The identification of nursery grounds and other essential fish habitats of exploited stocks is a key requirement for the development of spatial conservation planning aimed at reducing the adverse impact of fishing on the exploited populations and ecosystems. The reduction in juvenile mortality is particularly relevant in the Mediterranean and is considered as one of the main prerequisites for the future sustainability of trawl fisheries. The distribution of nursery areas of 11 important commercial species of demersal fish and shellfish was analysed in the European Union Mediterranean waters using time series of bottom trawl survey data with the aim of identifying the most persistent recruitment areas. A high interspecific spatial overlap between nursery areas was mainly found along the shelf break of many different sectors of the Northern Mediterranean indicating a high potential for the implementation of conservation measures. Overlap of the nursery grounds with existing spatial fisheries management measures and trawl fisheries restricted areas was also investigated. Spatial analyses revealed considerable variation depending on species and associated habitat/depth preferences with increased protection seen in coastal nurseries and minimal protection seen for deeper nurseries (e.g. Parapenaeus longirostris 6%). This is partly attributed to existing environmental policy instruments (e.g. Habitats Directive and Mediterranean Regulation EC 1967/2006) aiming at minimising impacts on coastal priority habitats such as seagrass, coralligenous and maerl beds. The new knowledge on the distribution and persistence of demersal nurseries provided in this study can support the application of spatial conservation measures, such as the designation of no-take Marine Protected Areas in EU Mediterranean waters and their inclusion in a conservation network. The establishment of no-take zones will be consistent with the objectives of the Common Fisheries Policy applying the ecosystem approach to fisheries management and with the requirements of the Marine Strategy Framework Directive to maintain or achieve seafloor integrity and good environmental status.

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Under the general framework of existing recruitment hypotheses, knowledge on the drivers and mechanisms involved in the determination of the year class strength of small pelagic fish (SPF) is briefly reviewed with focus on selected aspects of the adult and larval stages, related to breeding patterns, egg production, spawning habitats, reproductive potential and early life survival. An analysis of stock−recruitment time series data is carried out, showing that the maximum recruitment capacity of clupeoid stocks increases with the strength of temporal autocorrelation in recruitment (R) and decreases as the coefficient of variation of R becomes larger. Reproductive strategy in combination with the thermal and trophic conditions of the ecosystem and the life cycle pattern of the stock can influence the relative importance of high and low frequency variability in recruitment that combine to generate the population fluctuations of SPF. Selective fishing can reduce the reproductive potential and alter the spawning phenology of the stocks. To understand the ways by which the distribution, abundance and survival of larval stages are influenced by trophodynamic and physical factors, it is important to recognize all those milestones in fish ontogeny associated with significant changes in capabilities and behavior (e.g. onset of schooling). Temperature affects many parameters related to egg production and early life survival, but the relative importance of such temperature effects is expected to differ substantially in contrasting SPF habitats.

The diel variation in feeding intensity and daily ration of the sardine Sardina pilchardus (Walbaum, 1792) was investigated based on 50 pelagic trawl hauls carried out during the period of thermal stratification (July 2007 and July 2008) and mixing (December 2007 and February 2009) in a coastal area of the North Aegean Sea (eastern Mediterranean). Concurrently collected hydrographic (temperature and salinity), plankton (chlorophyll a, microzooplankton and mesozooplankton) and fish parameters (somatic condition, sexual maturity and catch per unit effort of sardine, CPUE) were used to explain seasonal and inter-annual variability in feeding periodicity and daily ration. A piecewise regression fitted to the weight-length data indicated a significant inflexion point at a length of ~100 mm that was used to split the fish sample into adults and juveniles. The stomach fullness index (stomach content mass/fish mass) was strongly dependent on size, and a generalized linear model was used instead to standardize stomach content mass. During summer, sardine fed consistently during daytime with a prominent peak at around sunset. In winter, high feeding rates were recorded in the early night (first 6 h after sunset) but not in the second half of the night. Field estimates of gastric evacuation rate (R) ranged from 0.101 to 0.225 h −1 and were strongly related to temperature (T ) (R = 0.075e 0.038T, r 2 = 0.785). Daily rations were estimated by applying the Elliott-Persson and the Eggers models and varied from 2.02 to 3.67% total weight (TW) in adults and 4.18 to 5.36% TW in juveniles. A significant positive relationship emerged when daily ration was regressed against the ratio of mesozooplankton biomass to sardine CPUE, implying a density-dependent rate of food consumption. KEY WORDS: Daily ration · Feeding periodicity · Sardine · Sardina pilchardus · Mediterranean Sea · Aegean Sea Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 437: [215][216][217][218][219][220][221][222][223][224][225][226][227][228] 2011 lowing a power function and is usually expressed as a proportion of body weight consumed within a diel cycle (daily ration: grams of food consumed per gram of fish weight per day) (Jobling 1998). The response of consumption to water temperature is domeshaped; feeding rates increase as temperature rises, reach a maximum at some intermediate temperature and further temperature increase leads to a drastic reduction in feeding rates (Jobling 1998). Recent attempts to couple small pelagic fish bioenergetics models with lower trophic level models (LTLs) have generally considered this size and temperature dependency of plankton consumption (e.g. Politikos et al. 2011). However, other factors may additionally affect food consumption (e.g. photoperiod, reproductive activity, previous days' consumption), but have been poorly investigated in fish (Jobling 1998 and references therein).Sardine stocks (Sardina pilchardus and Sardinops sagax) are generally found in productive...

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