Summary:The reproductive cycle of the flat oyster, Ostrea edulis Linnaeus, 1758, in Homa Lagoon, Izmir Bay, Turkey was examined from August 2008 to July 2009. Gonad samples were analysed histologically in order to determine the sex ratio and gonad development stage. Overall, the sex ratio was recorded as 2.2% female, 42.6% male, 37% hermaphrodite and 17.9% inactive. Glycogen content showed considerable variations between August and February, but decreased gradually thereafter. However, glycogen did not directly affect the reproductive cycle. Total lipid content was positively correlated with temperature and inversely correlated with salinity. In addition, this parameter was influenced by the reproductive activity, which is correlated with the fluctuation of the condition index and gonad index (P<0.05). However, the relationship between the protein index and the gonad index was negative (P<0.05). The results of this study showed that protein was the major energy resource. The condition index varied between 2.69±0.91 (February) and 12.29±1.45 (April) during the year. With respect to meat yield, oyster quality changed from "fine" to "special", except in December and February.Keywords: flat oyster; Ostrea edulis; reproductive cycle; biochemical composition; Aegean Sea; Homa Lagoon.Variación estacional de la actividad reproductiva y de la composición bioquímica de ostra plana (Ostrea edulis) en Homa Lagoon, bahía de Izmir, Turquía Resumen: El ciclo reproductivo de la ostra plana, Ostrea edulis Linnaeus, 1758, en Homa Lagoon, Bahía de Izmir, Turquía, fue examinado entre agosto de 2008 y julio de 2009. Las gónadas se analizaron histológicamente para determinar la proporción de sexos y su estado de desarrollo. La proporción de sexos encontrada fue 2.2% hembras, 42.6% machos, 37% hermafroditas y 17.9% inactivos. El contenido de glucógeno mostró considerables variaciones entre agosto y febrero, pero después de estos meses se produjo un aumento gradual. Sin embargo el glucógeno no afectó directamente el ciclo reproductivo. El contenido total de lípidos se correlacionó positivamente con la temperatura e inversamente con la salinidad. Además, este parámetro estuvo influenciado por la actividad reproductiva, que se correlaciona con la fluctuación del índice de condición y del índice gonadal (P<0,05). Sin embargo la relación entre el índice de proteí-na y el índice gonadal fue negativa (P<0,05). Los resultados de este estudio mostraron que la proteína era la principal fuente de energía. El índice de condición varió entre 2.69±0.91 (febrero) y 12.29±1.45 (abril) durante el año. En lo que respecta a la producción de carne, la calidad de las ostras pasó de "fine" to "special", excepto en diciembre y febrero.

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The growth and mortality rate of different size of mussels, Mytilus galloprovincialis, were compared in Mersin bay, Izmir. Mussel sampling was performed on a monthly basis over 1 year, together with hyrobiological parameters. Water temperature, salinity, chlorophyll a, total particulate matter (TPM) and particulate organic carbon (POC) were determined. Average chlorophyll a, TPM and POC values were 3.88±1.62 μg L−1, 13.12±3.68 mg L−1 and 252±121.89 μg L−1 respectively. Initial mean lengths of mussels for each size group were 10 mm (9.91±0.25 mm), 20 mm (20.14±0.29 mm), 30 mm (30.66±0.21 mm), 40 mm (40.14±0.21 mm), 50 mm (50.62±0.21 mm), 60 mm (59.77±0.21 mm) and 70 mm (69.47±0.62 mm). Maximum growth in length occurred during the spring–summer months. The annual length increments of mussel size groups were 46.22, 41.42, 30.3, 28.03, 20.63, 16.34 and 12.03 mm from small to large size groups respectively. Small mussels grew faster than large mussels and reached commercial size at the same time. Mortality was <5% for all groups at the end of the experiment.

The carpet shell clam (Tapes decussatus Linnaeus, 1758) is a candidate species for aquaculture development in Turkish waters. Our study aimed to assess the efficiency of three different methods (i.e., net, box and fenced ground) to maximize clam production. Two different net materials (hard plastic net and polyamide net) were tested in the net method trials. Conducted over 1 year between October 2001 and October 2002, an initial calibrated clam population, characterized by a 26.25 ± 0.035 mm shell length and 3.85 ± 0.06 g total wet weight was sampled on a monthly basis to carry out the experiments. By the end of the rearing cycle, clams reached 34.13 ± 0.38 mm and 9.09 ± 0.27 g in shell length and total wet weight, respectively. Significant differences in shell length and total wet weight among culture methods (P < 0.05) were reported. Both maximum growth and total wet weight, as well as survival rate (64%) were obtained using the hard plastic net method. Those overall results were likely due to both limited algae accumulation and crab predation when using hard plastic net. Therefore, this method appears the most suitable to develop further larger experimental clam aquaculture trials. Additional studies required to develop clam culture in Turkish waters are discussed.

Summary The aim of this report is to provide an overview of the current status of efforts on the potential rehabilitation of sturgeon populations in Turkish waters, describing the structure and the outcome of projects carried out since 2006 and identifying the strategic needs for sturgeon conservation measures at a national level. It is well known that there were six sturgeon species occurring around Turkish Black Sea coasts while entering the rivers, mainly Kızılırmak, Yeşilırmak, Sakarya and Çoruh Rivers for spawning. Anadromous sturgeon species have been strictly protected throughout Turkey since 1997. Conservation and management measurements have been implemented since 1970s. However, this was apparently with little success as stocks continued to decline and habitats deteriorated further, threatening the stocks with extinction. At the same time the needs for survival are not well documented. A project was initiated on 30 January 2006, consisting of seven‐work packages including studies on population structure, reproduction, habitat assessment, genetic variability between and within stocks and the development of protective management strategies and plans. The work covered the Turkish Black Sea coastline and the rovers Yeşilırmak, Kızılırmak, Çoruh and Sakarya. Actively sampled and/or accidentally caught specimens have been tagged by T‐bars and released after measurements and tissue sampling for genetic analyses. In addition, broodstocks of Russian sturgeon (Acipenser gueldenstaedtii), Beluga (Huso huso), and stellate (A. stellatus) are being built by rearing fish at the Central Fisheries Research (Yomra, Trabzon, Turkey) Institute. Reproduction studies have mainly focused on sperm collection, cryopreservation and induced spawning as well as on larval rearing.