The ecological management effectiveness (EME) of Marine Protected Areas (MPAs) is the degree to which MPAs reach their ecological goals. The significant variability of EME among MPAs has been partly explained by MPA design, management and implementation features (e.g. surface area, enforcement, age of protection). We investigated EME variability by employing, for the first time, Organization Science. Eight Mediterranean MPAs were taken into account as case studies to explore the relationships between EME and MPA features, such as: 1) organizational size (i.e. the ratio between the number of full-time employees and the total MPA surface area), 2) management performance (i.e. the level of effort exerted to enhance and sustain the MPA management, including enforcement), 3) total surface area, and 4) MPA age. The log-response ratios of fish biomass and density in protected vs unprotected (control) areas were used as a proxy of EME. Management performance, organizational size and, to a lesser extent, MPA age were positively correlated with the log-response ratio of fish biomass, whereas total surface area did not display a significant role. None of the four features considered was significantly correlated with the log-response ratio of fish density. Based on our findings, we argue that the employment of Organization Science in the management effectiveness assessment can assist MPA managers to reach MPAs goals more effectively, with a more efficient use of available resources.

1. Some of the factors that influence fish growth are intrinsic (e.g. genetic and physiological), while others are environmentally driven (e.g. temperature, food availability). Growth, therefore, has biological but also ecological implications, as it is influenced by the environment in terms of energy flow.2. In this study, the growth patterns of the striped red mullet, Mullus surmuletus, inside the buffer zone of the Marine Protected Area (MPA) of Torre Guaceto and in two locations (Monopoli and Molfetta) outside the MPA were investigated in the south Adriatic Sea (central Mediterranean).3. The growth parameters for the female population fraction were estimated using the otolith back-calculation technique: predicted asymptotic length (infinity) (TL ∞ ) = 313.781 mm, growth coefficient (K) = 0.236 year À1 and prenatal length (t 0 ) = À1.255 year for Molfetta; TL ∞ = 342.988 mm, K = 0.173 year À1 and t 0 = À1.828 year for Monopoli; TL ∞ = 404.394 mm, K = 0.199 year À1 and t 0 = À1.037 year for Torre Guaceto MPA. The results showed a significantly higher growth rate of female specimens of M. surmuletus, particularly 2 years and older, obtained from inside the MPA compared to those taken at the two outside locations.4. These findings suggest that fishing restrictions in the buffer zone of the MPA (where fish are more abundant and bigger) could be a more powerful driver for boosting individual fish growth than the mere 'density effect', which would have suggested lower growth rates associated with higher population densities.

No abstract