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131.
为探究大菱鲆(Scophthalmus maximus)在不同贮藏温度下品质特性与货架期的关系,将大菱鲆贮藏在-3℃、0℃、4℃、10℃和15℃温度下,测定其感官品质、挥发性盐基总氮(TVB-N)、菌落总数、硫代巴比妥酸值(TBA)、电导率的变化,并且观测肌肉的微观结构;采用低场核磁共振技术(Low-field nuclear magnetic resonance, LF-NMR)分析鱼肉中水分迁移状况,并且建立了TVB-N及菌落总数与贮藏时间和温度的动力学模型。研究发现,随着贮藏时间的延长,5种不同贮藏温度下鱼肉中不易流动水均减少,货架期终点各贮藏温度下的样品相对于新鲜鱼肉,其肌纤维结构均由紧密变得疏松;TVB-N和菌落总数变化预测模型中的活化能和指前因子分别为79.50、75.07 kJ/mol和1.3×10^14、7.62×10^12。选用10℃进行验证性试验,结果显示实测值与预测值相对误差在10%以内。因此,可根据TVB-N值及菌落总数对大菱鲆贮藏在-3℃~15℃的货架期进行实时预测。 相似文献
132.
David G Ainley Nadav Nur Joseph T Eastman Grant Ballard Claire L Parkinson Clive W Evans Arthur L. DeVries 《Fish and Fisheries》2013,14(3):343-363
We report the analyses of a dataset spanning 39 years of near‐annual fishing for Dissostichus mawsoni in McMurdo Sound, Antarctica, 1972–2011. Data on total length, condition and catch per unit effort (CPUE) were derived from the > 5500 fish caught, the large majority of which were measured, tagged and released. Contrary to expectation, the length frequency of the McMurdo Sound catch was dominated by fish in the upper two‐thirds of the overall distribution exhibited in the industrial catch for the Ross Sea shelf. Fish length and condition increased from the early 1970s to the early 1990s and then decreased. Fish length positively correlated with Ross Sea ice extent in early spring, a relationship possibly caused by more ice encouraging larger fish to move farther south over the shelf and into the study area. Fish condition positively correlated with the amount of open water in the Ross Sea during the previous summer (Feb), perhaps reflecting greater availability of prey with the higher productivity that more open water brings. Decreasing fish size corresponds to the onset of the fishery, which targets the large individuals. CPUE was constant through 2001 and then decreased dramatically. We hypothesize that this decrease is related to the industrial fishery, which began in the 1996–97 austral summer, and concentrates effort over the ice‐free Ross Sea continental slope. As a result of limited prey choices and close coupling among mesopredators of the region, Antarctic toothfish included, the fishery appears to be dramatically altering the trophic structure of the Ross Sea. 相似文献
133.
Rajabdeen Jannathulla Vanjiappan Rajaram Rajamohamed Kalanjiam Kondusamy Ambasankar Moturi Muralidhar Jagabattulla Syama Dayal 《Aquaculture Research》2019,50(12):3493-3506
Fishmeal is being trusted as the most reliable protein source due to its nutritional quality in terms of attractability, palatability, digestibility, excellent nutrient profiles to fulfil the dietary requirement of aquatic species. The aquaculture sector consumes >70% of global fishmeal, though aqua feeds constitute only 4% in total industrial feed production (900–1,000 Mt in 2018). The global fishmeal production has shown a downward trend of 26.50% during 2000 to 2018 due to the occurrences of El Niño–Southern Oscillationsand other climatic events, which in turn increased the fishmeal price from 452 USD/t (2000) to 1596.54 USD/t (2018). The increasing trend of aquaculture production along with reduced fish‐in/fish‐out ratios (0.63 in 2000 to 0.33, 0.22 in 2010 and 2015 respectively) indicates the resilience of the aquafeed sector for fishmeal replacement. The wide availability, reasonable price and reliable nutrient content made an interest in plant protein sources, but their utilization was limited due to poor digestibility, imbalanced profiles of essential nutrients and the presence of anti‐nutrients. Numerous methodologies are invented in recent times to enrich the nutritional qualities for maximizing the utilization of plant proteins in aquafeed formulations. The present review concludes that the aquafeed sector should use climate economics and technological innovations for substituting fishmeal to formulate the cost‐effective feeds. 相似文献
134.
Protein and energy nutrition of brook trout (Salvelinus fontinalis) at optimal and elevated temperatures
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The digestible protein (DP) and digestible energy (DE) requirements for maintenance and growth of brook trout (Salvelinus fontinalis) were determined using a factorial model at either optimum (15 °C) or elevated temperature (19 °C). Several key parameters of the factorial model were measured using a series of inter‐related studies. The maintenance requirements for DP and DE were 0.10 gDP kg?0.69 day?1 (15 °C) and 0.31 gDP kg?0.78 day?1 (19 °C), and 34.86 kJDE kg?0.84 day?1 (15 °C) and 46.14 kJDE kg?0.86 day?1 (19 °C). The total requirements for DP were 0.10 gDP kg?0.69 day?1 + 2.14PG (protein gain) (15 °C) and 0.31 gDP kg?0.78 day?1 + 1.98PG (19 °C). The total requirements for DE were 36.86 kJDE kg?0.84 day?1 + 1.58EG (energy gain) (15 °C) and 46.14 kJDE kg?0.86 day?1 + 1.64EG (19 °C). The partial efficiencies for growth were 0.47 (15 °C) and 0.51 (19 °C) for protein, and 0.63 (15 °C) and 0.61 (19 °C) for energy. Nutrient gain was lower at the elevated temperature; however, feed formulation for brook trout should be adjusted to match changes in nutrient requirements at different culture temperatures. The protein and energy requirements model will be useful for developing commercial feeds and feeding charts for brook trout. 相似文献
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136.
Sex change in coral reef fish 总被引:1,自引:0,他引:1
Masaru Nakamura Yasuhisa Kobayashi Saori Miura Mohamad Ashraful Alam Ramji Kumar Bhandari 《Fish physiology and biochemistry》2005,31(2-3):117-122
Gonadal differentiation can take many forms in fish, ranging from gonochorism, where individuals directly develop as male
or female and finally possess only testis or ovaries at sexual maturation, to hermaphroditism where the same individuals can
produce mature male and female gametes at some time in their lives. Hermaphrodite fish are, thus, an excellent model for studying
the plasticity of sex determination and differentiation in vertebrates. We have shown that sex steroids play a principal role
in sex differentiation and sex change in fish. Our laboratory implements several fish models that undergo sex change from
female to male or male to female or in both directions. In this review, we will briefly discuss recent advances in our understanding
of the mechanism of sex change in coral reef fish. 相似文献
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140.
Logging pattern and landscape changes over the last century at the boreal and deciduous forest transition in Eastern Canada 总被引:4,自引:0,他引:4
Forestry practices associated with the industrial era (since ~1900) have altered the natural disturbance regimes and greatly
impacted the world’s forests. We quantified twentieth century logging patterns and regional scale consequences in three sub-boreal
forest landscapes of Eastern Canada (117,000, 49,400 and 92,300 ha), comparing forestry maps depicting age and forest cover
types for early industrial (1930) and present-day (2000) conditions. Results were similar for the three landscapes, indicating
large-scale forest change during the twentieth century. In 1930, previous logging activities had been concentrated in the
lowlands and along the main hydrographical network, as compared to a more even distribution over the landscapes in 2000, reflecting
a decreasing influence of the environmental constraints on forest harvesting. In 1930, old-aged forests (>100 years) accounted
for more than 75% of the unlogged areas of the three landscapes, as compared to less than 15% for the present-day conditions.
Logging practices have thus inverted the stand age distribution of the landscapes that are currently dominated by young and
regenerating stands. The 1930 forest cover types showed a clear relationship with elevation, with conifers located in the
lowlands and mixed and deciduous stands restricted to the upper slopes. Between 1930 and 2000, 58–64% of the conifer areas
transformed to mixed and deciduous forests, such that no clear altitudinal relationships remained in 2000. We conclude that
twentieth century logging practices have strongly altered the preindustrial vegetation patterns in our study area, to the
point that ecosystem-based management strategies should be developed to restore conifer dominance, altitudinal gradients,
as well as the irregular structure inspired from old forest stands. 相似文献