Determination of Microplastic Pollution in Commercial Fish in the Middle Black Sea (Samsun), Türkiye

OZET: Bu calisma Orta Karadeniz de Eylul 2002 - Nisan 2003 tarihleri arasinda gerceklestirilmistir. Calismada ticari teknelerle avlanan, mezgit (Gadus merlangus euxinus), barbunya (Mullus barbatus ponticus), kalkan (Psetta maxima maeotica), istavrit (Trachurus mediterraneus) ve cinekop (Pomatomus saltator), baliklarinin sig ( 75m) su kesimlerine ait av verileri degerlendirilmistir. Calismada ozellikle mezgit ve barbunya baliklarinin buyukluklerinin, avlamanin yapildigi aylar ve derinliklere gore onemli olcude degistigi belirlenmistir (p 75 m). Length compositions on these species were also analysed. The mean lengths of whiting and red mullets were significantly different by months and depths (p<0.05). Most of these differences were observed in November and December. We conclude that, fishing season and depths at which trawlings were performed had significant effect on the size of species caught in the study area. But it was not the case for the all species concerned. Key words: Middle Black Sea, bottom trawl, catch composition

Effects of depth and season on species composition of catch and discard rate in the gillnet fishery on the south-eastern coast of the Black Sea was investigated in this study. for this purpose, fishing trials were carried out in the four different depth strata (0-14 m, 15-29 m, 30-49 m and 50 m≥) using multifilament gilnets with mesh sizes of 32, 34, 36 and 38 mm, from March 2013 to February 2014. In the fishing trials, a total of 2506 individuals (133.729 g) belongs to eight fish species were obtained which were whiting (Merlangius merlangus), red mullet (Mullus barbatus), pontic shad (Alosa immaculata), mediterranean horse mackerel (Trachurus mediterraneus), black scorpionfish (Scorpoena porcus), stargazer (Urascopus scaber), seahorse (Hippocampus sp.) and black-striped pipefish (Syngnathus abaster). Allmost catches for whiting, red mullet, pontic shad and mediterranean horse mackerel were of economic value, while all catches for the other species were were discarded. In the shallow waters varying between 0-14 m depth, red mullet and mediterranean horse mackerel were mostly caught. However, catches of especially mediterranean horse mackerel were decreased gradually with increasing water depth. The most caught fish species in deeper water strata more than 15 m was whiting. In the evaluation of the effect of the season on the species composition of catch, the whiting was the most caught fish species by the trial gillnets in all seasons. These fish species, except autumn season (in autumn, potic shad and Mediterranean horse mackerel) followed by red mullet in all seasons. On the orher hand, the rate of discard was determined as 10.2% in number and 15.9% in biomass. It has been found that the discard rate decreases gradually due to the increase in water depth. Seasonally, the lowest discard rate was calculated in winter, followed by autumn, spring and summer, respectively.

We report 7 new prey fishes in diet of the Black Sea bottlenose dolphins Tursiops truncatus (Montagu, 1821) and the first records of 9 prey items from their stomach contents: herring (Alosa sp.), sand smelt (Atherina sp.), horse mackerel (Trachurus mediterraneus), picarel (Spicara flexuosa), Mediterranean sand eel (Gymnammodytes cicerellus), Atlantic stargazer (Uranoscopus scaber), garfish (Belone belone), gobies (Gobiidae indet.) and blennies (Blenniidae indet.). Th e Atlantic stargazer was recorded as a prey species for the common bottlenose dolphin for the first time. Th e horse mackerel and the picarel, formerly recorded in the diet of Mediterranean bottlenose dolphins, now were frequently found in the examined Black Sea dolphins. Th e list of prey fishes for Black Sea bottlenose dolphins now includes 23 items, with many small pelagic and demersal fishes, and it is similar to that of Mediterranean dolphins. Whiting (Merlangius merlangus) is still an important prey species, as 50-70 years ago, whereas turbot (Psetta maeotica), not recorded by us, could lose its importance due to population decline. As before, red mullet (Mullus barbatus) is recorded in winter feeding. Feeding on mullets (Mugilidae) is not a universal trait, and it is possibly restricted to local geographical areas.

Length-weight relationships (LWR) were described for fourteen demersal and pelagic fish species; whiting (Merlangius merlangus), red mullet (Mullus barbatus), picarel (Spicara maena), scorpion fish (Scorpaena porcus), anchovy (Engraulis encrasicolus), sprat (Sprattus sprattus), horse mackerel (Trachurus mediterraneus), bluefish (Pomatomus saltatrix), turbot (Scophthalmus maximus), thornback ray (Raja clavata), shore rockling (Gaidropsarus mediterraneus) round goby (Neogobius melanostomus), black goby (Gobius niger) and stargazer (Uranoscopus scaber) caught with bottom trawl (12 mm mesh size) from the Eastern Black Sea. Samples were caught in depths from 10 m up to 60 m between April 2017 and March 2018 at monthly intervals. The minimum and maximum lengths and weights, length-weight relationships, parameters of a and b, ± 95% CI of b, r2, growth type (isometric or allometric) of samples, and statistical analyses of the relationship were determined. Estimates for parameter b of the length–weight relationship ranged between 2.44 and 3.54.

Habitat suitability models of five keynote Bulgarian Black Sea fish species relative to specific abiotic and biotic factors

Plastics have become an inseparable part of modern life as a consequence of their versatility, low cost, durability, and lightweight. In this study, the presence of microplastics (MPs) in the stomachs and digestive tracts of 243 individuals of leaping mullet (Chelon saliens (Risso, 1810)), red mullet (Mullus barbatus barbatus Linnaeus, 1758), surmullet (Mullus surmuletus Linnaeus, 1758), Mediterranean horse mackerel (Trachurus mediterraneus (Steindachner, 1868)), and sand steenbras (Lithognathus mormyrus (Linnaeus, 1758)), collected along the Marmara, Aegean, and Mediterranean coasts of Turkey was examined microscopically and through μ-Raman analysis. A total of 283 MP particles were extracted. Among the examined species, the average MP concentration was 1.1 MP per fish (MPs fish$^{-1}$). The number of MPs detected was 2.5 MPs fish$^{-1}$ for leaping mullet, 1.1 MPs fish$^{-1}$ for red mullet, 0.6 MPs fish$^{-1}$ for sand steenbras, and 0.4 MPs fish$^{-1}$ for Mediterranean horse mackerel and surmullet. The size of the MPs ranged from 0.028 to 4.909 mm. To determine the polymer types of the MPs, a μ-Raman analysis was conducted. The most frequently detected polymers were polypropylene (26%), polyethylene (21.9%), polyethylene terephthalate/polyester (8.2%), and cellulose (7.5%). The results of this study showed that MP pollution represents an emerging threat to the fish of Turkish marine waters.

In the present study, the production amount in the last five years (2015-2019) of Sinop province, which is located in the Black Sea Region and a significant part of fisheries production is carried out, was evaluated. For this purpose; Sinop Provincial Directorate of Agriculture and Forestry and TUIK (Turkish Statistical Institute) data were used. There are 2.326 commercial fishermen and 444 fishing boats in Sinop province. In the sea area of Sinop, 5 enterprises still produce culture fish in cages. The 2 potential marine culture areas identified in Sinop have an annual production capacity of 32.430 tons (31 enterprises). In addition, 5 bivalves (4.940 tons/year) and 1.000.000 number/year capacity juvenile fish production facilities are at the project stage. The total fisheries production of Sinop Province in 2019 was 34.620,9 tons, and 1.505 tons were obtained from aquaculture. In addition to these, 3.924 tons of fish processing facilities per year, and 35 tons of fish meal and oil processing facilities per year are operated. 66% of sea fish caught in Sinop are anchovy (Engraulis encrasicolus ponticus), 16% sprat (Sprattus sprattus phalericus), 13% horse mackerel (Trachurus trachurus), 3% bluefish (Pomatomus saltatrix) and 2% consists of other species. The most preferred marine fish by the consumers are anchovy (Engraulis encrasicolus ponticus), horse mackerel (Trachurus trachurus), whiting (Merlangus merlangus), red mullet (Mullus barbatus), bluefish (Pomatomus saltatrix), turbot (Psetta maxima) and bonito (Sarda sarda) and sea bream (Sparus aurata), sea bass (Dicentrarchus labrax) and rainbow trout (Oncorhyncus mykiss) are the culture fish species offered for sale throughout the year.

The quality of fish products is indispensably linked to the freshness of the raw material modulated by appropriate manipulation and storage conditions, specially the storage temperature after catch. The purpose of the research presented in this thesis, which was largely conducted in the context of a research project funded by Italian Ministry of Agricultural, Food and Forestry Policies (MIPAAF), concerned the evaluation of the freshness of farmed and wild fish species, in relation to different storage conditions, under ice (0°C) or at refrigeration temperature (4°C). Several specimens of different species, bogue (Boops boops), red mullet (Mullus barbatus), sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax), during storage, under the different temperature conditions adopted, have been examined. The assessed control parameters were physical (texture, through the use of a dynamometer; visual quality using a computer vision system (CVS)), chemical (through footprint metabolomics 1H-NMR) and sensory (Quality Index Method (QIM). Microbiological determinations were also carried out on the species of hake (Merluccius merluccius). In general obtained results confirmed that the temperature of manipulation/conservation is a key factor in maintaining fish freshness. NMR spectroscopy showed to be able to quantify and evaluate the kinetics for unselected compounds during fish degradation, even a posteriori. This can be suitable for the development of new parameters related to quality and freshness. The development of physical methods, particularly the image analysis performed by computer vision system (CVS), for the evaluation of fish degradation, is very promising. Among CVS parameters, skin colour, presence and distribution of gill mucus, and eye shape modification evidenced a high sensibility for the estimation of fish quality loss, as a function of the adopted storage conditions. Particularly the eye concavity index detected on fish eye showed a high positive correlation with total QIM score.

The study was conducted along the Fatsa coasts of the South-eastern Black Sea, to investigate the effects of depth and season on catch volume of the bottom gillnet fishery. During the study, fishing was carried out using multifilament gillnets with mesh sizes of 32, 34, 36 and 38 mm in each of the four different depth strata (0-14 m, 15-29 m, 30-49 m and ≥50 m) three times per month between March 2013 and February 2014 (except for July and August), with a total of 30 gillnet hauls performed. The results of the study revealed that in all seasons whiting (Merlangius merlangus) was caught most in the 30 m and deeper water layers. However, whiting catch increased with increasing water depth. Most red mullets (Mullus barbatus) were caught in the 0-14 m depth waters during spring, winter and autumn periods, while its catch was the greatest in the 15-29 m during the summer period. Catch of this species decreased gradually with increasing water depth. Another fish species was pontic shad (Alosa immaculata) which was caught least in the shallow waters. However, during all seasons its catch increased gradually with increasing water depth up to the 30-49 m depth strata. Nevertheless, it was determined that catch volume for this species decreased in the ≥50 m level again. On the other hand, Mediterranean horse mackerel (Trachurus mediterraneus) was mostly caught in the shallow waters (0-14 m and 15-29 m) during all seasons. Especially in the ≥50 m waters, no Mediterranean horse mackerel was sampled during the study. This study presents that amounts of catch for the fish species sampled were affected especially by water depth and seasons.

Concentrations of Mn, Fe, Co, Ni, As, Se, Cd, Ag and Pb in scale, skin, muscle, gills, liver and the gonads of Gilthead seabream (Sparus aurata), European seabass (Dicentrarchus labrax), Black Sea salmon (Salmo trutta labrax), Horse mackerel (Trachurus trachurus), Red mullet (Mullus barbatus) and Whiting (Merlangius merlangius euxinus) from the Black Sea, in Turkey, were investigated. Elemental analyses were performed with inductively coupled plasma-mass spectrometry after sample preparation by microwave digestion. Mean metal concentrations in different tissues were in the following ranges: Mn 0.09–23.1, Fe 0.58–326, Co 0.01–0.22, Ni 0.03–1.34, As 0.13–3.40, Se 0.13–4.42, Ag 0.01–0.18, Cd 0.32–6.25, Pb 0.02–0.38 mg kg−1 wet weight. Metal concentrations in the muscles of the examined species were generally lower than those in scale, skin, gills, liver and the gonads. The described method was validated by analysis of Dogfish Liver-certified reference material, DOLT-4.

Occurrence and characteristics of microplastics in fish of the Han River, South Korea: Factors affecting microplastic abundance in fish

Fish length–weight relationships are essential for estimating biomass and assessing fish population health, typically showing low variation within and between neighbouring stocks. This study investigates the length–weight relationships of Mediterranean horse mackerel (Trachurus mediterraneus) collected from the Sea of Marmara, the Middle Black Sea, and the Eastern Black Sea in Türkiye during 2022. In addition, the study assessed the sex ratio and condition factor of Mediterranean horse mackerel at each station, alongside an examination of length-frequency samples, providing a comprehensive analysis. The one-way ANCOVA analysis showed no significant differences in length–weight regression between the sexes. However, it identified a considerable area effect, with samples from the Sea of Marmara significantly differing from those in the middle Black Sea and Eastern Black Sea. Fish samples from the latter areas displayed moderate length–weight variation, which was close to the significance threshold with a p-value of 0.069. The growth pattern of Mediterranean horse mackerel consistently exhibited negative allometry across all sampled areas for both males and females, except for female Mediterranean horse mackerel from the middle Black Sea, which tended to follow an isometric growth pattern. This study revealed consistent results within neighbouring areas (Middle Black Sea and Eastern Black Sea) and significant variations when comparing the Black Sea and Sea of Marmara Mediterranean horse mackerel, emphasising notable large-scale spatial trends.

Microplastics (MPs) overlap in size with phytoplanktonand canbe ingested by zooplankton, transferring them to higher trophic levels.Copepods are the most abundant metazoans among zooplankton and themain link between primary producers and higher trophic levels. Ingestionof MPs has been investigated in the laboratory, but we still knowlittle about the ingestion of MPs by zooplankton in the natural environment.In this study, we determined the concentration and characteristicsof MPs down to 10 μm in zooplankton samples, sorted calanoidcopepods, and fecal pellets collected in the Kattegat/Skagerrak Sea(Denmark). We found a median concentration of 1.7 × 10–3 MPs ind–1 in the zooplankton samples, 2.9 ×10–3 MPs ind–1 in the sorted-copepods,and 3 × 10–3 MPs per fecal pellet. Most MPsin the zooplankton samples and fecal pellets were fragments smallerthan 100 μm, whereas fibers dominated in the sorted copepods.Based on the collected data, we estimated a MP budget for the surfacelayer (0–18 m), where copepods contained only 3% of the MPsin the water, while 5% of the MPs were packed in fecal pellets. However,the number of MPs exported daily to the pycnocline via fecal pelletswas estimated to be 1.4% of the total MPs in the surface layer. Ourresults indicate that zooplankton are an entry point of small MPsin the food web, but the number of MPs in zooplankton and their fecalpellets was low compared with the number of MPs found in the watercolumn and the occurrence and/or ingestion of MPs reported for nekton.This suggests a low risk of MP transferring to higher trophic levelsthrough zooplankton and a quantitatively low, but ecologically relevant,contribution of fecal pellets to the vertical exportation of MPs inthe ocean.

Microplastics accumulation in gastrointestinal tracts of Mullus barbatus and Merluccius merluccius is associated with increased cytokine production and signaling

The spatial distribution and abundance of microplastics in lake waters and ice during ice-free and ice-covered periods