This species is endemic to one single locality on Sardinia with an extent of occurrence (EOO) below 100 km² and an area of occupancy (AOO) of 1 km². The population has been decreasing for about 70% in the last ten years and the number of individuals declined from about 480. Major threats for this species are the urbanization of the coastal areas for tourist and recreation aims, and changes in native species dynamics. It is therefore classed as Critically Endangered.

This species is endemic to Sardinia, Italy, where it is only present in one locality called Casa del Cio, north of San Pietro island (Pignatti et al. 2001).

The EOO is less than 100 km² and the AOO is 1 km² calculated with a 1 x 1 km grid (Fenu et al. 2010).

The population has been decreasing by about 70% in the last ten years. The number of individuals declined from about 480 to about 130 due to decreasing habitat quality (Fenu et al. 2010). All individuals are in one subpopulation. The population is affected by fluctuation in the number of individuals.

It grows in coastal grassland and shrublands very close to the sea. The vegetation belongs to the Chritmo-Limonion and to the Cisto-Ericion (Fenu et al. 2010).

The major threats for this species are the urbanization of the coastal areas for tourist and recreation aims, and changes in native species dynamics. Due to the low number of individuals other threats are the low density, poor reproductive efforts and the restricted ecological range that affect the opportunity of the species to spread (Fenu et al. 2010).

Astragalus maritimus is listed as priority species on Annex II of the Habitats Directive and under Appendix I of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention).

The whole population is included in the Site of Community Importance "Isola di San Pietro” (ITB040027). The species is the subject of an INTERREG IIIB project of the Center for Biodiversity Conservation of the University of Cagliari. Since 2004, the population trend is monitored (Bacchetta et al. 2008).

About 55,000 seeds were stored in the Seed Bank of Sardinia (BG-SAR). Other seeds are stored in Soller (Spain), Catania and at the Millenium Seed Bank, Royal Botanic Gardens, Kew (UK).