摘要:

AbstractA high percentage (98.3%,N= 60) of the marbled grouperEpinephelus microdonindividuals 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, (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

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00621.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractNassau groupersEpinephelus striatusheld in a 37‐m3concrete 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 manipulat

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00622.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe effects of a mammalian growth hormone‐releasing hormone (GHRH), PrebGRF(1–78)OH (bGHRH), on growth and serum growth hormone (GH) levels were investigated in tilapiasOreochromis mossambicusandO. niloticus × O. aureus. Fish were injected intramuscularly or implanted intramuscularly (Silastic or cholesterol implants) with distilled water, 0.1 μg/kg bGHRH, 1.0 μg/kg bGHRH, 10.0 μg/kg bGHRH, or 100.0 μg/kg bGHRH and compared to untreated controls, fish implanted with 60 mg/kg 17α‐methyltestosterone (MT), or a combination of bGHRH concentrations plus either MT, 0.01 μg/kg of a thyroid hormone (T3), or 0.01 μg/kg of a glucocorticoid (DEX). The bGHRH increased serum GH levels in tilapia maintained at suboptimal temperatures (18 C). Serum GH levels were highest (5.3–0.45 ng/mL) for fish injected with 10.0 μg/kg bGHRH. Fish implanted with a Silastic implant containing 10.0 μg/kg bGHRH had significantly higher (4.35–0.35 ng/mL) serum GH levels than those with an equivalent dosage in a cholesterol implant. The addition of MT, thyroid hormones, and glucocorticoids did not increase serum GH levels above those obtained for fish receiving bGHRH alone. Tilapia reared at suboptimal temperatures and implanted with 10.0 μg/kg and 100.0 μg/kg bGHRH had significantly greater increases in weight and length than control fish. Fish implanted with bGHRH, MT or bGHRH plus MT had significantly higher moisture and protein content, while fat and ash contents were significantly lower than controls or sham‐implanted fish. Fish implanted with bGHRH or bGHRH plus MT had significantly higher gonadosomatic indices than fish implanted with MT alone, shams or non‐treated controls. This study demonstrates that a mammalian GHRH stimulates release of GH, promotes somatic and gonadal growth and may affect reproducti

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00623.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractSolvent‐extracted cottonseed meal was used in shrimpPenaeus vannameidiets at levels of 0, 13.3, 26.5, 39.8, 53.0 and 66.3%, substituting on an equal nitrogen basis for 0, 20, 40, 60, 80 and 100% of animal protein mix (53% menhaden fish meal, 34% shrimp waste meal and 13% squid meal). The feeds were formulated to contain 32% crude protein and 3,100 kcal metabolizable energy/kg. Each diet was fed to juvenile shrimp to satiation four times daily for 8 wk. Shrimp fed the three lowest dietary levels of cottonseed meal (0, 13.3 and 26.5%) had similar weight gain, feed consumption and survival. The performance of shrimp was adversely affected when diets containing more than 26.5% cottonseed meal, or 1,100 ppm free gossypol, were fed. Shrimp fed the diet with 39.8% cottonseed meal or 1,600 ppm free gossypol had depressed weight gain, reduced feed intake and high mortality. The groups receiving the two highest dietary levels of cottonseed meal lost weight by the end of week 4 and all shrimp in these treatments died within 6 to 8 wk. These adverse effects were probably due to the toxicity of free gossypol. Shrimp appeared to accumulate gossypol in the body as evidenced by light yellow‐green coloration in shrimp fed diets containing cottonseed m

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00624.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe staged addition of feed to fertilized fish ponds was evaluated by adding fertilizers to 15 ponds stocked with Nile tilapiaOreochromis niloticus, then adding feed at half ad libitum rates once fish in the ponds reached a target weight. Each pond was stocked with 750 fish (3 fish/m2), and each treatment included three ponds with first feeding at (a) 50 g, (b) 100 g, (c) 150 g, (d) 200 g, and (e) 250 g. Ponds in Thailand (at the Ayutthaya Freshwater Fisheries Station, Royal Thai Department of Fisheries) were maintained for 236–328 d until the fish reached 500 g.Growth was similar for all treatments under fertilizer alone (1.17 g/d) and was also similar when feed was applied (3.1 g/d). Feed application rates averaged 1.17% BW/d, indicating substantial use of natural food. Pond water quality did not deteriorate under supplemental feeding. Feed conversion rates averaged 1.03. Multiple regression indicated that 73.8% of the variance in growth was explained by design variables (feed input and days), while 86.2% of the variance in growth was explained by adding dissolved oxygen content and alkalinity into the equation.The most efficient system was to grow fish to 100–150 g with fertilizers alone, then add feed. First adding feed (at 50% ad libitum) once fish reached 100 g produced the highest predicted annual revenues ($6,164 per hectare). Results of this experiment indicated that either critical standing crop occurred early (before the first fish sample) or did not occur at all in these po

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00625.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractStreptococcal infection (Streptococcus iniae) was diagnosed sequentially in two tanks of hybrid striped bassMorone saxatilismale ×M. chrysopsfemale (Sunshine bass) grown in a commercial freshwater recirculation facility in western Massachusetts. The pathogen was isolated in the laboratory, biochemically and morphologically characterized, and antibacterial sensitivities determined.Streptococcus iniae‐induced lesions in the Sunshine bass were character at the gross and histopathological levels. Initial treatment with oxytetracycline was unsuccessful. Based on sensitivity results, enrofloxacin‐medicated feed was dosed at 10 mg/kg body weight for 10 d, while a subsequent trial was conducted at 5 mg/kg body weight for 10 d. Mortality of fish subsided promptly following initiation of enrofloxacin therapy, yielding a final mortality in the initial tank of 10.83% (control tank 55.5%) and in the second tank of 16.97% (control tank 39.8%). Tissue enrofloxacin residues, detected via a microbiologic bioassay, revealed greater quantities and longer duration of residues in various tissues from the 5‐mg as compared to the 10‐mg trial, potentially the result of adverse feed palatability. Enrofloxacin appears to have excellent potential as an antibacterial agent for treating susceptible bacterial diseases of Sunsh

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00626.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.—The European abaloneHaliotis tuberculata, a valuable macroalgivore, was introduced and acclimated for culture in a land‐based facility at Eilat, Israel, on the Red Sea (Gulf of Aqaba). Large quantities of high‐protein seaweed (Ulva lactuca) are produced there in biofilters used in fish mariculture. Although high water temperatures (25–27 C) inhibited summer growth, and in spite of the high salinity (41 ± 1 ppt). four groups of abalone of different sizes grew more in 1 yr than reported in their natural habitat. This fast growth is attributed to the long period (8 mo, from fall to spring) in which temperatures in Eilat waters are within the optimal range for this species, and to the high protein content of the seaweed. Winter timing of maximal growth as well as reproduction in Eilat was reversed compared with Europe, where they occur in summer. Gametogenesis began in December, and the gonads in most broodstock were spent by May.Haliotis tuberculataappears to have excellent potential for intensive mariculture i

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00627.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.—Mortality of oysters,Crassostrea virginica, caused by Juvenile Oyster Disease (JOD) has been a chronic problem the northeastern United States since 1988. To assist in identifying potential health management options, the effect of time of spawning and deployment of oysters on resultant growth and mortality was examined in the Damariscotta River, Maine. Broodstock oysters from a line selected for fast growth were spawned at 2‐wk intervals between 28 March and 19 July 1995. Duplicate groups of juvenile oysters from each spawn were deployed in floating trays between 23 May and 31 August. Mortality and size of all cohorts were determined from late June to early December. Cumulative mortality of oysters was related to the timing of deployment. Cohorts placed in the river before June or after mid‐August had cumulative mortalities of 20% or less. Oysters deployed between 8 June and 18 August had cumulative mortalities ranging from 64–96%. Growth of all cohorts was rapid immediately after deployment but decreased once JOD began to have an effect. Final size of oysters was directly related to age. This study determined that seed oysters placed in the Damariscotta River between June and mid‐August will experience high mortality and low growth. Potential management options to reduce JOD impact include 1) early spawning and deployment in May, ensuring that a mean shell height>25 mm is reached prior to August and 2) late spawning and deployment after mid‐August to avoid expo

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00628.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.—Purified diets were formulated and fed to seven groups of Nile tilapiaOreochromis niloricusfingerlings for 12 weeks. Six of the formulated diets contained 5 or 50 mg/kg of ascorbic acid equivalent supplied either by L‐ascorbic acid (AA), L‐ascorbyl‐2‐sulfate (AS) or L‐ascorbyl‐2‐polyphosphate (APP). The seventh basal diet was ascorbate‐free and served as the control. The study indicated that APP or AS was more effectively utilized as a source of vitamin C than equimolar AA in promoting growth, improving food conversion, and preventing scurvy in Nile tilapia. Fish fed the ascorbate‐free diet and the diet containing 5 mg AA/kg exhibited external signs of scurvy at 10 weeks. Diets containing 5 mg/kg of ascorbic acid from AS or APP provided some growth with no overt signs of scurvy indicating that this concentration of AS and APP might be near the minimum requirements for the species. The best growth, food conversion ratio, survival rate, and ascorbic acid content in liver were obtained with the diet containing 50 mg ascorbate equivalent/kg diet from APP followed by the diet containing 50 mg ascorbate equivalent/kg diet from AS. Fish fed diets with 50 mg ascorbic acidkg diet from AS and APP gained 27.9% and 36.2% more weight, respectively, than fish fed diets with 50 mg ascorbic acidkg diet from AA. These results indicated nearly equal ascorbic acid activ

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00629.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.—The effects of thermal and thermo/haline shocks on the tilapiasOreochromis mossambicusandO. aureus × O. niloricushybrids were investigated. Fingerlings were transferred abruptly from 25 C fresh water to fresh water or salt water (26 ppt) maintaining temperatures of 15, 20, 30 and 35 C. In fresh water, fish survival was not affected by temperature shock, but they suffered from a chill coma and developed fungal infection at 15 C. In salt water, thermo‐haline shock did not affect the survival ofO. mossambicus, while the survival rates of tilapia hybrids were 6.7, 100, 100, 70 and 59.7% at 15, 20, 25, 30 and 35 C, respectively. Plasma osmotic concentrations ofO. mossambicustransferred to 15 and 35 C salt water were quickly and sharply increased, but gradually decreased to lower levels. Osmotic concentrations of tilapia hybrids were also increased, but never returned to their initial (lower) levels over one week. This study revealed that these fishes are more tolerant to high rather than low temperature shocks andO. mossambicusare more resistant to thermo‐haline shocks rather than tilapia hybrids. It also indicated that thermo‐haline shocks should be minimized during fish transportation and acc

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1996.tb00630.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY