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

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.

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First observation on the mating behaviour of the endangered scalloped hammerhead shark Sphyrna lewini in the Tropical Eastern Pacific

Environmental Biology of Fishes ◽

10.1007/s10641-017-0668-0 ◽

2017 ◽

Vol 100 (12) ◽

pp. 1603-1608 ◽

Cited By ~ 6

Author(s):

P. Salinas-de-León ◽

E. M. Hoyos-Padilla ◽

F. Pochet

Keyword(s):

Mating Behaviour ◽

Eastern Pacific ◽

Tropical Eastern Pacific ◽

Sphyrna Lewini ◽

Hammerhead Shark ◽

Scalloped Hammerhead

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

Bulletin of Marine and Coastal Research ◽

10.25268/bimc.invemar.2011.40.0.133 ◽

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.

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Cadmium, mercury, and selenium in muscle of the scalloped hammerhead Sphyrna lewini from the tropical Eastern Pacific: Variation with age, molar ratios and human health risk

Chemosphere ◽

10.1016/j.chemosphere.2019.125180 ◽

2020 ◽

Vol 242 ◽

pp. 125180 ◽

Cited By ~ 1

Author(s):

Jorge Ruelas-Inzunza ◽

Felipe Amezcua ◽

Claire Coiraton ◽

Federico Páez-Osuna

Keyword(s):

Health Risk ◽

Human Health ◽

Human Health Risk ◽

Eastern Pacific ◽

Tropical Eastern Pacific ◽

Sphyrna Lewini ◽

Molar Ratios ◽

Scalloped Hammerhead

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Monitoring of the status of eleven bony and cartilaginous fish populations in the Malpelo Sanctuary of Fauna and Flora, Colombian Pacific

Bulletin of Marine and Coastal Research ◽

10.25268/bimc.invemar.2021.50.1.1084 ◽

2021 ◽

Vol 50 (1) ◽

pp. 105-120

Author(s):

Felipe Ladino ◽

Sandra Martínez ◽

María Duarte ◽

Natalia Vélez ◽

Sandra Bessudo

Keyword(s):

Management Plan ◽

Cartilaginous Fish ◽

Tropical Eastern Pacific ◽

Sphyrna Lewini ◽

Hammerhead Shark ◽

Scalloped Hammerhead ◽

The Status ◽

Silky Shark ◽

Spotted Eagle Ray ◽

Over Time

To determine trends over time in the relative abundance of species prioritized in the Malpelo Fauna and Flroa Sanctuary Management Plan, underwater visual censuses were done from April 2009 to August 2019. Data were collected for five species of bonefish: bluefin trevally (Caranx melampygus), longfin yellowtail (Seriola rivoliana), yellowfin tuna (Thunnus albacares), leather bass (Dermatolepis dermatolepis) and sailfin grouper (Mycteroperca olfax), and six cartilaginous fish: spotted eagle ray (Aetobatus laticeps), silky shark (Carcharhinus falciformis), Galapagos shark (Carcharhinus galapagensis), whitetip reef shark (Triaenodon obesus), whale shark (Rhincodon typus) and scalloped hammerhead shark (Sphyrna lewini). A negative non-significant trend in abundance through time was observed for most of the evaluated species, except A. laticeps and T. obesus, which showed positive non-significant trends. The hammerhead shark (S. lewini) was the only species that showed a statistically significant decrease in abundance over time. The results of this study highlight the urgent need to establish more effective fisheries management and regulation measures that promote the conservation of important fish species, not just inside the sanctuary but also within the Tropical Eastern Pacific.

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