Identification of the first nursery area of the Galápagos shark (Carcharhinus galapagensis) in the south-east Pacific Ocean.

The identification of important areas (i.e., nursery grounds) is essential for the conservation of most shark species. To assess whether Salas y Gómez Island serves as a nursery area for the Galápagos shark Carcharhinus galapagensis, we conducted a thorough literature review. Multiple lines of evidence show that young-of-the-year (YOY);  inhabiting the remote Salas y Gómez Island (1) present a higher density around Salas y Gómez Island than the surrounding deeper oceanic waters and in the south-eastern Pacific, (2) potentially display high fidelity to this area, and (3) demonstrate the repeated use of this area over multiple years. We also discuss the significance of this isolated island for the Galápagos shark population and propose specific research, management, and conservation actions for its preservation.

Characterization of a Peruvian coastal fishery targeting the Pacific guitarfish Pseudobatos planiceps.

From December 2012 to June 2014, 796 Pacific guitarfish were caught in 183 fishing sets in northern Peru. Catch occurred in 86.3% of sets. Most individuals caught were mature with a bias toward males. The mean total length for females and males was 83.4 cm, and 91.1 cm, respectively. The capture per unit effort (CPUE) was 12.6 ± 3.4 guitarfish (km.12 h)-1. The length-weight relationships showed that this species presents a sexual dimorphism in growth. These results support the importance of Sechura Bay as a key area for this species. This study represents the first species-specific fishery data for the Pacific guitarfish.

Diet, trophic interactions and possible ecological role of commercial sharks and batoids in northern Peruvian waters.

The Peruvian sea represents one of the most productive ocean ecosystems and possesses one of the largest elasmobranch fisheries in the Pacific Ocean. Ecosystem-based management of these fisheries will require information on the trophic ecology of elasmobranchs. This study aimed to understand the diet, trophic interactions and the role of nine commercial elasmobranch species in northern Peru through the analysis of stomach contents. A total of 865 non-empty stomachs were analysed. Off northern Peru, elasmobranchs function as upper-trophic-level species consuming 78 prey items, predominantly teleosts and cephalopods. Two distinctive trophic assemblages were identified: (a) sharks (smooth hammerhead shark Sphyrna zygaena, thresher shark Alopias spp. and blue shark Prionace glauca) that feed mainly on cephalopods in the pelagic ecosystem; and (b) sharks and batoids (Chilean eagle ray Myliobatis chilensis, humpback smooth-hound Mustelus whitneyi, spotted houndshark Triakis maculata, Pacific guitarfish Pseudobatos planiceps, copper shark Carcharhinus brachyurus and school shark Galeorhinus galeus) that feed mainly on teleosts and invertebrates in the benthonic and pelagic coastal ecosystem. This study reveals for the first time the diet of T. maculata and the importance of elasmobranchs as predators of abundant and commercial species (i.e., jumbo squid Dosidicus gigas and Peruvian anchovy Engraulis ringens). The results of this study can assist in the design of an ecosystem-based management for the northern Peruvian sea and the conservation of these highly exploited, threatened or poorly understood group of predators in one of the most productive marine ecosystems.

Niveles de mercurio en el tiburón martillo Sphyrna zygaena (Carcharhiniformes: Sphyrnidae) del norte del Perú / Mercury levels in the Smooth Hammerhead Shark Sphyrna zygaena (Carcharhiniformes: Sphyrnidae) from Northern Peru

El tiburón martillo (Sphyrna zygaena (Linnaeus, 1758)) es una de las especies de elasmobranquios más utilizada para consumo humano en el Perú. Sin embargo, se desconoce los niveles de mercurio que contiene su carne. Este trabajo tuvo como objetivo evaluar los niveles de mercurio hallados en el músculo del tiburón martillo y su posible implicancia en la salud humana. Además, determinar si existe una correlación entre el tamaño del tiburón y los niveles de mercurio. Analizamos 27 muestras de músculo de neonatos y juveniles capturados en el norte del Perú. La concentración de mercurio varió entre 0.13 - 0.85 mg kg-1 peso húmedo. Se encontró una relación negativa y significativa entre el tamaño corporal del tiburón y los niveles de mercurio. Este trabajo representa el primer estudio que evalúa los niveles de mercurio de tiburones en el Perú. Si bien los valores hallados fueron menores a lo recomendado por la Organización Mundial de la Salud (< 1 mg kg-1), se recomienda ampliar este tipo de estudios en individuos adultos de tiburón, así como en otros recursos hidrobiológicos de consumo humano.

The smooth hammerhead shark Sphyrna zygaena (Linnaeus, 1758) is one of the elasmobranch species most used for human consumption in Peru. However, the level of mercury in hammerhead muscle tissue is unknown. This study assessed the level of mercury found in the muscle of hammerhead sharks and its relation with human health. Moreover, we evaluated the relationship between shark body size and mercury levels. We analyzed 27 muscle samples of neonates and juveniles captured in northern Peru. Mercury concentrations varied between 0.13 and 0.86 mg kg-1 wet weight. Moreover, we found a negative and significant relationship between shark body size and mercury levels. This study represents the first evaluation of mercury levels of sharks in Peru. Although the values found do not exceed levels recommended by the World Health Organization (< 1 mg kg-1), we recommend expanding this study to include other size classes of sharks as well as other marine resources used for human consumption.

Shark fisheries in the Southeast Pacific: A 61-year analysis from Peru.

Peruvian waters exhibit high conservation value for sharks. This contrasts with a lag in initiatives for their management and a lack of studies about their biology, ecology and fishery. We investigated the dynamics of Peruvian shark fishery and its legal framework identifying information gaps for recommending actions to improve management. Further, we investigated the importance of the Peruvian shark fishery from a regional perspective. From 1950 to 2010, 372,015 tons of sharks were landed in Peru. From 1950 to 1969, we detected a significant increase in landings; but from 2000 to 2011 there was a significant decrease in landings, estimated at 3.5% per year. Six species represented 94% of landings: blue shark ( Prionace glauca), shortfin mako ( Isurus oxyrinchus), smooth hammerhead ( Sphyrna zygaena), common thresher ( Alopias vulpinus), smooth-hound ( Mustelus whitneyi) and angel shark ( Squatina californica). Of these, the angel shark exhibits a strong and significant decrease in landings: 18.9% per year from 2000 to 2010. Peru reports the highest accumulated historical landings in the Pacific Ocean; but its contribution to annual landings has decreased since 1968. Still, Peru is among the top 12 countries exporting shark fins to the Hong Kong market. Although the government collects total weight by species, the number of specimens landed as well as population parameters (e.g. sex, size and weight) are not reported. Further, for some genera, species-level identification is deficient and so overestimates the biomass landed by species and underestimates the species diversity. Recently, regional efforts to regulate shark fishery have been implemented to support the conservation of sharks but in Peru work remains to be done.