Exploitation Rate

ABSTRACT
Objective. Growth and mortality parameters of Cachana Cynopotamus atratoensis Eigenmann, 1907 in the cienaga Grande de Lorica, Sinu river basin, Colombia, were estimated. Materials and methods. The length frequency analysis to the information collected between January 2001 to December 2002, was applied. Results. The estimated values for asymptotic length, growth rate and age at zero length were 43.4 (±0.52) cm of total length, 0.29 (±0.02) year-1 and -0.53 years, respectively. Total mortality was estimated at 0.97 year-1, natural mortality at 0.72 year-1, fishing mortality at 0.25, the average catch size was 24.8 cm total length, being fully recruited to the fishery with 16.6 cm total length, with low exploitation rate (E: 0.26). Conclusions. Cachana is a fish with medium longevity and growth rate with low exploitation rate, suggesting that there is still no overfishing on the species. However, as it is an very important fish in the food security of fishermen and their families, its necessary to increase the basic biology research pointing to the management and conservation of the species in the cienaga and the Sinu basin.

Octopus cyanea is a commercially important cephalopod in the Western Indian Ocean (WIO) region, but scientific information to inform management strategies for the species is limited. A study was conducted in 2014, 2015, 2017 and 2018 to investigate biological parameters including growth, mortality, exploitation rates and recruitment patterns in the sea around Mafia Archipelago, Tanzania. Virtual population analysis (VPA) indicated differential mortality between two sampling sites; the lowest and highest fishing mortality of F = 1.5yr-1 and F = 2.7yr-1 were observed in Bwejuu (Dorsal mantle length, DMT = 18-20 cm) and Jibondo (DMT = 8-12 cm) fishing villages, respectively. The maximum exploitation rate (Emax), which gives the maximum relative yield per recruit, was estimated at 0.380 and 0.379 for Jibondo and Bwejuu, respectively. The exploitation rates E 0.5, which corresponded to 50% of the unexploited stock relative biomass per recruit, were estimated at 0.248 for Jibondo and 0.24...

Objective. Growth and mortality parameters of Cachana Cynopotamus atratoensis Eigenmann, 1907 in the cienaga Grande de Lorica, Sinu river basin, Colombia, were estimated. Materials and methods. The length frequency analysis to the information collected between January 2001 to December 2002, was applied. Results. The estimated values for asymptotic length, growth rate and age at zero length were 43.4 (±0.52) cm of total length, 0.29 (±0.02) year-1 and -0.53 years, respectively. Total mortality was estimated at 0.97 year-1, natural mortality at 0.72 year-1, fishing mortality at 0.25, the average catch size was 24.8 cm total length, being fully recruited to the fishery with 16.6 cm total length, with low exploitation rate (E: 0.26). Conclusions. Cachana is a fish with medium longevity and growth rate with low exploitation rate, suggesting that there is still no overfishing on the species. However, as it is an very important fish in the food security of fishermen and their families, its...