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The present study aimed to investigate variability in growth pattern and evaluate abundance of A. persicus based on catch data in the southern Caspian Sea water in a period of 27 years (1991-2018). The data of 72704 specimens were analyzed separately by sex (male, female and population), time (years) and region (coastal waters of Gilan, Mazandaran and Golestan provinces). The highest catch of this species was recorded in 1991 (6038 pieces of the fish) and the lowest catch was recorded in 2018 (292 pieces). During the period, the Golestan province had the highest number of catches (30851 pieces) and Gilan province had the lowest ones (11129 pieces). The maximum recorded fork length of this species was 240 cm in 2006. The results showed that the highest annual average fork length was 151 cm in 2007 and 2010 and the highest annual average total weight in 1993, 1994, 1996, 1997 and 2007, which was 26000 grams. The lowest annual average fork length was 139 cm in 2018 and the lowest annual average total weight was 600 grams in 2010 and 2012. The highest length frequency corresponded for the ranges of 136-148 and 148-160 cm in males and females, respectively. The females showed the highest catches in 1991, and the lowest in 2018, while the males had the highest in 1991, and the lowest in 2014. The females dominated the population in the period of 1991-2013, and after that this ratio was reversed. The allometric coefficient of growth (b) varied between 1.03 and 3.49 in the study period. The growth pattern was mostly positive allometric in first decade of study (1991-2001), isometric or negative allometric in the second decade of study period (2001-2011), and negative in third decade (2011-2018). During the study period, the condition factor of the fish varied between 0.61 and 0.80, and the average of the factor for the whole period of study was 0.72. Generally, the catch of A. persicus in the southern Caspian waters decreased more than 95% from 1991 to 2018 (a period of 27 catch-years). [ABSTRACT FROM AUTHOR]

The kutum of the Caspian Sea has long been familiar with the life of coastal people, so that it has played a significant role in the economy of the coastal cities of the south of the Caspian Sea, and the living resources of the Caspian Sea, especially its economic fish stocks, have been seriously attacked in the past few years due to various crises. The study of growth parameters and intra-population structure makes interpretation, analysis and predictions related to the abundance of populations of a species possible, and Sefidrood River, as the most important fishing river of the country in Gilan province, plays a very important role in reproduction and stock enhancement of kutum. It was studied for a period of 10 years (2010 to 2019).The highest average total length and total weight for both males and females was obtained in 2014, which was 44.41 cm and 943.72 grams for males, and 50.49 cm and 1401.98 grams for females, respectively. Other years had significant differences (P<0.05). The type of growth pattern for kutum population was obtained in 2013, 2014 and 2017 from isometric type, in 2010, 2011, 2012, 2015, 2016, positive allometric type and in 2018-2019 from negative allometric type. The highest value of the condition coefficient was obtained in 2019 and the lowest in 2015 (P<0.05). The results showed that in all the studied years, total length and total weight also increased with increasing age for the population. The infinite length (L∞) in the populations in the 10-year period was between 73.11-87.74 cm. The range of growth rate (K) in this study for populations was between 0.08-0.19. Zero age index (t0) for populations was between -0.46 until -0.93, and Monro's Phi index (ф) was obtained between 6.18 until 7.28 in populations. [ABSTRACT FROM AUTHOR]

Variability in growth allometry of two prawn species Palaemon adspersus and Palaemon elegans was investigated in the Gorgan Bay, SE Caspian Sea, during a period between May 2019 and April 2020. Resalts showed that females grew to a larger size than males in both species. TW – TL relationship in P. adspersus was positive allometric for Both sex, while in P. elegans was positive allometric for females and negative allometric for males. In P. adspersus TL – CL relationship was CL = 0.2162TL + 0.002 for females and CL = 0.2087TL + 0.0096 for males. In P. elegans TL – CL relationship was CL = 0.2451TL – 0.0908 for females and CL = 0.2043TL + 0.0372 for males. Mean condition factor (CF) of females was larger than that of males in both species, and it was observed significant difference in the mean condition factor between species and month. In general, differences in growth pattern were observed between males and females as well as the two species studied. [ABSTRACT FROM AUTHOR]