Age and growth for the scalloped hammerhead shark, sphyrna lewini (griffith and smith, 1834) along the central pacific coast of mexico

2001 ◽  
Vol 27 (4) ◽  
pp. 501-520 ◽  
Author(s):  
V. Anislado-Tolentino
Keyword(s):  
Pacific Coast ◽  
Age And Growth ◽  
Central Pacific ◽  
Sphyrna Lewini ◽  
Hammerhead Shark ◽  
Scalloped Hammerhead

scholarly journals Age and growth of the Scalloped Hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834), from the southern Brazilian coast

2011 ◽  
Vol 71 (3) ◽  
pp. 755-761 ◽  
Author(s):  
JE. Kotas ◽  
V. Mastrochirico ◽  
M. Petrere Junior
Keyword(s):  
Growth Parameters ◽  
Growth Models ◽  
Calculated Data ◽  
Age And Growth ◽  
Brazilian Coast ◽  
Sphyrna Lewini ◽  
Hammerhead Shark ◽  
Scalloped Hammerhead ◽  
Marginal Increment ◽  
Best Fit

Age and growth studies for the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834) caught along the southern Brazilian coast, were based on ring measurements of vertebrae sections of 115 males, 116 females and 14 unknown sexed sharks between 48 and 344 cm total length (TL). The von Bertalanffy growth models were best fit using back-calculated data. The growth parameters obtained for males, were L∞ = 266 cm; K = 0.05/year; L0 = 47 cm. For females, L∞ = 300 cm; K = 0.05/year; L0 = 51 cm. An adult female reached 217 cm TL and was 31.5 years old. On the other hand, an adult male was 29.5 years old and measured 234 cm TL. Longevity estimate for males and females was 55 years. Therefore, S. lewini is a long-lived fish. Ageing precision, based on the IAPE index, was 5.6%. Marginal Increment analysis based on MIR index from hammerheads smaller than 105 cm, compared with the percentual of opaque and hyaline bands found per month ageing whole vertebrae, showed an annual ring formation, i.e., in winter.

scholarly journals CARACTERIZACIÓN DE LA PESCA DEL TIBURÓN MARTILLO SPHYRNA LEWINI , EN LA PARTE EXTERNA DEL GOLFO DE NICOYA, COSTA RICA

2009 ◽  
Vol 1 ◽  
pp. 175 ◽  
Author(s):  
Ilena Zanella ◽  
Andrés López ◽  
Rándall Arauz
Keyword(s):  
Costa Rica ◽  
Outer Part ◽  
Shark Species ◽  
Central Pacific ◽  
Sphyrna Lewini ◽  
Hammerhead Shark ◽  
Total Length ◽  
Management Actions ◽  
Scalloped Hammerhead ◽  
Gulf Of Nicoya

En el ámbito nivel mundial, el tiburón martillo (Sphyrna lewini) es una de las especies más afectadas por la sobrepesca y el aleteo. Recientemente se incorporó a la Lista Roja de la UICN como especie en peligro de extinción. El presente estudio pretendió caracterizar la pesca y la distribución de S. lewini en la parte externa del Golfo de Nicoya. Para lograr este propósito, se realizaron muestreos entre marzo del 2006 y mayo del 2007 y se analizaron los tiburones martillo capturados por pescadores artesanales afiliados a la Cooperativa artesanales de Pescadores de Tárcoles (CoopeTárcoles R. L.), que faenan en la parte externa del Golfo de Nicoya. Para cada tiburón, se determinó la longitud total, la zona de pesca donde se capturó y el arte utilizado. En total se analizaron 273 tiburones. Se identificó un área de crianza primaria en el Peñón y se determinó que existe una relación lineal positiva entre la longitud total y la profundidad de la zona de pesca (R2 = 0.4296; p ‹ 0.0001), y la longitud total y la distancia de la zona de pesca de la desembocadura del río Grande de Tárcoles (R2 = 0.4052; p ‹ 0.0001). Los tiburones de menor tamaño (crías) se encontraron en la zona del Peñón, donde las aguas son poco profundas, turbias y productivas, ofreciendo a las crías alimento y protección de los depredadores. Por lo cual, se recomienda proteger esta zona, en particular en marzo, abril y mayo, época de nacimiento de las crías.The scalloped hammerhead shark (Sphyrna lewini) is one of the shark species most impacted by overfishing, and is currently listed by the IUCN Red List as an Endangered.  This research sought to characterize the distribution of S. lewini in the external area of Gulf of Nicoya, central Pacific coast of Costa Rica, based on observations from a coastal artisanal fishery. From March 2006 to May 2007, we analyzed scalloped hammerhead shark landings by members of the Tarcoles Artisanal Fishermen's Cooperative (CoopeTárcoles R. L.), who operate in the outer part of the Gulf of Nicoya. We measured the total length of each shark, recorded the reported location of capture, and the gear used. In total, we recorded data for 273 sharks landed. We determined that total length holds a positive linear relationship with the depth of the fishing area (R2 = 0.4296, *** p <.0001) as well as with the distance from the mouth of the Tárcoles River (R2 = 0.4052, *** p <.0001). The smaller sharks (pups) were caught in a fishing site known as Peñon, slightly north of the mouth of the Tarcoles River, where the waters are shallow, turbid and highly productive, providing food and shelter for the pups.  As pups mature and attain larger sizes, they move towards deeper waters away from the Tarcoles River, out of the Gulf of Nicoya. We identify Peñon as a primary nursery for scalloped hammerhead sharks, and recommend management actions that seek to reduce fishing effort between March and May, when pups are born.

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

Residency of the scalloped hammerhead shark (Sphyrna lewini) at Malpelo Island and evidence of migration to other islands in the Eastern Tropical Pacific

2011 ◽  
Vol 91 (2) ◽  
pp. 165-176 ◽  
Author(s):  
Sandra Bessudo ◽  
German Andres Soler ◽  
A. Peter Klimley ◽  
James T. Ketchum ◽  
Alex Hearn ◽  
...  
Keyword(s):  
Tropical Pacific ◽  
Eastern Tropical Pacific ◽  
Sphyrna Lewini ◽  
Hammerhead Shark ◽  
Scalloped Hammerhead ◽  
Malpelo Island

scholarly journals Feeding strategy of the night shark (Carcharhinus signatus) and scalloped hammerhead shark (Sphyrna lewini) near seamounts off northeastern Brazil

2009 ◽  
Vol 57 (2) ◽  
pp. 97-104 ◽  
Author(s):  
Teodoro Vaske Júnior ◽  
Carolus Maria Vooren ◽  
Rosangela Paula Lessa
Keyword(s):  
Food Web ◽  
Deep Water ◽  
Feeding Strategy ◽  
Northeastern Brazil ◽  
Sphyrna Lewini ◽  
Marine Food Web ◽  
Hammerhead Shark ◽  
Scalloped Hammerhead ◽  
Marine Food

A total of 425 stomachs of night shark (Carcharhinus signatus), and 98 stomachs of scalloped hammerhead shark (Sphyrna lewini), from longline and surface gillneters near seamounts off northeastern Brazil, were analysed between 1992 and 1999. Both predators prey upon reef and benthopelagic fishes, migrant cephalopods and deep water crustaceans, showing similar feeding niches (Schoener Index T=0.75). The great prey richness of the diets may reflect the fact that the marine food web for these species is very extensive in this region. Due to the concentration for feeding of both predators in the seamounts, intense fisheries should be monitored to avoid localised depletions.

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