Climate change 2014 - Synthesis Report

Effects Of Climate Change

Sedative and anesthetic properties of essential oils and their active compounds in fish: A review

The Mediterranean Sea is classified as a “data-poor” region in fisheries due to its low number of assessed stocks given its biodiversity and number of exploited species. In this study, the CMSY method was applied to assess the status and exploitation levels of 54 commercial fish and invertebrate stocks belonging to 34 species fished by Turkish fleets in the Eastern Mediterranean (Levantine) and Black Seas, by using catch data and resilience indices. Most of these marine taxa currently lack formal stock assessments. The CMSY method uses a surplus production model (SPM), based on official catch statistics and an abundance index derived from scientific surveys. The SPM estimates maximum sustainable yield (MSY), fishing mortality (F), biomass (B), fishing mortality to achieve sustainable catches (Fmsy), and the biomass to support sustainable catches (Bmsy). Our results show the estimated biomass values for 94% of the stocks were lower than the required amount to support sustainable fisheries (Bmsy). Of the 54 stocks, 85% of them can be deemed as overfished; two stocks were not subject to overfishing (Sardina pilchardus and Trachurus mediterraneus in the Marmara Sea) while only one stock (Sprattus sprattus in the Black Sea) is healthy and capable of producing MSY. Annual values of the stock status indicators, F/Fmsy and B/Bmsy, had opposing trends in all regions, suggesting higher stock biomasses could only be achieved if fishing mortality is drastically reduced. Recovery times and levels were then explored under four varying F/Fmsy scenarios. Under the best-case scenario (i.e., F = 0.5Fmsy), over 60% of the stocks could be rebuilt by 2032. By contrast, if normal fishing practices continue as usual, all stocks will soon be depleted [if not already] (F = 0.95Fmsy), whose recover may be impossible at later dates. The results of this study are supported by previous regional assessments confirming the overexploitation of Turkish fisheries is driving the near-total collapse of these marine wild fisheries. Hence, the need to urgently rebuild Turkey’s marine fisheries ought to be prioritized to ensure their future viability.

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First Large-Scale Eastern Mediterranean and Black Sea Stock Assessment Reveals a Dramatic Decline

The changes in a marine community in the northern Adriatic Sea were explored over a period of 65 years using landings data from a commercial fishing fleet, and the role of fishing pressure and environmental variations in driving these changes was investigated. A total of 40 taxonomic categories, including one or several species, were analysed, representing 93·7% of the total landings. From 1945 to 2010 a significant decrease in the evenness index was observed, indicating a trend towards landings dominated by fewer taxa. The composition of the landings showed a temporal shift during the 1980s; from 1945 to the 1980s a continuous, clear change in composition took place, probably driven by an increase in fishing pressure as well as riverine nutrient inputs. Since the 1980s, a different trend of changing composition emerged. Among the analysed predictors, fishing capacity, summer seawater temperature, inflow from the Po River (the major river of the northern Adriatic Sea) and nutrients were related to the changes in landings. In relation to life-history traits of the landed species, the community shifted from large, late-maturing species to more fecund, smaller and earlier-maturing species. A high fishing pressure is probably the major cause of these changes, possibly acting synergistically with environmental variations.

Long-term changes in community composition and life-history traits in a highly exploited basin (northern Adriatic Sea): the role of environment and anthropogenic pressures.

Length-weight relationships were estimated for 16 fish species caught from the Trabzon coast (Eastern Black Sea) between January and December 2007. The b values in the LWR, W=aLb varied between 2.736 and 3.433, with a mean of 3.105±0.084.

Length-Weight Relationship for 16 Fish Species From the Eastern Black Sea, Türkiye

The effects of feeding frequency on growth performance, feed efficiency and size variation of juvenile Black Sea turbot, Psetta maxima were investigated. A factorial design of two feeding rates (ad libitum, n=240, weight=23.8 ±0.70 g and total length=11.0 ±0.09 cm; and 1% of bo- dyweight of fish per meal, n=240, weight=38.6 ±0.45 g and total length=13.0 ±0.03 cm) and three feeding frequencies (one meal in 2 days, one meal a day, two meals a day) with two rep- licates of each treatment combination were applied in this experiment. Feeding frequencies did not affect fish survival rates (P>0.05). The final body weight and specific growth rate (SGR) were higher in group one meal a day at both feeding rates. There were no significant differ- ences the final body weight and SGR values among the groups (P>0.05). Similar responses were observed for condition factor, feed conversion ratio (FCR) and body weight increase (BWI), and the best FCR and BWI were obtained in the same group. The coefficient of varia- tions (CV) in fish weight increased between initial and final weightings in all replicate groups. However, the CV of fish weight was not significantly affected by feeding frequency (P>0.05). In conclusion, growth performance, SGR and FCR were better in once-daily feeding, and it ap- pears that under the conditions of this experiment, feeding once a day to satiation was suffi- cient for maximal growth.

THE EFFECT OF FEEDING FREQUENCY AND FEEDING RATE ON GROWTH PERFORMANCE OF JUVENILE BLACK SEA TURBOT (Psetta maxima, Linneaus, 1758)

Members of the Engraulidae (anchovies) fuel large fisheries around the globe, helping to fulfil demands for food. On the other hand, unpredictable catches that are a very common occurrence with respect to this family can have drastic consequences on economies of different countries. Like many other fisheries, the Black Sea anchovy fishery is a very good example of a fishery greatly affected by abrupt peaks and troughs in landings. In this work, the existing knowledge on the species' overwintering behavior and exploitation patterns along the south coast of the Black Sea is re-evaluated with respect to recent observations. The strong seasonality and very short fishing season are noted as the main characteristics regulating development of the fishery over time. Climatic variability may sometimes generate favorable overwintering conditions outside areas where anchovy aggregations are usually expected, resulting in a temporal shift in overwintering grounds. As most fishing activity takes place on these...

On Black Sea Anchovy and Its Fishery

An experiment was conducted to determine the effects of optimal feeding frequency on growth performance, feed efficiency, nutrient utilization and body composition in juvenile flounder. Four feeding frequencies of one (F1), two (F2), three (F3) and four (F4) times a day were evaluated as treatments in triplicate for a period of 60 days. Forty-seven hatchery produced juveniles (2.5 ± 0.7 g) were stocked into 160-L rectangular fiberglass tanks and fed with a commercial diet containing 54 % protein to satiation. At the end of the experiment, the final weight of F1, F2, F3 and F4 were 5.06 ± 0.29, 5.91 ± 0.42, 6.24 ± 0.42 and 6.16 ± 0.46 g, respectively. Growth rates and feed consumption were highest in F3 and lowest in F1. Feed conversion ratios ranged between 0.83 ± 0.04 and 0.90 ± 0.03. There were no significant differences in either moisture or ash content of the fish groups. Protein content decreased with increasing feeding frequency, while lipid content partly increased with increasing feeding frequency. Nitrogen intake and lipid intake were significantly higher in fish fed under F3 and F4 treatment, whereas the nitrogen gain decreased and lipid gain increased with increasing feeding frequency. It is concluded that the flounder juveniles can achieve maximum growth performance and better nutrient utilization when they are fed a given ration two times a day. The findings have practical significance toward establishing an appropriate flounder nursery rearing and will directly benefit the nursery operations.

Effect of feeding frequency on growth, feed efficiency and nutrient utilization of juvenile flounder (Platichthys flesus luscus)

Regime et strategie alimentaire chez la raie pastenague commune Dasyatis pastinaca (Linnaeus, 1758) sur les cotes turques de la Mer Noire. Le regime alimentaire de la raie pastenague commune Dasyatis pastinaca est etudie pour la premiere fois sur des specimens recoltes sur les cotes turques de la Mer Noire entre juin 2007 et mai 2008. Les individus ont ete recoltes au chalut de fond entre 20 et 40 m de profondeur. Globalement, des proies appartenant a 8 taxons differents ont ete identifiees au niveau specifique. L'analyse des contenus stomacaux a mis en evidence que cette espece se nourrit habituellement de crustaces. Upogebia pusilla est la proie principale. D'autres proies telles que l'anchois Engraulis encrasicholus, le mulet rouge Mullus barbatus ponticus et le crabe Liocarcinus depurator sont consommees occasionnellement alors que le chinchard Trachurus mediterraneus, le crabe Carcinus mediterraneus, la crevette Crangon crangon et le bivalve Venus gallina sont consommees en petite quantite. Des tests non parametriques ont ete appliques pour evaluer le role des variations saisonnieres, ontogeniques et du sexe sur le regime alimentaire. Les differences observees ne sont significatives qu'entre les saisons.

İlhan Aydin

Papers

Length-Weight Relationship for 16 Fish Species From the Eastern Black Sea, Türkiye

THE EFFECT OF FEEDING FREQUENCY AND FEEDING RATE ON GROWTH PERFORMANCE OF JUVENILE BLACK SEA TURBOT (Psetta maxima, Linneaus, 1758)

On Black Sea Anchovy and Its Fishery

Effect of feeding frequency on growth, feed efficiency and nutrient utilization of juvenile flounder (Platichthys flesus luscus)

Diet and feeding strategy of the common stingray Dasyatis pastinaca (Linnaeus, 1758) on the Turkish coast of southeastern Black Sea