Growth pattern and proximate composition of five cartilaginous fish species from Lagos Lagoon and its coast

Abstract

Length - weight relationship, as well as the nutritive values of some selected species of cartilaginous fishes were examined from the  Lagos lagoon and its environs which lies within latitude 6° 26'–6° 37' N and longitude 3° 23'-4° 20' E. The following five cartilaginous  fishes; Raja miraletus, Dasyatis margarita, Squalus megalops, Sphyrna couardi and Rhinobatos albomaculatus were used for the study  and a total of fifty-four fish samples were collected for four months between May and August. Length and weight measurements were  taken, and the proximate composition of the fish was analyzed using standard AOAC methods. Results for most of the fishes revealed  negative allometric growth (b< 3). The sex ratio (Male: Female) were 1:1.16; 1:1.28; 1:1.15; 1:1.30; and 1:10 for Raja Miraletus; Dasyatis  Margarita; Squalus Megalops; Sphyrna Couardi; and Rhinobatos Albomaculatus respectively. The proximate analysis revealed that Raja  miraletus, Squalus megalops, Rhinobatos albomaculatus, Sphyrna couardi, Raja miraletus and Sphyrna couardi have the highest values of crude protein, carbohydrates, moisture content, ether extract, crude fibre and ash content at 25.85%, 4.88%, 66.17%, 3.08%, 4.76% and  2.35% respectively. The fishes belong to the high protein–low–fat category and can be recommended in human diets to prevent protein  deficiencies.