An ecological niche modelling (ENM) approach was used to predict the potential feeding and spawning habitats of small (5-25 kg, only feeding) and large (>25 kg) Atlantic bluefin tuna (ABFT), Thunnus thynnus, in the Mediterranean Sea, the North Atlantic and the Gulf of Mexico. The ENM was built bridging knowledge on ecological traits of ABFT (e.g. temperature tolerance, mobility, feeding and spawning strategy) with patterns of selected environmental variables (chlorophyll-a fronts and concentration, sea surface current and temperature, sea surface height anomaly) that were identified using an extensive set of precisely geo-located presence data. The results highlight a wider temperature tolerance for larger fish allowing them to feed in the northern - high chlorophyll levels - latitudes up to the Norwegian Sea in the eastern Atlantic and to the Gulf of Saint Lawrence in the western basin. Permanent suitable feeding habitat for small ABFT was predicted to be mostly located in temperate latitudes in the North Atlantic and in the Mediterranean Sea, as well as in subtropical waters off north-west Africa, while summer potential habitat in the Gulf of Mexico was found to be unsuitable for both small and large ABFTs. Potential spawning grounds were found to occur in the Gulf of Mexico from March-April in the south-east to April-May in the north, while favourable conditions evolve in the Mediterranean Sea from mid-May in the eastern to mid-July in the western basin. Other secondary potential spawning grounds not supported by observations were predicted in the Azores area and off Morocco to Senegal during July and August when extrapolating the model settings from the Gulf of Mexico into the North Atlantic. The presence of large ABFT off Florida and the Bahamas in spring was not explained by the model as is, however the environmental variables other than the sea surface height anomaly appeared to be favourable for spawning in part of this area. Defining key spatial and temporal habitats should further help in building spatially-explicit stock assessment models, thus improving the spatial management of bluefin tuna fisheries

Ceyhan, T., Akyol, O., Ayaz, A., and Juanes, F. 2007. Age, growth, and reproductive season of bluefish (Pomatomus saltatrix) in the Marmara region, Turkey. – ICES Journal of Marine Science, 64: 531–536. Bluefish (Pomatomus saltatrix) are distributed widely along the Turkish coasts, and are regularly captured, especially in the Sea of Marmara during their spawning migration to the Black Sea from the Mediterranean in spring and during their return migration south in early autumn. Age, growth, and reproductive season are reported. The ages of 1114 bluefish were determined from otoliths. The age groups ranged from 0 to III, and mean fork lengths (and weights) were 14.4 ± 0.12 cm (38.2 ± 1.02 g), 19.5 ± 0.06 cm (93.7 ± 0.86 g), 27.5 ± 0.48 cm (238.5 ± 11.3 g), and 33.3 ± 0.50 cm (431.9 ± 17.08 g) for each age group, respectively. The von Bertalanffy growth parameters were L_∞ = 51 cm, K = 0.228, and t₀ = −1.26 y. The reproductive period, evaluated from gonadosomatic indices, began in early spring and extended until August.

Catch rate, CPUE, biomass ratios and size selectivity from traditional longline and trammel nets of Turkish coastal small-scale fisheries were investigated in order to describe the Smooth-hound shark (Mustelus mustelus) fishery. The SELECT method was used to estimate the selectivity parameters of a variety of models for the trammel nets inner panel of 150 and 170 mm mesh sizes. Catch composition and proportion of the species were significantly different in longline and trammel nets. While mean CPUE of longline was 119.2±14.3 kg/1000 hooks, these values for 150 and 170 mm trammel nets were 5.3±1.2 kg/1000 m of net and 12.7±3.9 kg/1000 m of net, respectively. Biomass ratios of the by catch to Smooth-hound catch were found to be 1:0.32 for 150 mm trammel net, 1:0.65 for longline and 1:0.73 for 170 mm trammel net. The estimated modal lengths and spreads were found to be 91.1 and 16.2 cm for 150 mm and 103.2 and 18.4 cm for 170 mm, respectively. The modal lengths of the species as well as the spread values increased with mesh size.

Bu çalışma Orta Karadeniz’den 11 balık türünün boy-ağırlık ilişkilerini rapor etmektedir. İlişkilerin b değeri Liza aurata için 2.523 (±0.62)’ten Sarda sarda için 3.445 (±0.56)’e değişmektedir. b’nin medyan değeri 2.933’tür. Karadeniz’de balık türlerinin boy-ağırlık ilişkileri üzerine bilgi hala eksik ve tamamlanmamıştır. Sonuç olarak bu makale, özellikle ilk kez verilen S. aurata ve Diplodus annularis 'le birlikte bazı Karadeniz balıklarının, boy-ağırlık ilişkilerine katkıda bulunmaktadır.

A total of 989 red mullets, Mullus barbatus ponticus , from the Black Sea were monthly collected from commercial gill/trammel net and bottom trawl fisheries, especially landed at Sinop Fishing Port, between December 2015 and December 2016. Total lengths and weights of red mullet specimens were ranged from 9.2 cm to 19.2 cm (average: 13.3 ±1.3 cm) and from 8.2 g to 68.6 g (average: 25.7 ±8.0 g), respectively. The samples were grouped densely between 13 and 15 cm. Minimum landing size (MLS) is 13 cm for Mullus barbatus according to Turkish Fisheries Regulation Circular. Thus, 39% of all samples in this study are under legal size. The LWR equation calculated was W = 0.0137 × TL 2.902 ( r 2 = 0.92). Age groups of red mullets in the Black Sea were ranged from I to IV. The mean lengths according to age groups (I, II, III, and IV) were 11.43 ±0.04 cm, 13.22 ±0.04 cm, 15.24 ±0.06 cm, and 18.44 ±0.29 cm, respectively. According to GSI values, reproduction of red mullets is between May and July with the peaks of June–July. T he estimated von Bertalanffy growth parameters with standard errors were L ∞ = 17.64 ±1.43 cm, k = 0.43 ±0.13, and t 0 = –1.33 ±0.37. The m ortality rates (M, F, and Z), and exploitation rate (E) of M. barbatus ponticus were 0.91 year –1 , 0.52 year –1 , 1.43 year –1 , and 0.36, respectively.