Some aspect of reproductive biology of Schizothorax zarudnyi
Among 13 fish species observed in Hamoon Lagoon, Chah-Nimeh of Hamoon basin and open water sources, Hamoon Mahi (Schizothorax zarudnyi) is one of the most valuable economic species in Sistan basin. This study performed during October 2001 to September 2002. Totally 697 Schizo/horax zarudnyi were examined, including 403 females and 294 males. Length and weight variation of samples were 24.5-62. I cm and 137-2204 g, respectively. The most weight and length frequency in samples were 500-600g and 35-40 cm. The GSI value has significant difference in males and females (p <%l). During June and February the minimum and maximum mean of GSI in female fish was 0 77% and 9.298%, respectively. The minimum and maximum mean of GSI value in males was 0.82% and 662%, which observed during July and February, respectively. During March and April, these items gradually reduced and has .no significant difference. The HSI increased before increasing of GSI. In females and males, HSI, increased during October to March and October to February, respectively. During significant increase in GSI (after September), the CF value was less than 1%. It was increased during March to June. There was significant difference in GI value between male and female fishes. The minimum of GI mean in males and females was 4.7% and 4.615% respectively, in February. In June, when exogenous feeding began, the maximum of GI mean observed which was 857% and 9.16% in males and females, respectively. The mean absolute and relative fecundity in fish weighing 460g to 1380g was 26256 and 34418 eggs, respectively. Fish weight has the most correlation coefficient with absolute fecundity(r = 0.64). The Lm50 in male and female fishes was 29-31 cm and 38-40 cm, respectively the correlation between lengths and weight in males and females were 0946 and 0.965, respectively. In probability level of 0.99, the sex ratio of male / female was not near to expected rate (l : l), Sexual maturation was divided into 6 separated phases. In March, female fishes show the most prevalence of phase IV of sexual maturation. In April, the prevalence of phase IV reduced and phase VI of sexual maturation increased, In female fishes which caught in Chah-Nimeh of sistan, phase V of sexual maturation was not observed. From May, phase [V of sexual maturation had not been observed and phase VI . had the most frequency (66%), after that phase II had the most frequency (about 33%). Ln male fishes, the most frequency of IV was observed in February (850/0), it was reduced to 70% in March and phase V of sexual maturation revealed (30%). In May, the ovaries of matured fishes examined and indicated one group of oocyte with less than 400g diameter. This trend continued till August (temperature was 22.31 Oc — 23.24Oc and length of day was 12.5-13.5 h ). In October, another group of oocyte having more than 500g diameter and new characteristics, appeared in ovary. The trend of oocyte growth continued that in March and April reached to its maximum rate (1600-2200g). Regarding many investigated indices, Hamoon Mahi is an Iteroparous species showing a synchronous ovary development and single spawner. It reveals the highest sexual maturity during March and April at 14-18 Oc. It is migratory Potamodromous species. That in March and April, during no flow water periods in the river and absence of migration of fishes to flowing waters: gonad in females are damage and resorbed
| Main Authors: | , |
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| Format: | Report biblioteca |
| Language: | Persian |
| Published: |
Iranian Fisheries Science Research Institute
2004
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| Subjects: | Schizothorax zarudnyi, Hamoon, Reproduction, Biology, |
| Online Access: | http://hdl.handle.net/1834/14225 |
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