ABSTRACT
The use of alizarin red S (ARS) marked tilapias could provide valuable fisheries management information to evaluate fish stocking events and may facilitate aquaculture management practices. As a new technique in fishes, the aim of this study was to compare and evaluate the chemical marks produced in tilapia juveniles by ARS through two treatments: 1) 12 hours of immersion and 2) immersion after osmotic induction. This was analyzed at three concentrations: 50, 75 and 100mg/l, and in three structures: otoliths, fish scales and caudal fin rays of Oreochromis niloticus juveniles. After three culture months 80% of specimens were analyzed and significant differences (p<0.05) in mark intensity were detected between treatments for otoliths and fin rays, but not for fish scales. Significant differences between concentrations were found for the 12h immersion treatment, while no significant differences were detected with osmotic induction. Our results showed that marks appeared at all concentrations, and none of the concentrations produced weak marks. Osmotic induction had a greater mortality than the 12h immersion procedure. After eight culture months the rest of the specimens were analyzed and the mark permanence was observed in all cases. According to the present results we recommend the marking process of 12h immersion treatment at 100mg/L concentration.
El uso de alizarina roja S (ARS) para marcar tilapias podría proporcionar información valiosa para el manejo de su pesquería. Para evaluar pesquerías acuaculturales manejadas con siembras o repoblamientos de peces se comparó y evaluó la marca producida por la alizarina roja S, empleando dos tratamientos: 1) Inmersión en ARS durante 12h; e 2) Inmersión en ARS después de un choque osmótico. El análisis se realizó a tres concentraciones: 50, 75 y 100mg/l y en tres estructuras: otolitos, escamas y radios de la aleta caudal de Oreochromis niloticus. Ochenta por ciento de los ejemplares fueron cultivados durante tres meses y analizados posteriormente. Los resultados mostraron diferencias entre las concentraciones de la marca para el tratamiento de 12h de inmersión mientras que no hubo diferencias entre las concentraciones para el tratamiento con inducción osmótica. Se encontraron diferencias en la intensidad de la marca entre los tratamientos para otolitos y radios de las aletas pero para las escamas no hubo diferencias significativas. Todas las concentraciones produjeron marcas (desde débiles a intensas), sin embargo la concentración de 100mg/l no produjo marcas débiles. El tratamiento por inducción osmótica presentó mayores niveles de mortalidad. Después de ocho meses de cultivo el resto de los ejemplares fueron analizados y se observó la permanencia de las marcas en todos los casos. En vista de lo anterior, para los propósitos de marcaje se recomienda el uso del tratamiento de inmersión por 12h y una concentración de 100mg/l.
Subject(s)
Animals , Anthraquinones , Aquaculture/methods , Coloring Agents , Cichlids/growth & development , Fisheries , Mexico , Time FactorsABSTRACT
Hatchery seeds released into open coasts for wildstock enhancement are often a biological pollutant and affect the recipient ecosystem integrity. We studied morphological changes in two hatchery populations of the starry flounder Platichthys stellatus; one released into the open coast from the hatchery (released population) and the other kept in the hatchery (captive population). The released population differed significantly from the captive population 3-36 months after release from the hatchery. Two-way ANOVA comparison revealed that 11 of 15 starry flounders differed significantly in morphological measurements, 10 of 15 differed in pigmentation, and 5 of 15 differed in morphometric ratios between the two populations. Pigmentation on the blind side (a representative sign of captive flounders) also differed between the two populations with an occurrence rate of 22.7% for the former and 39.5% for the latter groups. The released population was more similar to wild populations than to captive populations in terms of morphology; namely, longer and broader heads, a narrower body shape, longer fins, and a shorter and narrower peduncle.
ABSTRACT
The objective of this study was to evaluate the genetic diversity and the parental contribution of Piaractus mesopotamicus in the production of offspring in the semi-natural system of reproduction. Twenty parental fishes (eleven males and nine females) and the total of 100 larvae were evaluated by microsatellite marker. The parents and offspring had thirty-one alleles and heterozygosity of 0.550 and 0.563, respectively. The females were fertilised by two up to six males while the males fertilised three up to five females. The contribution of the females and males to the offspring were 66.6 and 58 percent, respectively. Such results indicated no loss in the genetic variability in the offspring, and the parents had multiple paternity and reasonable contribution to the offspring production.
O objetivo deste trabalho foi avaliar a diversidade genética e a contribuição parental de Piaractus mesopotamicus na produção de descendência no sistema seminatural de reprodução. Vinte peixes parentais (onze machos e nove fêmeas) e o total de 100 larvas foram avaliados por meio do marcador microssátelite. Os parentais e a progênie tiveram trinta e um alelos e heterozigosidade de 0,550 e 0,563, respectivamente. As fêmeas foram fertilizadas por dois até seis machos enquanto machos fertilizaram três até cinco fêmeas. A contribuição de fêmeas e machos para a descendência seja 66,6 e 58,0 por cento, respectivamente. Tais resultados não indicam diminuição da variabilidade genética na progênie e os parentais apresentaram paternidade múltipla e razoável contribuição à produção de descendência.
ABSTRACT
Avaliou-se o efeito do sistema seminatural na diversidade genética de um estoque de Brycon orbignyanus, utilizado em programas de repovoamento, com o marcador molecular RAPD. Vinte e quatro reprodutores, 12 machos e 12 fêmeas e 95 larvas da progênie foram analisados. Os nove primers utilizados produziram 90 fragmentos, dos quais 94,4 por cento foram polimórficos. Houve diferença significativa na frequência de 20 dos 90 fragmentos entre os reprodutores e sua progênie sem a presença de fragmentos exclusivos. O índice de diversidade genética de Shannon, a porcentagem de fragmentos polimórficos e a diversidade genética de Nei foram mais altos nos indivíduos da progênie. A similaridade genética foi maior nos indivíduos do estoque de reprodutores. A análise de variância molecular mostrou que a maior parte da variação está dentro de cada grupo (89,1 por cento) e não entre os grupos (10,9 por cento). A identidade e a distância genética entre os estoques foram de 0,944 e 0,057, respectivamente. Assim, a utilização do sistema seminatural evitou a mortalidade de reprodutores B. orbignyanus e conservou a variabilidade genética da progênie.
The effect of the semi-natural system on the genetic diversity of a Brycon orbignyanus stock, used in stock enhancement programs, was evaluated with the RAPD molecular marker. Twenty-four broodstocks - 12 males and 12 females - and 95 larvae of the offspring were analyzed. The nine used primers produced 90 fragments, of which 94.4 percent were polymorphic. There was significant difference in the frequency of 20 out of the 90 fragments between the broodstocks and their offspring without the presence of exclusive fragments. The Shannon genetic diversity index, the percentage of polymorphic fragments and the Nei gene diversity were higher in the offspring individuals. Genetic similarity was higher in broodstock individuals. The analysis of molecular variance results showed that the major part of the genetic variation is within the groups (89.1 percent) and not between them (10.9 percent). The identity and genetic distance between the groups were 0.944 and 0.057, respectively. Like this, the use of the semi-natural system avoided the mortality of B. orbignyanus broodstocks and conserved the genetic variability of the offspring.