SIZE STRUCTURE, CONDITION FACTOR AND LENGTH-WEIGHT RELATIONSHIP OF PERIWINKLE, TYMPANOTONUS FUSCATUS VAR RADULA (MOLLUSCA, LINNAEUS, 1758) IN IKO RIVER ESTUARY, SOUTHEASTERN NIGERIA

ABSTRACT The size structure, condition factor, and length-weight relationship of Tympanotonus fuscatus var radula (Linnaeus, 1758) in Iko River estuary in Southeastern Nigeria was studied for six months (August 2023 to January, 2024) to provide valuable insights into the population structure and wellbeing of the species in the study area. The results revealed a total of 343 individuals were used for this study. The total shell length ranged between 3.10–4.00 cm (Mean±Std err: 3.3767±0.028); total shell width ranged from 0.80-1.60cm (Mean±Std err: 1.2186±0.024) and total shell weight ranged from 1.80-4.30g Mean±Std err: 2.5837±0.093). The frequency displayed normal curve with the highest frequency at length class of 3.5 cm. The overall mean condition factor recorded in this study was 6.8605±0.317 and ranged from 3.44-8.09. The juvenile class (3.1-3.4 cm) had mean condition value of 7.598±0.1305 and ranged from 7.32-8.09, while the condition factor of the adult class (3.5-4.0 cm) ranged 3.44-7.23 with mean value of 5.7769±0.20. The values decreased with increase in size of the species. Regression equation derived from the logarithmically transformed data of shell length and weight was Log W= Log -0.05584+ 1.962, Log TL R2= 0.796, P< 0.02, confirming the growth pattern of T.fuscatus to be negatively allometric. The calculated b- values for weight-girth and length–girth relationships were 0.449 and 0.517 respectively. The relationship between shell total length and weight showed a highly significant positive correlation. The maximum shell length of 4.0 cm and shell weight of 4.30g indicate over exploitation of the species. Therefore, the study recommended the cultivation of species to compensate for the overexploitation of the species in Iko River estuary in Southeastern Nigeria.