6. Length-Weight Relationship and Growth Parameters of Grey Mullets (Pisces: Mugilidae) in Two Estuaries in Ghana

Abstract

Grey mullet populations in the rivers Pra and Volta estuaries in Ghana were studied to provide information on their
length-weight relationship and growth parameters. Fish samples were collected monthly for 18 months from local
fishermen using cast net, drag net and gill nets. Six species of grey mullets were identified: sickle fin mullet, Liza
falcipinnis (Valenciennes, 1836), large-scaled mullet, Liza grandisquamis (Valenciennes, 1836), grooved mullet,
Liza dumerilii (Steindachner, 1870), white mullet, Mugil curema Vallenciennes, 1836, banana mullet, Mugil
bananensis (Pellegrin, 1928) and striped mullet, Mugil cephalus Linnaeus, 1758. Length-weight relationship for
3.06 the various species in the Volta and Pra estuaries, respectively, were: L. falcipinnis, BW = 0.0158 SL and BW =
2.85 3.24 2.92 3.03 0.0255 SL ; L dumerillii, BW = 0098 SL and BW = 0.0223SL ; M. bananensis, BW = 0.0191SL and BW =
3.10 3.14 3.17 2.85 0.0175 SL ; M. cephalus, BW = 0.0574 SL and BW = 0.0134 SL ; M. curema, BW = 0.0311 SL and BW =
2.5 3.01 0.0247 SL . That for L. grandisquamis, which was found only in the Pra estuary, was BW = 0.0204 SL ,
indicating isometric growth since the regression coefficient b was not significantly different from 3.0 (P > 0.05).
The regression coefficient b for the other species was either significantly higher or lower than 3.0 (P < 0.01),
suggesting allometric growth. Except L. dumerilli, L¥and K for the same species from the two estuaries differed.
estimated
The highest
in
L
the ¥of
study
56.6 cm
indicates
(SL) and
that
growth
the sizes
performance
of grey mullets
index (
in
Æ)
the
of 4.99
two estuaries
were estimated
were smaller
for M. cephalus
compared
. The
to
L
the ¥ same species from other countries in the tropics.