Size Composition of Fish By-Catch Species from Industrial Shrimp Trawl Fishery in Nigerian Coastal Waters
Abstract: Fish species
composition of by-catch in the industrial shrimp trawl fishery in Nigeria was
investigated with the Sciaenidae family being the most prevalent by-catch fish
species. In order of prevalence Pseudolithus elongatus with a mean weight and
length of 15.28g and 86.39mm, respectively and Pseudolithus typus (n= 102)
having an average weight of 18.76g and mean length of 88.01mm. Other fish
by-catch species include Pseudolithus senegalensis (n= 99, mean weigh = 15.49g,
mean length= 88.60mm); Galeoides decadactylus (n= 59, mean weight= 15.26g, mean
length= 87.66mm); Pteroscion peli (n= 48, mean weight= 16.05g, mean length =
88.23mm); Drepane africana (n= 33, mean weight= 13.29g, mean length= 45.73mm)
and Cynoglossus senegalensis (n= 11, mean weight= 21.78g, mean length =
86.45mm). Despite the small number of Cynoglossus senegalensis, it had the
highest weight contribution to the by-catch. Significant (P<0.01)
relationship exists between weight and length of fish species. The adjusted R2
of the parameters indicated that 19.4% of the weight gained is accounted for by
increase in length of Pseudolithus elongatus; 1.7% in Pseudolithus typus; 31.7%
in Pseudolithus senegalensis; 13.7% in Galeoides decadactylus; 7.8% in
Pteroscion peli; 57.4% in Drepane Africana; and 48.9% in Cynoglossus
senegalensis. The by-catch associated with shrimp trawls should be properly
monitored and controlled to reduce the quantity of non-target fish species in
their catch. Also, the use of diamond-shaped 44mm mesh size for shrimp should
be encouraged or made mandatory for fishers to reduce fish by-catch.
Keywords: Shrimp, by-catch,
fishery, weight
Author: I O Taiwo, O A Olopade
Journal Code: jpperikanangg170051
