Morphological studies of Macrobrachium macrobrachion and Macrobrachium vollenhovenii from Badagry Creek, Lagos, Nigeria: Need for conservation

Abstract

Abayomi Abdul-Azeez Jimoh, Magret Abosede Lawal

Prawns are of nutritional and economic importance, while morphological studies aid in the proper identification of organisms. Thus, considering the importance of prawns and need to provide morphological information, 150 samples of Macrobrachium macrobrachion and 100 samples of M. vollenhovenii were collected from fishmongers along Badagry Creek and examined for meristic and morphometric features. M. macrobrachion and M. vollenhovenii exhibited negative allometry with “b” values of 2.51 and 1.48 respectively. Males of both prawns were larger than the females. There was a high and positive correlation between total length and carapace length (M. macrobrachion, r = 0.84; M. vollenhovenii, r = 0.85) and between total length and rostral length (M. macrobrachion, r = 0.82; M. vollenhovenii, r = 0.80). Both prawns had more spines on the dorsal than the ventral side of the rostrum. Males predominated over females with a sex ratio of 1:1.83 (M. macrobrachion) and 1:1.08 (M. vollenhovenii). At 5% level of significance, there was a significant difference in the sex ratio recorded for M. macrobrachion, but there was no significant difference for M. vollenhovenii. The negative allometry recorded for both M. macrobrachion and M. vollenhovenii from Badagry Creek might suggest an over-exploitation of these prawns and reduction in natural productivity of the Creek as a result of anthropogenic activities; therefore, it is important that measures be put in place to address these possible causes with a view to ensure the survival and availability of these prawns.