Randall Arauz

Marine Watch International · Costa Rica

Debido a que muchas especies de tiburones cuentan con poblaciones compartidas entre varios países del POT, resulta indispensable contar con programas estandarizados que permitan la comparación de datos en la región y ayuden a establecer políticas de manejo y conservación regionales adecuadas. En este sentido, los programas de marcaje y monitoreo de...

Global biodiversity targets require nations to designate 30 % of their marine waters as protected areas by 2030. Sharks, rays, and chimaeras (hereafter 'sharks') are key components of aquatic ecosystems; however, over a third are globally threatened with extinction. Across the Central and South American Pacific Ocean region, we (i) assessed trends...

Marine turtles are a group of imperiled marine megafauna particularly vulnerable to anthropogenic stressors. Most long‐term studies of marine turtles are based on nesting surveys which focus on numbers of eggs, hatchlings, and nesting females. However, we know less about long‐term abundance trends of immature and adult turtles in the marine environ...

Long-distance movements associated with environmental and ecological drivers are common in a wide array of mobile marine species. Understanding such movements and associated drivers is particularly important for management and conservation of threatened species, which may be exposed to anthropogenic threats throughout their range. Pacific nurse sha...

Overfishing, fueled by the demand for pelagic fish to supply domestic and international markets, is the main threat to marine biodiversity in the Eastern Tropical Pacific. Fishery-induced mortality has been pointed out as the main cause for the decline of populations of sea turtles and sharks in the region, especially during pelagic longline operat...

#SharksRWildlife

The Eastern Tropical Pacific (ETP) is one of the last regions where large aggregations of the critically endangered scalloped hammerhead shark (Sphyrna lewini) can still be observed. In this regard, we comparatively assessed the seasonality in S. lewini’s relative abundance within three marine protected areas (MPAs) of the ETP and explored its rela...

This document summarizes the current conservation status of the scalloped hammerhead shark (Sphyrna lewini) in the Eastern Tropical Pacific (ETP), including knowledge gaps and conservation priorities. We used a semi-systematic literature review to compile and classify a total of 166 documents (i.e., scientific articles and grey literature) regardin...

In Corozalito beach, Costa Rica, Olive Ridley turtles (Lepidochelys olivacea) nest both solitarily and in arribadas. The predation of solitary nests was monitored from 2008 to 2021, recording date, time, sector of the beach, zone, status of nest (predated or partially predated) and predator when possible. We recorded 4450 predated nests in total (N...

Bull shark (Carcharhinus leucas) is a near‐threatened elasmobranch species capable of moving between the fresh and salty waters of tropical and subtropical coastal areas, for which we still lack important ecological information. During their first years of life, bull sharks use estuarine systems as nursery areas, making them highly susceptible to e...

Defining demographically independent units and understanding patterns of gene flow between them is essential for managing and conserving exploited populations. The critically endangered scalloped hammerhead shark, Sphyrna lewini, is a coastal semi-oceanic species found worldwide in tropical and subtropical waters. Pregnant females give birth in sha...

Variability and climate change due to anthropic influence have brought about alterations to marine ecosystems, that, in turn, have affected the physiology and metabolism of ectotherm species, such as the common hammerhead shark (Sphyrna lewini). However, the impact that climate variability may have on this species’ distribution, particularly in the...

The species and sizes of sea turtles present in the Bahía Málaga Conservation Mosaic, Valle del Cauca, were characterized between 2016-2020 through aquatic monitoring and voluntary delivery by native fishermen. The registry of individuals was determined by aquatic monitoring, which was divided into three phases: exploratory sampling, continuous sam...

Almost 25% of skates and rays' information worldwide is insufficient to assess their extinction risk. We reported the first seven confirmed records of the rough eagle ray (Aetomylaeus asperrimus) along the north Pacific coast of Costa Rica. These findings suggest that encounters with this species are rare, possibly associated with oceanographic pat...

Sea turtles in Malaga Bay, Colombian Pacific.

Costa Rica hosts two renowned olive ridley (Lepidochelys olivacea) arribada beaches: Nancite and Ostional. In addition, the country hosts a third nascent arribada beach in Corozalito. We documented the frequency of arribada events in Corozalito (9°50′55.40″ N; 85°22′ 47.67″ W) from 2008 to 2021 and the abundance of egg-laying females during 12 arri...

Many conservation projects relocate sea turtle eggs to hatcheries to protect the sea turtle nests from the anthropogenic and natural threats they face in the early stages of development. The Rescue Center for Endangered Marine Species (CREMA) manages four sea turtle conservation projects on the nesting beaches of the Southern Nicoya Peninsula in Co...

Latin American countries have a high diversity of sharks, rays, and chimaeras, yet many species are at high risk of extinction due to numerous threats. The conservation of chondrichthyans is key to achieving healthy and productive aquatic ecosystems, and countries in Latin America are increasingly recognizing the need for aligning conservation stra...

Almost 25% of skates and rays’ information worldwide is insufficient to assess their extinction risk. We reported the first seven confirmed records of the rough eagle ray (Aetomylaeus asperrimus) along the north Pacific coast of Costa Rica. These findings suggest that encounters with this species are rare, possibly associated with oceanographic pat...

Defining demographically independent units and understanding gene flow between them is essential for managing and conserving exploited populations. The scalloped hammerhead shark, Sphyrna lewini , is a coastal semi-oceanic species found worldwide in tropical and subtropical waters. Pregnant females give birth in shallow coastal estuarine habitats t...

We present a compilation of published telemetric results, complemented by the addition of new results where necessary, to justify the expansion of the marine protected areas in the Eastern Pacific. In addition, we furnish evidence that fishing effort by commercial vessels, carrying position-monitoring, satellite-communicating radio beacons, has dim...

106,107 ✉ replying to A. V. Harry & J. M. Braccini Nature https://doi.org/10.1038/s41586-021-03463-w (2021) Our global analysis 1 estimated the overlap and fishing exposure risk (FEI) using the space use of satellite-tracked sharks and longline fishing effort monitored by the automatic identification system (AIS). In the accompanying Comment, Harry...

This article is a response to Murua et al.'s Matters Arising article in Nature, "Shark mortality cannot be assessed by fishery overlap alone," which arose from arising from N. Queiroz et al. Nature https://doi.org/10.1038/s41586-019-1444-4 (2019).

Trophic position and niche width are fundamental components of a species’ ecology, reflecting resource use, and influencing key demographic parameters such as somatic growth, maturation, and survival. Concepts about a species’ trophic niche space have important implications for local management and habitat protection, and can shed light about resil...

Is ahark finning ocurring in MSC certified fisheries?

This report analyses the effectiveness of the various methods and the reasons for their implementation in different jurisdictions, concluding that a Fins Naturally Attached (FNA) policy, when accompanied by adequate monitoring and surveillance measures to ensure compliance with the regulation, is now well-established as the only effective method to...

Ponencia ante la Comisión de Biodiversidad del Congreso de Ecuador.

Snapper catch increases in small scale spotted rose snapper (Lutjanus guttatus) fisheries of Pacific Costa Rica after shrimp trawling banned nation-wide as of August of 2019.

The mangrove cat-eyed snake Leptodeira rubricata (Cope, 1893) is known to occur from the Central Pacific mangrove forest in Costa Rica to the western extreme of Panamá. We observed and photographed a specimen of Leptodeira rubricata in an estuary at Guanacaste, Costa Rica. The new record represents the northernmost occurrence for this species.

ABSTRACT. Association of sharks with Las Gemelas Seamount and first evidence of connectivity with Cocos Island, Pacific of Costa Rica. Introduction: Seamounts and oceanic islands are known as hotspots of pelagic biodiversity, which highly migratory species use as natural biological corridors. Although marine protected areas have been established in...

Sporadic aggregations of decapod crustaceans can occur for various reasons and in some cases their drivers are poorly understood. Objective: Here, we present our observations of an apparently rare massive aggregation of pelagic swimming crabs, Euphylax dovi. Methods: During a research cruise at Cocos Island (5°32’34” N, 87°05’06” W), we encountered...

Long-distance movements of sharks within and between islands pose substantial challenges for resource managers working with highly migratory species. When no-take zones do not cover the critical areas that sharks use as part of their lifecycle, exposure to fishing activities can be significant. Shark movements between the Marine Protected Areas (MP...

we examined relationships between sand and in-nest temperatures and olive ridley emergence success,hatchling sex ratios and incubation periods in a solitary nesting population on Playa Coyote, Costa Rica. While arribada populations of olive ridleys are relatively better documented, this study provides novel information relevant to many locations wh...

Effective ocean management and the conservation of highly migratory species depend on resolving the overlap between animal movements and distributions, and fishing effort. However, this information is lacking at a global scale. Here we show, using a big-data approach that combines satellite-tracked movements of pelagic sharks and global fishing fle...

La inclusión de una especie amenazada o en peligro de extinción bajo el Apéndice II de la Convención Sobre el Comercio Internacional de Especies Amenazadas de Fauna y Flora Silvestres (CITES) busca regular su comercio internacional cuando el mismo ha sido identificado como causal del estado de conservación actual de la especie y principal amenaza p...

Many species of sharks form aggregations around oceanic islands, yet their levels of residency and their site specificity around these islands may vary. In some cases, the waters around oceanic islands have been designated as marine protected areas, yet the conservation value for threatened shark species will depend greatly on how much time they sp...

An opportunistic sighting of a reef manta ray (Mobula alfredi) along the northeastern corner of Cocos Island, Costa Rica, represents the first sighting of this species nearly 6000 km from the nearest confirmed sighting location in the Marquesas Islands and the first record of this species on either side of the American continent. Cocos Island is si...

Isla del Coco (Costa Rica) forms part of the five oceanic islands of the Eastern Tropical Pacific and is well known for its high biodiversity and great endemism. While several marine biological and oceanographical surveys have been conducted around the island over the past 35 years, an integrated, systematic view of the shallow water system is lack...

Costa Rica led the international effort with Brazil and Honduras, to list hammerheads sharks under Appendix II of CITES in 2013. However, implementation has been since lacking. Illegal hammerhead shark fin exports were exposed in 2014, after which over 900 kilos of hammerhead shark fins were exported in violation of CITES on December 24 of 2014 and...

Leatherback turtles (Dermochelys coriacea) have declined dramatically in the eastern Pacific Ocean (EP) in recent decades. Traditionally, population assessments have relied on the numbers of turtles on the beaches with the highest abundance of turtles (index beaches) and often disregarded the importance of nesting beaches with smaller, but still re...

Small-scale coastal fisheries can cause detrimental impacts to non-target megafauna through bycatch. This can be particularly true when high-use areas for such species overlap with fishing grounds, as is the case with hawksbill turtle (Eretmochelys imbricata) aggregations at lobster gillnet fishing sites in El Salvador and Nicaragua. We quantified...

The Eastern Tropical Pacific is rich with ocean predators such as large schools of scalloped hammerhead sharks. This ocean region, which stretches down the Pacific Coast from the Gulf of California to Ecuador, is known as a treasure trove of wonders by divers, wildlife enthusiasts, and eco-adventurers. It is home to a host of endemic, native and mi...

Con el objetivo de lograr el cumplimiento de los reglamentos nacionales e internacionales impuestas por la CITES, desde Julio del 2014, hemos estado trabajando en la capacitación sobre la identificación morfológica y genética de las especies involucradas en el comercio de aletas. En este contexto, la presente exposición mostrara una descripción de...

Scarce information is available on the foraging grounds of Eastern Pacific sea turtle populations, which hinders the design of efficient national and regional conservation strategies. We surveyed five locations along Costa Rica’s North Pacific between 2010-2013 using 45cm mesh turtle tangle nets, with the aim to explore and document new foraging si...

La dinámica trófica íctica representa la línea base de información para establecer planes de manejo sobre este recurso. El análisis de contenido estomacal de individuos descargados en los puertos, provee de una gran cantidad de información en este apartado. El pargo manchado (Lutjanus guttatus) es la especie más importante para la flota pesquera ar...

Conservation and reproductive activity of Olive Ridley sea turtles (Lepidochelys olivacea) in Punta Banco, a solitary nesting beach in South Pacific Costa Rica: Management recommendations after sixteen years of monitoring. Sea turtle nesting activity was monitored in Punta Banco, South Pacific Costa Rica uninterruptedly for sixteen years, accompani...

Sea turtle nesting activity was monitored in Punta Banco, South Pacific Costa Rica uninterruptedly for sixteen years, accompanied by conservation activities such as nest relocation in hatcheries. Hatching success evaluations were held for “in situ” and relocated nests. We hereby evaluate the reproductive biology of the olive ridley sea turtle (Lepi...

Entre 1999 y 2010 se realizaron observaciones a bordo de embarcaciones palangreras costarricenses. La abundancia relativa del tiburón sedoso (#indiv/1000 anzuelos) aumentó en proporción directa a la distancia de la costa, y disminuyó de 4.7 en 1999 a <1 en 2008. Además, se detectó una disminución estadísticamente significativa en su talla. Se recom...

Marine top predators are common at offshore bathymetric features such as islands, atolls, and seamounts, where most pelagic reef fish reside, while certain sharks perform inter-island movements between these formations. Scalloped hammerhead sharks are known to school in great numbers at small islands and seamounts in the eastern tropical Pacific (E...

The hawksbill turtle (Eretmochelys imbricata) is critically endangered throughout its global range and is particularly threatened in the eastern Pacific, a region where our knowledge of the ecological traits is very limited. Understanding habitat preferences of hawksbills at different life stages is necessary to create effective local and regional...

Commercial fishing is responsible for declines in both the abundance and biomass of many marine species (Ward and Myers 2005). The Marine Stewardship Council's (MSC) Sustainable Seafood Certification Program focuses on fishery modifications to reduce such impacts on marine species and ecosystems. On the Nicoya Peninsula in northwestern Costa Rica,...

Conservation Recommendations. This study demonstrated how a desolate sea turtle beach can be affected by man-made debris, mostly plastics. We found an alarmingly high density of garbage (0.14 pieces per m2), which is similar to densities in heavily populated/tourist areas like Armação dos Búzios, a beach near Rio De Janeiro, Brazil (0.14 pieces per...

Understanding distribution ranges and the daily movement patterns of pelagic fishes are key aspects for the establishment and planning of protected areas for their conservation. In this study the vertical and horizontal movements of scalloped hammerhead sharks, Sphyrna lewini, were recorded in Malpelo and Cocos Island using satellite telemetry. Nin...

The global decline in shark populations over the last few decades has been a key consideration in the development of marine protected areas around oceanic islands. Cocos Island lies in the Pacific Ocean 340 miles from Costa Rica. It is surrounded by a 12 mile area of protected waters where fishing of any kind is not permitted. The Revillagigedo Arc...

En el ámbito nivel mundial, el tiburón martillo (Sphyrna lewini) es una de las especies más afectadas por la sobrepesca y el aleteo. Recientemente se incorporó a la Lista Roja de la UICN como especie en peligro de extinción. El presente estudio pretendió caracterizar la pesca y la distribución de S. lewini en la parte externa del Golfo de Nicoya. P...

a b s t r a c t Mahi-mahi (Coryphaena hippurus) is a resilient pelagic species that could provide long-term highly pro-ductive fisheries. Using FAO data we document enormous increases (746%) in reported global mahi-mahi landings since 1950. Detailed mahi-mahi fisheries records are limited, but an observer program monitor-ing Costa Rica's Pacific ma...

Sixty nine hammerhead sharks, Sphyrna lewini, were tagged at Malpelo Island (Colombia) with ultrasonic transmitters during March 2006, 2007 and 2008, as part of a study to understand their residency at the island and their horizontal and vertical movements. Five sharks visited Cocos Island, 627 km distant from Malpelo. One of the sharks that appear...

En 1998 da inicio el proyecto Playas de Anidación Nicoya Sur, o Plans. Este proyecto coordina acciones con las organizaciones de base, público en general y entidades gubernamentales, para promover la protección, conservación, investigación y manejo de los recursos marino-costeros del cantón Nandayure (Guanacaste). Hasta ahora, en el marco del proye...

Our research aims to identify longline fishing gear modifications that can improve fishing selectivity and reduce incidental capture of non-target species. Catch rates and anatomical hook locations (AHL) were compared when using a 14/0 standard “control” circle hook with a 0° offset and an experimental “appendage” hook in a Costa Rican longline fis...

Sixty nine hammerhead sharks, Sphyrna lewini, were tagged at Malpelo Island (Colombia) with ultrasonic transmitters during March 2006, 2007 and 2008, as part of a study to understand their residency at the island and their horizontal and vertical movements. Five sharks visited Cocos Island, 627 km distant from Malpelo. One of the sharks that appear...

Sharks present strong intraspecific changes in feeding habits, which may vary according to size, geographic location and season. This study analyzed the stomach contents of 52 juvenile scalloped hammerhead sharks (25 females and 27 males) caught by artisanal vessels in the Gulf of Nicoya. Regarding the organisms found in the stomachs, 41.07 % were...

While little is known about hawksbill turtles Eretmochelys imbricata in the eastern Pacific Ocean, available information suggests that the population has declined substantially in recent decades and could be near extirpation in the region. To evaluate the current status of the population more effectively and to determine the feasibility of recovery...

This study compared the catch rates of targeted dolphinfish or mahimahi ( Coryphaena hippurus ), and sea turtles and other fish bycatch in a shallow‐set Costa Rican longline fishery using 14/0 circle hooks with and without a 10° offset. The effect of hook offset on hooking location and injury in captured sea turtles, specifically if the hooking was...