Meat Yield and Shell Dimension of Smooth Scallop (Flexopecten glaber) Caught from Çardak Lagoon in Canakkale, Turkey
In this research, meat yield and shell dimension of smooth scallop (Flexopecten glaber) were specified. 150 individuals of smooth scallop were caught by dredges seasonally in Cardak lagoon on Canakkale strait, Turkey. According to results, the relationship of total shell length between total shell weight was determined as TW = 0.5207* TL 2.4533 (R2= 0.73). Moreover, meat yield of scallop was determined highest as whole meat in spring and as adductor muscle in summer. This paper reveals basic growth data of smooth scallop and its preliminary study for Cardak lagoon which is important bivalve inhabiting area.
A preliminary study on the traits of Chamelea gallina (Linnaeus, 1758) in the Gulf of Antalya, Mediterranean Coast of Turkey (Levantine Sea)
This study aimed to examine on some properties and to draw attention to why it cannot create an intensive stock amount of Chamelea gallina (Linnaeus, 1758) in the Gulf of Antalya in the Mediterranean coast of Turkey, Levantine Sea. Specimens of C. gallina displayed total shell legths of 6 to 32 mm, mean 14.5 mm and total weights of 0.1 to 11.44 g, mean 1.82 g. The total shell length and total weight relationship of C. gallina was calculated as TW =0.3333 * TSL 2.9894 (R² =0.9850). The mean meat yield was found as 12.10±0.9264%. A small number of C. gallina samples were collected. The majority of the collected striped venus were determined as empty shell. It was observed that the razorfish (Xyrichtys novacula) were fed with C. gallina during research. Finally, these results may draw attention the reasons why this species cannot form an intensive stock amount. It is thought that the empty shells of the striped venus can be caused from feeding of the razorfish (X. novacula) with C. gallina and environmental factor changes.Keywords: Chamelea gallina; length; weight; meat yield; mediterranean
Lake Muzahi, Rwanda: limnological features and phytoplankton production
Lake Muhazi, a small lake of Rwanda (East Africa) was studied from 1986 to 1990. A dramatic decrease of the catch of Oreochromis niloticus (350 T y−1 in the fifties vs 30 T y−1 in 1982) suggested a loss of productivity or overfishing. In the same period, other ecological changes occurred: the submerged macrophytes regressed and there was a decrease in Secchi depth (0.65 m in 1987 vs 1.5 m in the fifties). Compared to other lakes of the same area, the plankton production seemed low. The results of the present study characterize lake Muhazi as a shallow lake with a rather unstable diurnal stratification and with slight differences in mixing regime between its eastern, deepest part and its western, shallowest part. Secchi disk depth does not vary seasonally to a large extent. The water has a rather high mineral content (conductivity of about 500 µS cm−1 at 25 °C) and low concentrations of dissolved N and P, except in the hypolimnion, where NHinf4sup+-N can be high.Two species, Microcystis aeruginosa and Ceratium hirundinella, account for most of the phytoplankton biomass, which is about 50–80 mg chlorophyll a m−2 in the euphotic zone, usually with little seasonal variation. Daily gross production estimates amount to about 6 to 9.5 g O2 m−2 d−1 with a significant difference between the two parts of the lake. Data on C:N and C:P ratio in the phytoplankton suggest that some N deficiency might occur in the eastern part. Moreover, the Zm:Zc ratio could also lead to rather low net production rates (0.21–0.25 d−1 for a mixed layer of 4 m)In conclusion, the primary production of lake Muhazi is medium for African lakes and the hypothesis that decreased planktonic production could account for a reduced fish production should be discarded. Whereas the present yield of the fishery is only 20 kg ha−1 y−1, the yield estimated from primary production ranges between 46 and 64 kg ha−1 y−1. This could be reached through proper management. Finally, some hypotheses are given to explain the ecological changes which occurred in the lake.