Population dynamics and some biological aspects of Palaemon elegans in the Guilan province waters

Samplings were carried out weekly in coastal waters of the Guilan province (Caspian Sea) by a hand net with 0.5mm mesh size during 1996-1997. The results of one year sampling showed that the mean total length(T.L.) of this shrimp (pooled data of females and males) was 28.58±5.58mm (x±SD), and were 26.46±4.30 and 30.01±6.30mm in males and females, respectively. For ovigorus females, mean T.L was 36.16±3.13mm, also the minimum and maximum T.L of the males were 12.6 and 41.1mm, respectively. In females these figures were found 10.7 and 43.4mm, respectively. The length-weight relationship for the males and females were determined as W=0.0002 TL2.97 (R2=92.13) and W=0.00002 TL2.98 (R2=92.84), respectively. Spawning season was determined from May to September. The average absolute fecundity was 796±320, with a range of 360 and 1660. There is a direct retationship between fecundity and T.L. Females provided 59.42% and males 40.56% of the population, the sex ratio deviated from 1:1 (P<0.05). The growth coefficient of Loa for females, males and pooled data based on powell-wetheral methods were 42.6, 34.4 and 42.5, respectively. The growth coefficient of K based on Shepherd method were 2.1, 2.3 and 2.5 for females, males and pooled data, respectively. Natural mortality rate (M) calculated as 2.29, 2.29 and 2.28 per year for females, males and pooled da1a, respectively. Total mortality rate was calculated as 2.38, 2.50 and 2.61 per year for females, males and pooled data, respectively. ; Published