Habitat Preferences of Juvenile Abalone (Haliotis mariae Wood, 1828) Along the Dhofar Coast of Oman and Implications for Conservation

Abstract

Surveys were conducted along the eastern Dhofar coast of Oman to investigate densities and habitat preferences of juvenile Haliotis mariae (< 3 cm SL). Average density was 0.62 m-2 (SD 0.56); average urchin density was 3.4 urchins m-2 (SD 3.9). Relationships between juvenile abalone densities and small boulders (<30 cm in diameter (Ø)) tested significant (p = 0.049), as did those between juvenile abalone and urchin densities (p = 0.031). Selectivity (w) and standardized (B) ratios quantifying the relative probability of selection by juvenile abalone for different categories of resource available were calculated. For the studied area B values tested significantly different for (p = 0.004) the different habitats, urchins, boulders <30 cm, 30> <50 cm, and >50 cm Ø, respectively. B values were highest for urchins (6 times that for small boulders), and for boulders <30 cm Ø (double that for boulders 30> <50 cm Ø). B values for boulder habitats decreased as boulder size increased. Urchin utilisation by juvenile abalone as shelter ranged between geographic areas from a minimum of 15.5% to a maximum of 47.6%. The proportion of total habitat that is preferred by more than 97% of juvenile abalone found, including urchins and boulders < 50 cm Ø, comprises 29% of surveyed substratum. While the role urchins play on wild juvenile H. mariae has not proved vital, it is definitely significant. Although juvenile densities are low and are not currently limited by the availability of suitable habitat, it is crucial to identify and conserve those microhabitats that support recruitment of H. mariae. The abundance of these areas should be among the criteria used in selecting protected conservation areas.