Fisheries of Meuthynnus Affinis and Scomberomorus Cmerson in relation to oceanographic and atmospheric parameters off the coastal waters of Dar es Salaam, Tanzania

The present study was conducted to assess how fisheries of E. affinis and S. commerson relate to seasonal variations in- and atmospheric parameters off the coastal waters of Dar es Sal Tanzania.. Fisheries data of the two species of fish, oceanographic and atmosphericparameters were collected between April to September 2008 and November 2008 to February 2009 during southeast monsoon (SEM) and northeast monsoon (NEM) seasons respectively. A total of 2,591 E. affinis and 722 S. commerson were collected in both NEM and SEM seasons. Significantly higher seasonal variations in the catch- per unit effort (CPUE) were observed for fishing trips undertaken during the day (p = 0.042) and at night (p = 0.045) for E. affinis and S. commerson (p = 0.004), respectively. Both oceanographic (seas surface temperature and salinity) and atmospheric (temperature, rainfall, solar radiation and wind speed) parameters showed a significant correlation to CPUE of E. affinis (r = range from - 0.58 to 0.98). For S. commerson, only the oceanographic parameters correlated significantly to CPUE (r = range from - 0.58 to - 0.79). The relationship between length-weight (exponent b) for samples of different sexes and seasons showed an isometric growth for both E. affinis and S. commerson. Gonad-somatic index revealed a year round spawning for both species. Mean stable isotopes of '3C and '5N values showed that the two species feed on marine fish at different trophic position and they varied significantly (p< 0.05) with negative values and a wide range of trophic level were season whereas the most neg observed in NEM for E. affinis and in SEM for S. commerson. In conclusion, the present "fluence of oceanographic and atmospheric parameters on the findings showed the in and S commerson implying that they have impacts on the population CPUE of E. affinis an . al indices of these species. Therefore, long term monitoring of the dynamics and biological and atmospheric parameters on the population impacts regarding ocean dices of E. affinis and S. commerson is recommended.