Mass Production of Striped Patao Eugerres brasilianus Juveniles in Cuba

Abstract.— Two spawning and larval rearing trials with striped patao Eugerres brasilianus were conducted at Tunas de Zaza, Cuba, to develop a method for experimental-scale mass production of juvenile fish. Mature striped patao were captured from coastal lagoons in September 1988 and January 1989. Sexually mature females and males were induced to spawn by treatment with human chorionic gonadotropin (HCG). After spawning, eggs were collected and placed in 1.2-m³ cylindroconical fiberglass incubators at densities of 150 and 200 eggs/L. About 1 h before hatching, eggs were transferred to 5–m³ concrete tanks. Larvae were fed a mixture of marine microalgae, rotifers, copepods, and Artemia nauplii; artificial food was supplied at 30 d post-hatch as a shrimp diet with 25% protein and 0.1–0.4 mm particles. Fourteen of 20 females spawned after 2 or 3 HCG injections (total dose = 6–10 IU/g body weight). Fecundity was 467–2,167 eggs/g body weight. Egg incubation time in seawater (38–39 ppt salinity) was 15–17 h at 29–30 C and 21–23 h at 25–26 C, with 98–100% hatching rate. The oil droplet and yolk sac were consumed by 3 to 5 d post-hatch and first food (rotifers) was eaten during second day. High larval mortalities began after the first month. Growth in 39- ppt seawater was faster (0.41 ± 0.01 md/d) at 29.1 ± 0.3 C than at 25.2 ± 0.2 C (0.27 ± 0.008 mm/d). Overall survival was 6–12.5% with tinal densities of 5–10 juveniles/L after 48–60 d. A total of 132,000 juveniles was harvested from the two rearing cycles.     

Natural Spawning and Mass Larviculture of Black Porgy Acanthopagrus schlegeli in Captivity in Taiwan

Abstract.— The black porgy Acanthopagrus schlegeli is one of the most important marine fish cultured in Taiwan. Wild-caught broodstock were spawned naturally in captivity at water temperatures of 19–26 C in 1989 and 1990. Females produced 352,000 to 957,000 eggs per female during the spawning period. The hatched larvae were reared in 45-m³ rectangular cement tanks and fed initially on rotifers, Brachionus plicatilis . followed by Artemia nauplii. and finally weaned onto an artificial diet. Larviculture trials to 40 d produced juveniles of 13.1–14.2 mm average total length, at a survival rate ranging from 18.3 to 74.8%. Lordotic deformation was observed in the juvenile stage. However, when an oil skimmer was used to remove the oil film on the water surface, the incidence of lordosis was reduced from 14.4 to 6.1%. High mortality of the larvae occurred during the initial 10–15 d after hatching and cannibalism was observed when larvae reached 7 mm total length. Juveniles grew to size of 83.7–101.4 mm total length with survival rate of 27.9–28.2% in 100 d. The results indicate that the present technique can be used for mass seed production of black porgy.     

Artificial Propagation of Mutton Snapper Lutjanus analis, A New Candidate Marine Fish Species for Aquaculture

Abstract Wild-caught mutton snapper Lutjanus analis , a high-value marine food fish species, matured in flow-through seawater (36 g/L) tanks after 3 yr in captivity. On 31 May 1995, a female with a mean oocyte diameter of 382 μm was injected with human chorionic gonadotropin (HCG) (500 IU/kg body wt.) followed 24 h later by a second injection (1,000 IU/kg body wt.). At the time of the second injection, three males were injected with HCG (500 IU/ kg body wt.). Voluntary spawning occurred 33 h after the first injection, with a total of 534, 781 eggs released. Fertilization rate was 75.7%, while average diameter of fertilized eggs was 783 μm. Embryos were stocked in a 30-m³ outdoor tank at a density of 10.5/L. On day 2 post-hatching (d2ph), larval density was 8.61 larvae/L, and average notochord length was 2.6 mm. Larvae were fed ss-type rotifers from dl-d28ph, Artemia nauplii from 0–08ph, and artificial diets (52–48% protein) from d24-d38ph. On d38ph, fish averaged 0.308 g and 22.2 mm standard length. Survival (from d2ph) was 14.3%, with a total of 36,900 post-metamorphic juveniles produced. On d97ph, 1,390 hatchery-reared juveniles (avg. wt. = 10.5 g) were stocked into two 14.5-m³ recirculating seawater tanks (695 fish/tank; 48 fish/m³) and fed a 56% protein pellet. After 168 d, fish averaged 140.8 g, with a survival rate of 97.8% and a feed conversion ratio (dry wt./wet wt.) of 1.2. These preliminary results reveal the mutton snapper to be a prime, new candidate species for commercial cultivation.     

Creation of artificial upwelling areas for brown trout, Salmo trutta, spawning in still water bodies

Abstract  Brown trout, Salmo trutta L., spawning sites were constructed by creating areas of artificial upwelling water, 252 ± 37 mL m⁻² min⁻¹ (95% CL), through appropriately sized spawning gravel substrate in 3 m² vessels buried in the bottom of a 150-m² pond. Natural spawning occurred in the vessels during autumn 2001–2004, with hatching and alevin swim up the following spring. In areas of upwelling, egg survival was 85–95%, while no live eggs were observed in areas without upwelling. In areas with upwelling, the maximum density of live eggs at the eyed stage was 570–1510 eggs m⁻². In spring 2004 and 2005, the density of alevins was estimated at 322 (±187) m⁻² and 567 (±217) m⁻², respectively, in areas with upwelling water, compared with 35.2 ± 25.4 m⁻² in areas without upwelling water in 2004.     

Voluntary Spawning of Captive Nassau Groupers Epinephelus striatus in a Concrete Raceway

Nassau groupers Epinephelus striatus held in a 37-m³ concrete raceway were conditioned to spawn 3 mo later than in their home waters. After being held in the raceway for 15 mo, four female and two male groupers spawned voluntarily over a 4-d period in March 1994, producing 10.3 million eggs. By December 1994, two females had been removed. During March 1995, one of the remaining two females spawned on three consecutive days (60 cm TL, 1,172,000 eggs) and the other only on the third day (47 cm TL, 488,000 eggs). In April 1995, three females (including one held in isolation for 6 mo, then replaced 6 d before the first spawn) produced more than 9.8 million eggs in 4 d. The isolated female spawned 8 d after being placed in a cage in the raceway and 4 d after release in the raceway.
Individual females spawned as many as nine times a day for 1–4 d. Spawning occurred from 3.5 d before until 8.5 d after the full moon. A 30-d interval elapsed between March and April 1995 spawning periods. Fertilization was in the range 83–100% and hatching 90–100%. Spawns occurred in a temperature range of 23.1–27.9 C; however, based on spawning frequency and volume and on egg development, 24–27 C seems most suitable. These results and other evidence support the view that Nassau groupers can be conditioned to spawn any month of the year, mainly by manipulating temperature.     

Ontogeny of anti-predator behavior in hatchery-reared jack mackerel Trachurus japonicus larvae and juveniles: patchiness formation, swimming capability, and interaction with jellyfish

ABSTRACT:   Laboratory rearing and behavioral observations of larval and juvenile jack mackerel Trachurus japonicus were conducted to elucidate their life-history traits with emphasis on the interaction with the moon jellyfish Aurelia aurita . Jack mackerel were raised from naturally spawned fertilized eggs and they attained 10.3 ± 0.7 (mean ± standard deviation) mm in body length (BL) by 30 days post hatching (dph) and 26.6 ± 1.8 mm BL at 48 dph raised at 19.3–25.0°C. Patchiness (dense aggregation) was confirmed from 5–16 dph (2.9–5.9 mm BL) during the day and from 9–48 dph (4.0–27 mm BL) at night. Cruise and burst swimming speeds were 1.5–1.9 BL/s and 16–24 BL/s, respectively, during larval and juvenile stages, in experimental tanks. Although escape performance from jellyfish was not different between the larvae of jack mackerel and chub mackerel Scomber japonicus , both species showed better survival compared to red sea bream Pagrus major larvae of a similar size. Although jack mackerel were slow in growth, their slow cruise swimming may reduce the chance of encountering predators and fast burst swimming may help escape from gelatinous predators.     

Natural spawning, early development and first feeding of the semicircle angelfish [Pomacanthus semicirculatus (Cuvier, 1831)] in captivity

Successful natural spawning of Pomacanthus semicirculatus in captivity from 11 September to 18 October, 2006 is described for the first time. Each female laid an average of 230 000 eggs during the spawning period. Fertilized eggs were spherical, transparent and buoyant and had a mean diameter of 0.61 ± 0.03 mm (mean ± SD). Embryonic development lasted 18–21 h at 28.5 °C. Newly hatched larvae were 1.35 ± 0.02 mm in total length (TL) with 27 (12+15) myomeres and had an oil globule in the ventroposterior area of the yolk sac. Larvae completed yolk absorption within 3 days post hatching at 2.37 ± 0.05 mm TL. Larvae were fed either 100% microalgae ( Nannochloropsis sp.), 100% s-type rotifers ( Brachionus rotundiformis ), 100% dinoflagellates ( Gonyaulax sp.) or different combinations of the three (50%:50%:0%, 30%:35%:35%) to determine the effect of live feed on the survival rate. The survival was significantly ( P <0.001) better in larvae fed a combination of diets (30%: 35%: 35%) than others. These results indicate that P. semicirculatus is a potential species for captive-breeding programmes and the use of a combination of diets (microalgae plus s-type rotifers and dinoflagellates) may be a suitable first food for fish larvae.     

The use of alizarin complexone for immersion marking of the otoliths of embryos and larvae of the turbot, Scophthalmus maximus (L.): dosage and treatment time

The purpose of this work was to determine the efficacy of marking turbot, Scophthalmus maximus (L.), eggs and larvae with alizarin complexone (ALC) for use in enhancement programmes and in studies of the ecology and behaviour of the species. The main aim was to determine the optimum dosage and treatment time for large batches of larvae destined for release into the sea.Eggs and larvae were immersed in a range of ALC concentrations (0–60 mg L^–1) for various times (3–24 h). On day 8 after hatching, eggs marked with the different ALC dosages had 99% marking success and had mainly good-quality or very-good-quality marks, whereas larvae achieved 100% success and had mainly very-good-quality marks. The best results were obtained after marking larvae with ALC at 60 mg L^–1 for 6–24 h.During the first months after marking, the fluorescent rings formed in the otoliths were easily detected when directly examined with a UV microscope, no prior preparation of the otoliths was necessary, but after 7 months the marks become faint as the otoliths get thicker, so it is necessary to cut or polish the otoliths before examination.     

Lipid Nutrition and Feeding of Cobia Rachycentron canadum Larvae

This study examined the fatty acid composition of cobia Rachycentron canadum eggs and yolksac larvae, as well as the ovaries of wild caught females as an initial guide to lipid nutritional requirements. A 2-wk feeding study also was conducted to investigate the effectiveness of four dietary treatments on the growth and survival of cobia larvae. Cobia eggs in the tailbud stage contained 31.4 ± 1.3 μg lipid/egg. After hatching, the amount of lipid decreased significantly (P < 0.05) from 28.3 ± 0.3 to 23.2 ± 0.1 μg lipid/larvae during the yolksac larval stage (days 1 to 3 after hatching). Ovaries from wild caught adults and captive spawned eggs and yolksac larvae contained high levels of PUFAs with docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA) accounting for approximately 80% of the total suggesting that cobia larvae may have a high dietary requirement for these fatty acids. For the feeding study, larvae were fed: 1) Artemia only; 2) enriched rotifers for 1 d only + microparticulate diet (day 313); 3) enriched rotifers for 3 d (day 3–5) + Artemia (day 3–13); and 4) enriched rotifers for 6 d (day 3–8) + Artemia (day 3–13). Cobia larvae began feeding on rotifers 3 d after hatching and on newly hatched Artemia nauplii by the fifth day following the onset of exogenous feeding (day 7). On day 7, no differences in larval growth were found among larvae fed rotifers for 3 versus 6 d, whereas larvae fed only Artemia or rotifers for I d followed by microparticulate diet were significantly smaller (P < 0.05) and did not survive beyond day 9 and 13, respectively. The results of the feeding study indicate that cobia larvae require rotifers for a minimum of 4 d following the onset of exogenous feeding.     

Development of embryos and larvae in the common Japanese conger Conger myriaster

Development of embryos and larvae in the common Japanese conger Conger myriaster was observed after artificial fertilization. Eggs were obtained from females matured artificially by hormone injections and milt was obtained from males matured naturally. Fertilized eggs were kept in seawater at 12–14°C. The first cleavage occurred at 4 h, epiboly began at 24 h, the embryonic body was formed at 38 h and hatching occurred at 84 h after insemination. Newly hatched larvae were approximately 2.5 mm (total length) and similar to those of Anguilla japonica in terms of external features. The mouth and anus opened on the 7th day after hatching. Pigments began to appear at the tip of the tail on the 10th day. The total length of the larvae reached approximately 8 mm on the 11th day. Eye pigmentation began on the 14th day. One larva lived for 19 days without food.     

Sperm Characteristics of Precocious 1-year-old Male Striped Bass Morone saxatilis

Abstract.— Captive-reared, 10-mo-old, male striped bass Morone saxatilis were sampled monthly for testicular development between February and June 1994. One of the five males sampled in February showed precocious testicular development and had a gonado-somatic index (GSI) of 1.26%. while the other four fish had immature testes with a mean GSI ± s^x, of 0.17 ± 0.03%. Spermiating individuals were present from April to June. In April the average body weight (BW) of spermiating males was 65 ± 4 g and their GSI reached a mean value of 4.75 ± 0.52%. In June, milt collected from ten precocious males contained motile spermatozoa with a mean of 31 ± 7% of the sperm showing forward movement. Mean milt volume and sperm concentration were 1.67 ± 0.41 mL/kg BW and 92.3 ± 1.8 ± 10⁹ spermatozoa/mL. respectively. These data show that male striped bass reared in captivity can reach sexual maturity during their first year. This is one year earlier than previously reported for striped bass in mid-Atlantic regions.     

Reproductive biology of whitespotted bamboo shark Chiloscyllium plagiosum in northern waters off Taiwan

ABSTRACT:   In total, 491 whitespotted bamboo sharks were collected from northern Taiwanese waters from February 2002 to February 2003. The sex ratio of the specimens was 0.65, total length (TL) ranged from 35.3–85 cm, and weight ranged 124–2580 g. The mean size at first maturity was estimated to be 64.9 and 65.6 cm TL for females and males, respectively, based on the relationship between mature percentage and TL. The ovulation season was estimated as March to May based on gonadosomatic index (GSI) variations and captive observation. The monthly changes in GSI of males suggested that the mating season was from December to January. The inconsistency between mating and ovulation seasons suggested that females have sperm storage and delayed fertilization. One or two eggs were deposited every 6 or 7 days on average. Deposition of eggs extended for 2 months, and fecundity was 8 ± 3.8 eggs. Thirteen of 48 eggs deposited in 2003 were hatched and the hatching rate was 0.27. The hatching period was 107 ± 9.3 days with accumulated water temperature ranging from 2372–2835°C.     

First studies of embryonic and larval development of Coilia nasus (Engraulidae) under controlled conditions

Herein, we describe the embryonic and larval development stages of Coilia nasus, an anadromous fish that is indigenous to the Yangtze River and the northwest region of the Pacific Ocean. The success of artificial breeding programmes and modern methods of reproduction allowed us to accurately describe the development stages of C. nasus. These stages were recorded using a binocular microscope and a digital camera‐equipped microscope, and histological and scanning electron microscopy observations were also conducted. Development can be divided into four periods: embryonic, prelarval, larval and juvenile. The fertilized eggs were spherical, transparent, non‐adhesives and buoyant, with an average diameter of 0.80±0.10 mm. Complete early embryonic development took place within 40–43 h post hatching, and the new hatchlings were 2.85±0.20 mm long. The mouth openings (0.25–0.35 mm) appeared at day 6 post hatching. Complete metamorphosis took place by day 60, at which time the larvae transformed into juveniles (65±5.8 mm) and attained skin coloration.     

Progress in Controlled Maturation and Spawning of Summer Flounder Paralichthys dentatus Broodstock

Abstract— Wild-caught, adult summer flounder Paralichthys dentatus (avg. wt. = 740 g; range = 264–1,540 g; N = 60), collected in northeastern US coastal waters during October 1994, were transported to Vero Beach, Florida in March 1995 and held in 2.6-m³ indoor tanks through November 1995 under two artificial photothermal regimes: (1) natural regime, simulating natural habitat conditions; and (2) accelerated thermal regime, with seasonal temperature changes advanced by one month. A third group of fish was held in outdoor tanks under ambient photothermal conditions. Under all photothermal conditions, onset of vitellogenesis was associated with declining daylength and temperature, beginning in the accelerated group, then progressing to the natural and the ambient groups. From 20 September to 28 November 1995, 23 vitellogenic stage females from the accelerated and natural regimes were implanted with a cholesterol-cellulose pellet containing LHRH-a (100 μg/kg body wt). Females with initial mean oocyte diameters ranging from 258–456 μm spawned voluntarily 2.5–5.5 d postimplantation, while no maturational response was obtained from females with mean diameters ranging from 165–231 μm. Two females were spawned twice during the study period by LHRH-a pellet implantation. Infrequent, natural spawning without hormone intervention was also obtained. Females released from 22.7–396.9 × 10³ eggs on the first day of spawning, with fertilization and hatching rates of 0–93.470 and 0–81.1%, respectively.     

Embryonic and larval development of honeycomb grouper Epinephelus merra Bloch

Spawning and successful rearing of larvae of honeycomb grouper Epinephelus merra Bloch 1793 upto juvenile stage was accomplished at the finfish hatchery of Mandapam Regional Centre of Central Marine Fisheries Research Institute during 2004. The fertilized eggs were free, spherical and buoyant with size ranging from 710 to 730 μm. Complete early embryonic development took place within 24–27 h and hatching occurred. The hatchlings measured 1.5 mm. Mouth opening (115 μm) appeared at 72 h when the larvae were 2.2 mm in size. Pectoral fin developed on the fifth day. Complete metamorphosis took place and by the 60th day the larvae transformed into juveniles (45 mm) and attained skin colouration and honeycomb pattern.     

Induced Final Maturation and Spawning of the Marbled Grouper Epinephelus microdon Captured from Spawning Aggregations in the Republic of Palau, Micronesia

A high percentage (98.3%, N = 60) of the marbled grouper Epinephelus microdon individuals captured from spawning aggregations during July and August 1993 in the waters surrounding the island of Koror, Republic of Palau, Micronesia, were in the stage of maturity at which final maturation and spawning could be hormonally induced. The sex ratio of the captured fish was highly skewed towards males (4 male:1 female). Sexually immature females comprised the smallest size class, (<0.6 kg body weight (BW) or 33.0 cm total length (TL)), while sexually mature females were restricted to the 0.6–1.5 kg BW (33.0–46.4 cm TL) groups. Males predominated in size classes >0.6 kg BW, and individuals >1.5 kg BW (46.4 cm TL) were exclusively male. All females with oocytes that averaged ( N = 50) >400 μm in diameter were successfully induced to spawn by a two-injection protocol using human chorionic gonadotropin (HCG) at total dosages of 2,100–3,200 IU/kg fish. All males used in the spawning trials were administered a single injection of HCG at dosages of 500 or 1,000 IU/kg fish. Fecundity ranged between 7.96 × 10⁵−1.24 × 10⁶kg BW, average spawned egg diameters ranged between 769–832 μm, percent fertilization ranged between 32.6%–99.9%, and hatching percentages were >90.0%. Total fat content of eggs obtained from a pooled spawning event was 14.1 mg/100 mg dry weight. The data indicate that HCG is a suitable treatment for the induction of spawning in marbled grouper females that possess a mean oocyte diameter of 400 μm or greater.     

Growth of 0+ perch (Perca fluviatilis) predating on 0+ bream (Abramis brama)

Abstract – Larvae and juveniles of perch Perca fluviatilis and bream Abramis brama of Lake Speldrop, a highly eutrophicated gravel-pit lake in the floodplain of the Lower Rhine, were used in laboratory experiments to study predation of perch on bream. In the first series of experiments (control), 0+ perch of 30 mm total length (TL) did not prey on 0+ roach of about 24 mm TL. The perch fed only on zooplankton, resulting in low growth rates of 0.17 mm  ·  day⁻¹. In the second series of experiments, perch (30 mm TL) were combined with 0+ bream with an average TL of 14 and 19 mm at different ratios. As in the first series, even a nine-fold higher amount of zooplankton food had no significant influence on the growth rate of perch, regardless of the perch:bream ratio. At a perch: bream ratio of 7:1 and 4:4 all bream were eaten by the perch and restocked twice daily. At the end of the experiment, the TL of perch at a perch:bream ratio of 7:1 was significantly lower compared to a perch:bream ratio of 4:4 (mean growth rates at 7:1 of 0.16 mm  ·  day⁻¹ and at 4:4 of 0.35 mm  ·  day⁻¹). At the perch:bream ratio of 1:7, perch fed on bream in varying amounts, averaging between 3 and 12 bream per day and per individual. After 20 days, the final length of these fish was always significantly higher than the TL of perch at other perch:bream ratios and increased in correlation to number of bream eaten per day (mean growth rate 1.13 mm  ·  day⁻¹). The results are discussed with respect to the piscivore-dominated fish community of the eutrophied Lake Speldrop. ^Note     

Larval development in European hake (Merluccius merluccius L.) reared in a semi-intensive culture system

Eggs of European hake (Merluccius merluccius L.) were stripped from fish caught at sea. Larvae were kept under semi‐intensive conditions at around 12°C. In addition, eggs were incubated in single wells at 9.2, 12.7 and 14.5°C, where hatching, development and survival were closely examined. During the larval stage, a total of 299 larvae were sampled to follow development and growth. In addition a small number of juveniles were sampled. Larvae hatched approximately 4 days after fertilization, and were 2.9 mm in total length (TL). At 6‐day post hatching (dph), the larvae were 4.1 mm (TL), the jaw apparatus was developed, and the larvae had started to feed. Most of the growth during the early larval period is restricted to the head, and there is almost no increase in length for the first 3–4 weeks post hatching. Teeth and pelvic fins appear at 25 dph. Development of unpaired fins at approximately 30 dph marks the start of the larval–juvenile transition. Weaning to formulated feed was accomplished 50 dph, when external morphology was similar to that of adult hake.     

牙鲆室内人工养殖试验

报道了室内养殖牙鲆的试验结果,１９９２年－１９９５年进行的小规模试验。将受精卵培育至鱼苗、成鱼直至成熟亲鱼。在水温为２－２５℃范围内,经过３６个月将全长为５．３ｃｍ鱼苗培育至全长为４６．８ｃｍ、体重为１７８０ｇ的商品鱼,成活率为５０．６％。１９９７年－１９９８年进行的生产性养殖试验,在水温为１０－３３℃范围内。经过１０个月将全长为５．４ｃｍ鱼苗养至全长为３３．４ｃｍ、体篝为３５６ｇ的商品鱼、成活率