Prediciendo los efectos del ENSO y el cambio climático en la distribución del tiburón martillo juvenil en el norte de Perú

El tiburón martillo (Sphyrna zygaena) está amenazado de extinción debido a las pesquerías del sudeste del Pacífico. Sin embargo, existen pocos esfuerzos para manejar sus pesquerías sosteniblemente, para lo cual se requiere conocer el uso de su hábitat. Por lo tanto, esta investigación tiene como objetivo predecir la distribución espacial del tiburón martillo en los escenarios actuales de La Niña y El Niño y su distribución en el cambio climático futuro. 2994 ocurrencias de tiburones juveniles (2009 y 2017), y ocho factores ambientales fueron modelados utilizando Maxent. Los resultados indican que los predictores ambientales de distribución más importantes fueron la profundidad, la temperatura de la superficie del mar y la clorofila-a (indicador disponibilidad de presas). La mayor idoneidad del hábitat se predijo en la región central oceánica durante La Niña y en zona costera del norte en El Niño. Estos hábitats presentan condiciones oceanográficas y batimétricas únicas que resultan en zonas de alta productividad marina. En escenarios futuros de cambio climático, se predice que la idoneidad del hábitat será más costera, aumentando su vulnerabilidad a la pesca. Para mejorar la conservación del tiburones martillo y su ecosistema, estas áreas de alta idoneidad deberían ser una prioridad para futuras investigaciones y manejo.The smooth hammerhead shark (Sphyrna zygaena) is one of most captured shark species by southeastern Pacific fisheries. Their distribution and habitat use is poorly understood hindering the identification of critical habitats for their conservation and the possible impacts of environmental change on species distribution. The aim of this research was to predict the spatial distribution of smooth hammerheads based on habitat suitability from the Northern Humboldt Upwelling System (NHUS) off northern Peru. (06ºS-11ºS). To achieve this, three analyses were performed: i) characterize their population structure, ii) identify environmental factors that affect their distribution, and iii) predict their spatially and environmentally suitable habitat under current La Niña and El Niño scenarios and projected to a future scenario of ocean warming between the years 2040- 2050. Between the years 2009 and 2017, 7485 sharks were measured and georeferenced obtained from a small-scale driftnet fishery. Their ecological niche was modelled using the program MaxEnt. The results indicate that neonate and juvenile smooth hammerheads are the dominant life-stage in the northern part of NHUS where this area probably represents a nursery area. The spatial distribution of sharks varies according to their ontogeny, and at seasonal and El Niño Southern Oscillation (ENSO) conditions. Sharks were closer to the coast during warmer (summer and El Niño conditions) periods. Four environmental variables were identified as important predictors of species distribution: depth, sea surface temperature (SST), chlorophyll-a, as a proxy of prey availability-, and, to a lesser degree, salinity. During current conditions, the highest suitable habitat was predicted in the central-offshore and shifted to northern-coastal part of the study area (close to the ecotone zone; 6ºS) in La Niña and El Niño conditions- respectively- as the coastal upwelling area, during El Niño warm conditions, offers the coolest environment and the highest productivity. Unique bathymetric conditions are associated with these areas (i.e. shelf break, marine canyons, narrow continental shelf, and coastal topography) generating oceanographic conditions (i.e. marine fronts, upwelling) which result in zones of exceptional high marine productivity. Under future climate change scenarios, the habitat suitability of smooth hammerheads will shift to a more coastal distribution. To enhance the conservation of smooth hammerheads and their supporting ecosystem, these areas of high suitability should be a priority for fishery management and under future scenarios of climate change, their coastal distribution could increase their catchability. Furthermore, these areas of highest suitability should be considered as candidates for a dynamic pelagic marine protected area

An updated checklist of Chondrichthyes from the southeast Pacific off Peru

7 páginas.-- This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International LicenseThe first updated and comprehensive checklist of Chondrichthyes from the southeast Pacific off Peru, based on the revision of scientific literature, is presented. The group of Chondrichthyes in the Peruvian coast is composed of 115 species that include 66 species of sharks, 43 species of batoids, and six species of chimaeras. We present nine new records and one recent discovery obtained from secondary sources. For some species, we also compiled the extensions in the geographic distributionsPeer reviewe

Ensamble de batoideos costeros en el norte del Perú: Conocimiento preliminar: Assemblage of coastal batoids in northern Peru: Preliminary knowledge

Abstract.- This preliminarily study aims at increasing our understanding of an assemblage of coastal batoids on the northern coast of Peru by determining species composition, body size structure and its behaviour in marine-coastal zone of Los Órganos, Piura Region, Peru. During 20 field trips, between the years 2016, 2017, and 2019, eighty-six individuals were sampled belonging to eight species: Zapteryx xyster (n= 22), Narcine entemedor (n= 11), Urobatis tumbesensis (n= 7), Urotrygon chilensis (n= 40), Pseudobatos planiceps (n= 1), Urobatis halleri (n= 1), Gymnura crebripunctata (n= 2), Aetobatus laticeps (n= 2). In the study area, a predominance of adult females was observed for Z. xyster, N. entemedor and U. chilensis. These preliminary results suggest that during the morning some batoid species (i.e., Z. xyster, N. entemedor, U. chilensis) use the coastal zone to rest since they are found inactive and partially or totally buried in the sand - N. entemedor could be also hunting through ambush. Future studies should determine if this is a gestation area for some of these batoid species

Batoid fishery in Peru (1950-2015): Magnitude, management and data needs: Pesquería de batoideos en Perú (1950-2015): Magnitud, manejo y necesidades de información

Historical landings from the Food and Agriculture Organization (1950–2015) were used to estimate the contribution of the Peruvian batoid fishery to the eastern Pacific Ocean, and species-specific landings from Instituto del Mar del Peru (1997-2015) were used to identify the most-landed species, their landings sites and monthly variation throughout the year, and fishing gear types most used. The regulatory and research landscape were evaluated toward identifying potential gaps that may be hindering conservation and management of batoids in Peru. Results showed that in the eastern Pacific, Peru ranked second, after Chile, for batoid landings from 1950 to 2015. Of the twenty-three species of marine batoids that interact with Peruvian fisheries, the most landed taxonomic groups, from 1997 to 2015, were: Myliobatis spp. (i.e., M. chilensis and M. peruvianus; 45% of batoids landings), Mobula spp. (primarily M. mobular, and secondarily M. thurstoni, M. munkiana, M. tarapacana; 28%), Pseudobatos planiceps (6%), and Hypanus dipterurus (6%). Most of these species are landed in northern Peru, where gillnets are the most-used fishing gear to capture them. Batoid landings occurred year-round; yet, for H. dipterurus and P. planiceps landings were highest during the austral summer. Only three management measures exist for batoids fisheries in Peru for three species (i.e., M. birostris, Pristis pristis, Rhinoptera steindachneri) and two taxa (i.e., Mobula and Myliobatis) which are not fully enforced. Batoid research in Peru is limited, with only 25 publications from 1978 to 2022, in which the most studied species are Mobula birostris, M. chilensis and M. peruvianus. This study establishes an information baseline for batoids in Peru that can help guide their management, research, and conservation. &nbsp

Dieta del tiburón diamante Isurus oxyrinchus en el norte del Perú: Estudio preliminar: Diet of the shortfin mako shark Isurus oxyrinchus off northern Peru: A preliminary study

The shortfin mako shark (Isurus oxyrinchus) is considered one of the most important top predators in pelagic marine food webs. The diet of the shortfin mako shark was studied in northern Peru through the analysis of 25 stomach contents. Cephalopods were the most important prey group, followed by bony fishes and crustaceans. A total of 11 prey species were identified, with the Humboldt squid Dosidicus gigas being the most important prey, followed by the Ancistrocheirus lesueurii squid. The trophic level was 4.3 (tertiary predator) and the trophic niche width was 0.47 (intermediate degree of specialization). This study contributes to the limited knowledge about the ecology of the shortfin mako shark in northern Peru

Depredation by killer whales (Orcinus orca) on a blue shark (Prionace glauca) in Northeastern Atlantic

5 pages, 1 tableKiller whales (Orcinus orca) consume a wide variety of prey, including marine mammals, tele-ost fish, seabirds, sea turtles, and cephalopods (Ford, 2019). Killer whale populations throughout the world tend to exhibit dietary specialization, feeding selectively upon only a very small subset of prey species from the 200 species that they are known to predate (Heimlich-Boran, 1988; Baird etal., 1992; Ford, 2019). These ecological spe-cializations are maintained by their feeding habits and social behavior (e.g., acoustic repertoires), which result in reproductive isolation and, ulti-mately, genetic divergence (Ford & Ellis, 2014). Such ecologically specialized and reproductively isolated populations of killer whales are known as ecotypes. Around the world, 11 ecotypes have been identified: three in the northeastern Pacific, five in the Southern Ocean, and three in the north-eastern Atlantic (de Bruyn etal., 2013; Ford, 2019). These ecotype specializations reflect cul-tural traditions that have evolved over millennia in which feeding behaviors are passed from one gen-eration to the next by social learning (Ford, 2019)GM was supported by PTDC/MAR-BIO/4458/2012, IF/01611/2013, and NORTE-01-0145-FEDER-000031 grantsPeer reviewe

Diet of the rasptail skate, Rostroraja velezi (Rajiformes: Rajidae), off Piura, Peru

Batoids are among the least studied group of vertebrates and one of the most vulnerable to fishing. The rasptail skate, Rostroraja velezi, is a bycatch species in northern Peru for which there are no studies on its diet. This research aims to document the diet of R. velezi on the northern Peruvian coast and to determine if there are sex-based differences in the diet. A total of 74 R. velezi stomachs were collected, 59 of which had stomach contents. The cumulative prey curve showed reliability in the number of samples collected. According to the prey-specific index of relative importance, diet was dominated by Acanthephyra sp. (31%), other unidentified Caridea (15%), and unidentified teleosts (17%). A low significant difference in diet between sexes was found (R = 0.21, P < 0.01). The trophic position of R. velezi was 3.9 ± 0.7. This species displays bentopelagic feeding behavior and it is a secondary predator in northern Peru