Dynamics in the length-weight parameters of the mudskipper Periophthalmus barbarus (Gobiidae), in Imo River estuary, Nigeria

Seasonal and intersexual dynamics in parameters of the length-weight relati onship of the mudskipper Periophthalmus barbarus, from Imo River estuary, N igeria, were studied. The proportionality constant or intercept (a) was a s easonal in males, but in females it was significantly higher in the dry sea son (November-April) than during the rains (May-October) due to heightened breeding activity. The length exponent (b) depicted seasonal isometry in ma les. In females, isometry was evident in the dry season while a positive al lometry occurred during the wet season. The sizes of the smallest and large st specimens examined did not regulate variations in the magnitudes of (a) and (b) in both sexes. The insignificant intersexual variation in the lengt h-weight parameters suggests the possibility of using a single predictive l ength-weight equation for the population. However, the sexes exhibited diff erent monthly rank-orders of (a) and (b), thus making such composite estima tes unreliable for a study spanning up to a year. Values of (a) and (b) wer e inversely correlated in both sexes. The population dynamics implications of the results are discussed.