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

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 Poblaciones de tiburones en las bahías Chatham y Wafer del Parque Nacional Isla del Coco, Costa Rica

2016 ◽  
Vol 64 (1) ◽  
pp. 177 ◽  
Author(s):  
Ilena Zanella ◽  
Andrés López-Garro ◽  
Frank Martínez ◽  
Geiner Golfín-Duarte ◽  
Keylor Morales
Keyword(s):  
Sex Ratio ◽  
National Park ◽  
Marine Protected Area ◽  
Coral Cover ◽  
River Mouth ◽  
Common Species ◽  
Sphyrna Lewini ◽  
Scalloped Hammerhead ◽  
Reef Sharks ◽  
Carcharhinus Melanopterus

<p><strong> </strong>At least fourteen species of sharks live in the Marine Protected Area of Isla del Coco National Park (ICNP), some are resident species such as the whitetip reef shark (<em>Triaenodon obesus</em>); others are migratory and visit the National Park throughout the year, e.g. the scalloped hammerhead shark (<em>Sphyrna lewini</em>) and the whale shark (<em>Rhincodon typus</em>). Between March 2010 and August 2012 six expeditions out to the ICNP were carried, during this period 25 night trips (from 18:00 to 22:00 hr) for shark tagging were conducted in the Wafer and Chatham bays. During those trips, 185 sharks were analyzed: 81.1 % were whitetip reef sharks (<em>T. obesus</em>), 16.7 % were blacktip sharks (<em>Carcharhinus limbatus</em>), 1.1 % were blacktip reef sharks (<em>Carcharhinus melanopterus</em>) and 1.1% were silvertip sharks (<em>Carcharhinus albimarginatus</em>). The most common species in Bahía Chatham was <em>T. obesus</em>, while the most common one in Bahía Wafer was <em>C. limbatus</em>, which represented 80.9 % and 80.5 % of the total sharks caught, respectively. Regarding <em>T. obesus</em>, a sex ratio of 1.2 males per female was estimated (X<sup>2</sup>=0.09; p=0.17); in turn a sex ratio of 1.01 males per female was observed (X<sup>2</sup>=0.04; p=0.79) for <em>C. limbatus</em>. The average total length for <em>T. obesus </em>and <em>C. limbatus</em> was 103.66±13.91 cm and 76.58±14.56 cm respectively; suggesting that black tip sharks use those bays during immature stages. The results show an interspecific spatial segregation of the most common resident sharks at ICNP, apparently the clear waters and the coral cover of Chatham Bay are preferred by <em>T. obesus</em>; while the turbid waters of the Genio River mouth are preferred by <em>C. limbatus</em></p>

scholarly journals A BIBLIOGRAPHIC AND FIELD RECORD CHRONOLOGY OF SHARKS AT CABO PULMO NATIONAL PARK, GULF OF CALIFORNIA

2016 ◽  
Vol 31 (1) ◽  
pp. 55
Author(s):  
Hector Reyes -Bonilla ◽  
Arturo Ayala -Bocos ◽  
Francisco Javier Fernández -Rivera Melo ◽  
Ronald Zepeta -Vilchis ◽  
Andrea Asúnsolo-Rivera ◽  
...  
Keyword(s):  
Gulf Of California ◽  
National Park ◽  
Sphyrna Lewini

Cronología de tiburones del Parque Nacional Cabo Pulmo, Golfo de California; registros bibliográficos y de campo El arrecife de Cabo Pulmo en el suroeste del Golfo de California, México (23° 26´ N, 109° 25´ W), es considerado una de las áreas protegidas más exitosas del Pacífico americano, ya que durante este siglo han habido aumentos en abundancia y biomasa de peces carnívoros residentes (pargos, cabrillas, jureles, tiburones, etc.). Ello se debe al régimen de no pesca y el buen estado de conservación que le permiten mantener niveles altos de productividad primaria y secundaria. El aumento en el flujo de materia y energía ha provocado la llegada de especies de niveles tróficos altos como los tiburones, los cuales son más frecuentes y representan una atracción turística local. El objetivo del presente trabajo es presentar una cronología de la aparición de las distintas especies de tiburones en Cabo Pulmo, con base en bibliografia, trabajo de campo y consultas con residentes locales, guías de buceo y especialistas que han visitado la zona en los últimos 15 años. Los resultados muestran que en el arrecife de Cabo Pulmo se han registrado 11 especies de tiburones de 9 géneros y 6 familias; ocho de estas fueron anotadas en diversas fuentes bibliográficas; aquí se cita por primera vez la ocurrencia de tres más (Sphyrna lewini, Gynglymostoma cirratum y Carcharhinus longimanus). La llegada de estas especies a la zona arrecifal pudiera ser indicativo de un buen estado del ecosistema local, por ello es de esperarse que los próximos años se registre un número mayor de especies de tiburones, o de su biomasa.

scholarly journals An Investigation into Marmot Migration in Grand Teton National Park

1996 ◽  
Vol 20 ◽  
pp. 78-82
Author(s):  
George Montopoli ◽  
Nick Visser ◽  
Hank Harlow
Keyword(s):  
National Park ◽  
Movement Patterns ◽  
Snow Melt ◽  
Marmota Flaviventris ◽  
Long Distance ◽  
The North ◽  
North Fork ◽  
Males And Females ◽  
Study Sites ◽  
Long Distance Movement

In 1994 and 1995, a high abundant winter snowfall at higher elevations appeared to result in long distance movement patterns by yellow-bellied marmot (Marmota flaviventris) over snow to lower, snowfree elevations where food was more available. As the snow melted and food became abundant, the marmots return to higher altitudes. In 1996, we continued to investigate the potential for migrational movements, by studying two study sites at different elevations in the North Fork of Cascade Canyon. Four marmots at each site were implanted with intraperitoneal tracking transmitters. Of eight marmots that were equipped with intraperitoneal transmitters, six demonstrated significant movements of greater than 0.5 km, one did not, and one most likely died as a result of predation before any movement could be observed. Of the six that demonstrated significant movements within the canyon, only one moved distances greater than 1 km. Marmots, after emerging from hibernation, migrated down canyon to snowfree areas as they become available. With progressive snow melt, most marmots move upward to higher elevations, but not to the extent originally expected. Instead, they moved to the first available habitat where food was obtainable, and other (dominant) marmots accepted their presence. This movement is exhibited in both males and females, yearlings and adults, and melanistic and normal colored marmots.

scholarly journals A first observation of spermatogenesis in mature male scalloped hammerheads (Sphyrna lewini) from Zinkwazi, KwaZulu-Natal, South Africa

2020 ◽  
Author(s):  
Helené J. Coetzee ◽  
Kristina Naidoo ◽  
Ina Wagenaar
Keyword(s):  
South Africa ◽  
Reproductive Organs ◽  
Mature Male ◽  
Seminiferous Tubules ◽  
Stages Of Development ◽  
Biometric Data ◽  
Sphyrna Lewini ◽  
Histological Assessment ◽  
Scalloped Hammerhead ◽  
Kwazulu Natal

Abstract Sharks are not only threatened, but also have a low fecundity as they are being overfished. The shark family, Sphyrnidae, consists of nine species of which three are found in South African oceans. One of the three Sphyrnidae species, the scalloped hammerhead (Sphyrna lewini) are the most common, but their biology and mode of reproduction are not extensively studied in terms of their reproductive biology. The aim of this study was to describe the germ cell development in the testes of sexually mature male scalloped hammerheads. Three individual male S. lewini were caught at Zinkwazi, KwaZulu-Natal, South Africa. The sharks and their reproductive organs were weighed and measured to collect the biometric data for the condition factor and the gonado-somatic index. Following standard necropsy, the testes were fixed in Bouin’s solution and processed for histological assessment. The histological assessment revealed that the testes of S. lewini consist of seminiferous tubules which form part of a larger lobular structure with germ cells in different stages of development, from spermatogonia to mature spermatozoa. Seven stages of development were identified during the process of spermatogenesis, similar to what has been described for elasmobranchs. In conclusion, this study provides evidence that the testes of S. lewini are diametrical and polyspermatocystic and conforms to the testes structure of elasmobranch males.

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.

Global phylogeography of the scalloped hammerhead shark ( Sphyrna lewini )

2006 ◽  
Vol 15 (8) ◽  
pp. 2239-2251 ◽  
Author(s):  
K. M. DUNCAN ◽  
A. P. MARTIN ◽  
B. W. BOWEN ◽  
H. G. DE COUET
Keyword(s):  
Sphyrna Lewini ◽  
Hammerhead Shark ◽  
Scalloped Hammerhead
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