STOCK ASSESSMENT AND ASPECTS OF REPRODUCTION OF TRICHIURUS LEPTURUS AND LUTJANUS FULGENS IN GHANAIAN WATERS

ABSTRACT 

The  ribbonfish, Trichiurus  lepturus and  golden  African  snapper,  Lutjanus fulgens are  actively  and  locally  exploited  by  commercial  fishers  along  the coast  of  Ghana.  To bridge the  knowledge  gap  on  these  species,  size composition,  growth  and  mortality  as  well  as  aspects  of  reproduction  were assessed. Samples were collected from major fish landing sites along the coast of Ghana from September 2018 to August 2019. Length-frequency data were used  to  estimate  growth  and  mortality  rates  and  exploitation  ratio.  Total lengths  of  T.  lepturus sampled  ranged  between  24.8  and  103.9  cm  with  a unimodal  distribution  of  55  cm.  The  length-weight  relationship,  BW  = 0.0002TL3.3437 (r = 0.98) indicated positive allometric growth. The asymptotic length (L∞), growth coefficient (K) and age at zero length (to) for  T. lepturuswere estimated as 133.66, 0.46 yr-1 and -0.88, respectively. Total (Z), fishing (F) and natural (M) mortality rates of  T. lepturuswere estimated at 2.69 yr-1, 2.03 yr-1 and 0.66 yr-1, respectively. The length at first capture (Lc) was lower than the length at first maturity (Lm). Spawning occurred all year round with a peak  spawning  period  from  March  to  June.  Fecundity  was  estimated  to  be 17,440  ±  1,250  eggs  (mean  ±  SE).  For  Lutjanus  fulgens, the  total  length sampled ranged between 16.2 and 45.6 cm with a length-weight relationship of BW = 0.0192TL2.8959 (r = 0.97) indicating isometric growth. The  L∞, K  and towere estimated as 51.09, 0.47 yr-1and -0.30, respectively.  Z, Fand  Mof L. fulgens were  estimated  at  2.69  yr-1,  1.91  yr-1 and  0.78  yr-1, respectively.  The study showed that the stocks enter the exploitation phase just before attaining maturity with Lcestimated at 31.51 cm and Lmat 33.7cm. Mean fecundity was estimated to be 77,833 ± 13,012 eggs. Peak spawning period of L. fulgenswas observed  from  June  to  September.  There  was  no  significant  difference