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The Age and Growth of Callinectes amicola (De Rochebrune, 1883) from Okpoka Creek, Niger Delta, Nigeria

Author(s): J.F.N. Abowei

Journal: International Journal of Animal and Veterinary Advances
ISSN 2041-2894

Volume: 1;
Issue: 2;
Start page: 73;
Date: 2009;
Original page

Keywords: C. am nicola | age | growth Okpoka Creek | Nigeria

The Age and growth of Callinectes amicola from Okpoka Creek in the Niger Delta area of Nigeriawas studied for a period of one year (January – December 2007).The size classes 30!39.9mm and 40!49.9mmconstituted the highest w ith 31.0% and 31.5% respectively. Very small size class below 10mm was completelyabsent and largest size group (70!79.9mm) were very few (0.2%). The results of the modal length-at-agerevealed that all the sexes of Callinectes belonged to the age groups 1 to 3 years. Four year classes with modalclasses ranging from 6.7 ! 68.3mm for males; 5.0–78.3mm for female and 5.8–75.8mm for combined sex. Theannual carapace length increment was highest in year class 1+ and declined with time for both sexes andcombined. The absolute increment was: male (17.5mm for 1!2y, 14.1 mm for 2!3y and 20.53mm annualmean); female (18.3 for 1!2y, 10.8 for 2!3y and 24.43 annual mean) and combined (18.3mm for 1!2y,12.5mm for 2!3y and 24.43mm annual mean). Relative increment was male (47.7% for 1!2y, 26.0% for 2!3yand 36.85% annual mean); female (37.2% for 1!2y, 16.0% for 2!3y and 26.60% annual mean) and combined(40.7% for 1!2y, 19.7% for 2!3y and 30.20% annual mean). Instantaneous rate of increase was male (0.390for 1-2y, 0.231 for 2!3y and 0.311 annual mean); female (0.316 for 1-2y, 0.148 for 2!3y and 0.232 annualmean) and combined (0.341 for 1!2y, 0.180 for 2!3y and 0.261 annual mean). Powell!Wetherall plot was L4(61.80mm), K (0.995 yG1) and Z/K (1.694). The length at age data was L4 (61.80mm), K (2.10 yG1), to (1.220),N (3.90) and Rn(0.122) ELEFAN 1 scans routine was L4 (61.80), R (2.10), N (3.90) and Rn (0.121). The nonseasonedversion of the Von Bertalanffy Growth Function (VBGF) was L4 (87.305mm), K (0.636 yG1), to(0.889) and N (3.685). The longevity or maximum age (Tmax) was 4.7 years. The overall growth parametersobtained were: L4 = 61.80, K= 1.244yG1, to = 1.0545, Z/K = 1.694, R = 0.995, N =3.825 and Rn =0.121.
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