Longest recorded migration of a silky shark (Carcharhinus falciformis) reveals extensive use of international waters of the Tropical Eastern Pacific.

Despite being a heavily fished species, little is known about the movements of silky sharks (Carcharhinus falciformis). In this study, we report the longest (in duration and distance traveled) and most spatially extensive recorded migration for a silky shark. This shark, tagged with a fin-mount satellite transmitter at the Galapagos Islands, traveled >27,666 km over 546 days, making two westerly migrations into international waters as far as 4755 km from the tagging location. These extensive movements in an area with high international fishing effort highlights the importance of understanding silky shark migrations to inform management practices.

Understanding the sources of marine litter in remote islands: The Galapagos islands as a case study.

Determining the sources of marine litter is necessary to mitigate this increasing global problem. Plastic bottles are useful tracers of marine litter and constitute the main item (24%) stranding on remote beaches in the Galapagos Islands. The aim of this study was to estimate the abundance of plastic bottles in remote beaches and inferred their sources. To do so, we collected plastic bottles at 60 remote Galapagos Island beaches from 2018 to 2022. 76% of beaches were qualified as badly polluted, with >34 bottles·100 m-1. Most identified bottles came from Peru (71%), followed by China (17%) and Ecuador (9%). Although most locally-sold products are made in Ecuador, they contribute little to beach litter loads. Polyethylene terephthalate bottles with lid (necessary for litter dispersal) represented 88% of all bottles, demonstrating that most of the litter reaching the Galapagos comes from distant sources, mainly from South America. However, bottle ages indicate that at least 10% of Peruvian, 26% of Ecuadorian, and all Chinese bottles likely were dumped from ships. Reducing marine litter reaching the Galapagos Islands requires tackling litter leakage from land-based sources in South America and better compliance with regulations banning the dumping of plastics and other persistent wastes from ships.

A first assessment of the distribution and abundance of large pelagic species at Cocos Ridge seamounts (Eastern Tropical Pacific) using drifting pelagic baited remote cameras.

Understanding the link between seamounts and large pelagic species (LPS) may provide important insights for the conservation of these species in open water ecosystems. The seamounts along the Cocos Ridge in the Eastern Tropical Pacific (ETP) ocean are thought to be ecologically important aggregation sites for LPS when moving between Cocos Island (Costa Rica) and Galapagos Islands (Ecuador). However, to date, research efforts to quantify the abundance and distribution patterns of LPS beyond the borders of these two oceanic Marine Protected Areas (MPAs) have been limited. This study used drifting-pelagic baited remote underwater video stations (BRUVS) to investigate the distribution and relative abundance of LPS at Cocos Ridge seamounts. Our drifting-pelagic BRUVS recorded a total of 21 species including elasmobranchs, small and large teleosts, dolphins and one sea turtle; of which four species are currently threatened. Depth of seamount summit was the most significant driver for LPS richness and abundance which were significantly higher at shallow seamounts (< 400 m) compared to deeper ones (> 400m). Distance to nearest MPA was also a significant predictor for LPS abundance, which increased at increasing distances from the nearest MPA. Our results suggest that the Cocos Ridge seamounts, specifically Paramount and West Cocos which had the highest LPS richness and abundance, are important aggregation sites for LPS in the ETP. However, further research is still needed to demonstrate a positive association between LPS and Cocos Ridge seamounts. Our findings showed that drifting pelagic BRUVS are an effective tool to survey LPS in fully pelagic ecosystems of the ETP. This study represents the first step towards the standardization of this technique throughout the region.

Multi-tissue stable isotope analyses reveal temporal changes in the feeding patterns of green turtles in the Galapagos Marine Reserve.

Knowledge of feeding patterns of highly migratory species is critical for understanding their habitat use and informing the management of their populations. The Galapagos Islands are one of the most important nesting and feeding areas for green turtles (Chelonia mydas) across the tropical eastern Pacific, yet little is known about the feeding patterns of this species. The isotopic composition of different tissues has been used to gain insight into the trophic dynamics of mobile aquatic consumers whose trophic behavior is difficult to directly measure. To elucidate the temporal feeding patterns and isotopic niche sizes of Galapagos green turtles, stable isotope analyses were performed on multiple tissues (skin and carapace) collected at the two most important nesting areas in the archipelago: Bachas and Quinta Playa. The δ13 C and δ15 N signatures on the skin and carapace samples from 56 adult females revealed significant differences between tissues (p = .001 and p = .021, respectively) and nesting areas (p = .011 and p = .003, respectively). These differences suggest a shift from oceanic feeding grounds to neritic habitats before nesting. The carapace isotope values indicated an offshore feeding strategy and a greater isotopic niche (SEAc = 1.91‰2 ), whereas the skin isotope values represented an inshore feeding strategy with a narrower niche (SEAc = 1.37‰2 ), likely related to the consumption of specific coastal prey. Our results suggest that Galapagos green turtles feed across different habitats, and this information can be applied to improve the management of this endangered species.