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211.
Effects of high dose of vitamin A on reproduction and egg quality of Japanese flounder Paralichthys olivaceus 总被引:2,自引:0,他引:2
Hirofumi Furuita Hideki Tanaka Takeshi Yamamoto Manabu Shiraishi Toshio Takeuchi 《Fisheries Science》2001,67(4):606-613
ABSTRACT: The present study was conducted to investigate the effects of dietary vitamin A on reproduction and egg quality in Japanese flounder Paralichthys olivaceus . Broodstock were fed experimental pellets containing two levels of vitamin A [11 × 103 IU/100 g (control diet; CD), 337 × 103 IU/100 g (experimental diet; ED)] for approximately 2 months before spawning and during the spawning period. Two groups of five females (average weight 1.4 kg) and 10 males (average weight 0.7 kg) were randomly allocated to two 30 m3 indoor tanks. Total egg production of the CD group was slightly higher than the ED group. Percentage of buoyant eggs and hatching rate of the ED group were significantly higher than the CD. In other egg quality parameters, such as percentage abnormal larvae and starvation tolerance of larvae, no notable difference was found between these two groups. At the end of the experiment, the skin color of broodstock in the ED group was darker than that of the CD group. Vitamin A content in eggs of the ED group was significantly higher than that of the CD group. However, the difference in vitamin A content in eggs between the ED and CD groups was much smaller than that in the liver of the females between the two groups. These results indicate that feeding broodstock a higher level of vitamin A increases the vitamin A content in eggs but does not affect egg quality in Japanese flounder because excess dietary vitamin A was stored mainly in the broodstocks' liver. 相似文献
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A major concern in larvae production is a mass mortality caused by fish diseases. In larvae production, pumped‐up natural seawater filtered through a sand filter system is used for fish rearing, and microalgae and rotifer cultures. Here, we investigated the community structures of eukaryotic microbes, as well as total bacteria and vibrios, in various processed ‘waters’ used in a larvae production site. We observed that ultraviolet irradiation of seawater was effective to reduce not only total bacteria and vibrios but also eukaryotic microbes. Moreover, the community structures of total bacteria and vibrios in rearing waters for fish larvae were different from those in rotifer cultures fed with Chlorella, but rather similar to those in natural seawater and microalgae cultures. These results suggest that the bacterial community in rearing waters may originate mainly from natural seawater and then be selected by microalgae in rearing water. Overall, this study provides useful information for avoiding the risk of fish disease outbreaks in a larvae production site. 相似文献
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The maturation of the digestive functions in sea bass (Dicentrarchus labrax) larvae was evaluated by the enzymatic profile of pancreas and intestine brush border membranes. Sea bass larvae were weaned at day 25 with three simplified diets different by their protein nature: 100% fish meal (FP), 100% casein mixture (CP) and 50% fish meal-50% casein mixture (CFP). The casein mixture contained 35% of hydrolysate. The control group was fed live preys. The specific activity of amylase decreased with age irrespectively of the diets whereas the specific activity of trypsin was enhanced. The casein mixture reduced pancreatic secretion in amylase and trypsin. The CFP group differed from the other groups fed on compound diets, exhibiting as soon as day 32 high activities of brush border enzymes, similar to controls. This sharp increase between day 25 and 32 appeared to be crucial for larval survival. The addition of a protein hydrolysate in a weaning diet seems to facilitate this maturation process. 相似文献
218.
2003年春季东海区浮性鱼卵和仔稚鱼种类组成及数量分布 总被引:13,自引:2,他引:13
本文分析研究了2003年春季东海区(27°00′~34°00′N)150m以浅海域浮性鱼卵、仔稚鱼的种类组成及数量分布。共鉴定49种鱼类的鱼卵、仔稚鱼,其中31种鉴定到种,隶属于26科、29属。优势种类为日本鳀、方氏云鳚、太平洋鲱。带鱼、小黄鱼等经济鱼类鱼卵、仔稚鱼数量少,鲱形目鱼类鱼卵、仔稚鱼数量较多。鱼卵、仔稚鱼分布主要在近海禁渔线附近海域。 相似文献
219.
基于30余年渤海鱼卵、仔稚鱼历史调查资料的整理分析并结合产卵场补充调查,以1982~1983年周年逐月调查资料为本底,采用多元统计学方法分析30余年渤海鱼类种群早期补充群体群聚特性(物种多样性和关键种群)的季节变化和年代际变化,并掌握结构更替过程中优势种和重要种协同消长规律。分析结果显示,渤海各调查季节(冬季除外)鱼卵、仔稚鱼种类数以及资源丰度指数呈先降后升变动趋势。当前鱼卵种类数仅为20世纪80年代1/2左右,资源丰度不足20世纪80年代的1/10;仔稚鱼种类数和资源丰度仅为20世纪80年代的3/4左右,但冬季仔稚鱼种类数和资源丰度指数呈现上升趋势。各调查时期相同季节鱼卵优势种变化不明显,但仔稚鱼优势种变化幅度超过鱼卵,底层重要经济种类早期补充群体优势度急剧下降;鱼卵和仔稚鱼物种多样性水平在升温季节较高而在降温季节较低,调查期内各季主要呈现先降后升变动趋势。鱼类早期补充群体种类更替现象明显,近年来种类更替率呈现明显加快趋势。各调查时期相同季节各适温类型产卵亲体种数均呈现先降后升变动趋势,但各适温类型种数所占比例和全年综合各适温类型种数所占比例基本稳定。各调查时期相同季节各主要栖所类型产卵亲体种类数也均呈现先降后升变动趋势,全年综合陆架浅水中上层鱼类种数所占比例升高,中底层和底层鱼类所占比例有所下降。近30年在多重外来干扰作用下,渤海鱼类早期补充过程各个关键环节已随其栖息地(产卵场)生境要素发生不可逆变化或变迁。渤海鱼类种群早期补充群体群聚特性和结构更替是环境-捕捞胁迫下鱼类群落内多重生态位的交替失调和渔业资源结构性衰退的具体表现。 相似文献
220.
K. HAMRE A. SRIVASTAVA I. RØNNESTAD A. MANGOR-JENSEN & J. STOSS 《Aquaculture Nutrition》2008,14(1):51-60
The current best practice intensive culture of larval Atlantic cod includes feeding rotifers from onset of exogenous feeding until 25–30 days after hatching. These larvae grow considerably slower and develop higher frequencies of deformities than larvae reared in semi‐extensive systems, using copepods as feed. The present study compares the micronutrient concentrations in rotifers with those of copepods, with the aim of identifying nutrients that may be limiting for normal growth and development of cod larvae. An additional criterion used is the nutrient requirements given for fish in general, by NRC (1993) , as nutrient requirements of cod remains to be determined. Rotifers were fed on four different diets, consisting of baker's yeast with cod liver oil (3.3 : 1 dry weight (DW)/v), baker's yeast with Algamac 2000TM (3.5 : 1 DW), baker's yeast with live algae Chlorella (4.1 : 1 DW), and Culture Selco 3000TM (CS). CS was a complete commercial diet for rotifers while the other diets are considered as based on raw ingredients. Compared with copepod nutrient levels, rotifers grown on yeast‐based diets supplemented with either cod liver oil, Algamac 2000 or Chlorella were apparently sufficient for covering the requirements in cod larvae for all the B‐vitamins, except thiamine. Rotifers cultured on the CS diet also had sufficient amounts of thiamine. Of the minerals, only calcium and magnesium were sufficient, using this criterion while iron was on the borderline. However, with reference to the requirements given for larger fish ( NRC 1993 ), only thiamine, vitamin A, manganese, selenium and perhaps copper, appear too low in the rotifers cultured without extra micronutrient supplementation. The other nutrients were present at levels intermediate between copepod and fish requirement levels. This study suggests that it is necessary to develop enrichment techniques to produce rotifers with sufficient amounts of all micronutrients. Such techniques will also be important tools for determining which nutrients are present at levels below the actual requirements in cod larvae. 相似文献