Preservation of refrigerated sperm of the mutton snapper with diluents and modified atmosphere

O objetivo deste trabalho foi avaliar o efeito de diferentes diluentes, em atmosfera normal e modificada, na preservação de sêmen refrigerado da cioba – Lutjanus analis. Amostras de sêmen de 30 peixes foram avaliadas quanto à taxa de motilidade, duração da motilidade, concentração espermática e espermatócrito. Para a refrigeração a 4ºC, três diferentes diluentes, com distintas composições iônicas e valores de pH distintos, foram testados em atmosfera normal e atmosfera modificada (100% oxigênio). Posteriormente, um teste de fertilização foi realizado para avaliar a viabilidade do sêmen refrigerado. No experimento de refrigeração, a taxa de motilidade e a duração da motilidade foram adequadas, durante 72 horas, para os diluentes A (48±7%;190±26 s) e B (41±4%; 160±22 s) em atmosfera normal. Na atmosfera modificada, a qualidade do sêmen caiu drasticamente durante as primeiras 24 horas, independentemente do diluente utilizado, e não houve vantagem em sua utilização. A taxa de fertilização com sêmen refrigerado por 24 horas, tratado com diluente A, não diferiu daquela com sêmen fresco, e ambas foram superiores à obtida com sêmen refrigerado por 48 horas.The objective of this study was to evaluate the effect of different diluents at normal and modified atmosphere on the preservation of refrigerated sperm of the mutton snapper Lutjanus analis. Sperm samples o  30 fishes were evaluated for motility rate, motility time, sperm concentration and spermatocrit. For the refrigeration at 4ºC, three different diluents with distinct ionic compositions and pH values were tested at normal and at modified atmospheres (100% oxygen). Afterwards, a fertilization test was accomplished to evaluate the viability of the refrigerated sperm. In the refrigeration experiment, the motility rate and the motility time were maintained appropriate for 72 hours for the extender A (48±7%, 190±26 s) and B (41±4%, 160±22 s) at normal atmosphere. At the modified atmosphere, the sperm quality fell drastically during the first 24 hours, independently of the utilized diluent, and there was no advantage in its use. The fertilization rate with refrigerated sperm for 24 hours, treated with the diluent A, was not different from that of fresh sperm, and both were higher than the one obtained with refrigerated sperm for 48 hours

Influencia do fotoperíodo em cultivo de larvas de robalo-peva, Centropomus parallelus

: Aiming verify influences of photoperiod in larvae of robalo peva, classified as visual predators, two experiments were accomplished in laboratory of sea fish farming of UFSC. In the first, larvae were used from 0-14 days. Survival and standard length (Sl) were analyzed. In the second, larvae were used among 31-62 days and it was evaluated: survival; Sl, total length (Tl); weigh (g); Index of alimentary conversion (IAC), feeding rate, growth specific daily rate (SGR) and factor of condition of Fulton (K). Were used 9 tanks (4,5 L, with 180 and 35 larvae/tank, in experiments 1 and 2, respectively). The treatments were: 12, 18 and 24 hours of light, in triplicate (12 h, 18 h and 24 h respectively). Rotifers (Brachionus sp.), Artemia and ration for weans they were supplied in the experiments 1 and 2 respectively. The largest values of Sl showed in treatments 24 h and 18 h. In the second, weight; Tl and IAC and feeding rate were larger in 18 h. We recommended illumination with 18 hours in the two studied larval periods.Objetivando verificar a influencia do fotoperiodo em larvas de robalo-peva, classificadas como predadoras visuais, realizaram-se dois experimentos no laboratório de piscicultura marinha da UFSC. No primeiro utilizaram-se larvas de 0 a 14 dias analisando-se sobrevivência (%) e comprimento padrão (Cp). No segundo, utilizaram-se larvas entre 31 a 62 dias e avaliaram-se: sobrevivência; comprimento total (Ct); peso (g); Índice de conversão alimentar (ICA), taxa de alimentação (%), taxa de crescimento específico (TCE) e fator de condição de Fulton (K). Utilizaram-se 9 tanques (4,5 L, com 180 e 35 larvas/tanque, nos experimentos 1 e 2, respectivamente). Os tratamentos, em triplicata, foram 12, 18 e 24 horas de luz (12 h, 18 h e 24 h respectivamente). Forneceram-se rotíferos (Brachionus sp.) no experimento 1 e matanáuplios de Artemia e ração para desmame no experimento 2. Os maiores valores de Cp ocorreram nos tratamentos 24 h e 18 h. No experimento 2, o peso e o Ct foram maiores em 18 h, assim como melhores ICA e taxa de alimentação. Recomenda-se iluminação com 18 horas nos dois períodos larvais estudados

Análise econômica do robalo-comum, Centropomus undecimalis, cultivado em gaiolas flutuantes no Sul do Brasil

 The economic viability of common snook culture was evaluated from a simulated marine farm with 20 cages of 225m³, with a production cycle of two years, fish with a final weight of 500g and annual production of 45 tons. To scale the production costs, the effectve operating cost (EOC), total operating cost (TOC), total production cost (TPC) were considered.The indices for evaluating profitability were the Internal Rate of Return (IRR), the Return on Capital (RC) and the Net Present Value (NPV). The TPC was USD $305,820 year-1, with USD$6.79 kg-1. Sensitivity analysis by the variation of the feed conversionrate (FCR) reinforces the importance of good production practices, such as adequate food management, use of balanced diets. The factors: juvenile price, feed cost and sales price, more dependent on the market, require a greater ability of the producer to apply commercial and marketing strategies to contain the production cost and avoid the reduction of the sales price. The high cost of installing culture structures and management equipment suggests projects with a minimum rate of attractiveness of 23%, minimum volume of 6,500m³, productivity of 20kg m-³, annual production of 65 tons, FCR below 1.6 and marketing price above USD$8.39 kg-1. A viabilidade econômica do cultivo do robalo-flecha foi avaliada a partir de uma fazenda marinha simulada com 20 tanques-rede de 225m³, com ciclo de produção de dois anos, peixes com peso final de 500g e produção anual de 45 toneladas. Os custos de produção considerados foram o custo operacional efetivo (COE), custo operacional total (COT), custo total de produção (CTP). Os índices para a avaliação da rentabilidade foram a Taxa Interna de Retorno (TIR), o Retorno do Capital (RC) e o Valor Presente Líquido (VPL). O CTP foi de USD$305,820 ano-1, com USD$6.79 kg-1. A análise de sensibilidade pela variação da taxa de conversão alimentar (TCA) reforça a importância das boas práticas de produção, como o manejo alimentar adequado, uso de dietas balanceadas. Os fatores: preço dos juvenis, custo da ração e preço de venda, mais dependentes do mercado, necessitam de uma maior habilidade do produtor em aplicar estratégias comerciais e mercadológicas para conter o custo de produção e evitar a redução do preço de venda. O alto custo de instalação das estruturas de cultivo e equipamentos de manejo sugere projetos com taxa mínima de atratividade de 23$8,39 kg-1

Indução de desova com fertilização natural e artificial e incubação de ovos do robalo-peva (Centropomus parallelus)

The artificial propagation of the wild fat snook, Centropomus parallelus, was investigated in laboratory. This study tested a protocol for spawning induction using human Chorionic Gonadotropin (hCG) and an incubation system with different egg densities. Females were injected with 1,100 IU of hCG/Kg, and males with 500 IU/Kg. Fish were held in tanks of 160L capacity, with two males and one female. Temperature was 23,9-27,3ºC and salinity was 35. A total of 19 hormonal inductions were carried out, resulting in 7 natural spawnings and 12 with artificial fertilization. The best fertilization and hatching rates were obtained when ovulation occurred at 32-36 h post-induction (816-972 hour-degrees). The average relative fecundity was 373.000 eggs/Kg of body weight. Viable larvae were obtained in 43% of the natural spawning trials, and in 58% of the artificial spawning trials. In the incubation system, density was 553 to 1,705 eggs/L, using 9 incubators with 37L capacity inside a 2,000-L tank. Eggs were maintained in an open flow-through system with continuous aeration. After 19 hours, the number of hatched larvae was 305 to 850/L. Spearman test showed no correlation between egg density and hatched larvae (P>0.05). The average hatching rate was 52%.Reprodutores selvagens do robalo-peva, Centropomus parallelus, foram induzidos a reproduzir em laboratório. Este estudo testou um protocolo de indução de desova com uso de Gonadotrofina Coriônica humana (GCh) e de incubação com diferentes densidades de ovos. Doses de 500 e 1100 UI de GCh/Kg foram aplicadas em machos e fêmeas, respectivamente. Os peixes foram mantidos em tanques de 160L, com dois machos para cada fêmea. A temperatura foi de 23,9-27,3ºe a salinidade em torno de 35. De 19 induções realizadas, 7 desovas foram naturais e 12 com extrusão e fertilização artificial. As desovas mais produtivas ocorreram após um período de latência de 32-36h (816-972 horas-grau) pós-indução. a fecundidade relativa média foi de 373.000 ovos/Kg. Larvas viáveis foram obtidas em 43% das induções com desova natural, e em 58% quando houve fertilização artificial. Na incubação, foram estocados de 553 a 1705 ovos/L, em nove incubadoras de 37L, imersas num tanque de 2000L, com renovação de água constante e aeração. Após 19 horas, 305 a 805 larvas/L eclodiram em cada incubadora. Não existiu correlação entre o número de ovos estocados e o de larvas eclodidas (P>0,05). A taxa de eclosão média foi de 52%

Economic analysis of common snook, Centropomus undecimalis, cultured in floating cages in southern Brazil

 The economic viability of common snook culture was evaluated from a simulated marine farm with 20 cages of 225m³, with a production cycle of two years, fish with a final weight of 500g and annual production of 45 tons. To scale the production costs, the effectve operating cost (EOC), total operating cost (TOC), total production cost (TPC) were considered. The indices for evaluating profitability were the Internal Rate of Return (IRR), the Return on Capital (RC) and the Net Present Value (NPV). The TPC was USD $305,820 year-1, with USD$6.79 kg-1. Sensitivity analysis by the variation of the feed conversion rate (FCR) reinforces the importance of good production practices, such as adequate food management, use of balanced diets. The factors: juvenile price, feed cost and sales price, more dependent on the market, require a greater ability of the producer to apply commercial and marketing strategies to contain the production cost and avoid the reduction of the sales price. The high cost of installing culture structures and management equipment suggests projects with a minimum rate of attractiveness of 23%, minimum volume of 6,500m³, productivity of 20kg m-³, annual production of 65 tons, FCR below 1.6 and marketing price above USD$8.39 kg-1

First basis for a sustained juvenile production technology of fat snook Centropomus parallelus Poey

A larval, weaning and nursery trial with fat snook Centropomus parallelus Poey was conducted in Santa Catarina, Brazil. Spawning of captive broodstock was induced with 50 µg/kg LHRHa and fertilized eggs (82.7%) were stocked in two 1,800 L tanks at a mean density of 41.3 eggs/L. Larval hatching averaged 92%. Nannochloropsis oculata (Droop) Hibberd was introduced daily from day 1 until day 20 post-hatch (d20ph). Rotifers Brachionus rotundiformis Muller were supplied during the first month and Artemia meta-nauplii from d19ph to d66ph. Weaning was carried out from day 51 to day 66 with a 43.6% protein dry diet, supplied together with Artemia meta-nauplii. An abrupt temperature drop of 5ºC during the night of d26ph began the first mass mortality period, which lasted for 3 weeks. Mortality during weaning and nursery was less than 4%. A total of 10,200 juveniles (52.4 ± 1.4 mm and 1.25 ± 0.06 g) were harvested with a survival of 6.5%, mean final density of 2.8 fish/L and biomass of 3.5 kg/m3. Food conversion rate during nursery was 1.283 and the increase in variance of the size distribution in total length was 7.5%