COS 236-5 - Centipede nets: A potential new gear for sampling mangrove-dwelling fishes

Abstract: Mangrove forests provide myriad ecosystem services and are widely believed to provide critical habitat for juvenile fish and shrimp that support coastal economies. Over 20% of global mangrove cover has been lost in the last 50 years, and understanding the potential ecological ramifications of this loss is important. Despite this, relatively little is known about how fish utilize mangrove areas, primarily due to the inherent difficulty of sampling within the complex structure of mangrove prop roots and pneumatophores, especially in turbid areas. Lacking direct sampling methods, many mangrove fish studies rely on the assumption that species captured in nearby channels or beaches—often collected with cast nets, trawls, seines, or gillnets—are the same species that would be found directly within mangrove habitats. This could lead to inaccurate conclusions about the ichthyofaunal diversity of these habitats. “Centipede nets” are passive fish traps comprised of a cylindrical net stretched over a series of rectangular frames (typically 20- to 35-cm wide), with funnel-shaped entrances on alternating sides. They are adaptable to structurally complex environments and are used by commercial fishers in southeast Asia. They have not been used experimentally outside of China, despite showing promise as a potential fisheries research gear within mangrove habitats. We are systematically assessing the efficacy of centipede nets for sampling fishes directly within mangroves in the Eastern Pacific. Following an initial standardized sample of mangroves throughout the Gulf of Nicoya, Costa Rica, abundance and species richness were compared among samples collected using centipede nets, seines, and cast nets. Preliminary results show that of approximately 50 species collected, 29 were found in centipede nets, and 20% were captured exclusively by centipede nets. Based on our findings, this new sampling method should be considered as a standardized gear for use in future mangrove fish studies.