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The knowledge of morphological relationships and particularly of those concerning fish body girth (G) with total length (TL) is necessary in gear selectivity and specifically the technical measures to avoid capture of undersized individuals. This study concerns 24 marine species exploited by the small-scale coastal fleet in the Aegean Sea (eastern Mediterranean Sea), for 6 of which, the TL-G relationships are mentioned for the first time in the Mediterranean Sea and the adjacent seas. Samples were collected seasonally, from April 2016 to February 2017. The coefficients of the linear regression of body girth in three body positions, (Geye, posterior to the eye; Ghead at the posterior end of the operculum; Gmax at the maximum body depth), with the total length were estimated for each species and for the groups formatted when Geye, Ghead and Gmax were plotted against total length for all the species combined. Statistically significant differences among the three groups were detected (ANCOVA, P<0.001). Comparison of the total length-body girth relationships for 18 species previously studied in different geographic areas of the Mediterranean and the adjacent seas, showed differences mainly with the results from Portuguese waters for certain species populations. Based on the resulted equations, the maximum girth (G max) corresponding to the Minimum Conservation Reference Size (MCRS) and to the total length at maturity (L m) were calculated for each species. Identified mesh sizes respective to G max values were quite larger than the minimum legal mesh size for gillnets and the inner sheet of trammel nets, indicating that the relevant current fisheries regulations cannot meet the requirements for sustainable exploitation of fish resources., Poznavanje morfoloških odnosa, a posebno onih koji se tiču maksimalnog obujma tijela ribe (G) s ukupnom dužinom (TL) potrebito je za određivanje selektivnosti alata, a posebno za tehničke mjere za izbjegavanje hvatanja nedoraslih jedinki. Ova studija se odnosi na 24 morske vrste koje se iskorištavaju u priobalnoj ribolovnoj floti u Egejskom moru (istočno Sredozemno more), za 6 od kojih se TL-G odnosi prvi put spominju u Sredozemnom moru i susjednim morima. Uzorci su prikupljani sezonski, od travnja 2016. do veljače 2017. Koeficijenti linearne regresije obujma tijela u tri položaja tijela (G eye, posteriorno od oka; G head na stražnjem kraju operkuluma; Gmax na maksimalnoj visini tijela), s ukupnom duljinom procijenjene su za svaku vrstu i za skupine oblikovane kada su Geye, Ghead i Gmax ucrtani u odnosu na ukupnu duljinu za sve vrste zajedno. Utvrđene su statistički značajne razlike između tri skupine (ANCOVA, P<0,001). Usporedba odnosa ukupne duljine i obujma tijela za 18 vrsta koje su prethodno istraživane u različitim geografskim područjima Sredozemlja i susjednih mora, pokazala je razlike uglavnom s rezultatima iz portugalskih voda za određene populacije vrsta. Na temelju dobivenih jednadžbi izračunat je maksimalni obujam (Gmax) koji odgovara minimalnoj referentnoj veličini očuvanja (MCRS) i ukupnoj dužini pri zrelosti (Lm) za svaku vrstu. Identificirane veličine oka koje odgovaraju Gmax vrijednostima bile su dosta veće od minimalne zakonske veličine oka za mreže stajačice i unutarnju ploču troslojnih mreža, što ukazuje da relevantni trenutačni propisi o ribarstvu ne mogu ispuniti zahtjeve za održivo iskorištavanje ribljih resursa.

The state of marine systems subject to natural or anthropogenic impacts can be generally summarized by suites of ecological indicators carefully selected to avoid redundancy. Length-based indicators capture the status of fish community structure, fulfilling the Marine Strategy Framework Directive (MSFD) requirement for Descriptor 3 (status of commercial fish species). Although the MSFD recommends the development of regional indicators, a comparison among alternative length-based indicators is so far missing for the Mediterranean Sea. Using principal component analysis and dynamic factor analysis, we identified the most effective subset of length-based indicators, whether or not based on maximum length. Indicator trends and time series of fishing effort and environmental variables are also compared in order to highlight the individual and combined capability of indicators to track system changes across geographical sub-areas. Two indicators, typical length and mean maximum length, constitute the smallest set of non-redundant indicators, capturing together 87.45% of variability. Only in combination can these indicators disentangle changes in the fish community composition from modifications of size structure. Our study supports the inclusion of typical length among the regional MSFD Descriptor 3 indicators for the Mediterranean Sea. Finally, we show dissimilarity between the western and eastern-central Mediterranean, suggesting that there are sub-regional differences in stressors and community responses., Generalmente, el estado de los sistemas marinos sujetos a impactos naturales o antropogénicos puede ser resumido mediante un conjunto de indicadores ecológicos, cuidadosamente seleccionados para evitar la redundancia. Los indicadores basados en la talla reflejan el estado de la estructura de la comunidad de peces, cumpliendo el requisito de la Directiva Marco de la Estrategia Marina (MSFD) para el Descriptor 3 (estado de las especies de peces comerciales). Si bien MSFD recomienda el desarrollo de indicadores regionales, en el Mar Mediterráneo no se ha hecho hasta ahora una comparación entre los distintos indicadores disponibles basados en la talla. Mediante el análisis de componentes principales y el análisis de factores dinámicos, identificamos el subconjunto más eficaz de indicadores basados en la talla, estén o no basados en la talla máxima. Las tendencias de los indicadores y las series temporales del esfuerzo de pesca y las variables ambientales también son comparadas para resaltar la capacidad individual y combinada de los indicadores para detectar los cambios del sistema a través de las subáreas geográficas. Dos indicadores, Longitud Típica (TyL) y Longitud Máxima Media (MML), constituyen el conjunto más pequeño de indicadores no redundantes, captando juntos el 87.45% de variabilidad. Solo si se combinan, estos indicadores pueden discernir entre los cambios en la composición de la comunidad de peces y las modificaciones de la estructura de tallas. Nuestro estudio respalda la inclusión de TyL entre los indicadores regionales del descriptor 3 de MSFD para el mar Mediterráneo. Finalmente, mostramos diferencias entre el Mediterráneo occidental y el Mediterráneo centraloriental que sugieren diferencias subregionales en cuanto a factores impactantes y las respuestas de la comunidad.

The main characteristics concerning distribution, size structure and total mortality of two of the most important decapod crustaceans of commercial interest in the Mediterranean Sea, Nephrops norvegicus and Parapenaeus longirostris, are studied along the European Mediterranean coasts. The study is based on data collected during a series of six trawl surveys performed in spring from 1994 to 1999 from the Gibraltar Straits to the Aegean Sea. The population size structure identified in the different geographical sectors is analysed taking into account two bathymetric sectors: continental shelf and upper slope. Differences in N. norvegicus population demographic structure among geographical sectors, as well as in total mortality, appear to be highly related to different exploitation levels. Size structure in P. longirostris also shows a great heterogeneity throughout the different geographical sectors. Considering that both species are heavily exploited all along the studied area, the observed differences can be interpreted as different responses to exploitation related to the widely differing life history characteristics of the mentioned species. In fact, N. norvegicus is a long-lived, benthic, burrowing species with low growth and mortality rates, and P. longirostris an epibenthic short-lived species characterised by higher rates of growth and mortality

Daily catches of Loligo vulgaris and the fishing effort of commercial beach-seiners operating along the coasts of the Thracian Sea were recorded between October 1994 and May 1995. Taking into account the spatial distribution of the ports, the squid fishing grounds and the daily activity of the beach-seiners, five coastal zones were determined for the monitoring of fishery data. Multivariate analysis failed to show significant differences between the monthly catch rate (cpue) in the zones. However, Loligo vulgaris cpue was clearly seasonal, with a distinct peak in November and an evident decline from winter to spring. Temperature, rainfall and local wind records were used in making a preliminary investigation into meteorological factors that may affect beach-seine catches of squid. Multiple linear regression analysis revealed that temperature is a highly significant explanatory variable for cpue variation, whereas the intensity of the wind plays an important role, but mostly during winter. Rainfall was significantly related to variation in cpue in one zone. Cpue was generally negatively correlated with air temperature and rainfall. Most significant correlations of cpue with wind were also negative