Seasonal variation in the length-weight relationship and condition factor of thirty fish species from the Shimoni artisanal fishery, Kenya

Abstract

Seasonal variation in the length-weight relationship (LWR) and condition factor were assessed for 3 704 fish specimens constituting 30 fish species belonging to 11 families. The fish were sampled from artisanal fisher catches on the south coast of Kenya between March 2014 and March 2015. The regression results for the LWR were 0.57 for Siganus luridus and 0.97 for Lutjanus argentimaculatus during the northeast monsoon (NEM), and 0.76 for Scolopsis ghanam and 0.98 for Parupeneus macronema during the southeast monsoon (SEM). The ‘b’ values ranged from 1.8 for Siganus luridus to 4.3 for Plectorhinchus gaterinus during the NEM, and 1.4 for Plectorhinchus chubbi to 3.2 for Parupeneus heptacanthus during the SEM. The mean ‘b’ values for the SEM and NEM seasons were 2.73 and 2.63 respectively and significantly differed from 3 (t–test, P < 0.5). Mean condition factors of 0.37 (S.E = 0.01) during the NEM, 0.34 (S.E = 0.01) during the SEM for Hemiramphus far and 0.56 (S.E = 0.03) during the NEM, and 0.59 (S.E = 0.03) during SEM for Cheilio inermis were recorded indicating that these species were feeding poorly, the environment was not conducive, or that high competition for food from other species existed, while the other species had mean condition factors above 1 during the two seasons. The condition factor significantly differed for eleven species during the two seasons (P < 0.05).