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| Suquet, Marc; Rochet, Marie-joelle; Gaignon, Jean-louis. |
| Because of natural complexity, field studies are often inconclusive with regards to the ultimate cause of a given change observed in wild animal populations. As a consequence, there is scope to develop an Experimental Ecology Approach (EEA). In this paper, we favour the use of experimental ecology studies to evaluate the effects of environmental factors on fish biology. We identify the advantages of EEA: disentangling the effects of several factors and identifying their respective roles, generating artificial scenarios and increasing our capability to collect and analyse data. This study emphasises the constraints of this approach: fish biological performances may be altered by rearing conditions, by domestication and by the prevention of some behaviours.... |
| Tipo: Text |
Palavras-chave: Cod; Field study; Environmental parameters; Laboratory experiments; Experimental ecology. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-714.pdf |
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| Moharram, S.G.; AKEL, E.H.K.H.. |
| Reproductive aspects in addition to condition factor and hepatosomatic index were analyzed for Cichlid: Tilapia zillii collected from the beach-seiners operating in Abu Qir Bay during the period from June 2000 to February 2001. The overall sex ratio (M/F) was 1: 1.05. Length at first sexual maturity was 8.7 cm for females and 9.7 cm for males. Gonadosomatic index revealed that spawning season lasted from June to September with peak in July. Macroscopic examination for the gonads of T. zillii indicated that adult females had 4 stages of gonadal development (matureII; vitellogenic stage III; ripe stage IV and spent V). The maturity stages of males were three (matureII, mature III, and ripe stage). The microscopic features of gonadal sections of both females... |
| Tipo: Journal Contribution |
Palavras-chave: Field study; Reproduction; Condition factor. |
| Ano: 2007 |
URL: http://hdl.handle.net/1834/1878 |
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| Ramadan, A.M.; El-Halfawy, M.M.; Mahmoud, W.F.. |
| Reproductive characteristics of Liza ramada in Timsah Lake showed that the male reaches first sexual maturity smaller than the female at a total body length of 14 cm. and 16 cm., respectively. Overall sex ratio is 1: 1.7 for males to females. The gonado-somatic index of males was lower than that of females. Where, the maximum GSI values were recorded in November 5.03 % and 12.4 % for males and females, respectively. The maturity stages of male and female Liza ramada are morphologically separated according to the changes in shape, size and colour of the gonad in different successive stages. These stages are virgin, maturing virgin, developing, developed, gravid and spent stages. Histologically, the oocyte maturation showed the following phases; first growth... |
| Tipo: Journal Contribution |
Palavras-chave: Field study; Histology; Reproductive cycle; Mullet fisheries. |
| Ano: 2007 |
URL: http://hdl.handle.net/1834/1905 |
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| Ghobrial, M.G.; Okbah, M.A.; Gharib, S.M.; Soliman, A.M.. |
| Barley straw has received, recently, considerable attention as an algicide, which could be used to control algal growth in fishponds. It is regarded as cost-effective, user friendly and environmentally sounds. On the other hand, the submerged wetland macrophytes are crucial for the stabilization of clear water state in shallow lakes, by their active production of anti-algal compounds (allelochemicals) through allelopathy. Microcosm experiments using barley straw and the submerged macrophytes: Najas marina L., Potamogeton pectinatus L. and Ceratophyllum demersum L. in culture media with fishpond water were carried out outdoors to simulate the situation as natural as possible. Nutrients concentrations were measured beside the analysis of phytoplankton and... |
| Tipo: Journal Contribution |
Palavras-chave: Field study; Phytoplankton; Fish ponds; Phytoplankton; Fish ponds; Http://aims.fao.org/aos/agrovoc/c_13344; Http://aims.fao.org/aos/agrovoc/c_2929. |
| Ano: 2007 |
URL: http://hdl.handle.net/1834/2210 |
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