<p><strong> </strong>Isla del Coco National Park (ICNP), Costa Rica, is renowned for its large aggregations of pelagic species, especially sharks (Carcharhinidae and Sphyrnidae), billfish (Istiophoridae) and tuna (Scombridae). The high abundance of these sought after species, attracts commercial fishing vessels that enter the protected waters of the Park. Illegal fisheries thus represent one of the biggest threats to the ecological integrity of this World Heritage Site. The ICNP dedicates important resources to protection and control via regular surveillance patrols, along the 12 nautical miles that have Marine Protected Area (MPA) status. During 2012, 2013 and between January and August 2014, 405 surveillance patrols within the MPA found 108 fishing lines, more than 13 000 hooks, seized more than 500 km of fishing line and 257 pelagic individuals. The yellowfin tuna (<em>Thunnus albacares</em>) was the most abundant species, representing more than 72.3 % of the total catch; seized individuals had a mean total length of 153.35±23.19 cm (Min=90 cm; Max=190 cm); which indicates that most individuals were adults. Analysis of monthly CPUE showed that the highest relative abundance of illegally caught <em>T. albacores</em> was between May and August of each year, with a mean relative abundance of 26.13±54.71, 11.63±23.79, 13.71±24.52 tunas per 1 000 hooks in 2012, 2013, 2014, respectively. This species had a high survival rate (nearly 80 % of the individuals found on the lines were still alive), probably due to the short fishing lines used by illegal fishermen, combined with the swift intervention of rangers. The CPUE of <em>T. albacares</em> found in this study is greater than records in Costa Rica’s Exclusive Economic Zone (0.74 and 0.44 per 1 000 hooks respectively). These results highlight the importance of ICNP as an aggregation site for <em>T. albacares</em> and the need for its effective protection. It is important that ranger intervention continue to be as rapid and effective as possible, in order to decrease the impact of illegal fishing on the marine biodiversity of the ICNP. </p><div> </div>

<p>The Scalloped hammerhead shark, <em>Sphyrna lewini</em> is a coastal and pelagic circumglobal species that resides within coastal warm temperate and tropical seas. <em>Sphyrna lewini</em> exhibits strong intraspecific segregation: neonates and young-of-the-year spend the first part of life in coastal inshore waters (nursery grounds), while adults migrate offshore, returning to protected nursery habitats for mating and pupping. On December 3, 2014, at approximately 19:00 hr, four young-of-the-year <em>S. lewini</em> were caught with hand line in Wafer Bay, Isla del Coco, Costa Rica (5°32’42.4” N - 87°03’45.3” W). A total of three males (total length (TL): 73, 73, 76 cm) and one female (TL: 75 cm) were recorded. The presence of these individuals at Isla del Coco suggests that a pregnant female gave birth in or near Wafer Bay, which may be a nursery ground for <em>S. lewini</em>. We recommend further study to evaluate the presence and movements of young-of-the-year and juvenile <em>S. lewini</em> in Wafer Bay to determine if this was an isolated incident or if the bay is a nursery ground for <em>S. lewini</em>.</p><div> </div>

Introducción: El tiburón punta blanca (Triaenodon obesus) es una especie de arrecife de aguas tropicales, no migratoria, que ha demostrado no tener una alta conectividad costera, como la observada para otras especies de tiburón, sin embargo posee la distribución más amplia de todas las demás especies de tiburón de arrecife del Indo-Pacífico. T. obesus, es una de las especies de tiburón más comunes en el Parque Nacional Isla del Coco (PNIC), y no presenta una estacionalidad marcada. En las bahías localizadas en el norte del PNIC, Bahía Chatham y Bahía Wafer, reside una saludable población del tiburón punta blanca de arrecife. A pesar de ser una especie abundante en las bahías Chatham y Wafer del PNIC, la información sobre su residencia resulta escaza. Objetivo: Conocer sobre el uso de hábitat y los movimientos del tiburón punta blanca de arrecife mejorará su manejo en el PNIC y en otros lugares del Pacífico Tropical Oriental. Para esto se realizó un estudio preliminar sobre la residencia en las bahías Chatham y Wafer del PNIC, utilizando telemetría acústica. Métodos: Se realizó una expedición de marcaje de tiburones al Parque Nacional Isla del Coco entre el 25 de noviembre al 5 de diciembre del 2014. Durante esta expedición se realizaron 2 giras nocturnas entre las 18:00 y las 22:00 a Bahía Chatham y Bahía Wafer y se marcaron 8 individuos de T. obesus con telemetría acústica y se instalaron dos receptores, uno en cada bahía. Resultados: Entre noviembre 2014 y diciembre 2015 los tiburones punta blanca marcados fueron detectados por los receptores instalados en las bahías en un total de 278 706 ocasiones. Los tiburones T. obesus marcados permanecieron largos periodos en las bahías Chatham y Wafer, El índice de Residencia (IR) medio de los T. obesus marcados fue de 0.97±0,03, reportando una tendencia en la baja del número total de detecciones durante las horas nocturnas. Los tiburones punta blanca de arrecife mostraron una alta fidelidad al sitio de marcaje, que se ve reflejado en los elevados índices de residencia reportados, particularmente altos en comparación con otras especies de tiburón de arrecife. Las detecciones de los tiburones en las bahías tienden a disminuir a partir de las 18:00 horas, cuando el tiburón punta blanca se vuelve activo para cazar en el arrecife. Conclusiones: En conclusión, los tiburones punta blanca poseen una alta residencia y fidelidad, lo cual confirma su bajo rango de hogar. El Área Marina Protegida de la Isla del Coco probablemente brinda una protección efectiva a la población del tiburón punta blanca de la pesca ilegal.

Shark populations in Chatham and Wafer bays, Isla del Coco National Park, Costa Rica. At least fourteen species of sharks live in the Marine Protected Area of Isla del Coco National Park (ICNP), some are resident species such as the whitetip reef shark (Triaenodon obesus); others are migratory and visit the National Park throughout the year, e.g. the scalloped hammerhead shark (Sphyrna lewini) and the whale shark (Rhincodon typus). Between March 2010 and August 2012 six expeditions out to the ICNP were carried, during this period 25 night trips (from 18:00 to 22:00 hr) for shark tagging were conducted in the Wafer and Chatham bays. During those trips, 185 sharks were analyzed: 81.1 % were whitetip reef sharks (T. obesus), 16.7 % were blacktip sharks (Carcharhinus limbatus), 1.1 % were blacktip reef sharks (Carcharhinus melanopterus) and 1.1% were silvertip sharks (Carcharhinus albimarginatus). The most common species in Bahía Chatham was T. obesus, while the most common one in Bahía Wafer was C. limbatus, which represented 80.9 % and 80.5 % of the total sharks caught, respectively. Regarding T. obesus, a sex ratio of 1.2 males per female was estimated (X 2 =0.09; p=0.17); in turn a sex ratio of 1.01 males per female was observed (X 2 =0.04; p=0.79) for C. limbatus. The average total length for T. obesus and C. limbatus was 103.66±13.91 cm and 76.58±14.56 cm respectively; suggesting that black tip sharks use those bays during immature stages. The results show an interspecific spatial segregation of the most common resident sharks at ICNP, apparently the clear waters and the coral cover of Chatham Bay are preferred by T. obesus; while the turbid waters of the Genio River mouth are preferred by C. limbatus. Rev. Biol. Trop. 64 (Suppl. 1): S177-S186. Epub 2016 February 01.

The blacktip reef shark Carcharhinus melanopterus, is one of the most common Indo-Pacific reef sharks. On April 29, 2012, a juvenile male blacktip reef shark measuring 89 cm total length (TL), was incidentally caught during a research expedition in Chatham Bay, Isla del Coco National Park, Costa Rica, located in the Tropical Eastern Pacific. This is the first record of the species from Isla del Coco National Park, Costa Rica, and from the Tropical Eastern Pacific. Citation: López-Garro, A., I. Zanella, G. Golfín-Duarte & M. Pérez-Montero. 2012. First record of the blacktip reef shark Carcharhinus melanopterus (Carcharhiniformes: Carcharhinidae) from the Eastern Tropical Pacific. Rev. Biol. Trop. 60 (Suppl. 3): 275-278. Epub 2012 Dec 01.