Age, growth, mortality and population structure of the oyster, Crassostrea madrasensis, in the Moheskhali Channel (southeastern coast of Bangladesh)

Abstract

SummaryThe population structure, age, growth, mortality and harvest intensity of the oyster Crassostrea madrasensis were examined in the Moheskhali Channel, Bangladesh between June 2003 and May 2004. The channel is a representative habitat for the area. C. madrasensis monthly length frequency data were analyzed using FiSAT software for estimating population parameters, including asymptotic length (L µ ), growth coefficient (K) and recruitment pattern to assess the status of the stock. Asymptotic length (Lµ) and growth co-efficient (K) were 20.88 cm and 0.35 year, respectively. The growth performance index (u¢) was calculated with 2.18. The growth pattern showed negative allometric growth (b < 3), with an asymptotic weight (W µ ) of about 1124.6 g. The oyster attained an average length of 6.17 cm at the end of 1 year. Total mortality (Z) by length-converted catch curve was estimated at 1.78 year )1 , fishing mortality (F) at 0.77 year )1 , and natural mortality (M) at 1.01 year )1 . The exploitation level (E) of C. madrasensis was 0.43, while the maximum allowable limit of exploitation (E max ) was 0.45 for the highest yield. The recruitment pattern was continuous, displaying a single major peak event per year. Habitat temperatures were 25.5-31.0°C (mean ± SD, 29 ± 1.62°C); salinity range was from 12.36 to 26.0 ppt (mean ± SD, 19.6 ± 4.7 ppt). The exploitation level (0.43) indicated that the oyster stock was exploited at almost maximum yield in this channel.

Análise biomorfométrica da ostra-do-mangue cultivada no litoral amazônico

“…Os valores de r divergentes nas relações das medidas morfométricas com as biomassas totais e viscerais são similares aos valores encontrados por outros autores [28,30,31,32,33,34,36,37,38] [40] com a ostra C. brasiliana, ressalta-se uma relação inversa ao rendimento encontrado por classes de tamanho. Sendo assim, enquanto esses autores evidenciaram maiores rendimentos da carne em indivíduos adultos, neste estudo, os maiores rendimentos foram encontrados na classe "Semente" (Figura 2).…”

Life history of the riverine cyprinid Henicorhynchus siamensis (Sauvage, 1881) in a small reservoir

“…Fish growth was assumed to follow the von Bertalanffy growth function (VBGF), which was modified by Somers (1988) as: where L t is length at time t , L ∞ is the asymptotic length, K is the growth coefficient and t 0 is the theoretical age at length zero. Analyses were carried out using the ELEFAN routine in FiSAT‐II software (Gayanilo et al., 2002), which can be applied to both fish and shellfish (Nurul Amin et al., 2008). The steps to be analyzed by reconstructing the LFD from the initial estimates of L ∞ and K have already been described (Amarasinghe and De Silva, 1992).…”

Reproductive pattern and population dynamics of commercial red swamp crayfish (Procambarus clarkii) from China: implications for sustainable aquaculture management

“…In fish or crayfish population dynamics studies, understanding of population parameters such as growth (growth coefficient K and growth parameter index Ø ′), mortalities (total mortality rate Z , natural mortality rate M , and fishing mortality rate F ) has important implications for population assessment (Rochet et al, 2000). Estimates of these parameters provide fundamental information for predicting population growth and developing sustainable exploitation strategies (Nurul Amin, Zafar & Halim, 2008; Ochwada-Doyle et al., 2014).…”