Volume 43, No. 02, Month MAY, Year 2019, Pages 43 - 56
Reproductive biology, trophodynamics and stock structure of ribbonfish (trichiurus lepturus linnaeus, 1758) in tropical marine waters of the bight of benin
This study was an attempt to understand the exploitation rate and mortality parameters of
Trichiurus lepturus Linnaeus, 1758 for sustainable exploitation and conservation of this important fish
species in Ogun coastal waters, Nigeria. Reproductive biology, trophodynamics and stock structure of
the population was assessed from ribbonfish captured with graded gillnets (18, 22, 26, 30, 40, 45, 50,
65, 70, 75, 80 and 90 mm, knot-to-knot). A total of 1,616 individuals of T. lepturus were captured
and subjected to descriptive and inferential statistical tools. Sex ratio of males: females (0.4:1) was
significantly (x2=32.144; p=0.0007) different from unity. Peak spawning seasons were December and
July. Total fecundity ranged between 7,051 and 12,456 eggsyr-1. In stomach contents, juveniles of
ribbonfish dominated the finfish group with an index of relative importance (IRI) value of 42.6%, while
Penaeids occurred most in the shellfish group with IRI value of 17.3%. Feeding intensity showed that
juveniles fed mostly on prawns and crustaceans while adults fed more on finfishes. T. lepturus exhibited
positive allometric growth with modal classes of 35-36.9 and 45-46.9 cm; von Bertallanfy model gave
an asymptotic-length (L∞) of 69.3 cm. Exploitation rate of T. lepturus is 0.73, which indicates that the
stock of T. lepturus is marginally over-exploited.
Keywords
Fecundity, Feeding-intensity, Fish eggs, Stock-structure