia. The determination of density dependence of growth is not simple, as both river width and depth, as single variables of habitat and relative biomass, and density were not significantly correlated with breakpoints. The significant relationship between breakpoints and the mean weight of brown trout ( x _p) suggests that differences in breakpoints were inversely related to brown trout density. The implications of density dependence for management of streams holding resident brown trout are discussed.  相似文献   

Dispersion of stocked brown trout, Salmo trutta L., and landlocked salmon, Salmo salar L., from stocking sites in Lake Oulujärvi, Finland     

T. VEHANEN  P. HYVÄRINEN  & J. ASPI 《Fisheries Management and Ecology》1998,5(3):177-188

Movement and recaptures of two hatchery-reared brown trout, Salmo trutta L., stocks and landlocked salmon, Salmo salar L., released at different sites in regulated Lake Oulujärvi, were studied in relation to release site. Five groups of fish from each stock were released in approximately equal numbers. Most of the fish released in June and July were recaptured within 3 months, whereas the majority of the fish released in early winter (October and November) were caught the following spring, about 7–9 months after stocking. The release site had a significant effect on recapture rate. The results showed that fishing restrictions targeted mainly at gill net fishing are needed to preserve the stocked fish from overfishing. Significantly fewer recaptures were observed from the landlocked salmon stocking compared with brown trout. The recaptures from the landlocked salmon stocking indicated more active movement and less clumping compared with the two brown trout stocks.  相似文献   

Density of brown trout, Salmo trutta L., and Atlantic salmon, Salmo salar L., parr after point and scatter stocking of fry     

E. Jokikokko 《Fisheries Management and Ecology》1999,6(6):475-486

Atlantic salmon, Salmo salar L., and brown trout, Salmo trutta L., fry were point and scatter stocked in the early part of June at densities of 63–263 fry 100 m⁻² per species in the River Viantienjoki, a small river in northern Finland, and their population densities were assessed in late summer. Both species were always stocked together in similar quantities. Point stocking was used in the first 2 years and scatter stocking in the following 2 years. In point stocking, there was no correlation between the distance from the stocking sites (maximum = 250 m) and parr density in census sites ( r = −0.013 and 0.019 for brown trout and Atlantic salmon, respectively). The stocking density of fry did not influence parr density in August by either method or by species. Stocking density explained only from 11% to 23% of the parr survival depending on the species or stocking method. The mean densities of Atlantic salmon and brown trout parr did not differ significantly from each other at any fishing site ( P > 0.05). Both point and scatter stocking appear to be suitable methods for use in small rivers. The parr densities depend more on the other factors (e.g. habitat quality) than the stocking method, and the choice between methods could be based on the time and labour available.  相似文献   

Comparison of the performance of brown trout, Salmo trutta L., and rainbow trout, Oncorhynchus mykiss (Walbaum), in a put-and-take fishery     

M. G. PAWSON 《Aquaculture Research》1991,22(2):247-257

Abstract. Stock and catch statistics for a small (5–5ha) lowland put-and-take trout fishery have been used to investigate the relative catchability of brown, Salmo trutta L., and rainbow, Oncorhynchus mykiss (Walbaum), trout. Brown trout were consistently less vulnerable to fly fishing than rainbows, and were particularly difficult to catch between mid-June and September. As a consequence, the turn-over of rainbow trout stock was more rapid than that of brown trout, but eventual recapture levels of both species were similar at around 90% of the fish stocked. In these circumstances, brown trout could be regarded as a long-term investment for fishery managers, with rainbows providing more'instant'sport.  相似文献   

Transgenerational marking of brown trout Salmo trutta f.f., using an 84Sr spike     

A. Zitek  J. Irrgeher  M. Kletzl  T. Weismann  T. Prohaska 《Fisheries Management and Ecology》2013,20(4):354-361

The maternal transmission of a naturally occurring and non‐toxic minor isotope of strontium (⁸⁴Sr) to the central otolith region of the progeny of a typical European freshwater fish species, brown trout, Salmo trutta f.f. L. was accomplished. The focus was to apply minimum doses of a non‐toxic solution at physiological salt concentration to minimise potential adverse effects on the fish. Female spawners were intraperitoneally injected with doses of 12.5 and 30.2 μg ⁸⁴Sr kg^?1 fish. Eggs were stripped and the resulting progeny were reared in a hatchery for about 1 year before sampling the otoliths. Strontium isotope ratios in the otoliths of the offspring were measured by cross‐sectional line scans using laser ablation‐multiple collector‐inductively coupled plasma mass spectrometry (LA‐MC‐ICPMS). Otolith cores of marked juveniles showed a significantly elevated ⁸⁴Sr/⁸⁶Sr ratio compared with control fish and to otolith regions created after hatching. Mass marking of cohorts of progeny from individually spiked brown trout with Sr isotopes is therefore possible for dispersal and migration studies without the necessity of handling eggs and applying other larval marking methods like immersion.  相似文献   

Assessment of movements of resident stream brown trout, Salmo trutta L., among contiguous sections of stream     

J. H. Knouft  J. R. Spotila 《Ecology of Freshwater Fish》2002,11(2):85-92

Abstract – The present authors studied the movements of resident stream brown trout, Salmo trutta L., in Valley Creek, Chester County, Pennsylvania, USA, using mark-recapture techniques as well as radio telemetry. The novel characteristic of this study is that the entire stream was sampled during recapture, thus minimizing the possibility of bias during this portion of the analysis. The authors tagged 627 trout between June and September, 1995, and made 94.6% of recaptures in December, 1995, and 98.5% of recaptures in March, 1996, within 800 m of the initial tagging sites. They also implanted six trout with radio transmitters and made 94.6% of contacts within 800 m of the initial implantation sites. The data, which were pooled from mark-recapture and radio telemetry studies, show that 95.5% of all recaptures and contacts were within 800 m of initial tagging sites. These results, derived from complete stream sampling, support previous studies indicating that a high percentage of resident stream salmonids remain in the same area of stream throughout the year.  相似文献   

Survival and distribution of pond- and hatchery-reared 0+ brown trout, Salmo trutta L., released in a Swedish stream     

I. NÄSLUND 《Aquaculture Research》1992,23(4):477-488

During 1985-88, a total of 17500 under-yearling (0+) brown trout. salmo trutta L., were released in Låktabäcken Creek in Swedish Lapland. Of these, 15500 had been reared in a pond adjacent to the creek during their first summer, where they fed on natural prey. The other 2000 were conventionally reared hatchery fish fed dry food pellets. All fish were released in the autumn (size 6O-70mm) at the confluence of the pond outlet and the creek. Electrofishing revealed that the stocked fish gradually spread downstream from the point of release at the expense of the resident wild trout population. In 1989, stocked fish accounted for 70-90% and 30-50% of the trout population in the upper and lower stretches of the creek respectively. No long-term changes in total trout densities or standing crop occurred as a result of stocking. First-year survival of fish released in the creek varied between 15 and 30% over the 4 years. After 3 years, 5% of the stocked fish remained in the creek. Planted fish grew less rapidly than wild fish during the first year in the creek. Pond fish had a higher survival rate than hatchery fish and showed a greater propensity to disperse from the point of release.  相似文献   

Cardiac disorders in farmed adult brown trout, Salmo trutta L.     

C Mercier  J Aubin  C Lefrançois  G Claireaux 《Journal of fish diseases》2000,23(4):243-249

During summer in Brittany, France, sea farmed brown trout, Salmo trutta L., regularly experience a high mortality rate which is associated, at least in part, with cardiac disorders (aneurysms and infarcts). The present study is preliminary to a more extensive research programme, the objective of which is to determine to what extent the physiological performance of the cardiovascular system of brown trout is affected by the environmental conditions the fish experience in farm cages. We conducted a 2-week in situ experiment during which the heart rate of eight sea water acclimatized individuals was telemetered using acoustic tags. During the experimental period, water temperature ranged from 16.0 to 17.6 °C. Water oxygen saturation was above 80% at all times and salinity was very high (35.5‰) but stable. Although they were unfed and not active, seven of out the eight tagged animals displayed near maximum heart beat frequencies, which ranged between 83 and 98 beats per minute (bpm). On the other hand, the eighth animal exhibited medium-range heart rates (50–70 bpm). Using phase delay maps, we established that the maximum heart rate of brown trout at 17 °C was in the range of 96–100 bpm. This result suggests that in our experimental conditions, the heart rate of most of our inactive fish was between 85 and 100% of maximum myocardial performance. We hypothesize that the cardiac failures observed in brown trout during summer are most likely a result of strenuous workloads imposed on the cardiovascular system by a combination of elevated temperature, high salinity and possibly season-related decreased hypo-osmoregulatory abilities.  相似文献   

Feeding by hatchery-reared brown trout, Salmo trutta L. released in lakes     

B. O. JOHNSEN  O. UGEDAL 《Aquaculture Research》1989,20(1):97-104

Abstract. Shortly after their release in two Norwegian lakes (3 hours to 3 weeks), hatchery-reared brown trout, Salamo trutta L., yearlings were recaptured, and their feeding was compared with that of wild brown trout. Investigations were conducted during three different periods (June, August and September). In all three periods most of the hatchery-reared fish started feeding immediately after their release. The amounts of exuviae from Ephemeroptera larvae and Chironomidae pupae found in the stomachs of hatchery-reared trout decreased with time, indicating that their feeding habits were influenced by a learning process. However, within one week of their release, hatchery trout appeared to be feeding on wild prey as well as did wild fish.  相似文献   

Migratory behaviour of brown trout, Salmo trutta L: importance of genetic and environmental influences   总被引：1，自引：1，他引：0  

I. Näslund 《Ecology of Freshwater Fish》1993,2(2):51-57

Lake Storvindeln in northern Sweden supports a population of fast-growing lake-run brown trout. Spawning and early rearing take place in the River Vindelälven, while most growth occurs in the lake (piscivory). A smaller tributary to the lake, Låktabäcken Creek, holds a resident, early maturing, short-lived brown trout population, although no migratory barriers have existed since 1947. To establish a lake-run trout population, fry from the migratory R. Vindelälven stock were introduced into the creek during 1985–1991. Introduced trout descended to the lake prior to maturing. As a result of the introduction, large adult trout returned from L. Storvindeln to the creek to spawn in 1991 and 1992; i. e., the introduced trout were able to complete a migratory life cycle. Genetic factors appeared to have a primary influence on the predisposition to migrate in this case, and it is suggested that migratory populations rarely develop from strictly resident ones.  相似文献