scholarly journals VERTICAL AND HORIZONTAL MOVEMENTS OF THE SCALLOPED HAMMERHEAD SHARK (SPHYRNA LEWINI) AROUND MALPELO AND COCOS ISLANDS (TROPICAL EASTERN PACIFIC) USING SATELLITE TELEMETRY

2016 ◽  
Vol 40 ◽  
Author(s):  
Sandra Bessudo ◽  
Germán A. Soler ◽  
Peter A. Klimley ◽  
James Ketchum ◽  
Randall Arauz ◽  
...  
Keyword(s):  
Satellite Telemetry ◽  
Movement Patterns ◽  
Eastern Pacific ◽  
Depth Range ◽  
Tropical Eastern Pacific ◽  
Sphyrna Lewini ◽  
Scalloped Hammerhead ◽  
Distribution Ranges ◽  
Cocos Island ◽  
Hammerhead Sharks

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. Nine sharks were tagged with satellite transmitters during March 2006, 2007 and 2008 at Malpelo Island, and three hammerhead sharks were tagged at Cocos Island in June 2008. The sharks moved between islands in the Tropical Eastern Pacific and made regional movements from Malpelo to the south of Cocos and around the Malpelo ridge. When away from the island, sharks made infrequent nocturnal short dives down to 1000 m where temperatures were as low as 4 °C. For a shark that was tracked for five months, results indicated significant differences between the time spent at different depth ranges, as well as an interaction between depth, water layers, and the time of the day. The shark swam mostly at surface waters (0-10 m) during the cold water season, and spent more time at the deepest depth range (>100 m) during nigh time. Further long-term studies on shark movement patterns are required for a better management of this highly mobile and vulnerable species.

scholarly journals Movements of scalloped hammerhead sharks (Sphyrna lewini) at Cocos Island, Costa Rica and between oceanic islands in the Eastern Tropical Pacific

PLoS ONE ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. e0213741 ◽  
Author(s):  
Elena Nalesso ◽  
Alex Hearn ◽  
Oscar Sosa-Nishizaki ◽  
Todd Steiner ◽  
Alex Antoniou ◽  
...  
Keyword(s):  
Costa Rica ◽  
Oceanic Islands ◽  
Tropical Pacific ◽  
Eastern Tropical Pacific ◽  
Sphyrna Lewini ◽  
Scalloped Hammerhead ◽  
Cocos Island ◽  
Hammerhead Sharks

scholarly journals The Effects of Climatic Variability on the Feeding Ecology of the Scalloped Hammerhead Shark (Sphyrna lewini) in the Tropical Eastern Pacific

2021 ◽  
Vol 8 ◽  
Author(s):  
Camila Arnés-Urgellés ◽  
Pelayo Salinas-de-León ◽  
Etienne Rastoin-Laplane ◽  
Leandro Vaca-Pita ◽  
Jenifer Suárez-Moncada ◽  
...  
Keyword(s):  
Feeding Ecology ◽  
Climatic Variability ◽  
Eastern Pacific ◽  
Isotopic Niche ◽  
Tropical Eastern Pacific ◽  
Climatic Fluctuations ◽  
Sphyrna Lewini ◽  
Hammerhead Shark ◽  
Enso Events ◽  
Scalloped Hammerhead

Climatic variability changes ocean productivity and generates systematic cascading effects in marine food webs. Studying the feeding ecology of top predators, such as sharks, can provide insights into the overall health of marine ecosystems. We conducted a 4-year study to evaluate seasonal and inter-annual trophic variations and their relationship with El Niño Southern Oscillation (ENSO) on the largest aggregation of scalloped hammerhead shark (Sphyrna lewini) in the Tropical Eastern Pacific (TEP). We used δ13C and δ15N signatures to gain a better understanding of hammerheads’ feeding strategies as well as variations of their isotopic niche. Our results suggest that the hammerhead sharks in the Galapagos Marine Reserve respond to climatic fluctuations, with La Niña event potentially benefiting their trophic needs as the overall marine productivity increased in the region. This work is the first of its kind in the TEP and provides insights on how climate variability influences the feeding ecology of this critically endangered species. It also highlights the need to incorporate climate-related conservation strategies into the management of this species since ENSO events become more frequent and intense in the face of climate change.

scholarly journals Hybridization between sympatric hammerhead sharks in the western North Atlantic Ocean

2019 ◽  
Vol 15 (4) ◽  
pp. 20190004 ◽  
Author(s):  
Amanda M. Barker ◽  
Douglas H. Adams ◽  
William B. Driggers ◽  
Bryan S. Frazier ◽  
David S. Portnoy
Keyword(s):  
Atlantic Ocean ◽  
First Generation ◽  
North Atlantic Ocean ◽  
Western Atlantic ◽  
Sphyrna Lewini ◽  
Scalloped Hammerhead ◽  
Wide Range ◽  
Hammerhead Sharks ◽  
Conservation Concern ◽  
Globally Distributed

Hybridization between closely related species has been documented across a wide range of taxa but has not been well studied in elasmobranchs. Hammerhead sharks have drawn global conservation concern because they experience some of the highest mortality rates among sharks when interacting with fisheries. Here we report on the detection of hybrids between the globally distributed scalloped hammerhead ( Sphyrna lewini ) and recently described Carolina hammerhead ( S. gilberti ) which are only known from the western Atlantic Ocean. Using a genomics approach, 10 first-generation hybrids and 15–17 backcrosses were detected from 554 individuals. The identification of backcrosses demonstrates hybrids are viable, and all backcrosses but one involved a scalloped hammerhead. All hybrids but one possessed Carolina hammerhead mtDNA, indicating sex-biased gene flow between species. Repeated hybridization and backcrossing with scalloped hammerheads could lead to the loss of endemic Carolina hammerheads.

Residency and diel movement patterns of the endangered scalloped hammerhead Sphyrna lewini in the Revillagigedo National Park

2020 ◽  
Vol 96 (2) ◽  
pp. 543-548 ◽  
Author(s):  
Alejandro Aldana‐Moreno ◽  
E. Mauricio Hoyos‐Padilla ◽  
Rogelio González‐Armas ◽  
Felipe Galván‐Magaña ◽  
Alex Hearn ◽  
...  
Keyword(s):  
National Park ◽  
Movement Patterns ◽  
Sphyrna Lewini ◽  
Scalloped Hammerhead ◽  
Diel Movement

Inter-island movements of scalloped hammerhead sharks (Sphyrna lewini) and seasonal connectivity in a marine protected area of the eastern tropical Pacific

2014 ◽  
Vol 161 (4) ◽  
pp. 939-951 ◽  
Author(s):  
James T. Ketchum ◽  
Alex Hearn ◽  
A. Peter Klimley ◽  
César Peñaherrera ◽  
Eduardo Espinoza ◽  
...  
Keyword(s):  
Protected Area ◽  
Marine Protected Area ◽  
Tropical Pacific ◽  
Eastern Tropical Pacific ◽  
Sphyrna Lewini ◽  
Scalloped Hammerhead ◽  
Hammerhead Sharks

scholarly journals Short Communication: Genetic diversity of scalloped hammerhead sharks (Sphyrna lewini) landed in Muncar Fishing Port, Banyuwangi

2019 ◽  
Vol 20 (4) ◽  
pp. 1154-1159 ◽  
Author(s):  
FAQIH AKBAR ALGHOZALI ◽  
DIAH PERMATA WIJAYANTI ◽  
AGUS SABDONO
Keyword(s):  
Genetic Diversity ◽  
Short Communication ◽  
Polymerase Chain Reaction Amplification ◽  
Haplotype Diversity ◽  
Population Expansion ◽  
Fishing Ground ◽  
Sphyrna Lewini ◽  
Scalloped Hammerhead ◽  
Hammerhead Sharks ◽  
Longline Fisheries

Abstract. Alghozali FA, Wijayanti DP, Sabdono A. 2019. Short Communication: Genetic diversity of scalloped hammerhead sharks (Sphyrna lewini) landed in Muncar Fishing Port, Banyuwangi. Biodiversitas 20: 1154-1159. The majority of sharks caught in Indonesian fisheries were bycatch products from the tuna longline fisheries, but some regions in Indonesia fish the sharks as their main target. One of these regions is located in Muncar, Banyuwangi, which fishes the endangered Scalloped Hammerhead sharks (Sphyrna lewini) as target species. This research aimed to study the genetic diversity of the endangered Scalloped Hammerhead sharks landed in Muncar Fishing Port, Banyuwangi. Genetic analysis was done through PCR (Polymerase Chain Reaction) amplification and sequencing of the mitochondrial DNA COI (Cytochrome Oxidase subunit I) gene. Out of the 37 samples collected, 30 were successfully amplified and sequenced.The results showed moderate haplotype diversity (Hd: 0,582 ± 0,079) and low nucleotide diversity (π: 0,00392± 0,0024) with five haplotypes (h) and 26 polymorphic sites (S). Tajima’s D neutrality model values indicated a population expansion event. Two different clades were determined through phylogenetic analysis and by GenBank sequences comparison. These results provided basic information and present status of the Scalloped Hammerhead sharks population genetically within the fishing ground (Makassar Strait-Kangean Islands).

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