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Maravelias, C. D., Hillary, R., Haralabous, J., and Tsitsika, E. V. 2010. Stochastic bioeconomic modelling of alternative management measures for anchovy in the Mediterranean Sea. – ICES Journal of Marine Science, 67: 1291–1300.The purse-seine fishery for anchovy in the Aegean Sea consists of two main fleet segments (12–24 and 24–40 m vessels); this paper investigates economically and biologically preferable effort and capacity scenarios for the fishery. Attention is paid to a bioeconomic analysis of fleets composed of segments with varying levels of efficiency (in terms of catch rate) and costs (fixed and variable) and the role this might play in optimal effort allocation at a fleet level. An age-structured stochastic bioeconomic operating model for Aegean anchovy (Engraulis encrasicolus) is constructed. It attempts to account robustly for the multiple uncertainties in the system, including (i) the effort–fishing mortality relationship, (ii) the selectivity, and (iii) the stock–recruit dynamics of the population. A method is proposed for determining the economically optimal level of long-term effort in a fishery such as this, with similar characteristics in terms of stock dynamics, fishery, and markets. Lower values of effort and capacity are predicted to yield greater future profit when viewing the fleet in its entirety, but even lower values may be advisable to maintain the long-term biological integrity of the stock. The results may prove useful in balancing the productivity of the stock with the harvesting capacity of the fleet, while managing to ensure the long-term profitability of the fleet along with the sustainability of the resource. [ABSTRACT FROM PUBLISHER]

Generalised additive models (GAMs) were used to test the hypotheses that red mullet ( Mullus barbatus) and hake ( Merluccius merluccius) abundances are related to the bathymetry, spatial location and the temperature-based variability of the NE Mediterranean. Data were collected during a 2-year period (1996–1997) of quasi-synoptic sampling using demersal trawl surveys in the northern Aegean Sea. The results of this study supported these hypotheses. It was found that geographic position and sea bottom characteristics influence the temporal distribution patterns of red mullet and hake. Data are presented that reveal species-specific aggregation patterns and an important habitat utilisation of the area. The modelled species’ abundances showed a strongly non-linear dependence on the explanatory covariates. This study, although not directly dealing with spawning, also provided evidence that red mullet and hake demonstrate environmental and bathymetric preferences in the months posterior to spawning. Mean red mullet abundance was consistently highest in areas with warmer bottom waters in the east and west than in the centre, these areas having shallower depths (35–60 m) and bottom temperatures around 19°C. The red mullet appeared to avoid the cold bottom waters (<16°C) of the deeper regions. Results indicated that areas with the highest hake abundances were located in waters of ∼160 m having bottom temperature of ∼16°C and avoided the shallower waters (<70 m) regardless of their bottom temperature. The present findings also suggested that colder bottom waters at all depths were associated with lower-than-average hake abundance. Red mullet and hake preferences for areas with specific bathymetric and ocean environmental conditions are believed to be linked to the oceanography of the NE Mediterranean ecosystem. [ABSTRACT FROM AUTHOR]