Determination of growth parameters, Age structure and sex ratio of Pike (Esox lucius Linnaeus, 1758) from Anzali wetland

The aim of this study was to record growth parameters، age structure and sex ratio of Pike (Esox lucius) from Anzali wetland. 337 specimens were caught by fixed gill net (32-84 mm stretched mesh size) and fyke net (48-64 mm stretched mesh size) during November 2010 to Jun 2011. The age rang was 2+ to 6+ years for male and 3+ to 7+ years for female. 81. 59% of age composition was belonging to year classes of 3+ and 4+. Male to female sex ratio was obtained 1. 12:1 that was not differed significantly (P>0. 05). Total length (TL) and weight (W) ranged from 28. 4 to 62. 8 cm and 100 to 1900 g respectively. The b value of the length-weight relationship for male ranged 2. 945 that showed isometric growth (P>0. 05) and for female ranged 3. 144 that showed positive allometric growth (P<0. 05). Mean of Relative weight (Wr) was calculated 0. 923±0. 009 and 0. 996±0. 011 for male and female respectively that was differed significantly (P<0. 05). Instantaneous growth coefficient (G) was obtained 0. 44 and 0. 52 for male and female respectively. Growth performance index (ϕ) was calculated 3. 10 and 3. 04 for male and female respectively. The estimated von Bertalanffy growth parameter values were (L∞= 77. 34 cm، K= 0. 21 yr- and t0= -0. 27 yr; L∞= 91. 95 cm، K= 0. 13 yr- and t0= -0. 82 yr) for male and female respectively. Also infinity weight (W∞) was estimated 2610. 03 g and 4102. 68 g for male and female respectively.