虹鳟排卵前后血清中性类固醇激素浓度变化的研究

对虹鳟(Salmo gairdneri)排卵前后血清17β-雌二醇(17β-E_2),睾酮(T)和17α-羟-20β-双氢孕酮(17α20βP)的含量进行了测定。17β-E_2从排卵前15天的18.1ng/ml急骤下降到排卵前3—6天的2ng/ml,并继续下降,至排卵时仅为0.9ng/ml。睾酮在虹鳟雌鱼血清中的含量很高,血清浓度从排卵前9天的峰值水平143.3ng/ml缓慢下降,排卵时为24.3ng/ml。17α20βP的血清浓度变化明显,排卵前15天,该激素浓度接近于基线水平或甚至低得不能被检测,排卵前9天开始迅速上升,到排卵前3天达到峰值350.6ng/ml,排卵时为302.2ng/ml。本研究进一步证实了17α20βP在鲑鳟鱼类卵母细胞最后成熟过程中的生理作用,是一种诱发卵母细胞成熟的类固醇激素。临排卵前,血清17β-E_2浓度的下降,可能调节了17α20βP大量分泌的时间;17α20βP的大量分泌是卵母细胞达到最后成熟和排卵不可缺少的一环。注射合成的大麻哈鱼(Oncorhynchus keta)促性腺激素释放激素(s-GnRH)及其类似物(s-GnRH-A),诱发虹鳟血清类固醇激素17β-E_2,睾酮和17α20βP的变化趋势与自然排卵时的变化相类似。经注射药物诱发排卵的鱼,较对照组提早一周排卵,而且排卵较同步和集中。     

Salmon prices in France and the UK: Does origin or market place matter?

Abstract

There have been several attempts to distinguish farmed Atlantic salmon by origin using trademarks. Whether there exist different regional markets for salmon, and in particular whether the UK market is separate from the market in continental Europe, is also an issue that has received attention. To address these questions, we investigate the relationship between Norwegian and Scottish salmon both in France and the UK, and between Scottish salmon in France and the UK. The analysis is carried out by investigating how the development of prices is related using co‐integration tests.     

Development of two telemetry-based systems for monitoring the feeding behaviour of Atlantic salmon (Salmo salar L.) in aquaculture sea-cages

Two novel acoustic transmitter tags intended to reflect feeding behaviours in farmed Atlantic salmon (Salmo salar L.) were developed and tested in this study. Using information from the literature and video recordings of feeding salmon, measurements of swimming depth and motion (acceleration) were identified as two promising sensing principles on which to base the tag development. Video footage and laboratory studies were used to develop corresponding algorithms that translated depth and acceleration measurements into compound parameters reflecting the different aspects that discern feeding activity from other activities. Field tests performed in a sea-farm were used to verify the functionality of the tags, and indicated that both tag types had potential in distinguishing between feeding and non-feeding behaviour. Additionally, both depth- and acceleration-based tags were seen to have applications to fish monitoring and farm management beyond that of observing feeding in salmon, in giving recordings of the vertical swimming behaviour of fish over extended periods of time as well as indications of the activity changes of fish due to external influences. These results suggest that fish telemetry using sensor-based transmitter tags could represent a useful tool in future fish farm management.     

Growth stimulation of juvenile abalone <Emphasis Type="Italic">Haliotis discus hannai</Emphasis> by feeding with salmon growth hormone in sodium alginate gel

We examined the ability of salmon growth hormone (sGH) in sodium alginate (SA) gel to accelerate the somatic growth of juvenile abalone, Haliotis discus hannai, by feeding. After the feeding of sGH at 50 μg or 100 μg in 350 mg SA gel, immunoreactivity to sGH in body fluid was maximal after 12 h, and was still detectable at 24 h. No immunoreactivity was observed in the control group. Following the feeding of sGH at 0.5 mg or 5 mg/8 g of SA gel at 7- and 14-day intervals, there was a greater increase in shell length and body weight than in the control. In abalone, sGH can be transported from food into the circulatory system and subsequently improve somatic growth.     

A computer vision system to analyse the swimming behaviour of farmed fish in commercial aquaculture facilities: A case study using cage-held Atlantic salmon

Knowledge of fish behaviour plays an important role in aquaculture farm management. Video systems are the most common and cost-effective way of observing behaviours in commercial aquaculture operations. However long term observation is not feasible due to a limited ability to analyse footage manually. This paper describes preliminary findings obtained via computer vision software that was developed to automatically analyse fish movement and behaviours in aquaculture sea cages. Results show that the system is capable of detecting fish shapes in video recordings and from these shapes quantifying changes in swimming speed and direction continuously throughout the day. Also variations between days were detected and these may have been associated with the daily shift in the tidal cycle. The system has the potential to act as an alarm to farm operators, informing them about unusual fish behaviours on a continuous, real-time basis. It also has potential to assist in the evaluation of fish welfare.     

Contributions of salmon-derived nitrogen to riparian vegetation in the northwest Pacific region

We examined the relationship between the annual escapement of salmon and the δ ¹⁵N of willow (Salix spp.) leaves to evaluate the contribution of marine-derived nutrients (MDN) to riparian vegetation around the Pacific Northwest and Northeast regions. Foliar δ ¹⁵N values ranged from −3.42‰ to 4.65‰. The value increased with increasing density of carcasses up to 500 fish/km and 1500 fish/km. δ ¹⁵N values were variable at carcass densities below 500 fish/km. Possible factors affecting the fluctuation of δ ¹⁵N at reference sites are: (1) denitrification; (2) the presence of N₂-fixing trees, such as alder; and (3) agricultural runoff. δ ¹⁵N values at the sites with carcass densities over 500 fish/km were consistently high, while a value of δ ¹⁵N below zero was observed at only one site (Rusha River; δ ¹⁵N = −1.87‰). At this site, most adult pink salmon returned to limited locations near the estuary because steeper channel gradients acted as a migration barrier, resulting in the negative δ ¹⁵N value. Nevertheless, we concluded that our results showed evidence of the feedback of MDN to terrestrial vegetation, although the use of the δ ¹⁵N value as a terrestrial end member at spawning sites is limited. If the relationship between the enrichment index, which is expressed as the values using a mixing model, and salmon abundance was estimated, the availability of MDN in riparian ecosystems could possibly be evaluated and will lead to the establishment of escapement goals. An erratum to this article is available at .     

Measuring the cost of risk avoidance in brown bears: Further evidence of positive impacts of ecotourism

The objective of this study was to determine the cost to female brown bears with cubs of avoiding risk, or perceived risk, from both large adult male bears and ecotourists. We measured salmon consumption by brown bears in British Columbia under different risk scenarios (the presence and absence of large male bears and people). Declines occurred despite superabundant food where consumption was never limited by salmon abundance.While there were significant changes in the proportion of time spent foraging and in the consumption of captured fish between periods with and without ecotourists present, there was no change in foraging effectiveness, catch per unit effort.Selection of sub-optimal habitats to reduce predation risk incurs energy costs. Risk avoidance reduced daily salmon consumption by females with cubs by more than one third. By associating with people, females with cubs were able to avoid encounters with large, potentially aggressive males, which avoided people in both time and space. Controlled human activity at feeding sites can provide a temporal feeding refuge for vulnerable age/sex classes. This is the first study to quantify the energetic cost of intra-specific risk-avoidance for a large carnivore.     

秦岭细鳞鲑分布与保护对策

调查了秦岭细鳞鲑在秦岭的分布及其生存状况,介绍了其保护中存在的问题,提出保护对策,以为秦岭细鳞鲑的保护提供参考。     

曙红与鲑鱼精蛋白显色反应的研究

[目的]对曙红与鲑鱼精蛋白显色的反应进行研究。[方法]采用分光光度法,研究曙红(醇溶)与鲑鱼精蛋白在聚乙烯醇(PVA)存在时的结合反应,并且研究了显色反应的条件和影响灵敏度的因素,确定了最佳反应条件。[结果]以试剂空白为参比,曙红-硫酸鱼精蛋白复合物的最大吸收波长为542 nm,最大吸收波长处的吸光度与蛋白质的浓度呈良好的线性关系,可用于蛋白质的定量测定。[结论]该方法灵敏度高、线性关系好、试剂稳定、毒性小,且曙红、硫酸鱼精蛋白复合物不易黏附在容器壁上,操作简便、快速、结果准确。     

Quality Changes in Chum Salmon (Oncorhynchus keta) Caviar (ikura) Affected by Thermal Pasteurization,Storage Time,and Packaging Material

Changes in quality parameters including pH, water activity, texture, and lipid oxidation were studied in pasteurized chum salmon (Oncorhynchus keta) ikura samples packaged using two films with different oxygen transmission rates (OTR) (40 and 62 cm³·m^?2·day^?1; F-40 and F-62), during 60 days storage at 4°C. No significant differences in pH and water activity (a_w) were observed between ikura packaged using two different films with different OTR (P > 0.05). However, compared to the first day of study, water activity decreased significantly in ikura (P < 0.05). Ikura thiobarbituric reactive substance (TBARS) in the pouches significantly increased during the storage at 4°C (P < 0.05). Both pouches showed similar trends in TBARS until day 29, while after day 29, ikura packaged in F-62 (OTR = 62 cm³·m^?2·day^?1) showed a significant increase in TBARS compared to F-40 with less OTR (P < 0.05). The texture of ikura became softer compared to the first day; however, no significant difference was observed between the ikura samples in two pouches (P < 0.05). The quality changes of ikura measured during storage indicate that packaging ikura in a lower OTR film would provide greater quality retention than one with higher OTR.