陆封型大西洋鲑的池塘养殖及生物学研究

对从美国缅因州格兰特湖引进陆封型大西洋鲑发眼卵,经过人工孵化、培育的3龄鱼种的生长发育、摄食、形态、生物学以及养殖环境等因素进行了观察和研究。     

陆封型大西洋鲑生物学特性与移植驯化技术

本文报道了陆封型大西洋鲑移植驯化技术及养殖生物学跟踪观察结果。通过引进陆封型大西洋鲑发眼卵，在水温3～11℃的条件下进行孵化，积温达到140～22l度日孵出仔鱼，孵化率达到85％；历经3周年流水低温育种，培育出苗种10万尾。采用强化培育，人工调控环境生态因子诱导亲鱼性成熟的方法，育出后备亲鱼5万尾，成熟亲鱼0．4万尾，成功地实现了大西洋鲑在我国全人工繁殖的研究工作。     

陆封型大西洋鲑的全人工繁殖

本文报道了陆封型大西洋鲑全人工繁殖的实验结果。 2 0 0 0年 1月从美国缅因州格兰特湖增殖站引进的陆封型大西鲑发眼卵 ,在北京房山中国水产科学研究院鲟鱼繁育技术工程中心进行了发眼卵孵化、苗种培育 ,亲鱼养成实验研究。结果表明 :引进的发眼卵经 930d ( 1 1 783度日 )培育成产卵亲鱼 ,雌、雄亲鱼成熟系数分别为 42 7%、 4 2 3% ;怀卵量为 1 0 98～ 362 1粒 /尾 (叉长 36～ 5 5cm) ,平均卵径 5 4mm (吸水膨胀前 )、 6 2mm(吸水后 ) ;平均卵重 8 5粒 /g (吸水后 )、 7 5粒 /g (吸水前 ) ;精液浓度 2 0 0亿个 /ml,精子寿命 70～ 90s,精子快速运动时间为 2 0～ 40s;个体繁殖率E (粒 )与叉长 (L)的相关公式为E =1 32 5L - 3671 8,相关系数r=0 89。受精卵在水温 6～ 1 1℃进行孵化 ,达到发眼所需积温为 2 64 5℃·d ;达到破膜所需 483℃·d ;仔鱼上浮所需 880℃·d。试验亲鱼雌、雄按 2比 1配组 ,1 0 75尾雌鱼共采卵 90 47万粒 ,受精率为 89 88%、发眼率为77 83%。产卵后 ( 3个月后 )存活率分别为雌鱼 30 % ,雄鱼 1 0 %。     

陆封型大西洋鲑发眼卵孵化和稚鱼养殖

本文报道了从美国引进的陆封型大西洋鲑发眼卵孵化和稚鱼养殖试验情况。经42天孵化，发眼卵的孵化率为81．85％，仔鱼至上浮稚鱼成活率为96．8％，稚鱼成活率为80％。     

碧流河水库陆封型香鱼生物学特性的演变

1982年碧流河水库建成后，被陆封在水库中的香鱼（Plecoglossus altivelis)经10余年适应后，其生物学特性发生了很大变化，其中一部分个体春季水温上升后暂不进入河道，而留在水库中生活，至7月份才进入河道，与刚陆封时不同，在其植物食性阶段，消化道内有大量浮游植物出现，繁殖期也由9－10月提前到8－9月，性腺发育速度明显加快，个体进一步变小。     

陆封型大西洋鲑发眼卵孵化及苗种培育试验

本首次报道了陆封型大西洋鲑发眼卵孵化技术，孵化水温3－11℃，积温达到140－221度日破膜孵出稚鱼，孵化率北京房山87．6％，黑龙江渤海81．9％，经21－28d胚后发育上浮平游开食。同时介绍了苗种培育技术和管理方法。     

陆封型大西洋鲑肌肉营养成分分析

应用生化分析方法对养殖的陆封型大西洋鲑2龄和3龄鱼肌肉中的营养成分和蛋白质中氨基酸组成及含量进行了定量分析。结果显示：2龄和3龄陆封型大西洋鲑肌肉中蛋白质含量分别为19．85％和20．20％；脂肪含量为2．74％和4．73％；水分含量为76．30％和74．74％；灰分含量为2．59％和1．95％。陆封型大西洋鲑肌肉蛋白质中含有18种氨基酸，总量分别为17．88％和18．40％，其中10种人体必需氨基酸含量为9．15％和9．96％。     

大西洋鲑肌肉营养成分分析

利用常规方法测定大西洋鲑肌肉中水分、粗蛋白、粗脂肪、灰分、粗纤维、无氮浸出物等营养成分进行分析检测。结果表明:大西洋鲑肌肉鲜样中水分含量为73.62%,粗蛋白含量为19.40%,粗脂肪含量为4.52%,灰分含量为1.93%,,无氮浸出物含量为0.53%。大西洋鲑肌肉(干样)蛋白质中含有氨基酸16种,氨基酸总量为73.69%,必需氨基酸7种,必需氨基酸总量为31.40%,鲜味氨基酸4种,鲜味氨基酸总量为30.29%,蛋白质,鲜美程度优于草鱼、白甲鱼和鳙鱼,略低于鳜鱼和黄鳝,是一种具有较高开发养殖价值的水产优良品种。     

大西洋牙鲆的生物学特性

大西洋牙鲆 (Atlanticflounder) ,主要分布于北美洲大西洋沿岸 ,是西北大西洋所产四种牙鲆中的一种较大型鱼类。为了改变我国牙鲆鱼种单一的局面 ,我们首次于 2 0 0 2年 9月 1 2日从美国GreatBayAquaculture,LLC .引进犬齿牙鲆鱼苗5 0 0 0尾试养 ,养殖 1 2个月平均体重达 5 93g     

不同地区陆封型马苏大麻哈鱼人工养殖效果比较

为探讨陆封型马苏大麻哈鱼人工养殖的可能性,对在吉林、山东、北京等地人工养殖马苏大麻哈鱼的效果进行了比较。试验结果表明,图们江陆封型马苏大麻哈鱼在土池塘和水泥池中均可以养殖,水泥池流水养殖效果较好。水泥池流水养殖24月龄试验鱼规格:吉林(368.54±101.03)g,北京(678.75±78.34)g,山东(846.21±244.81)g,3个地区养殖场出池的马苏大麻哈鱼体质量存在极显著差异(P0.01),生长速度高于野生种群。引种到山东、北京后,出池规格和单产水平比在原产地养殖明显提高。通过改善生存环境,延长适温生长期,提供良好的鲑鳟鱼饲料,国产陆封型马苏大麻哈鱼具有很高的养殖开发价值,其最佳放养密度和适宜生长水温有待于进一步研究。     

Allozyme heterozygosity and development in Atlantic salmon, Salmo salar

The development of Atlantic salmon (Salmo salar) parr was monitored during the first year in a fresh-water hatchery environment to test whether multilocus heterozygosity (computed for six allozyme loci: _s AAT-4^*, IDDH-1^*, IDDH-2^*, IDPH-3^*, _s MDH-3,4^* and_m MEP-2^*) is associated with growth (body mass, fork length) and maturity status (mature male parr). The length frequency distribution of population was unimodal in September, but was clearly bimodal by December. UMG fish tended to be more heterozygous and had higher growth rates than LMG fish. The heterozygosity of UMG fish and mature male parr (MMP) did not differ significantly but MMP showed lower growth rates than UMG. There were positive correlations between the number of heterozygotic loci and the fork length, weight or growth rates of individuals.     

Adiposity and growth of post-smolt Atlantic salmon Salmo salar L.

The long‐term adipose homeostasis seen in mammals gives rise to a ‘lipostatic’ model in which signals produced in proportion to fat stores serve to regulate energy intake. An extension of this predicts an impact of these signals on growth; downregulation of feeding in animals with increased adiposity should result in reduced growth. This was tested by monitoring fat deposition and growth in Atlantic salmon Salmo salar L. provided with feeds that differed in fat content. Salmon parr (mass c. 20 g) were fed either high‐ (H: 34%) or low‐fat (L: 22%) feeds, based on either fish (F) or vegetable (V) oils for 6 months to create groups of fish that differed in adiposity (10–12% and 5–7% body fat) at parr–smolt transformation (mass c. 130 g). Fish fed the high‐fat feeds deposited more body fat, and this was confirmed by measurement of fat concentrations in the fillet, viscera and remaining carcass. The fish were then grown‐on in sea water (c. 35 g L^?1, 8 °C, 24L:0D) for 14 weeks while being fed either high‐ or low‐fat feed formulated with fish oil to give the following treatments: HF→ H, HF→ L, LF→ L, LF→ H, HV→ H, HV→ L, LV→ L, LV→ H. Although fish exposed to the various feed treatments did not differ markedly in growth rate (SGR range 1–1.14% day^?1) over the 14 weeks of rearing in sea water, the results were in general agreement with predictions from the ‘lipostatic’ model, i.e. fish with the greatest fat reserves after the parr–smolt transformation grew more slowly than fish that were ‘leaner’ at this time. This suggests that adiposity, or ‘fatness’, may exert a negative feedback on feeding in salmon, thereby having an influence upon growth.     

Unstable release strategies in reared Atlantic salmon, Salmo salar L.

The effects of year, size, sexual maturity and release date on the probability of recapture of tagged Atlantic salmon, Salmo salar L., released from a Swedish hatchery in the Baltic Sea were examined. The probability of recapture varied among years for individuals which were juvenile when released (1988, 13.5%; 1989, 4.4%; 1990, 1.2%) or previously mature males (1988, 1.9%; 1989, 0.5%; 1990, 0.4%). Body size was positively associated with the probability of recapture in each release year for both life-history types. Inter-annual changes in recapture rates were similar for both large and small smolts. There was a significant effect of life-history type on recapture rates in 1988 and 1989, but not in 1990. There was a significant effect of release date on recapture rates in 1988 and 1990, but not in 1989. The maximum recapture rates were associated with different release dates in each year, i.e. 27 May 1988, 6 June 1989 and 21 June 1990.     

Variation of juvenile Atlantic salmon (Salmo salar) body composition along sedimentary links*

Johnston P, Bergeron NE. Variation of juvenile Atlantic salmon (Salmo salar) body composition along sedimentary links.
Ecology of Freshwater Fish 2010: 19: 187–196. © 2010 John Wiley & Sons A/S Abstract – The objective of this study was to determine the proximate body composition of juvenile Atlantic salmon along the sequence of aquatic habitat types created by longitudinal changes in the riverbed substrate of two rivers (i.e., sedimentary links units). Interesting trends in the body composition were observed but our initial hypothesis, that fish of the upstream sections have higher energy content, was nevertheless not verified. No common longitudinal pattern was detected in the body composition (water, lipid, energy density) along the studied rivers. Trends in the body constituents were different between age‐classes and rivers, whereas they were highly variable within‐ and among‐samples. There was however a common trend in the pattern of variations, with the coefficient of variations increasing in the downstream direction for almost all constituents, age‐classes and rivers. Potential abiotic and biotic factors that might have contributed to these observations are discussed.     

Lake-use by juvenile Atlantic salmon (Salmo salar L.) and other salmonids in northern Norway

Abstract– The utilization of lakes, and inlet and outlet streams by juvenile Atlantic salmon ( Salmo salar L.), brown trout ( Salmo trutta L.) and Arctic charr ( Salvelinus alpinus (L.), were investigated in 16 watercourses northern Norway, all known to inhabit salmon stocks. In lakes, fish were caught by small mesh size gill nets, while in rivers fish were caught electrofishing. In the shallow littoral (0-3 m depth) there were juvenile salmon in 15 of 19 investigated lakes, juvenile trout in 17 and juvenile charr in seven. Trout dominated significantly in numbers in the shallow littoral of seven lakes, while salmon and charr dominated in three lakes each. When trout and salmon were frequent in the shallow littoral, charr was usually not present in this habitat, but were found in the profundal zone in most of the lakes. Atlantic salmon parr utilized both shallow and deep lakes, and used both stones and macrophytic vegetation as shelter. The utilization of lakes by salmon parr seemed to be closely related to utilization of small inlet streams for spawning. In most inlet and outlet streams salmon dominated over trout in numbers, while charr were absent. This is the first documentation of lake-use by naturally occurring salmon parr in Scandinavia.     

Incidence of hybridization between Atlantic salmon, Salmo salar L., and brown trout, Salmo trutta L., in Ireland

The substantial growth of the farmed salmon industry in Europe since the 1970s has highlighted concerns regarding the genetic impact of escaped farmed salmon on wild salmonid stocks. High incidences of salmon × trout hybrids have been recorded in rivers situated near intensive salmon farming in Norway and Scotland, which may be indicative of a breakdown in reproductive isolation between salmon, Salmo salar L., and brown trout, Salmo trutta L. In the present study, salmonid fry and 0+ parr were collected from rivers in western Ireland. Allozyme and minisatellite DNA analysis were carried out on fry to determine the frequency of F1 hybrids from 10 rivers located within 38 km of salmon farms and three rivers at least 80 km from salmon farms. A total of 49 hybrids were recorded from 4135 salmonid fry (frequency = 1.2%). Mitochondrial DNA analysis showed that all hybrids arose from Atlantic salmon female × brown trout male crosses. Hybrid parr were recorded from one of the low-risk rivers (1.0%), but were present in seven out of the 10 catchments located within 38 km of salmon farms, with frequencies ranging from 0.7% to 3.1%. The results of the present survey, which represents the first extensive record of the levels of salmon-trout hybridization in Ireland, are discussed in relation to the continued growth of salmon farming in this country.     

Retention of the synthetic antioxidant butylated hydroxyanisole in Atlantic salmon (Salmo salar) fillets

Butylated hydroxyanisole (BHA) is a phenolic antioxidant that is used as a food additive, particularly in fats and oils, and it is also authorized as a feed additive in the European Union for all animal species with a maximum concentration of 150 mg kg^?1 feed (alone or in combination with ethoxyquin and/or butylated hydroxytoluene). Information on the BHA levels in food of animal origin is scarce, as is literature on the transfer of BHA from feed to animal products. Consequently, the current feeding trial was conducted under realistic rearing conditions to determine the retention of BHA in Atlantic salmon (Salmo salar) fillets. Four different concentrations of BHA in feed were tested (0, 48.5, 92.5 and 225 mg BHA kg^?1 feed), and fish were sampled after 4, 8 and 12 weeks dietary exposure, and after a 2‐week starvation period, which is representative of commercial salmon farming in Norway. The levels of BHA in salmon fillets were fairly dose dependent during the feeding period. A steady state in fillet residues was reached after 4 weeks of administration of BHA. After the 2‐week withdrawal period, BHA was not detectable (<7 μg kg^?1) in either fish fillets or livers.     

Use of biological reference points for the conservation of Atlantic salmon, Salmo salar, in the River Lune, North West England

Abstract  The development and use of biological reference points (BRPs) for salmon, Salmo salar L., conservation on the River Lune, England were examined. The Lune supports recreational and net fisheries with annual catches averaging 1332 and 2146 salmon, respectively. Using models transported from other river systems, BRPs were developed that were exclusive to the Lune; specifically the number of eggs deposited and carrying capacity estimates for age 0+ and 1+ parr. The conservation limit was estimated at 11.9 million eggs, and to ensure that the conservation limit was exceeded 80% of the time, the management target was set at 14.4 million eggs (equivalent to ∼5000 adults). Between 1989 and 1998 the management target was exceeded in only 2 years. Comparison of juvenile salmon densities in 1991 and 1997 with estimates of carrying capacity indicated that 0+ and 1+ parr densities were at around 60% of carrying capacity and may relate to the number of eggs deposited in 1990 and 1996 being approximately 70% of the target value. From, and including, the 2000 fishing season, regulations to ensure that the conservation limit is met 4 years out of 5 were introduced. These consisted of a reduction from 26 to 12 haaf nets, from 10 to seven drift nets and a four-fish bag limit for the rod fishery. In the period between 2000 and 2004 there was a marked increase in the estimated number of salmon spawning and the management target value of ∼5000 spawning adults was exceeded in all years. There was also an increase in the juvenile salmon population. The estimated level of exploitation in the net and rod fisheries reduced from 29.9% to 13.8% and from 26.4% to 14.8% respectively, after the introduction of the regulations.     

Response of juvenile Atlantic salmon, Salmo salar, to the introduction of salmon carcasses in upland streams

Abstract  The role of nutrients in the production of Atlantic salmon, Salmo salar L., in oligotrophic upland catchments is poorly understood. Atlantic salmon carcasses were introduced to 12 upland streams in the River Conon catchment, Scotland, UK, to assess potential nutrient limitation and evaluate a potential role for migratory Atlantic salmon in nutrient import. The objective was to test the hypothesis that nutrient supplementation would increase juvenile Atlantic salmon biomass. Streams received one of six treatment levels up to a maximum of one carcass per 15 m² of wetted area with duplicates at each level, and study areas were sampled to measure salmon biomass in treated and reference reaches. There was a significant positive relationship between treatment addition level and response of juvenile salmon biomass. At higher carcass addition levels, salmon biomass in treatment sections was approximately twice that in paired reference sections. The results are discussed in the light of management methods in upland regions and the likely role of cultural oligotrophication in suppressing current levels of salmon production.