Preliminary results of experiments on the rearing of Tasmanian flounders, Rhombosolea tapirina and Ammotretis rostratus

Tasmanian species of flounder were cultured successfully following stripping and fertilizing eggs after hormone-induced ovulation. The larvae were fed rotifers followed by Artemia nauplii. Survival rates of larvae from first-feeding to metamorphosis, which were as high as 94–98% for R. tapirina and 65% for A. rostratus, indicate that both species can be readily cultured in captivity.     

Experiments of the rearing of larval turbot, Scophthalmus maximus L.

Experiments on the live food requirements of cultured turbot larvae are described. A mixture of six species of unicellular algae did not sustain early larvae, but the growth and survival of larvae fed with rotifers were considerably improved when the rotifers were feeding on Isochrysis galbana rather than on Dunaliella tertiolecta. Oyster (Crassostrea gigas) larvae offered alone or with rotifers, did not produce higher larval growth or survival than rotifers alone. Black tanks were found to be more suitable than white tanks for rearing larval turbot.     

Induced spawning and larval rearing of the white seabream, Mylio berda

The white seabream, Mylio berda, was induced to spawn spontaneously by hormone injections of synahorin or human chorionic gonadotropin for over 3 months between December and April in Hong Kong. Fertilized eggs were also obtained during the peak spawning period between February and March through natural spawning or artificial insemination. The hatched larvae were reared in 500-1 circular tanks and fed initially on rotifers, Brachionus sp., followed by brine shrimp nauplii or copepod nauplii and finally weaned onto fish meat. Larval rearing trials for growth and survival to 60 days produced larvae of average length, 26.2 mm, at survival rates ranging from 1.32 to 11.62%.     

Gaffkemia in the California spiny lobster, Panulirus interruptus: Infection and immunization

Infection (gaffkemia) can be induced in the California spiny lobster (P. interruptus) with injections of Pediococcus homari (formerly Gaffkya homari). An LD_{5 0} of 10³ microbes per ml hemolymph is observed at 17°C. Prior immunization of lobsters (P. interruptus) with an avirulent strain of P. homari protects lobsters against 100 × LD_{5 0}. This is the first report of acquired immunity to P. homari in a susceptible species. The high incidence of gaffkemia in American lobsters (Homarus americanus) held in live holding facilities makes prophylactic measures essential in regions outside the enzootic area of the North Atlantic to avoid inadvertent transplantation of the disease to other susceptible populations of animals.     

Larval rearing and development of the brown spotted grouper, Epinephelus tauvina (Forskål)

Epinephelus tauvina (Forskål) has spawned naturally in captivity. The larvae were reared to metamorphosis using rotifers, Artemia nauplii, copepods and minced shrimp meat. The developmental stages from hatching through to metamorphosis are described. Larvae grew from 2.25 mm total length at hatching, to 31.40 mm by day 50. Two mortality peaks were observed: the first between days 4 and 5, and the second between days 24 and 35. The first peak corresponded to first feeding and the unsuitability of rotifers, and the second to the change from feeding Artemia nauplii to copepods, which were not available in sufficient quantities.     

Productivity improvement of Lysmata seticaudata (Risso, 1816) larval rearing protocol through modelling

The Monaco shrimp Lysmata seticaudata (Risso, 1816) is a marine ornamental species whose ecology and biology, as well as its larval culture has previously been addressed. The objective of the study was to predict and improve productivity of this species rearing protocol through modelling. The models developed intend to help aquaculturists to maximize survival to postlarva, decrease larval duration and increase synchronism of metamorphosis and newly metamorphosed postlarvae size by manipulating temperature, diet, first feeding period and stocking density.The models developed allow us to conclude that the L. seticaudata rearing protocol productivity can be improved by raising larvae at a density of 40 larvae L^− 1 and fed newly hatched Artemia nauplii since hatching to zoea V, and with Algamac 2000™ enriched Artemia metanauplii from zoea V to metamorphosis to postlarvae.By providing more productive protocols to aquaculturists, destructive practices and wild collection may be reduced.     

精养团头鲂池塘沉积物微生物群落的结构特征及组成多样性分析

为了研究精养团头鲂池塘冬季不投饵期间沉积物不同层次细菌群落结构的特征,实验分层次采集池塘沉积物,采用PCR-DGGE(变性梯度凝胶电泳技术)及基因测序技术,对池塘沉积物垂向空间分布的微生物群落特征及多样性的组成进行分析。结果显示:精养团头鲂池塘的整个停饵期间沉积物微生物群落的丰富度(平均为38)和多样性指数(平均为3.18)均较高,说明精养池塘沉积物中微生物数量多、种类丰富。上层(0~10 cm)和中层(10~20 cm)沉积物的微生物群落Shannon指数(3.29、3.27)略高于下层(20~30 cm)的Shannon指数(3.17),底层沉积物样品的指数最小(2.96),说明在底层沉积物中微生物群落结构趋于稳定,菌群多样性变化较小。精养团头鲂池塘的整个停饵期间沉积物样品中上层(0~10 cm和10~20 cm)微生物的群落结构相似性较高(80%以上),而底下层(20~30 cm和30~40 cm)与中上层微生物的群落结构相似性较低(63%以上),说明通过微生物群落结构的相似性程度可以大致看出样品的空间顺序。微生物群落组成多样性的结果显示:精养团头鲂池塘沉积物在整个停饵期间包含的菌群分属于8个门:变形菌门(β-、γ-、δ-亚群)(33.33%)、绿弯菌门(19.05%)、拟杆菌门(14.29%)、蓝细菌门(9.52%)、螺旋体门(9.52%)、硝化螺旋菌门(4.76%)、酸杆菌门(4.76%)、厚壁菌门(4.76%);结果表明变形菌门为精养团头鲂池塘沉积物在停饵期间的优势菌群,δ-变形菌亚群(14.29%)是变形菌门中的优势菌群。本实验以期得到不同种类微生物的分子信息从而为以后筛选有益菌群奠定基础,并为团头鲂精养池塘微生态环境的人工调控提供依据,从而为适时监测养殖生态环境运营状况建立快速的分子生物学分析方法。     

Improvement of the method for propagation,larval and postlarval rearing of the wels (Silurus glanis L.)

Using the old method of spawning it is impossible to produce wels larvae in quantities sufficient for a special fry farm economically. Because of this, a large-scale intensive method had to be developed, similar to those for other species which are propagated in hatcheries. A method for storing breeders was elaborated which included sewing their mouths shut and consequently eliminating injuries. Pituitary treatment — practised by others before — was applied, and disadvantages of the method (such as the development of furuncles) eliminated. A method for taking sperm from males with the help of a special syphon was developed.To avoid losses, larvae were reared in basins until they reached the size of 2–2.5 cm. Using this method considerable quantities of fry were produced in our hatchery.     

Experiments in rearing rabbitfish (Siganus rivulatus) in sea water

The initial experiments in rearing rabbitfish (Siganus rivulatus) in sea water indicate that this fish may be suitable for commercial cultivation. Juveniles are available in large numbers during summer and fall along the Mediterranean and Red Sea coast of Israel. Juveniles collected in Eilat (Red Sea) were kept in tanks and submerged cages and fed fish pellets. After 29 days in tanks, the first group of fish which averaged 0.91 g upon capture increased in weight to an average of 3.7 g. A subsequent school of juveniles kept in sea cages for 84 days increased in weight from an average of 7.3 g to 28.5 g.     

Studies on the presentation of artificial diets for rearing the larvae of Penaeus japonicus Bate

The preparation of microencapsulated diets for rearing the larvae of Penaeus japonicus is described. Once the correct microcapsule size and feeding concentration had been determined, experiments showed that survival rates of 50% to post-larva were possible. Comparative experiments using artificial diets in the form of free particulates indicate that survival rates may be even higher (66–68%) on these diets providing precautions are taken to avoid bacterial blooms. Further investigations revealed that microencapsulated semi-defined diets may be used to determine the nutritional requirements of Penaeus larvae.     

Preliminary studies on rearing of the gilthead seabream, Sparus aurata (L.), in brackish water ponds

The first attempt to rear the gilthead seabream, Sparus aurata, in brackish water ponds in Egypt was conducted from April 1976 to February 1977. Experimental ponds were stocked with Sparus aurata fry of about 32 mm and 1.5 g average length and weight respectively at a rate of 3000 fry per one feddan of pond water (i.e. 0.42 ha). The growth rate was recorded monthly. An average length and weight of 190 mm and 78 g respectively was attained after 8 months without supplementary feeding or fertilization of pond water. mathematical equations expressing length-weight relationship and condition factor were derived for both wild and reared fish. The higher values of condition factor obtained for the reared fish in comparison to the wild fish signify their improved condition and hence their suitability for farming in Egypt.     

Isolation of Pediococcus homari, etiological agent of gaffkemia in lobsters,from a California estuary

Virulent Pediococcus homari, the etiological agent of gaffkemia, a disease enzootic in Atlantic lobsters (genus Homarus), was isolated from two sites in Anaheim Bay, Calif. The concentration of P. homari was in the order of 1–10 bacteria per ml of sample. This is the first known report of free-living P. homari in the Pacific; the bacterium was previously reported to exist in infected decapod Crustaceae and sediments from the Atlantic. Introduction of P. homari may have occurred through transport of infected Homarus americanus (Atlantic lobster), or by discharge of water in contact with them.     

The induced spawning of the grey mullet, Mugil macrolepis (Aguas) Smith and the large-scale rearing of its larvae

The grey mullet, Mugil macrolepis (Aguas) Smith could be induced to spawn by the administration of pituitary alone from the same species. The threshold dose was found to be three and four glands as the first and second injections after a 6-h interval. About 40% of the experiments were successful. The hand-stripped eggs were artificially fertilized with milt by the dry method.The embryonic development of the eggs are briefly described. The majority of the fertilized eggs hatched out about 23 h after fertilization. The salinity of the water ranged from 29 to 31‰ and temperature from 26 to 29°C.A method for the large-scale rearing of mullet larvae is outlined. “Seasoned greenwater” is produced by keeping slightly manured brackish water for about a fortnight in small tanks which can be exposed to sunlight in the afternoon. Blooms of Chlorella sp. developed and the larvae fed on the microplankton. The larvae at about 1 cm in length fed exclusively on copepods. Hence copepod cultures were maintained simultaneously in manured cisterns for feeding the mullet larvae until they accepted artificial feeds.     

Captive spawning and larval rearing of California yellowtail (Seriola lalandi)

A captive population of California yellowtail (Seriola lalandi) was used to document spawning patterns, including measures of egg production, population fecundity and egg and larval quality from 2007 to 2010. Spawned eggs were also used to document larval development and to develop rearing techniques for aquaculture in the region. Broodstock growth and condition factor were best when feeding rations were maintained at 10–15% body weight week^?1 during the warm summer months. A winter ration based on satiation feeding was typically 4% body weight week^?1. During the 4‐year study period, the only broodstock health issue was an infestation by the parasitic gill fluke Zeuxapta seriolae, which was readily treated. Spawning occurred naturally in the 140 m³ tank when the ambient water temperature reached 16°C and ended when the temperature exceeded 22°C. Egg production reached a maximum in 2010 when 43 spawn events were recorded from a pool of nine females yielding 36.8 million eggs in total. The average female size at this time was 20 kg, which equated to a total annual population fecundity of approximately 226 000 eggs kg^?1 female year^?1. Larval rearing trials yielded survival rates as high as 5.8% from egg to 50 days post‐hatch (dph). Successful larval culture methods included the addition of algae paste for green water culture, rotifers (20 rotifers mL^?1) at 2 dph and Artemia (5 Artemia mL^?1) at 6 dph. Larvae were transferred from the incubation tank at 10 dph to a shallower tank with 33% greater surface area to accommodate the larvae's strong orientation to surface waters. This research represents the first documentation of successful spawning and larval rearing for S. lalandi in the eastern Pacific.     

The biological response of the crayfish Procambarus clarkii to transplantation into California ricefields

The population dynamics of the crayfish Procambarus clarkii was studied in California ricefields to investigate the effects of range extension and to examine its potential for harvest. The species was shown to undergo distinct cycles of activity related to depth, temperature and reproduction. Juveniles were observed to have two peaks in activity during late summer and winter, while adults only had a single peak. Ovarian maturity was found during summer and maximum hatching occurred in late summer and winter. Males matured at 35.8 mm carapace length (CL) on the average, while females matured at 36.5 mm CL. A direct correlation between female egg production and body size was noted. P. clarkii in California were shown to be cued into similar cycles as Louisiana crayfish, even though the timing and extent of the hydrological cycle was considerably different. Breeding activity paralleled the Louisiana crayfish, while winter-spring juvenile growth rates (16.32 mm in 120 days) and biomass (208 kg/ha) were much lower. Crayfish emigration during ricefield draining was found to be substantial (31% of population) and may provide an excellent opportunity for harvest.     

Evaluations of rum distillation wastes,pharmaceutical wastes and chicken feed for rearing Tilapia aurea in Puerto Rico

Rum distillation wastes (solubles and yeast), pharmaceutical wastes (spent beer and spent beer plus solids), and a locally manufactured chicken feed were evaluated for their potential use in the culture of Tilapia aurea in Puerto Rico. The experimental products were compared to three types of controls: a commercial fish feed, an inorganic fertilizer, and an unmanaged system. The yield trials were conducted for 120 days in 9.3 m plastic pools. Three replications were made of each treatment. Survival of fish in the various treatments ranged from 80 to 96.7%. The highest mean standing crop at harvest (690 kg ha^?1 equivalent) resulted from the fish receiving the commercial fish feed. This was followed by the fish from the spent beer treatment (643 kg ha^?1 equivalent), inorganic fertilizer (559 kg ha^?1 equivalent), distiller's yeast (454 kg ha^?1 equivalent), spent beer plus solids (429 kg ha^?1 equivalent), chicken feed (413 kg ha^?1 equivalent), distiller's solubles (347 kg ha^?1 equivalent), and the unmanaged system (145 kg ha^?1 equivalent). The average feed conversion values for the fish fed the commercial fish feed and chicken feed were 1.53 and 2.06, respectively. Dissolved oxygen levels in pools treated with rum distiller's yeast declined from approximately 8.0 to 0.4 p.p.m. following initial application of the product. Dissolved oxygen depletions occurred after each subsequent application. All other systems had waters with dissolved oxygen concentrations generally suitable for fishculture.     

Hatching and rearing lobster larvae (Homarus americanus) in a disease situation

Lobster rearing facilities in the United States suffered severe losses of larval stages during the summer of 1974 hatching season. The organisms responsible for losses at the Bodega Marine Laboratory were the fungus Lagenidium sp. and epiphytic contaminants. Various systems and treatments were used in attempts to overcome the problems encountered. Postlarval lobsters were produced successfully in a semi-closed system using ultraviolet-irradiated sea water and a malachite green dip for eggs and larvae.     

Life‐history differences of juvenile Chinook salmon Oncorhynchus tshawytscha across rearing locations in the Shasta River,California

Salmon from different locations in a watershed can have different life histories. It is often unclear to what extent this variation is a response to the current environmental conditions an individual experiences as opposed to local‐scale genetic adaptation or the environment experienced early in development. We used a mark–recapture transplant experiment in the Shasta River, CA, to test whether life‐history traits of juvenile Chinook salmon Oncorhynchus tshawytscha varied among locations, and whether individuals could adopt a new life history upon encountering new habitat type. The Shasta River, a Klamath River tributary, has two Chinook salmon spawning and juvenile rearing areas, a lower basin canyon (river km 0–12) and upper basin spring complex (river km 40–56), characterised by dramatically different in‐stream habitats. In 2012 and 2013, we created three experimental groups: (i) fish caught, tagged and released in the upper basin; (ii) fish caught at the river mouth (confluence with the Klamath River, river km 0), tagged and released in the upper basin; and (iii) fish caught at the river mouth, tagged and released in the lower basin. Fish released in the upper basin outmigrated later and at a larger size than those released in the lower basin. The traits of fish transplanted to the upper basin were similar to fish originating in the upper basin. Chinook salmon juvenile life‐history traits reflected habitat conditions fish experienced rather than those where they originated, indicating that habitat modification or transportation to new habitats can rapidly alter the life‐history composition of populations.     

Laboratory culture and estimated life span of the Eastern Atlantic squid, Loligo forbesi Steenstrup, 1856 (Mollusca: Cephalopoda)

Abstract. First culture results are presented from four major experiments (lasting up to 478 days) on the commercially important squid species, Loligo forbesi Steenstrup, Details are provided on eggs, hatching, feeding, growth, survival, behaviour and sexual maturation. Best survival during the critical first 75 days was 15%. The hatchlings (up to 4.9mm mantle length, ML) are the largest among the genus Loligo , and the largest squid grown was a male 155mm ML and 124g. First schooling was observed only 40–50 days post-hatching. Spawning was not achieved although males reached maturity, females had maturing ova and mating was observed. The largest giant axon measured was 425μm in diameter (from a female 130mm ML), a size suitable for most biomedical applications. Laboratory data suggest a 2-year life cycle compared to fishery data which suggest a 1-year cycle.