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《Fisheries Research》1988,6(3):217-231
The general production model of Deriso-Schnute is modified to assess the stock of Wanshan Spring Decapterus maruadsi (T. & S.) in the South China Sea, using catch/effort data from 1960 to 1984. Limited data on age composition and growth were available and these were used to estimate growth parameters, the natural survival rate and proportions of fish recruiting at early ages. Stock-recruitment and catchability parameters were estimated by fitting the catch/effort data to the Deriso-Schnute model, using nonlinear parameter estimation. Equilibrium analysis for the fitted model suggests that the virginal stock was ∼63 600 tons, of which the maximum average yield is close to 17 900 tons and would be associated with an average biomass of ∼30 000 tons. To take this maximum would require approximately the present annual fishing capacity of 250 fishing boats, producing a 0.60 annual harvest rate. The present stock is at the lowest level on record; different recovery and management strategies were evaluated by computer simulations. Only ∼3 years would be needed for the stock to recover to optimum equilibrium biomass with no fishing, but it is suggested that a longer recovery period, under reduced fishing effort, would be preferable. 相似文献
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The effects of feeding level on growth, retention efficiency, faeces production and energy partitioning of redlip mullet were studied. A practical diet was used and fed at six levels from starvation, 1%, 2%, 3%, 4% of body weight (BW) to satiation for 3 weeks. The temperature was kept at 24±1°C. Reducing the feeding amount resulted in significantly lower weight gain, and retention efficiency was significantly affected by feeding levels and attained the maximum at maximum feeding intake. Feeding 2% BW was the minimum required for fish to maintain growth. Fish carcass composition under different feeding levels could be divided into three groups: (1) starvation and FL1; (2) FL2 and FL3 and (3) FL4 and satiation, with significant differences among the groups but no differences in the groups except that ash content remained at constant value. Body composition of fish of group 2 was close to initial fish. The thermal‐unit coefficient was 0.0381 at satiation, and significantly increased with increasing feeding levels. In order to accurately estimate basal metabolism (HeE), another trial on the relationship between HeE (kJ) and BW (g) was carried out. An exponential curve as HeE=0.1255BW0.8386 explained this relationship. Intake energy (IE) increased from 11.30 to 63.08 kJ per fish, matching with different feeding levels. Energy allocated to growth of IE decreased with reducing feeding amount. There was a linear relationship between metabolism energy and retention energy in percentage. 相似文献
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Hirofumi Furuita Hideki Tanaka Takeshi Yamamoto Nobuhiro Suzuki & Toshio Takeuchi 《Aquaculture Research》2003,34(6):461-468
This study investigated supplemental effects of vitamin A in diet on reproduction of Japanese flounder Paralichthys olivaceus (T & S). Broodstock were fed either a non‐supplemented diet (control diet; CD) or a vitamin A‐supplemented diet (supplemental diet; SD) 1 month before and during the spawning season. Both dietary groups began to spawn in mid‐January. At the beginning of spawning, no notable differences were found in spawning or egg quality between treatments. Egg production of the CD broodstock began to decrease from mid‐April and spawning stopped in late May, whereas the SD group continued to spawn until the end of June. Buoyant egg rate of the CD group was lower than that of the SD group throughout the spawning period. Hatching rate was not different between the CD and SD groups. The percentage of normal larvae in the CD group was significantly lower than in the SD group. It is concluded that a low vitamin A content in the diet has some negative effects on reproduction of flounder. The importance of supplementation of vitamin A in broodstock diet of the Japanese flounder is suggested. 相似文献
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Detritus, as a nutrients reservoir, affects the trophic structure and dynamics of communities and supports a greater diversity
of species and longer food chains. Detritivorous fish is an important organism to regenerate the nutrients from sediments.
Despite the numerous studies on the nutrients cycle in fish, only a few attempts have been made to quantify the regenerating
ability. In the present study, we chose the common detritivorous fish redeye mullet as the research object. Redeye mullet
is also a common poly-culture fish in China. Diet, including a commercial diet mostly used in aquaculture and a home-made
diet with contents close to detritus, was used and considered as a fixed factor. Temperature was also considered as a fixed
factor as much research has shown that temperature has significant effects on fish metabolism. Moreover, body size was regarded
as a covariate under analysis of covariance. Three key nutrients, namely carbon, nitrogen and phosphorus, were used to measure
the nutrient-regenerating ability of redeye mullet under laboratory conditions. The results showed that the nutrient regeneration
in percent of the consumption decreased with increasing temperature. Carbon and nitrogen regeneration of redeye mullet fed
on commercial diet was lower than those of the home-made diet group, while the opposite was found for phosphorus. In each
group, the amount of regenerated nutrients increased linearly with body size. Fed on the home-made diet, 5-g fish at 25°C
can regenerate 210.822 mg C, 37.533 mg N and 0.727 mg P per day. 相似文献
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“不产科技信息查询系统”以“金信桥全文检索管理软件”作为开发平台，根据水产科技信息资源及现有数据库的特点，对不同类型的数据按一定要求和规范进行标引和分类处理，同时进行各类数据库的结构设计，把各类数据转入相关的数据库中，建立可利用Internet浏览器进行和检索的综合性国内外水产科技信息查询系统。该系统的主要数据内容有：中国水产文摘数据库、国外水产文献数据库、水产科技成果数据库、水产专科数据库、渔用药物数据库、渔业政策法规数据库、水产机构名录数据库、馆藏图书书目数据库、病害防治技术咨询库、中国渔业概况、中国不产发展战略、水水养殖实用技术库等。 相似文献
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Ian Laing 《Aquaculture Research》2003,34(12):1107-1108
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Studies on the development of ova up to maturity clearly indicated that Psettodes erumei and Pseudorhombus arsius breed only once a year for 3 to 4 months in Porto Novo waters. Psettodes erumei spawns its eggs in two batches, while Pseudorhombus arsius spawns in a single batch. The spawning period of Psettodes erumei was from May to September, with the peak from May to August. Pseudorhombus arsius spawns during April to July, with the peak in April and May. Studies on the gonadosomatic indices confirm the above information. The size at first maturity of Psettodes erumei was 371–390 mm total length, and that of Pseudorhombus arsius was between 161 and 170 mm total length. Females always outnumbered males in both the species. Fecundity studies in both species showed direct correlations with total length and body weight. 相似文献
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To optimize the artificial reproduction of C. lazera for aquaculture, experiments were carried out on short-term sperm conservation as well as hypophysation and stripping of the females.When the sperms were stored at 5°C for 24 h, their fertilizing capability was reduced by 4% compared with freshly obtained sperm. However, dilution in a 0.9% naCl solution (up to 10?3) gave an average 9% increase of hatching success. This finding enables the use of one competent male to fertilize the eggs of many females. An alternative application of the finding enables homoplastic hypophysation, using the fresh pituitary of the male to induce ripening of the female, while the sperms are stored for later use.Correct timing of stripping of the females in relation to hypophysation proved to be critical for obtaining good hatching results. This was increasingly so when temperatures were high. The best results in these experiments were obtained when stripping took place 21, 11 or 7 h after hypophysation at 20, 25 and 30°C, respectively.At this time the eggs were flat, with the cytoplasm concentrated at the animal pole as a reddish-brown spherical cap. The incubation period of the eggs decreased with increasing temperature. In all instances a large proportion of deformed fry occurred wiich was inversely related to the hatching percentage. Incubation without a regular water exchange gave 4% more hatching, 6% less deformation and a shorter incubation period than incubation with water exchange.Hypophysation was repeated four times with 1-, 2- or 3-week intervals and resulted in successful stripping, fertilization and hatching of the eggs after each hypophysation. 相似文献
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Carole R. Engle Nathan M. Stone 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3):251-280
Increased attention has been paid in recent years to both positive and negative effects of increasing numbers of regulations on businesses in the United States. The decline in U.S. aquaculture has been attributed in part to increasing volumes of imports and high feed prices. However, there is increasing concern that the U.S. regulatory environment, as compared to that of international competitors, may also have contributed to this decline. More than 1,300 laws apply to U.S. aquaculture and even though the majority has been issued by individual states and apply only to specific types of aquaculture businesses in that state, the cumulative regulatory burden has increased over time. Major compliance categories include: 1) environmental management; 2) food safety; 3) legal and labor standards; 4) interstate transport of aquatic products; 5) fish health; and 6) culture of commercially harvested species. A substantial portion of the regulatory burden is the managerial and labor time spent on compliance in addition to the direct cost increases. The streamlined one-stop process adopted in Norway appears to have allowed growth of aquaculture within a comprehensive regulatory framework, yet the lack of such a streamlined approach in the United States appears to have contributed to the decline of existing industries and to serve as a deterrent to investment in newly emerging technologies. Favorable regulatory environments in countries that export to the U.S. contrast sharply with the increasingly inefficient, cumbersome and/or restrictive U.S. environment. Such disparities have created competitive disadvantages for U.S. producers. Attention is needed by policy makers to search for streamlining mechanisms and by the scientific community to address the growing competitive disadvantage to U.S. aquaculture to respond to increased global demand for farmed seafood. 相似文献
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M. A. R. GARCIA-ABIADO W. E. LYNCH Jr K. DABROWSKI S. CZESNY J. RINCHARD & J. STAFFORD 《Fisheries Management and Ecology》2002,9(2):105-110
Triploid hybrid saugeyes may be a desirable stocking alternative because diploid saugeyes are fertile and can compromise the genetic integrity of parental stocks. Four groups of saugeye eggs were heat-shocked 5 min after fertilization for 15 min at 31 °C, which resulted in an 86.7 ± 9.4% triploidy rate and 57.8 ± 24.3% survival to the eyed-stage. Heat shocked and control saugeyes were stocked in two ponds for 40 days at 395 000 ind. ha–1 . Mean length and weight of triploid and heat-shocked diploid saugeyes were greater ( P < 0.01) than unshocked diploid saugeyes. Survival of heat-shocked saugeyes (22.4%) was lower than unshocked saugeyes (94.7%). Heat-shocked fish ( n =25 851) harvested from ponds were stocked for 153 days in O'Shaughnessy Reservoir, Ohio, USA. Triploids were 34 mm shorter and weighed 41 g less than heat-shocked diploids ( P < 0.01). Mean length and weight of triploids were comparable with unshocked diploids elsewhere in Ohio. 相似文献
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Gina L. Shamshak James L. Anderson Frank Asche Taryn Garlock David C. Love 《Journal of the World Aquaculture Society》2019,50(4):715-727
U.S. seafood consumption has changed dramatically in recent decades and has become increasingly dominated by the consumption of a limited number of species that are primarily imported and predominantly sourced from aquaculture. In getting to this point, the United States has been, and still is, at the forefront of some of the most important trends in global seafood markets. Hence, discussing the factors influencing U.S. seafood consumption patterns is an interesting and informative endeavor and will most likely also have strong predictive power for the continued development of seafood markets in the United States. In this article, we will discuss the transitions in the U.S. seafood market, primarily focusing on the period from 1990 to the present, highlighting the main factors that facilitated this development. This article provides an overview of U.S. landings, aquaculture production, exports, and imports and also explores contributing trends in global export and import markets. This will be followed by a discussion of U.S. per capita consumption patterns and an examination of the consolidation of species consumed over time. Finally, implications for future trends in seafood consumption and production are discussed. 相似文献
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Abstract. Mycobacterium infection was found in pejerrey, Odonthestes bonariensis Cuvier & Valenciennes, with and without saprolegniasis, in Japan. Many typical focal mycobacterial granulomas were found in the kidney, spleen, liver and pancreas, but they were not found in lateral musculature at sites of fungal infection, or in the intestine, ovary, heart and gills of infected fish. The isolated bacterium was photochromogenic and was identified as a rapidly growing species of the genus Mycobacterium. 相似文献