The methodology allowed us to discriminate seasonal and permanent occupations for Béniguet Island site, enriching archaeological observations. Our results also show that the largest shell middens yield all year round collection, on both islands, confirming the continuous occupation of these territories, despite uneven intensity of collection throughout the year. The most represented seasons are late winter and spring, both on Béniguet and Molène islands, and for LN and EBA suggesting an intensification of collection to compensate resource depletion toward the end of winter. These results complete and enhance the previous seasonality data existing on these sites demonstrating here that not only the number of analyzed shells but also their spatial distribution within the midden can impact the seasonality interpretation. This approach now needs to be completed by the determination of seasonality indicators on the other resources present in the middens, to truly grasp the domestic economies of these past insular populations.