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Serranus hepatus is a bycatch species in the Mediterranean trawl fishery for which knowledge on biological features such as otolith morphology is generally poor in the Mediterranean Sea. In the present study, the weight–length relationship, age, growth and ten otolith morphometric variables of this species were investigated in two distant areas, the Eastern Ionian and southwestern Aegean Seas. Isometric growth in weight was defined in both areas. Growth parameters also did not differ between the two study areas. Six of the otolith variables (radius, otolith length, otolith width, otolith area, perimeter and ellipticity) showed a significant relationship with size without significant differences between the two areas. Significant differences between the two areas were only defined for five of the morphometric variables (otolith length, width and area being the most important). Further studies to discriminate between potential stocks of S. hepatus seem to be necessary, information that is needed for stock identification, stock assessment and fisheries management. [ABSTRACT FROM AUTHOR]

The potential use of plant protein (PP) blends (soybean, wheat, rapeseed, corn gluten and wheat gluten) in the diet of juvenile meagre (Argyrosomus regius) was investigated at increasing levels to replace fishmeal (FM) (33% and 56%) in six isonitrogenous (480 g/kg) and isoenergetic (22 MJ/kg) diets, which were supplemented with crystalline lysine. Meagre juveniles (36 ± 0.6 g initial weight) were reared in triplicate for 60 days at 19.4 ± 2.4°C to evaluate their growth performance, feed utilization parameters, body proximate composition and the prevalence of systemic noninfectious granulomatosis. Results indicated that there was no significant difference (GLM ANOVA, p > 0.05) in growth performance and feed utilization parameters in meagre fed the diet containing 300 g/kg FM (33% FM replacement) compared to the control group (450 g/kg FM inclusion), although a trend showing inferior body gain and feed conversion ratio was observed. However, higher levels of FM replacement (56%) by PP blends (200 g/kg FM inclusion) significantly impaired growth performance, feed conversion and protein efficiency rates (p < 0.05), which may be linked to a decrease in feed intake and/or reduced levels of bioactive compounds or other micronutrients present in FM. On the other hand, increasing dietary lysine levels from 25 to 29 g/kg in the diets containing the same PP content and 200 g/kg inclusion of FM significantly improved growth performance in juvenile meagre. The replacement of FM did not affect lipidosomatic and hepatosomatic indexes in any of the experimental groups evaluated (p > 0.05). The aetiology of granulomatosis found in different tissues was not due to the presence of bacteria, as no bacterial structures were detected in histological slides when samples were stained with the Gram, Ziehl‐Neelsen and Fite‐Faraco staining. The presence of chronic systemic noninfectious granulomatosis was observed in meagre from all the experimental groups regardless the level of FM replacement by PP blends, indicating that the onset and progression of granulomatosis occurred insidiously at earlier life stages of meagre and persisted at variable levels thereafter. The liver and kidney were found to be the most severely affected tissues. [ABSTRACT FROM AUTHOR]

Data from the MEDITS bottom trawl surveys in the Eastern Ionian Sea, covering a depth range of 28 to 845 m were analysed for the period 1998–2008. For each trawling location, environmental and geographical parameters were recorded, while biomass, abundance, biodiversity and size-based metrics were estimated for the total megafaunal community, as well as for four taxonomic sub-communities (Osteichthyes, Chondrichthyes, Crustacea and Cephalopoda) which were expected to respond differently to environmental changes and fishing. In addition, biomass and abundance of ten species selected based on commercial interest, depth range and life history traits were explored, with particular emphasis on deep-sea species. Fishing effort data collected during the study period were analysed and showed a decreasing trend, mainly due to a decrease in the activity of static nets. The relation between the estimated parameters and environmental and spatial factors, as well as temporal (interannual) effects and the effect of fishing effort were explored using generalized additive models (GAMs). Results of GAMs showed that depth and location explained much of the variation in community metrics, probably reflecting mesoscale spatial features and species/communities requirements. Even though the different communities and species exhibited variant patterns in bathymetric and spatial distribution, some common aggregation patterns in productive areas were identified. Despite the relatively short time series, GAMs were effective in detecting increasing trends for several metrics; taking into account spatial factors further contributed to attributing the remaining deviance to temporal effects. These trends were partly explained by the observed decline of fishing effort, which is further supported by the fact that negative relations between several metrics and fishing effort were identified, for some of the selected communities and populations. Abundance, species richness and maximum length proved the most informative metrics concerning the effect of fishing. The current decline in fishing effort in the area seems to be a move in the right direction and should be complemented by additional measures aiming to prevent allocation of effort towards the deep sea. [ABSTRACT FROM AUTHOR]

The National Marine Park of Zakynthos (NMPZ) outlines its contribution to the conservation of the nesting activity of the loggerhead Sea turtles (Caretta caretta) in the Mediterranean. These species lay their eggs on the six beaches of Laganas Bay in a proportion that reaches the 26% of the total documented effort in Mediterranean. At the same time, the development of tourism industry in Laganas Bay may undermine the preservation of the natural environment, resulting to the emergence of many conflicts that are of particular importance. This paper used the Categorical Principal Component Analysis (CATPCA) to investigate the statistical relationships between the spatial and anthropogenic descriptors of the area. The main outcomes of the study indicate that there is a great variance between area's descriptors separating spatial from anthropogenic, and also the grouping of the nine selected areas of the study confirm the zoning system as it is presented in the management plan of the Park. The latter also suggests there is a high compliance of the tourism development to the existing measures for the protection of this conservation priority site. [ABSTRACT FROM AUTHOR]

Despite the efforts made during the last decade, the systematics of the sympatric species Alloteuthis media and Alloteuthis subulata still remains confused and the distribution of the two species in the Mediterranean Sea doubtful. The nine male specimens identified as Alloteuthis subulata in July-August 2008, represent the first finding of this species among samples of the "International Bottom Trawl Survey in the Mediterranean" (MEDITS), which is repeatedly carried out in the Eastern Ionian Sea since 1994. Morphometric data and tissue samples for molecular analysis were collected from these specimens, as well as from male and female specimens assigned to A. media from the same and near-by sampling stations. As the longer tale is the most evident characteristic to distinguish at least adult male specimens of the two species, the length of the anterior part of the mantle (from fin's edge to mantle opening) was used as the reference length upon which indices of different body dimensions were calculated. Genetic analyses using mitochondrial DNA cytochrome oxidase I (COI) gene sequences confirmed species allocation for all individuals assigned to A. subulata, whereas for A. media samples one female and an unsexed juvenile seemed to carry the A. subulata COI haplotype. Discriminant function analysis (DFA) of morphometric data suggested that length of arms, tentacles and tentacular clubs, all relatively smaller in A. subulata, constitute important variables allowing the distinction of the two species. [ABSTRACT FROM AUTHOR]

Diatoms exist in almost every aquatic regime; they are responsible for ∼20% of global carbon fixation and ∼25% of global primary production, and are regarded as a key food for copepods, which are subsequently consumed by larger predators such as fish and marine mammals. A decreasing abundance and a vulnerability to climatic change in the North Atlantic Ocean have been reported in the literature. In the present work, a data matrix composed of concurrent satellite remote sensing and Continuous Plankton Recorder (CPR) in situ measurements was collated for the same spatial and temporal coverage in the Northeast Atlantic. Artificial neural networks (ANNs) were applied to recognize and learn the complex non-monotonic and non-linear relationships between diatom abundance and spatiotemporal environmental factors. Because of their ability to mimic non-linear systems, ANNs proved far more effective in modelling the diatom distribution in the marine ecosystem. The results of this study reveal that diatoms have a regular seasonal cycle, with their abundance most strongly influenced by sea surface temperature (SST) and light intensity. The models indicate that extreme positive SSTs decrease diatom abundances regardless of other climatic conditions. These results provide information on the ecology of diatoms that may advance our understanding of the potential response of diatoms to climatic change. [ABSTRACT FROM AUTHOR]

The existence of excessive fishing capacity is globally recognized by resource managers as a major problem for fisheries, and it is responsible for the degradation of fishery resources and for significant economic waste. Estimates of fishing capacity and capacity utilization may provide helpful tools in designing an effective capacity management plan for Mediterranean fisheries. In this study, the fishing capacity and capacity utilization of eastern Mediterranean purse seiners were assessed using data envelopment analysis (DEA). Estimates were made for individual vessels based on the level of inputs used and outputs produced, relative to other vessels operating under similar conditions. Results indicated similar excess capacity for target species, which is in accordance with how the fishery operated. The 24–40-m fleet segment was found to be more efficient than the 12–24-m fleet segment in terms of landing weights. It was evidenced that purse seiners could have increased their catch during 2000–2005 by approximately 23% by increasing the variable inputs, for example days fished. Conversely, a fleet of smaller size could have achieved the reported catch. Under the condition that the remaining vessels will be fully utilized, a proportional decrease in the fleet size might seem a rational management measure towards reducing overexploitation and attaining sustainable fisheries in the eastern Mediterranean Sea. [ABSTRACT FROM AUTHOR]

The condition factor (K), the hepatosomatic index (HSI), the muscle total lipid content (TLC), the gonadosomatic index (GSI) and the stomach somatic index (SSI) of the four-spotted megrim Lepidorhombus boscii in the Aegean Sea were investigated as a function of season, gender and length to study relations of condition with feeding and maturity of specimens. The application of GLM analysis of covariance provided significant models for GSI, K, and TLC over most seasons and revealed the significant effect of gender on GSI, and of length on K and TLC, as well as the existence of significant interactions between the two factors. On the other hand, GLMs for HSI and SSI were either non-significant or very poor in explaining the variability of the two indices. Pearson's correlation coefficient showed a strong positive association between K and TLC, and both variables were negatively correlated to GSI in both sexes during most seasons. Our findings suggested that decreased condition was shown mainly by small specimens, and also by adult females, particularly during the spawning season, demonstrating, respectively, the increased energetic demands for growth in juveniles and for oogenesis in mature females that might have become more prominent due to the oligotrophic character of the study area. [ABSTRACT FROM AUTHOR]