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  • Sex ratio  (3)
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  • 1
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    Reproductive characteristics of Neogobius caspius from the southwest coasts of the Caspian Sea, Guilan Province of Iran (2018)
    Details
    Publication Date: 2021-05-19
    Description: Neogobius caspius is an endemic fish species in the Caspian Sea belonging to the family Gobiidae that ecologically play important role as a predator fish in the food chain .The main objective of this research was determination of some reproductive properties of N. caspius in the southwest coasts of the Caspian Sea. Sampling was carried out with a bottom trawler in three stations (Astara, Anzali and Chabuksar) from October 2004 until September 2005. The species was identified based on meristic parameters. The maximum gonadosomatic index (GSI) was recorded at 7.52% for male and 100.12% for female fish in June. A sharp decrease in GSI value from June to the end of September in both sexes was observed and we found that the spawning of the species takes place several times each year. Hence, the species is considered a late spawner. Female to male sex ratio was 1.47:1. Absolute fecundity was in the range 212-1234 eggs and the relative fecundity fluctuated between 18.73 and 29.89 eggs per each gram of the body weight. The correlation between absolute and relative fecundity with age was positive and with total length and full weight was negative. Egg diameter was in the range 0.06 to 0.23mm. The correlation between egg diameter, age and total length was positive.
    Description: Published
    Keywords: Food chains ; Endemic species ; Brackishwater fish ; Neogobius ; Gobiidae ; Neogobius caspius ; Brackish ; Biological surveys ; Sex ratio ; Males ; Gonadosomatic index ; Fecundity ; Fish physiology ; Reproductive cycle ; Body size ; Reproduction ; Females
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.87-98
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  • 2
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    Biological study and population dynamics of Carassius auratus gibelio in Anzali Lagoon (2018)
    Details
    Publication Date: 2021-05-19
    Description: Considering the reduction of valuable commercial fish in Anzali lagoon during last decades and presence of the silver crucian carp with high frequency; the research project or 'Biological aspects and population dynamics or Carassius auratus" was designed. The study area was stratified to four regions (Abknar, Siah-keshim, Markazi and Sheyjan). Sampling were carried out bi-weekly by using electro-shocker. The mean fork length and mean weight for both sexes were measured 19.5±5.8 cm, and 196.8±137.4 g respectively. Also, the mean age was estimated 2.6±1.3 years (n=750) and minimum and maximum fork length were measured 2.5 and 31.5 cm respectively. The mean length, weight and the age of silver crucian carp in Siah-keshim region were higher than the other regions. The spawning season of this species was found from May to June. The results showed a sex ratio of F:M=99.3:0.7. Some calculated population parameters were as follows: exploitation rate = 0.47, L∞ = 36.0 cm and K = 0.23 per year.
    Description: Published
    Keywords: Biological ; Commercial ; Population ; Carassius auratus gibelio ; Fish ; Silver crucian carp ; Carassius auratus ; Sampling ; Length ; Age ; Weight ; Spawning ; Species ; Sex ratio
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.57-70
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  • 3
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    Reproductive characteristics of Neogobius caspius from the southwest coasts of the Caspian Sea, Guilan Province of Iran (2021)
    In:  http://aquaticcommons.org/id/eprint/23734 | 18721 | 2018-07-21 17:15:15 | 23734 | Iranian Fisheries Science Research Institute
    Details
    Publication Date: 2021-07-15
    Description: Neogobius caspius is an endemic fish species in the Caspian Sea belonging to the family Gobiidae that ecologically play important role as a predator fish in the food chain .The main objective of this research was determination of some reproductive properties of N. caspius in the southwest coasts of the Caspian Sea. Sampling was carried out with a bottom trawler in three stations (Astara, Anzali and Chabuksar) from October 2004 until September 2005. The species was identified based on meristic parameters. The maximum gonadosomatic index (GSI) was recorded at 7.52% for male and 100.12% for female fish in June. A sharp decrease in GSI value from June to the end of September in both sexes was observed and we found that the spawning of the species takes place several times each year. Hence, the species is considered a late spawner. Female to male sex ratio was 1.47:1. Absolute fecundity was in the range 212-1234 eggs and the relative fecundity fluctuated between 18.73 and 29.89 eggs per each gram of the body weight. The correlation between absolute and relative fecundity with age was positive and with total length and full weight was negative. Egg diameter was in the range 0.06 to 0.23mm. The correlation between egg diameter, age and total length was positive.
    Keywords: Biology ; Biological surveys ; Sex ratio ; Males ; Gonadosomatic index ; Fecundity ; Fish physiology ; Reproductive cycle ; Body size ; Reproduction ; Females ; Food chains ; Endemic species ; Brackishwater fish ; Neogobius ; Gobiidae ; Neogobius caspius ; Brackish ; Caspian Sea ; Caspian Sea Eurasia ; Iran
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 87-98
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