Fishers as Potential Dispersal Agents for Corals: Balancing the Impact of Small-Scale Fisheries on a Pillow Coral Bed

Abstract

The Mediterranean Sea is home to the endemic pillow coral, Cladocora caespitosa, which thrives on stony or rocky substrates to form coral beds or banks. A C. caespitosa hotspot habitat was identified in the eastern Thermaikos Gulf, with densely populated, large colonies of over 0.5 m in diameter. Local small-scale fishers intentionally avoid operating in this area in order to prevent damage to their nets. The substrate in the adjacent fishing ground consists of a heterogeneous assemblage of soft substrates, mainly sandy sediments and patches of seagrass meadows, and scattered colonies of C. caespitosa. Nonetheless, the colonies were shown to be fragmented, and most were smaller than in the hotspot area. This indicates that this area is not the native environment of C. caespitosa, but rather transported from the hotspot region. Static nets, primarily trammel nets but also gillnets, were shown to capture C. caespitosa colonies, which are subsequently discarded by fishers and returned to the seafloor. It is thus anticipated that small-scale fishers contribute to the spread of the C. caespitosa population and the transfer from the hotspot area to the entire sandy zone, serving as potential dispersal agents. Indeed, the majority of C. caespitosa in the sandy region had living polyps present on them, and in many instances, the colonies attained the characteristic spherical shape. The role of small-scale fishers as dispersal agents of C. caespitosa colonies closely resembles the fragment-based transplant approach, applicable for the restoration of coral banks.