Spatial and seasonal differences in the top predators of Easter Island: Essential data for implementing the new Rapa Nui multiple‐uses marine protected area

Abstract

Reef fishes are an important component of marine biodiversity, and changes in the composition of the assemblage structure may indicate ecological, climatic, or anthropogenic disturbances. To examine spatial differences in the reef fish assemblage structure around Easter Island, eight sites were sampled during autumn and summer 2016–2017 with baited remote underwater video systems. To determine seasonal changes, quarterly (seasonal) sampling was conducted at five of those eight sites. Fifteen pelagic species of fishes were recorded during this study, some of which have not previously been recorded in scuba surveys, including the Galapagos shark (Carcharhinus galapagensis, Snodgrass & Heller, 1905) and tunas (Scrombidae). Significant spatial and seasonal differences were found in the fish assemblage. Fish assemblages from the south coast differed significantly from those along the west and east coasts, mainly due to the occurrence of top predators. Winter differed from other seasons, especially along the south coast where the island is more exposed to large oceanic swells and winds from Antarctica. Owing to the variety and high relative abundance of species recorded during this survey, baited remote underwater video systems seemed to be an effective method for studying top predators at Easter Island. The identification of priority zones for the protection of top predator species represents an important contribution of this study, in order to develop management and conservation strategies to be implemented in the newly created Rapa Nui multiple uses coastal marine protected areas.

Conservation of Rapa Nui waters strongly supported by publications in Aquatic Conservation

“…Even though crucial, the creation process was only the starting point, as the key will be the implementation of this MPA, and this will need a thorough effort by the local community and the Chilean State. The first step of the implementation is the development of the management plan, which is presently been built by the Rapa Nui Sea Council, and this process will also benefit from other papers recently, or in the process of being, published in AQC (Morales et al, 2019, 2020).…”

“…Interestingly, new publications in AQC continue to provide key scientific information for the future implementation of the Rapa Nui MUMPA (Morales et al, 2019, 2020), as their information is used for the Management Planning process presently underway. Morales et al (2020) has been key to demonstrate the need for creating a no‐take zone in the western side of MMHMP, inside the Rapa Nui MUMPA, as the park is insufficient to protect the Galapagos shark home range. Salas y Gómez Island, the core area, is at the edge of the MMHMP, thus sharks are constantly being exposed to fishing when they leave the park during their regular movement patterns.…”

“…Salas y Gómez Island, the core area, is at the edge of the MMHMP, thus sharks are constantly being exposed to fishing when they leave the park during their regular movement patterns. Further, Morales et al (2019) reported the first ever found nursery area for Galapagos shark at Rapa Nui, which should be a priority for full protection during the zoning process of the Rapa Nui MUMPA.…”

“…The management plan of the Rapa Nui MPA is presently being developed by scientists, led by the Sea Council, and will consider zoning of both MMHMP and Rapa Nui MUMPA. Interestingly, new research articles published in AQC, such as those by Morales et al (2019, 2020), are key for this process, as they provide crucial information on top predator distribution and movements that will be useful to define potential highly protected zones in the Rapa Nui MUMPA by the Sea Council, but also to evaluate the effectiveness of the limits of the MMHMP. Local management decisions based on applied science is a crucial need for MPA managers (Lewis et al, 2017), and these articles should also help in the implementation of other MPAs worldwide.…”

First sighting of a tropical benthic reef shark species at Rapa Nui: chance dispersal or a sign of things to come?

“…Due to a combination of the island's remote location, limited habitat diversity, sub‐tropical water temperature and relatively young geological age (Randall & Cea, ), the fish diversity at Rapa Nui is highly impoverished compared with other Pacific islands, with only 178 fish species currently recorded for the nearshore and epipelagic zones (Easton et al, ; Hernández et al ., ; Randall & Cea, ). Of these, only five are elasmobranchs, with only the Galapagos shark Carcharhinus galapagensis (Snodgrass & Heller 1905), listed as a year‐round resident in Rapa Nui waters (Morales et al ., in press ), whilst the remainder occur seasonally. Our report increases both the known distribution of T. obesus in the Pacific Ocean, as well as the number of transient elasmobranchs recorded for this remote region.…”