Age and growth of an Ecotype Cichlid 'Wesafu' in Epe Lagoon, Lagos, Nigeria.

摘要

The study was conducted to determine the age and growth pattern of 150 ecotype Cichlid, Wesafu, with size range of 78 mm and 414 mm collected from Epe Lagoon, Nigeria. The collection period was from August to November 2003 and April to May 2004. 900 fish scales were examined, while 232 were rejected because the scales were regenerated or irregular. Growth rings were counted and scale radii were measured. Results revealed that the mean range of observed lengths were 181+or-12.5, 265+or-11.6, 305+or-1.6 and 337+or-3.4 mm for ages 1+, 2+, 3+ and 4+, respectively. The most rapid growth in length occurred during the first year of life (181 mm at 1+ year of age), thereafter decreased to only 32 mm in the fourth year (+4 year). T-test revealed that there was no significant difference between mean back-calculated body length of male and female samples for ages 1+ to 3+. However, in the age group 4+, male specimens were significantly larger than the female. The fact that there is a high demand for this fish and it commands premium price can result to over exploitation, and maybe the reason wherein only 5 of the 150 specimens were of the age 4+, representing only 3.33% of total specimens. This raises serious conservation problems and the need for domestication and aquaculture of this highly valued fish in Lagos, Nigeria.