大西洋鲑的染色体核型

采用体内注射小牛血清、PHA培养法，取鱼体肾细胞经空气干燥法制备大西洋鲑（Salmo salar)的染色体玻片，并进行核型分析。试验结果表明：大西洋鲑的染色体数目为2n=56，其核型为18m＋38t，臂数NF：74。     

Population structuring in Atlantic salmon (Salmo salar): evidence of genetic influence on the timing of smolt migration in sub-catchment stocks

Abstract –  We compared timing of smolt migration for two populations of naturally spawned Atlantic salmon, Salmo salar , originating from an upper catchment (River Tummel) and a lower catchment (River Almond) tributary of the River Tay, Scotland. Smolts from the upper tributary began migration earlier than those from the lower tributary. On both occasions when fry derived from River Isla (lower tributary) stock were transferred to a location in the upper catchment, smolt migration was later than for native fish. Similarly, when fry from Tummel and Isla stocks were stocked in a common, upper catchment location, Isla origin fish migrated at a later date, in both of the two following smolt years. These differences are indicative of a genetic basis for the timing of smolt migration and suggestive of local adaptation. Mounting evidence points towards local genetic adaptation for the timing of expression of behaviours associated with migration. These aspects of variation should be accommodated in management theory and practices.     

No difference in survival, growth and morphology between offspring of wild-born, hatchery and hybrid brown trout (Salmo trutta)

Abstract –  We studied survival, growth and morphological characters in the offspring of native hatchery and wild-born anadromous brown trout ( Salmo trutta ) and their hybrids (wild-born female × hatchery male and wild-born male × hatchery female) in a 1-year field experiment. We also conducted laboratory studies where we examined social interactions between the offspring of the same hatchery and wild-born trout. All offspring were raised in a hatchery and nose tagged before being released into the stream. In total, 1125 individuals were released into the stream (1999) and a total of 614 individuals were recovered (2000). We found no differences in growth and survival between the offspring of hatchery, wild-born and hybrid trout. Morphology was also similar among groups, where only 38% females and 36% males were classified into the right category, which were only 12% better than random classification. In the laboratory experiment, we compared only the offspring of hatchery and wild-born trout with respect to growth, dominance, aggressiveness, feeding and activity. We found small differences between the offspring of hatchery and wild-born fish with respect to growth but this effect was not found in the field experiment. Our result suggests that the offspring of hatchery trout and hybrids between hatchery and wild-born trout performed equally well to the offspring of wild-born trout.     

Long-term changes in the sea-age at maturity and seasonal time of return of salmon, Salmo salar L., to Scottish rivers

Abstract Using catch data, changes in salmon, Salmo salar L., sea-age and seasonal return time were compared between several Scottish east coast rivers over the last 150–200 years. Parallel long-term trends were found, suggesting common influences affecting salmon at sea. Long-term associations with marine environmental factors were investigated by literature review and comparisons with an index of Icelandic sea-ice abundance. Apparent associations were shown to exist since about 1900, although the cause was not demonstrated. However, over a longer timescale, the same associations were not apparent. Unique gradual marine changes since 1900 may have resulted in perceptible associations with salmon data which may otherwise be imperceptible when short-term marine environmental variability is greater than long-term variability. Marine factors must affect salmon, but the complexity of the marine environment and controls on age at maturity and time of return mean that a retrospective analysis cannot be expected to identify the causal factors.     

Timing of spawning in cultured and wild Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in the River Vosso, Norway

Spawning time and size of wild and nonnative cultured female Atlantic salmon (Salmo salar L.) were studied in the River Vosso, Norway. Cultured immigrants were smaller, and peak spawning occurred 21 and 26 days earlier relative to wild salmon in 1991 and 1992, respectively. It was calculated that hatching and initial feeding of offspring of cultured females peaked 12 and 9 days earlier in spring 1992 and 19 and 8 days earlier in spring 1993 relative to offspring of wild females. Spawning time of the cultured salmon is similar to most Norwegian salmon populations and to cultured fish in other streams. In the River Vosso it also overlaps with that of brown trout (Salmo trutta L.), which may increase hybridization. The early time of breeding in nonnative fish indicates local adaptation in this trait in wild salmon. The consequences of early breeding of cultured fish are unpredictable in relation to spring temperatures but probably reduce their relative breeding success. The smaller size may also reduce the success of cultured females.     

Plasma and Tissue Levels of Trimethoprim in The Rainbow Trout,Salmo Gairdneri,After Absorption From Fresh and Salt Water

This is a comparative study of uptake of trimethoprim from 1) fresh water, 2) salt water after 7 days of adaption and 3) salt water without previous adaptation. The rate and extent of absorption were found to vary significantly. The salt water adapted group reached a plasma concentration of approx. 1 µg/ml after 10 h, the unadapted salt water group after 24 to 48 h and the fresh water group did not reach this concentration. The results are discussed in relation to the non-ionic diffusion theory and to the alterations taking place in euryhaline species of fish during adaptation to salt water.     

The status of host fish populations and fish species richness in European freshwater pearl mussel (Margaritifera margaritifera) streams

• 1. The status of host fish populations and fish species richness was investigated at 36 sites of 20 extant freshwater pearl mussel populations, including the drainages of the Elbe, Danube, Rhine, Weser, Aulne, Kemijoki and Tuuloma in Germany, the Czech Republic, France and Finland, by carrying out comparative electrofishings.
• 2. Brown trout (Salmo trutta f. fario) were found to be the available host fish for pearl mussels in all except one of the streams investigated with mean densities of 2861 ha^?1 (range 0–8710 ha^?1) and a mean biomass of 119 kg ha^?1 (range 0–478 kg ha^?1). Streams that had been frequently stocked with brown trout had higher trout biomass and densities of host fish than natural populations, but trout stocking had no positive effect in two of the streams investigated.
• 3. Fish species richness ranged from 2 to 16 species per stream and showed a negative correlation with host fish biomass and host fish densities. Undisturbed oligotrophic pearl mussel headwater streams usually only yielded a low number of fish species. Habitat degradation can reduce competitiveness of specialized trout and result in an increased abundance of ubiquitous or atypical species.
• 4. A link between the lack of juvenile pearl mussels and a lack of suitable host fish was only rarely observed. Functional pearl mussel populations with relatively high numbers of juveniles had significantly lower densities and biomass of host fish than pearl mussel populations without recent recruitment.
• 5. This study suggests that 0+ host fish are not necessarily required to sustain functional pearl mussel populations. Low densities of host fish can be compensated by the higher glochidia carrying capacity of older host fish with limited previous contact with pearl mussel glochidia, by the long reproductive period of mussels, and by low mortality rates of juvenile mussels during their post‐parasitic phase.

Copyright © 2005 John Wiley & Sons, Ltd.     

Protein to carbohydrate ratio in high-energy diets for Atlantic salmon (Salmo salar L.)

The effect of dietary protein to carbohydrate ratios (P/CH, weight percentage) of P34/CH21, P39/CH15 and P44/CH10 was studied in Atlantic salmon (Salmo salar L.) with respect to growth and feed conversion ratio (FCR) in one medium-scale experiment (Experiment 1) and to slaughter quality in two production scale experiments (Experiments 2A and 2B). The dietary fat was maintained at 290 g kg⁻¹ whereas the protein (fish meal) was exchanged with carbohydrate (wheat). Fish grown from approximately 1 to 4 kg were fed a restricted diet (iso-energetic on gross energy basis) or to satiation. Nitrogen, fat, starch and energy digestibilities were measured in a separate experiment. There were slight tendencies for lower growth (P = 0.06) and for higher FCRs (P = 0.06) in Experiment 1, and a slight tendency for a lower dress-out percentage in Experiments 2A and 2B (P = 0.10 and 0.20 respectively) with decreasing P/CH. The P/CH had no effect on the fat concentration of fillets, flesh colour or sexual maturation. The digestibility of starch decreased from 62.1% to 46.1% and the digestibility of energy from 84.9% to 79.5% when P/CH decreased from P44/CH10 to P34/CH21. Growth per unit digestible protein increased with decreasing P/CH. Feeding to satiation improved the growth but the FCR was higher than it was for restricted feeding. The calculated starch load per kg of fish growth increased with decreasing P/CH, whereas the effluent nitrogen decreased.     

Downstream migration of European lake trout, Salmo trutta f. lacustris L., and resident brown trout, Salmo trutta f. fario L., progeny in a Lake Constance affluent river

Abstract The local migratory behaviour of lake trout, Salmo trutta L., and resident brown trout, S. trutta L., progeny from an inflowing stream of Lake Constance was compared. No differences were detected with respect to emigration rate (3.5% and 4.2% for lake trout and resident trout, respectively), rate of residency (6.8% and 8.2% for lake trout and resident trout, respectively) and rate of survival (12.3% and 12.1% for lake trout and resident trout, respectively) one year after stocking. Some of the resident brown trout offspring became migrants and vice versa . The results indicate that the progeny of riverine brown trout contribute considerable numbers to lake trout stock.     

Genetic effects of introduced hatchery stocks on indigenous brown trout (Salmo trutta L.) populations in Spain

Abstract– To assess the levels of gene introgression from cultured to wild brown trout populations, four officially stocked locations and four nonstocked locations were sampled for one to three consecutive years and compared to the hatchery strain used for stocking. Allozyme analysis for 25 loci included those previously described as providing allelic markers distinguishing hatchery stocks and native populations. Different levels of hybridization and introgression with hatchery índividuals were detected in stocked drainages as well as in protected locations. These findings indicate that new policies for stocking and monitoring hatchery fish are needed if gene pools of wild Spanish brown trout populations are to be preserved.