Effect of salinity on survival and growth of blue crab, Callinectes amnicola from Lagos Lagoon, Nigeria

The effect of salinity on the survival and growth of Callinectes amnicola (De Rocheburne) from the Lagos Lagoon, Nigeria was monitored in the laboratory for 22 weeks. The crabs were euryhaline and tolerated a salinity range of 5 to 25 per thousand and had 90% survival at 15 and 20 per thousand. The highest gain in weight (173.0%) and carapace width (56.1%) was obtained at salinity of 15 per thousand. The highest specific growth rate (1.98) was obtained at 15 per thousand, while the lowest specific growth rate (-0.28) was recorded at 35 per thousand. The condition factor of the crabs showed a fairly consistent pattern at the different salinity levels with values ranging from 5.7 to 7.3. Complete moulting was obtained at salinity of 15 per thousand in the 12th week of the experiment. The crab with carapace width of 6.8 cm increased to 8.1 cm (19.1%) after moulting.