2 Environmental Influences on Gonadal Activity in Fish

Lam, T.J.

doi:10.1016/s1546-5098(08)60302-7

Cited by 240 publications

(199 citation statements)

References 175 publications

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“…December to February . Since water temperature plays a crucial role in stimulating spawning activity in fish (Lam 1983), these differences are likely to be related, at least in part, to the pronounced differences that exist between the water temperature regimes in these two widely separated areas. It is thus highly relevant that water temperatures during the middle of the spawning periods of S. schomburgkii on the lower west coast of Australia, i.e.…”

Section: Spawning Time and Periodmentioning

confidence: 99%

Comparisons between the biology of two co-occurring species of whiting (Sillaginidae) in a large marine embayment

et al. 2005

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SynopsisWe compare the biology of the tropical species Sillago analis and the temperate species Sillago schomburgkii in Shark Bay, a large subtropical marine embayment on the west coast of Australia. This environment constitutes the approximate southernmost and northernmost limits of the distributions of these two species, respectively. The annuli visible in sectioned otoliths of S. analis and S. schomburgkii were shown to be formed annually. Their numbers were thus used to age the individuals of these two species, which are morphologically very similar and live in the same habitats. Although the growth rates of S. analis and S. schomburgkii are very similar until maturity is attained, they subsequently diverge, with S. schomburgkii investing relatively more energy into somatic growth. The maximum total lengths and ages of both the females (320 mm, 6 years) and males (283 mm, 8 years) of S. analis were not as great as those of the females (383 mm, 9 years) and males (302 mm, 9 years) of S. schomburgkii. In Shark Bay, S. schomburgkii spawns earlier and longer than S. analis, i.e. August to December vs January to March, which would result in the juveniles of these two species recruiting into nursery areas at different times. In addition, S. schomburgkii spawns earlier and for longer in Shark Bay than in temperate marine waters ~ 800 km further south, presumably reflecting an earlier attainment in that subtropical embayment of the range of water temperatures over which this species typically spawns. However, although environmental conditions in Shark Bay and those temperate marine waters differ markedly, the growth of the corresponding sexes of S. schomburgkii in these two water bodies is similar.3

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Section: Spawning Time and Periodmentioning

confidence: 99%

Comparisons between the biology of two co-occurring species of whiting (Sillaginidae) in a large marine embayment

et al. 2005

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“…Fish responses to changing photoperiod include changes feeding rhythms and growth (Thorpe, 1978). Photoperiod alterations are used to stimulate or delay gonodal maturation, and thus to change spawning period or somatic growth (Lam, 1983). Thus, the influence of photoperiod has been tested for improvement of growth tax in some species.…”

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confidence: 99%

Tambaqui growth and survival when exposed to different photoperiods

et al. 2006

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The use of different photoperiods (light) were investigated during tambaqui (Colossoma macropomum) juvenile growth under captivity. Light intensity tested was: continuous dark (24hrs without light), natural photoperiod simulation (10hrs of light and 14hrs without light) and continuous light (24 with light). No mortality was recorded among treatments. Significant differences was observed after 50 days of experiment among mean fish weight, fish kept under a continuous darkness showed a better specific growth rate (6.02%) when compared to control fish (natural photo period, 3.67%). Fish exposed to continuous light presented the lowest mean specific growth rate (2.04%). It is possible to improve tambaqui juvenile weight gain performance when kept under continuous darkness. KEY-WORDSColossoma macropomum, juvenile fish, photoperiod, growth. Crescimento e sobrevivência do tambaqui exposto a diferentes fotoperíodos RESUMO Investigou-se o uso de diferentes fotos períodos (iluminação) durante o crescimento de juvenis de tambaqui (Colossoma

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“…Considerando que os fatores ambientais são os reguladores da periodicidade dos ciclos reprodutivos em teleósteos (Billard et al, 1978;Lam, 1983), a Figura 3 (A, B e C) exibe os dados de temperatura do ar, precipitação e disponibilidade atual de água no solo (DAAS), em Manaus-AM, durante o período de fevereiro de 2004 a fevereiro de 2005. O período de maior precipitação foi de fevereiro a junho e de novembro a janeiro (Figura 3B).…”

Section: Resultsunclassified

“…De acordo com Richer et al (1982) e Lam (1983), as espécies tropicais têm um período reprodutivo relativamente longo e podem até reproduzir durante todo o ano. Em geral, a complexidade dos fatores ambientais relacionados com a reprodução é muito grande, envolvendo precipitação, temperatura, incremento do nível das águas, diminuição da condutividade, pH, ciclo lunar, fatores sociais e contaminação ambiental.…”

Section: Discussionunclassified

“…Em geral, a complexidade dos fatores ambientais relacionados com a reprodução é muito grande, envolvendo precipitação, temperatura, incremento do nível das águas, diminuição da condutividade, pH, ciclo lunar, fatores sociais e contaminação ambiental. Breton et al (1980a, b) e Lam (1983) reportaram que as variáveis temperatura e precipitação são as mais importantes para o processo reprodutivo. Bláquez et al (1998) descreveram que o ciclo sazonal na reprodução é uma estratégia de muitos teleósteos para assegurar que o tempo de desova coincida com condições ambientais compatíveis e disponibilidade de suprimento alimentar necessários para a sobrevivência e crescimento das larvas.…”

Section: Discussionunclassified

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Aspectos reprodutivos e perfil hormonal dos esteróides sexuais do pirarucu, Arapaima gigas (SCHINZ,1822), em condições de cativeiro

et al. 2010

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RESUMOEsta pesquisa teve como objetivo caracterizar a reprodução e o perfil hormonal dos esteróides sexuais do pirarucu, Arapaima gigas, além de validar um aspecto do dimorfismo sexual secundário. O experimento foi realizado na Fazenda Santo Antônio II, em Presidente Figueredo-AM, no período de fevereiro de 2004 a fevereiro de 2005. Foram selecionados 24 exemplares e divididos em três grupos de oito peixes (grupo "A", "B" e "C" com pirarucus de mais de quatro anos de idade, com três anos e dois anos, respectivamente). Os pirarucus foram estocados em três tanques de 400m 2 , um para cada grupo. Aspectos comportamentais, como o interesse por alimento, brigas, formação de casais e presença de ninhos, foram observados ao longo de todo o experimento. Amostras de sangue foram coletadas mensalmente, de todos os peixes, observou-se a presença de uma mancha alaranjada no macho como uma característica sexual secundária. Foram mensurados os níveis de testosterona (T), 17beta-estradiol (E 2 ) e 17alfa-hidroxi-progesterona (17aOHP) através de radioimunoensaio (RIA) de fase sólida. Todos os machos dos grupos "A" e "B" puderam ser identificados pela mancha alaranjada na região inferior da cabeça, corroborada pela concentração de testosterona, comprovando o conhecimento empírico dos ribeirinhos. Os níveis de T e E 2 nos peixes do grupo "A" e "B" tiveram maiores picos no início do período de chuva, enquanto que o 17aOHP teve oscilações constantes e pequenos picos no final do período chuvoso, os peixes do grupo "C" acompanharam essa tendência em concentrações menores. PALAVRAS-CHAVE: pirarucu, reprodução, esteróides sexuais, Arapaima gigas. Reproductive Aspects and Sexual Steroids Hormonal Profiles of Pirarucu, Arapaima gigas (SCHINZ,1822), in Captivity Conditions ABSTRACTThe purpose of this study was to characterize the growth, reproduction and hormonal profile of pirarucu, Arapaima gigas, and validate one sexual dimorphism characteristic. The experiment was carried in the fish farm Santo Antonio II, Presidente Figueredo city in the state of Amazonas -Brazil, from February 2004 to February 2005 In the experiment, 24 fishes were selected and divided in three groups, with eight fish in each one. The pirarucus from "A" group were older than four years. In "B" group the fishes were three years old and in "C" group these were two years old. The pirarucus were stocked in 400 m 2 excavated ponds, one pond for each group. Reproductive behavior like feeding interest, fights, pair formation and presence of nest were observed. Blood samples were taken monthly from all fishes during the experiment period, the sexual dimorphism characteristic was observed. Testosterone (T), 17b-estradiol (E 2 ) and 17ahidroxi-progesterona (17aOHP) levels were measured by radioimunoassay (RIA) in solid phase. All males of group "A" and "B" could be identified by an orange mark under the head, and the levels of T validated this data, proving the empirical knowledge of river men. T and E 2 levels of group "A" and "B" picked in the beginning of raining period an...

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2 Environmental Influences on Gonadal Activity in Fish

Cited by 240 publications

References 175 publications

Comparisons between the biology of two co-occurring species of whiting (Sillaginidae) in a large marine embayment

Comparisons between the biology of two co-occurring species of whiting (Sillaginidae) in a large marine embayment

Tambaqui growth and survival when exposed to different photoperiods

Aspectos reprodutivos e perfil hormonal dos esteróides sexuais do pirarucu, Arapaima gigas (SCHINZ,1822), em condições de cativeiro

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