This study presents a new locality record of poisonous pufferfish, Lagocephalus sceleratus (Gmelin, 1789), one of the 18 worst invader fish species identified globally by IUCN, from the Sea of Marmara caught by a commercial purse seine fishing vessel while fishing anchovy on 22 February 2021. Previously, this invasive species was first recorded at the Gelibolu peninsula in the Sea of Marmara between September 2007 and October 2008. Lagocephalus sceleratus recorded in this study is larger in size with 142 mm total length than previous records (126 mm in 2007; 95 mm in 2008) for the Sea of Marmara. The presently reported record represents the first documented occurrence of this species in the Erdek Bay of the Sea of Marmara and the third documented record for the entire Sea of Marmara.

This study aimed to determine the potential changes in the fatty acid composition of frozen cultured sea bass (Dicentrarchus labrax) thawed at different environmental conditions. Sea bass fillets were thawed using four different methodologies: refrigerator (+4°C), water (+15°C), microwave (defrost mode) and ambient conditions (22±2°C). Some part of the fish was thawed once (on the 7th and 30th days), and the other part was thawed twice (on the 30th day). Thus, crude lipid analysis and fatty acid composition by gas chromatography were carried out in the thawed sea bass fillets. The results showed negative effects on the fatty acid composition caused by the different thawing methods. The most suitable thawing method was determined as refrigerator thawing, especially on the 30th day 1st thawing according to least loss of the lipid values (9.19±0.18%) and unsaturated fatty acids (C18:2 25.92±0.13%, C20:5 5.56±0.02%, C22:6n-3 8.90±0.09%, ∑PUFA 44.70±0.04%). Samples thawed in water and ambient conditions follow the refrigerator thawing method in terms of lipid and fatty acids. The highest lipid and fatty acid loss was observed in microwave thawing. Although the samples thawed in the refrigerator were better than the other groups in terms of lipid content and fatty acid composition, it is recommended to the consumers that frozen foods should be thawed only once and consumed immediately, and that fish should be frozen according to their needs and thaw as much as they can consume.

In August 2020, a total area of 38000 m2 around Gökçeada has been scanned to determine the current population status of Pinna nobilis. 9 stations (Yıldızkoy, Manastır, Marmaros, Gizli Liman, Laz Koyu, Kapıkaya, Karaçavuş, Karaçavuş shore and Kefalos) have been detected by means of SCUBA and ABC diving techniques. All specimens were found dead (total mass mortality of 100%). The total length range of P. nobilis was between 30.8 – 38.3 cm.

Sea snot, which was seen and reported in the Adriatic and Tyrrhenian Seas in the early 1990s, had been on Turkey's agenda as an environmental massive disaster from the winter months of 2021 until the end of summer in the Sea of Marmara. Due to the magnitude and topicality of the subject, the samples collected from the coastal areas where sea snot is observed in Marmara from January until July were examined. According to the results obtained, 5 classes were determined in sea snot. Species of algae that secrete mucilage, which provides stickiness to the formation, were also been identified in sea snot. These are 1 dinoflagellate, 2 Prymnesiosides, 5 diatoms, and 2 cyanobacteria species. 8 toxic planktonic species were detected in sea snot: 1 causing PSP poisoning and 3 of dinoflagellate causing DSP poisoning; 1 of prymnesiophisid that releases ichthyotoxin to the sea environment, and 3 of diatoms that cause ASP poisoning.

In the present study, mollusc species distributed in the Kemer Bay (Sea of Marmara) were determined seasonally (November, February, May, and August) in the years 2010 and 2011. The benthic samples were collected from different biotopes in 16 stations at depth ranging between 0.2 and 5 m by using a quadrate sampling gear. As a result of the evaluation of collected benthic materials, a total of 66 mollusc species belonging to 3 classes (Polyplacophora, Gastropoda, and Bivalvia) were identified. When the number of species and individuals are compared based on the seasons, maximum number of species (46 species) and individuals (168825 ind. m-2) were counted in autumn and spring, respectively. Mytilus galloprovincialis (Lamarck, 1819) and Mytilaster lineatus (Gmelin, 1791) were the most abundant species in all the seasons. Whereas, Bittium reticulatum (da Costa, 1778), Rissoa membranacea (Montagu, 1803), and Tricolia pullus pullus (Linnaeus, 1758) were characterized as species having the highest frequency index values in all seasons.

The evaluation of seafood processing wastes is an important issue in terms of both preventing environmental pollution and adding value to these wastes economically. The most practical method that can convert seafood processing waste into a valuable feed source and plant fertilizer is to make silage. In this study, the ripening times and nutritional components of fish silages prepared with direct addition of lactic acid bacteria culture (Streptococcus thermophilus), acidifying chemicals (formic acid) and yogurt, which is a fermented food, were compared. In the research, sardine fish (Sardina pilchardus) wastes (head, skin, bones, internal organs, etc.) were used in fish silage production. It was observed that all fish silages completed the ripening phase within a maximum of 10 days. It was determined that the moisture, ash, protein and lipid contents of the groups prepared with acid, bacteria and yoghurt ranged between 63-66%, 5.6-5.7%, 11.3-11.8% and 12.18-13.65%, respectively. As a result of the research, it was observed that fish silages made with the addition of yoghurt as an alternative to silages made with direct addition of pure bacterial culture or acid addition met the expectations in terms of both ripening time and nutrient components.

The lake management strategy of sediment dredging (removal) is periodically undertaken in shallow, eutrophic Mogan Lake, an important recreation area. This study aims to use certain indices - enrichment index (EF), contamination/pollution index (CF), degree of contamination (Cd), pollution load index (PLI), geoaccumulation index (Igeo), potential ecological risk index (Eri), integrated ecological risk index (PER), and mean probable effect concentration quotient (mPEC-Q) - to evaluate the state of sediment pollution in the lake after dredging. With this in mind, after dredging was completed, two stations in the littoral zone were selected. Station I was located especially where it would be reached by wastewater from mineral processing facilities and domestic areas; and Station II, where it would be reached by residential and agricultural wastewater. Surface sediment samples were taken repeatedly in May and November 2020 using a sediment grabber. According to the study findings, a) Among the heavy metals studied (Hg, As, Cd, Cr, Pb, Ni, Cu, and Zn), Cu, As, and Cd were found to have the highest enrichment and contamination indices; b) The pollution load index (PLI) values (1.30-2.26) suggest heavy metal pollution in the sediment, and the geoaccumulation index (Igeo) values show intensive Pb contamination at both stations in both months; c) In terms of potential ecological risk index (Eri), Cd was found to have a significant level of ecological risk index; d) The integrated risk index (PER) indicates that all heavy metals in the lake were present at moderate ecological risk levels. Ni and As were metals that had negative biological effects. The results indicate that a) Dredging is not a very effective tool for reducing pollution in the sediment; and b) As long as anthropogenic pollutants continue to enter the lake basin, sediment heavy metal levels should be routinely monitored, particularly those with ecological and biological effects on the sediment: Cu, Cd, Pb, Ni and As. It is predicted that the findings of this study will contribute to the sediment-focused monitoring efforts of organizations and local governments.

Amphibians, which can live in aquatic and terrestrial environments, are a good indicator of pollution in these areas. Although frog leg is not consumed frequently in some cuisines, including Turkey, it is important in terms of evaluating metal accumulation since it is preferred as human food in many European countries. In this study, the quantities of trace elements (Cd, Pb, Cu, Zn, As, Co, Cr, Ni, Mn, V) were measured in the edible tissues (muscles) of an amphibian species by sampling from two frog farms in Turkey. It was aimed to assess possible health hazards for humans by frog legs consumption comparing with the toxicological limit values, including provisional tolerable weekly intake (PTWI), target hazard quotient (THQ), and Hazard Index (HI). In general, the average values (µg kg−1) of trace elements were Zn (3.437.62)> Pb (69.22)> Cu (66.72)> Mn (35.07)> As (24.24)> Cr (11.47)> Ni (6.94)> Cd (6.51)> Co (2.97)> V (<0.001). The results indicated that concentrations of the analyzed trace elements were determined below the European Commission’s permitted levels and edible tissues of the marsh frog posed no carcinogenic health risk to humans.

This study was conducted to evaluate the parameters on growth performance, molting frequency and carapace coloration of marbled crab (Pachygrapsus marmoratus Fabricius, 1787). Crabs were collected from Urla, İzmir. The experiment was performed in 10 L plastic containers filled with 6 L of seawater at four different salinity levels (5‰, 15‰, 25‰ and 35‰). Ten crabs with an initial mean weight of 0.78±0.03 g were placed in each container with three replicates. Crabs were fed once a day with a commercial diet (46% protein and 18% lipid) for 12 weeks. At the end of the study, the final mean weight (FMW) of the 25‰ group was significantly higher than the 5‰ and 15‰ groups (P<0.05). Specific growth rates (SGR) of the 15‰ and the 35‰ groups and feed conversion ratio (FCR) of the 25‰ group were significantly higher than the 5‰ group (P<0.05). The mean molting frequency (MMF) of the 25‰ group was significantly higher than the 5‰ group (P<0.05). Final lightness (L*) of the 5‰ and 15‰ were significantly lower than their initials (P<0.05). Final redness (a*) of the 25‰ group was the highest among the experimental groups (P<0.05). Final yellowness (b*) of the 25‰ group was significantly higher than the 5‰ and 15‰ groups (P<0.05). According to the results, it is recommended to keep the salinity at 25‰ under marble crab rearing conditions. Further studies are needed to reveal the potential properties of this species in marine aquariums.

There has been a significant lack of data on product and input markets, aquaculture consumption characteristics, production, distribution and marketing issues, and supply and value chain in Turkish fishing and aquaculture sectors. Therefore, the study examined the competitiveness of the Turkish aquaculture industry. Time series data belonging the time period of 1976-2020 gathered from Food and Agriculture Organization (FAO), World Trade Organization and Turkish Statistical Institute (TURKSTAT) were used in the study. In the research, the competitiveness of the Turkish fishing and aquaculture sector has been explored by using the Balassa index, total factor productivity and production costs. The research results show that the fisheries in Turkey are small-scale, technological level are insufficient and there are financial problems. Based on the revealed comparative advantage (RCA) values of the world and EU, which are 0.65 and 1.86, respectively, Turkey 's has competitive power over EU countries, while the reverse is the case for the world. Although fisheries supply chain has been established in Turkey, the value chain has not yet been fully established and activated. The study suggests increasing the efficiency in aquaculture production, having a strong interaction with the market during the production phase, having a high awareness of the price trends and consumer needs throughout the supply chain, using modern production and distribution technologies, and developing effective extension/education activities to reach the desired point in the Turkish aquaculture sector. Quality standards should be at the international level to increase export opportunities and competitiveness of Turkish aquaculture sector.