In frame of fisheries management, a stock assessment using surplus production models incorporating environmental parameters was dealt with one of the most important commercially crustacean fisheries resources along th...In frame of fisheries management, a stock assessment using surplus production models incorporating environmental parameters was dealt with one of the most important commercially crustacean fisheries resources along the Tunisian coast, the Melicertus kerathurus stock. The analysis was carried out for a period of 17 years with a database including fishing efforts, catches, catch per unit effort (CPUE) and sea surface temperature (SST). CLIMPROD is the software used to select the appropriate model and fit to the fishery and environmental data. Overall, SST was positively correlated to the yield and abundance index (CPUE) explaining 47% and 57% of their variability respectively, nevertheless. The incorporation of the SST in global model demonstrated that the SST influenced both the catchability and the abundance of this species separately. In fact the impact of SST leads to consider a production model impacted on the one hand by a linear relationship between the CPUE and the fishing effort, and on the other hand by also a linear relationship between the CPUE and the SST for both catchability or abundance of the species. The interpretation of global model with environmental parameters is changed with the incorporation of climate parameter.展开更多
Objective:To study the seasonal variability of heterotrophic dinoflagellate in the station of Cercina(southern coast of Tunisia).Methods:Sampling was done in 2007 in Cercina station located in the western coast of Ker...Objective:To study the seasonal variability of heterotrophic dinoflagellate in the station of Cercina(southern coast of Tunisia).Methods:Sampling was done in 2007 in Cercina station located in the western coast of Kerkennah(34°41'27''N;11°07'45''E)(Southern Tunisia).Three replicates of water samples were taken during 10 days of each month.Environmental variables and nutrients were measured in situ.Results:A significant seasonal difference was observed for temperature and water salinity.The highest values were observed in spring and summer.No significant seasonal difference was,however,detected for nitrite,nitrate,ammonia,silica and phosphate.Sixty-five species of dinoflagellate were identified in the station of Cercina.Abundance of dinoflagellates fluctuated between seasons with values showing a significant seasonal and monthly difference.The highest mean abundance was recorded in spring in April,while the lowest abundance was detected in December in winter.Protoperidinium granii was the main species contributing to the dissimilarity between spring and winter with 13.98%followed by Peridinium sp.with 12.5%of dissimilarity and by Polykrikos sp.with 10.58%.Conclusions:Heterotrophic dinoflagellates proliferate in spring and summer.This increase was justified by the nutrient availability.Protoperidinium granii and Polykrikos kofoidii were the main heterotrophic dinoflagellate making difference between seasons and their densities were positively correlated with both temperature and salinity.展开更多
文摘In frame of fisheries management, a stock assessment using surplus production models incorporating environmental parameters was dealt with one of the most important commercially crustacean fisheries resources along the Tunisian coast, the Melicertus kerathurus stock. The analysis was carried out for a period of 17 years with a database including fishing efforts, catches, catch per unit effort (CPUE) and sea surface temperature (SST). CLIMPROD is the software used to select the appropriate model and fit to the fishery and environmental data. Overall, SST was positively correlated to the yield and abundance index (CPUE) explaining 47% and 57% of their variability respectively, nevertheless. The incorporation of the SST in global model demonstrated that the SST influenced both the catchability and the abundance of this species separately. In fact the impact of SST leads to consider a production model impacted on the one hand by a linear relationship between the CPUE and the fishing effort, and on the other hand by also a linear relationship between the CPUE and the SST for both catchability or abundance of the species. The interpretation of global model with environmental parameters is changed with the incorporation of climate parameter.
基金Supported by the Faculty of Sciences,Sfax,Tunisia.
文摘Objective:To study the seasonal variability of heterotrophic dinoflagellate in the station of Cercina(southern coast of Tunisia).Methods:Sampling was done in 2007 in Cercina station located in the western coast of Kerkennah(34°41'27''N;11°07'45''E)(Southern Tunisia).Three replicates of water samples were taken during 10 days of each month.Environmental variables and nutrients were measured in situ.Results:A significant seasonal difference was observed for temperature and water salinity.The highest values were observed in spring and summer.No significant seasonal difference was,however,detected for nitrite,nitrate,ammonia,silica and phosphate.Sixty-five species of dinoflagellate were identified in the station of Cercina.Abundance of dinoflagellates fluctuated between seasons with values showing a significant seasonal and monthly difference.The highest mean abundance was recorded in spring in April,while the lowest abundance was detected in December in winter.Protoperidinium granii was the main species contributing to the dissimilarity between spring and winter with 13.98%followed by Peridinium sp.with 12.5%of dissimilarity and by Polykrikos sp.with 10.58%.Conclusions:Heterotrophic dinoflagellates proliferate in spring and summer.This increase was justified by the nutrient availability.Protoperidinium granii and Polykrikos kofoidii were the main heterotrophic dinoflagellate making difference between seasons and their densities were positively correlated with both temperature and salinity.
