Growth and gonadal development in diploid and triploid turbot (Scophthalmus maximus)

This study determined the effect of triploidy on the survival, growth and gonadal development of turbot from 6 to 48 months of age. From 6 to 24 months of age (first sexual maturity), survival was similar in both ploidies (P > 0.05). From 24 to 48 months of age, after the first sexual maturity, survival was 91.9% in diploids and 100% in triploids, which did not exhibit the post-spawning-associated mortality. Growth was similar for both ploidies during the first year of life. After that, triploids grew significantly (P < 0.05) more that diploids, with more marked differences after each spawning season. From 24 to 48 months, the average weight difference between both ploidies was 11.4 ± 1.9%, ranging from 4.3 to 23.0%. At 47 months of age, the biomass of triploids was 10.3% greater in total weight and 14.3% greater in eviscerated weight. Gonads of triploid males were similar to that of diploids, whereas in triploid females, they were significantly smaller and rudimentary. A histological analysis carried out at 47 months of age showed complete sterility of triploids in both sexes. Sex ratio was 1 male (M):0.6 female (F), for diploids, significantly (P < 0.05) different from 1:1, and 1 M:3.3 F for triploids, significantly (P < 0.05) different from 1:1 and from the diploids. Since females grow more than males, culture of triploids benefited from the high female ratio, which helped to reduce size dispersion. In addition, their sterility allowed better performance by avoiding the reduction in growth that takes place during the spawning periods. Together, these observations indicate that triploidy induction can be an interesting option for turbot aquaculture, especially for the production of large-size fish of more than 2 years of age.     

阿根廷滑柔鱼雌性个体肌肉和性腺组织能量积累及其生殖投入

利用组织能量密度测定技术和残差指标分析方法,分析了阿根廷滑柔鱼雌性个体肌肉组织和性腺组织的能量积累及其分配规律。结果显示,足腕、胴体、卵巢、缠卵腺和输卵管复合体等组织的能量密度平均值分别为(22.75±0.60)、(23.42±0.68)、(25.15±2.08)、(21.49±1.46)和(25.12±3.02)k J/g。不同性腺成熟度等级,足腕、胴体和缠卵腺等组织的能量密度均不存在显著性差异,卵巢和输卵管复合体等组织的能量密度则差异显著。足腕、胴体等肌肉组织能量在性腺成熟度III期时达到最大值,卵巢、缠卵腺和输卵管复合体等性腺组织在I~III期时的能量积累缓慢,随后能量积累增长迅速,在生理性成熟后期(V期)或功能性成熟期(VI期)时达到最大值。随着性腺生长发育,肌肉组织能量占比逐渐下降,性腺组织能量占比逐渐增加。在性腺成熟度III~V期时,雌性个体肌肉组织能量部分转化用于性腺组织的生长发育,但这种生殖投入方式不影响肌肉组织的完整性。研究表明,阿根廷滑柔鱼生殖投入以外源性为主,但发育过程中肌肉组织存储能量部分转化以满足性腺发育对能量的需求。     

西南大西洋阿根廷滑柔鱼夏季产卵种群繁殖生物学的初步研究

根据我国鱿钓船于2012年12月—2013年3月渔汛期间,在西南大西洋公海海域作业时随机采集的阿根廷滑柔鱼夏季产卵种群样本(雌性148尾,雄性99尾),初步研究了其种群繁殖生物学。结果表明,渔汛期间阿根廷滑柔鱼夏季产卵种群雌性胴长172~252 mm,雄性胴长164~248 mm。随着月份推移,雌性占比逐月递减,从12月份的84.21%递减至次年3月份的27.03%;雄性个体占比则逐月递增,从12月份的15.79%递增至次年3月份的72.97%。雌性样本超过30%的个体性腺发育成熟并且部分处于繁殖期,雄性个体超过60%的个体性腺发育成熟并且部分处于繁殖期。雌雄个体的胴长和体质量均在性腺功能发育成熟时达到最大值,但是雌性胴长大于雄性,体质量却小于雄性。性腺指数、缠卵腺指数和精荚复合体指数随着个体生长逐渐增长。雌性个体性腺指数为0.001 2~0.31,平均值0.074;缠卵腺指数为0.003 1~0.55,平均值0.29;两者随着个体生长逐渐增长,在性腺功能成熟时达到最大值。雄性个体性腺指数为0.007 5~0.084,平均值0.038;精荚复合体指数为0.000 79~0.035,平均值0.012;两指数在繁殖期时达到最大值。     

池塘养殖斑节对虾生长、发育与性成熟

为了解不同养殖条件下斑节对虾的生长、外生殖器发育、性腺发育及性成熟之间的关系,对其养殖进行跟踪调查研究.结果显示:①斑节对虾雌雄外生殖器官发育和头胸甲长呈线性关系;②不同养殖环境条件下,斑节对虾性成熟生物学最小型个体无显著差异.雄性精荚出现的生物学最小型个体为头胸甲长3.1 cm,体长11.1 cm,体质量20.0 g;雄性性成熟个体的头胸甲长3.7 cm,体长13.0 cm,体质量37.0 g.池养雌性斑节对虾的性成熟生物学最小型个体以纳精囊的发育完全(可与雄虾交配)为标志,其最小性成熟个体的头胸甲长4.3 cm、体长15.1 cm、体质量53.0 g,雌性性成熟个体为头胸甲长5.0 cm,体长17.0 cm,体质量75.0 g以上;③池塘养殖斑节对虾性成熟与日龄和养殖环境相关.鱼塭雄虾精荚出现的最早时间为日龄120 d前后,其性成熟日龄约为160 d;池塘养殖雄虾精荚出现的最早时间为日龄150 d前后,其性成熟日龄约为260 d.鱼媪雌虾最早交配发生在日龄165 d前后,性成熟日龄205～236 d,池养雌虾最早交配发生在日龄240～ 280 d,性成熟日龄295～360 d以上.     

Artificial hatching substrate and different times of transfer to first feeding: Effect on growth and protease activities of the Atlantic salmon (Salmo salar)

Groups of Atlantic salmon (Salmo salar) eggs were hatched in a Californian incubation system with and without an astro-turf artificial substrate. Food was first presented at four different points in development. Dry weight development and protease activities were studied.Irrespective of time of transfer, the astro-turf-reared fry were heavier than flat-screenreared fry at the termination of the experiment. With respect to growth, the first and the fourth transfers were clearly suboptimal for the fry from both systems.     

Effect of two types of light on survival,growth and ovary development of Rana catesbeiana

The survival, growth and ovary development of post-metamorphic, juvenile and young adult bullfrogs (Rana catesbeiana) raised under two different types of light were measured. There was no significant difference in growth or mortality between bullfrogs raised under standard or “growlight” fluorescent light. No significant differences due to treatment were found in the development of the ovary. Most females reached ovarian maturity 12 months after metamorphosis.     

Growth of the golden grey mullet (Liza aurata (Risso)) in saltwater ponds during 1974

The growth rates of Liza aurata in saltwater ponds were measured during 1972, 1973 and 1974. The growth rate of L. aurata young of the year was 0.6–0.95 g per fish per day and that of fish in their second year of life was 0.85–1.0 g per fish per day.Body composition analyses were conducted on L. aurata in both the first and second years of life.A significant difference in length and weight was found between males and females of L. aurata in their second year of life.The results show that L. aurata can be stocked in saltwater ponds but that they will not be the main crop of fish.     

Growth, Survival and Feed Conversion Rates of Sea Bream (Sparus aurata) Cultured in Earthen Brackish Water Ponds Fed Different Feed Types

Sparus aurata were cultured during an 8-month period in brackish water (salinity about 25 ppt) in an extensive culture system comprising eight earthen ponds, each with a water surface of 2.1 ha. Initial mean wet weight of fish in all ponds varied from 13.6 ± 1.9 to 19.2 ± 2.6 g/fish. The eight ponds were randomly allocated one of four experimental treatments (two ponds/treatment). In the first treatment, ponds were fertilized monthly with 100 kg urea and 50 kg triple super phosphate. The other treatments (2–4) were fed a locally produced tilapia pellet feed containing 25% crude protein made using different processes. Fish in the second treatment were fed tilapia feed pelleted by compressing machine, whereas in treatments 3 and 4 the pellets were produced by extruder machine (Wenger). Pellets in treatment 3 were floating and in the fourth were semi-sinking. Fish were fed pellets twice daily at 6% of their biomass. The mean final body weight for each treatment respectively was 104.6, 118.9, 156.8 and 158 g. Specific growth rate (SGR) of 0.8, 0.79, 0.99 and 0.95%/day, were obtained in ponds using only inorganic fertilizer, compressed sinking pellets, extruded floating pellets and extruded semi-sinking pellets, respectively. Feed conversion ratios (FCR) for treatments with the extruded tilapia pellets were 2.2 and 2.6 g feed/g gain, which were significantly (P < 0.05) better than treatments with compressed pellets (3.2 g feed/g gain). Production/ha/year were 1389, 1358, 945 and 682 kg fish for the groups fed with extruded floating, extruded semi-sinking, compressed and natural food, respectively. Under the present experimental circumstances, Sparus aurata fed extruded floating tilapia pellets (25% crude protein and 2,600 kcal/g), showed the best productive performance.     

Experimental suspended culture of mussels (Mytilus edulis L.) in Wales using spat transplanted from a distant settlement ground

Spat of Mytilus edulis L. were transferred 300 km by road on collectors from an area of high and regular spatfall, but unfavourable culture conditions, to a raft at a site deficient in mussel settlement. Spat were collected on coir ropes and fibrous rubberized matting staked to intertidal settlement grounds in Morecambe Bay, northwest England. During January to April, 80 mm circumference ropes could collect 3 000–7 000 spat/m/week, with smaller numbers in other months, and fibrous matting sometimes also caught many spat.Spatted collectors were suspended in the Menai Straits, North Wales. Despite heavy losses from overcrowding, fast currents and turbulence, growth was sufficiently good for some rope populations to produce marketable crops after about 16 months. Mean lengths increased from 1.5–5.0 mm to 47.5 mm in the first year, and to 60 mm after 1.5–2 years. At about 55 mm, attained at ca 16 months, the best crops yielded 10–15 kg/m live weight, corresponding to 2–3 kg of cooked meat/m. Percentage meat yields from 40–50 mm mussels were equally good, suggesting that crops could be harvested below the present marketable size.Economic systems for collecting spat and for on-growing at controlled densities remain to be developed for different hydrographic conditions and scales of commercial operation in Britain.     

Bioencapsulated probiotics increased survival, growth and improved gut flora of turbot (Psetta maxima) larvae

Bacterial diseases are probably the major cause of mortality in aquaculture. The use of probiotics is one of the solutions to manage bacterial infections, by preventing the colonization and exclusion of pathogenic bacteria. The effect of two selected probiotics in turbot (Psetta maxima) larvae was evaluated. Turbot larvae were reared on three different dietary treatments consisting of newly hatched Artemia nauplii from day 16 to 34 post-hatch. Groups A and B were fed with Artemia-containing probiotics FAA and FAB, respectively, and group C was control group. Results indicated that the addition of probiotics increased survival and promoted turbot growth, showing that they were beneficial for the aquaculture of turbot. Moreover, turbot fed with bioencapsulated probiotics attained higher percentages of survival during its development.     

Seasonal distribution, age, growth, and reproductive biology of marbled sole Pleuronectes yokohamae in Tokyo Bay, Japan

ABSTRACT:   The seasonal distribution, age, growth and reproductive biology of marbled sole Pleuronectes yokohamae (Günther) from Tokyo Bay, Japan were studied. A clear seasonal distribution trend was observed, with P. yokohamae limited to the south of the bay in summer and expanding almost throughout the bay in other seasons. The formation and dynamics of hypoxic areas in the bay limited the northward distribution of P. yokohamae in summer. Age was determined by counting growth rings on otoliths; maximum ages were found to be 5 years for males and 6 years for females. The mean back-calculated length for females at each estimated age was greater than that for males. Growth of males and females was shown by the von Bertalanffy growth equations. Reproductive biology was studied on the basis of gonadosomatic indices and histological sections of gonads. The spawning season lasted from November to March, peaking in December and January. Sixty per cent of males at 1 year and all males ≥ 2 years had mature testes, whereas 6.7% of females at 1 year, 58.3% of females at 2 years, and all females ≥ 3 years had attained maturity.     

Induction of sex reversal in blue drum (Nibea mitsukurii) and gynogenetic yellow drum (Nibea albiflora) by oral administration of letrozole

The objective of this study was to test the efficiency of an aromatase inhibitor, letrozole (LZ), to induce masculinization in blue drum (Nibea mitsukurii) and gynogenetic yellow drum (N. albiflora). Two experiments (Exp‐1 and Exp‐2) were performed to investigate the effect of LZ on the growth, sex ratio and gonad development in these two fishes. In Exp‐1, blue drum were treated with oral administration of letrozole at different doses (0, 1, 10, 100 mg/kg). In Exp‐2, gynogenetic yellow drum were orally administered different doses of LZ (0, 10, 100 mg/kg) and a dose of 10 mg/kg 17α‐methyltestosterone (MT). The treatments in both experiments were performed from 25 to 85 days post hatch (dph). As a result, all the LZ‐treated fish were phenotypic males despite of slower growth than the control during the treatment period. Free spermatozoa were observed from 150 dph onwards and the gonadosomatic index of the LZ‐treated fish did not differ significantly from that in the control at maturity. However, the sex‐reversed fish induced by MT exhibited a high proportion (33.4%) of testicular abnormalities. Our results showed that oral administration of LZ was efficient in inducing sex reversal in drums, and thereby facilitated their mono‐sex culture.     

Breeding biology of Psettodes erumei (Bloch & Schn.) and Pseudorhombus arsius (Ham. Buch.) Pisces: Pleuronectiformes along Porto Novo coast (S. India)

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.     

枸杞岛贻贝养殖水域碳氮磷分布格局

于2013年贻贝成熟期和幼苗期对枸杞岛贻贝筏式养殖水域营养分布和碳分布格局开展相关实验。结果表明:从生态健康角度,夏季成熟期的贻贝养殖造成养殖海域氮、磷营养盐浓度升高,尤其是无机氮浓度显著高于非养殖区(P<0.05),养殖区处于受磷限制性的重富营养化,对其水体健康产生一定压力;秋季幼苗期贻贝养殖使养殖海域氮、磷浓度均降低,尤其是无机氮浓度显著低于非养殖区(P<0.05),与夏季分布格局相反,对水体有净化作用。从生态效应看,贻贝养殖使表层水体中溶解无机碳浓度显著低于非养殖区(P<0.05),产生碳汇效应;同时,贻贝养殖使水体中溶解有机碳浓度显著高于非养殖区(P<0.05),由于丰富的氮营养盐,溶解有机碳处于不稳定态,为碳源。因此,成熟期与幼苗期贻贝养殖对其水域健康产生不同作用,养殖的碳汇、碳源还有待进一步的系统研究。     

Preliminary observations on the effect of salinity on the reproduction and growth of freshwater Nile tilapia, Oreochromis niloticus (L.), cultured in brackishwater ponds

Abstract. Tilapia, probably Africa's best candidate for aquaculture, is faced by the problems of small size due to overpopulation in culture systems.
This paper reports the effect of high salinity on the reproduction of Oreochromis niloticus (L.) while testing the effect of a 20% protein supplemental feed on the growth and survival of this species in brackishwater ponds. The trial was run for 120 days in six 100-m² ponds with fingerlings having an initial average weight of 2·80g. Salinity in the ponds rose from 25 ppt. to 50 ppt. during the culture period. Sampling for reproduction check was conducted every 2 weeks and 20% of the fish population were weighed to monitor growth changes and adjust quantity of feed fed. A 20% protein feed was fed at the rate of 5% and 3% of the total fish biomass during the first and second, and third and fourth months of the trial respectively. After 120 days the fish in each replicate were counted and weighed in bulk to obtain total weight while 50 females from each replicate were dissected and gonads examined. Results showed that growth was significantly different ( P < 0·05) while percentage survival was not significantly different ( P > 0·05). 95% of the females were gravid but did not spawn. This suggests that gonadal development and onset of reproduction can be delayed by high salinities, which may be another practical method of population control in the culture of O. niloticus .     

Life-history of the flagfin shiner, Pteronotropis signipinnis, from a blackwater stream in southeastern Mississippi

Abstract – Flagfin shiners, Pteronotropis signipinnis , were collected from Sweetwater Creek, a second-order blackwater stream in southeastern Mississippi, during each month of 1996. Analysis of length frequency histograms indicated a life span of 1 to 2 years. Sex ratio was not different from a 1:1 ratio. Adult males were larger and more heavily pigmented near the abdomen than females. Females were reproductive from April to mid-August. All females attained sexual maturity by 27 mm SL and produced multiple clutches of ova. Clutch size varied from 12 to 101 ova and was correlated with SL. Mean mature oocyte diameter was 0.88 mm (range 0.76–0.96). Despite the relationship between clutch size and body size, P. signipinnis may be selected to invest in early reproduction rather than growth. This idea is supported by the small size at maturity in this species and is consistent with an opportunistic life-history strategy. ^Note     

Reproductive biology of the Japanese silver-biddy,Gerres equulus,in western Kyushu,Japan

The Japanese silver-biddy Gerres equulus (Temminck and Schlegel) is one of the most common shore fish in the costal waters of southern Japan and commercially important for the local fishery. In the present study, the reproductive biology of G. equulus is described for the first time and its spawning season and size at sexual maturity were determined. A total of 1081 specimens (484 males and 597 females) were collected in the Yatsushiro Sea, western Kyushu, Japan, from January 2001 to December 2002. Monthly changes in the gonadosomatic index exhibited higher values between June and September, with a peak in July, and the trend was similar for both sexes. Furthermore, the sequential development of the ovaries observed through the histological studies suggested that the spawning season of G. equulus continued from June to September. The female attained sexual maturity at a minimum size of 141 mm standard length. The simultaneous presence of postovulatory follicles and yolk globules in some ovaries indicated that this species is a multiple spawner.     

全程投喂配合饲料条件下池养中华绒螯蟹的生长性能及其性腺发育

于2012年5月至2013年11月,对池养中华绒螯蟹(Eriocheir sinensis)全程投喂配合饲料,观测扣蟹和成蟹阶段的生长规律、成活率、早熟率、性腺发育速度、产量、规格分布和饲料系数等。结果表明:(1)扣蟹阶段雌雄生长差异不显著(P0.05),增重率(WG)和特定增长率(SGR)为先上升后下降,整个扣蟹培育阶段的平均SGR为1.9%/d左右;平均成活率和早熟率分别为10.0%和4.9%,雌体的早熟率显著高于雄体(P0.05);一龄早熟蟹和正常扣蟹的平均体重分别为19.8 g和7.5 g左右,一龄早熟蟹和正常扣蟹的平均产量分别为229 kg/hm~2和2433 kg/hm~2;扣蟹培育阶段饲料投喂主要发生在7—10月,占全部饲料用量的80%以上,饲料投喂量与扣蟹体重及池塘水温具有一定的关系,扣蟹阶段饲料系数(FCR)为2.15。(2)成蟹养殖过程中,自6月份起雄体体重大于雌体,整个养殖阶段雄体的SGR显著高于雌体(P0.05);雌雄成蟹最终平均体重分别为126.1 g和181.1 g,雌、雄及总体成活率分别为61.30%、53.47%和58.4%,产量分别为412.20 kg/hm~2、536.10 kg/hm~2和950 kg/hm~2;成蟹养殖的饲料消耗主要发生在7—10月,其中育肥前期(9—11月)的饲料用量占50%左右,整个成蟹养殖阶段的FCR为2.63。(3)池养成蟹的生殖蜕壳主要发生在8—9月,雌体比雄体早20 d左右;雌体的性腺发育主要发生在生殖蜕壳后的9—10月,雄体的性腺发育时间跨度较长,生殖蜕壳前性腺指数已达0.8%左右;雌雄成蟹性腺发育期间肝胰腺指数均呈下降趋势。综上,全程投喂配合饲料能保证池养中华绒螯蟹的正常生长发育,可大规模推广应用于中华绒螯蟹养殖产业。     

室内工厂化养殖犬齿牙鲆的生长特性

对室内工厂化养殖的犬齿牙鲆生长特性进行了研究。结果表明,其生长旺盛期在2龄,日生长最快达5.52g/d,第1年平均为1.65g/d,第2年平均为2.34g/d,第3年平均为1.3g/d,第4年平均为0.75g/d。养殖1周年其平均体重可达600g左右,两周年达1500g;其全长和体重的关系为W=0.0076TL3.1785(R2=0.9765),全长与体高和标准体长的关系分别为TL=2.5685BD-0.6594(R2=0.9823),TL=1.1957SL-0.1724(R2=0.9922)     

Growth performance, morphometric traits and gonad development of induced reciprocal diploid and triploid hybrids between the mud loach (Misgurnus mizolepis Günther) and cyprinid loach (Misgurnus anguillicaudatus Cantor)

Two species of loach, the mud loach (Misgurnus mizolepis Günther) and the cyprinid loach (M. anguillicaudatus Cantor), are commercially important in Korea both for food and ceremonial purposes. The mud loach has superior potential for aquaculture in terms of growth, whereas the cyprinid loach has a more desirable body shape and colour. This study was conducted to produce reciprocal diploid and triploid hybrids and to evaluate their potential benefits in culture by examining growth performance, morphometrics and gonad development. Reciprocal diploid and triploid hybridization was performed by artificial insemination without or with the induction of triploidy. The successful formation of diploid or triploid karyogamy was verified by flow cytometric analysis. Body weights of induced reciprocal diploid hybrids were intermediate between those of the two parental species, i.e. hybrids were heavier than cyprinid loach but lighter than mud loach. In contrast, the growth performance of triploid hybrids was similar to that of their corresponding maternal parents. Diploid hybrids showed intermediate morphometric traits between the two species; however, the body proportions of triploid hybrids were more similar to those of the maternal species than the paternal species. Histological analyses indicated that reciprocal diploid hybrids of both sexes were able to reach maturity, as evidenced by the presence of mature oocytes or spermatozoa in the gonad tissues. However, triploid hybrids showed stringent sterility at the gonadic level; the sizes of ovaries and testes were much smaller, and gonad development was abnormal and significantly retarded.