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Purse-seine vessels commonly interact with dolphins. The total number of dolphins accidentally killed in the world's purse-seine fisheries may be substantial, even if interaction rates are generally low. This paper describes an industry Code of Practice (CoP) that was established in Australian purse-seine fishery after an observer program detected high dolphin interaction rates that had not been reported in fishery logbooks. Key features of the CoP are search and delay procedures designed to prevent encirclements and release procedures that minimise mortalities. Extrapolation from observer data (3.9% of net sets observed), suggested that 449 dolphin encirclements and 423 mortalities occurred in 2004-05, the year before the CoP was established. A decade later, observer data suggest that annual encirclements and mortalities had been reduced by 87% and 97%, respectively. Searches were highly effective in detecting the presence of dolphins. Dolphins were not encircled in > 85% of net-sets made after searches determined that dolphins were absent from the fishing area. Opening the front of the net resulted in the successful release of all dolphins in > 86% of encirclement events. Discrepancies between interaction rates estimated from observer data and those recorded in logbooks have decreased over time. This study demonstrated that codes of practice that specify changes in fisher behaviour can be effective in mitigating the interactions of purse-seine fisheries with dolphins. The avoidance and release procedures documented in the CoP for the South Australian sardine fishery are simple and, if adopted in other purse-seine fisheries, could substantially reduce global mortality of dolphins. [ABSTRACT FROM AUTHOR]

We studied the influence of trammel nets on the behaviour and spatial distribution of bottlenose dolphin in the Aeolian Archipelago, Southern Italy. Ninety-six dolphin groups were followed for 98.75 h from 2005 to 2011 during 400 boat surveys. Thirty-three dolphins were photo-identified, and their age and sex were estimated. The encounter rates, residency times, and group sizes were used to model the spatial distribution of dolphins with trammel nets and physiographic variables. Principal Component Analyses were applied to find the habitats selected for different behavioural activities. Encounter rates were significantly higher in early summer when trammel nets were more abundant. Residency times were spatially correlated to the mean number of trammel nets. Group sizes increased with distance from coast but decreased with abundance of trammel nets. Males preferred smaller groups than females, and groups with calves were larger than the other groups. Resting, socializing, and playing groups were larger than groups of dolphins engaged in travelling, foraging, and feeding. Spatial segregation between groups of dolphins with different sizes was observed. Although dolphins benefit from taking fish in trammel nets, this interaction can be dangerous because the fishermen can use harmful methods to deter dolphins from the net. Herein, we proposed that males prefer habitats where they have a higher probability of locating/capturing a desirable prey such as coastal areas with a greater amount of trammel nets; while for other activities, they may move into safer areas. On the contrary, females prefer habitats for reasons not associated with prey such as social behaviours, resting, or calf care/learning; and they may spend more time in the safest areas, at a distance from the coast, simply feeding when the opportunity presents itself. This study showed that group size/composition data are of critical importance for modeling dolphin-habitat relationships with significant consequences in terms of conservation strategies. [ABSTRACT FROM AUTHOR]