An exploration of the population characteristics and behaviours of the white shark in Guadalupe Island, Mexico (2014–2019): Observational data from cage diving vessels

2021 ◽  
Author(s):  
Omar Santana‐Morales ◽  
Rebeca Zertuche‐Chanes ◽  
Edgar M. Hoyos‐Padilla ◽  
Chugey Sepúlveda ◽  
Edgar E. Becerril‐García ◽  
...  
Keyword(s):  
Observational Data ◽  
White Shark ◽  
Population Characteristics ◽  
Guadalupe Island

Unraveling the white shark observation tourism at Guadalupe Island, Mexico: Actors, needs and sustainability

Marine Policy ◽  
2020 ◽  
Vol 119 ◽  
pp. 104056 ◽  
Author(s):  
Mercedes I. Meza-Arce ◽  
Luis Malpica-Cruz ◽  
Mauricio E. Hoyos-Padilla ◽  
Francisco J. Mojica ◽  
María Concepción Arredondo-García ◽  
...  
Keyword(s):  
White Shark ◽  
Guadalupe Island

Statistical modelling reveals spatial, temporal, and environmental preferences for white sharks at an oceanic aggregation site

2020 ◽  
Vol 655 ◽  
pp. 171-183
Author(s):  
EE Becerril-García ◽  
RO Martínez-Rincón ◽  
F Galván-Magaña ◽  
O Santana-Morales ◽  
EM Hoyos-Padilla
Keyword(s):  
Feeding Habits ◽  
Generalized Additive Models ◽  
Statistical Modelling ◽  
Time Of Day ◽  
White Shark ◽  
Additive Models ◽  
Environmental Preferences ◽  
Data Set ◽  
Aggregation Site ◽  
Guadalupe Island

Guadalupe Island, Mexico, is one of the most important white shark (Carcharodon carcharias) aggregation sites in the Eastern Pacific. In the waters surrounding Guadalupe Island, cage diving has been carried out since 2001 during August-November; however, there is scarce information regarding the factors associated with this seasonal aggregation. The purpose of this study was to describe the probability of occurrence of white sharks relative to spatial, temporal, and environmental factors in Guadalupe Island. Generalized additive models (GAMs) were used to describe the effect of sea surface temperature, water visibility, tide, moon phase, cloud cover, time of day, and location on white shark occurrence. GAMs were generated from a data set of 6266 sightings of white sharks, classified as immature males, mature males, immature females, and mature females. A sexual segregation related to month was observed, where females arrived after males during late September. GAMs evidenced a segregation of white sharks according to the analysed variables, which is consistent with previous observations in this locality. Environmental preferences for each white shark category are potentially influenced by feeding habits, sexual maturation, and reproduction. This study constitutes a baseline of the effect of the environment on the occurrence of white sharks in Guadalupe Island, which can be used in further studies regarding management and conservation in future climatic and anthropogenic scenarios. Its relevance is related to the understanding of its ecology in oceanic environments and the presence of this threatened species during the ecotourism season.

How much is too much? A carrying capacity study of white shark cage diving in Guadalupe Island, Mexico

Marine Policy ◽  
2021 ◽  
Vol 131 ◽  
pp. 104588
Author(s):  
Omar Santana-Morales ◽  
E. Mauricio Hoyos-Padilla ◽  
Alfonso Medellín-Ortíz ◽  
Chugey Sepulveda ◽  
Rodrigo Beas-Luna ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
White Shark ◽  
Guadalupe Island

scholarly journals Diving deeper into the underlying white shark behaviors at Guadalupe Island, Mexico

2021 ◽  
Author(s):  
Marc Aquino‐Baleytó ◽  
Vianey Leos‐Barajas ◽  
Timo Adam ◽  
Mauricio Hoyos‐Padilla ◽  
Omar Santana‐Morales ◽  
...  
Keyword(s):  
White Shark ◽  
Guadalupe Island

scholarly journals A first estimate of white shark, Carcharodon carcharias , abundance off Central California

2011 ◽  
Vol 7 (4) ◽  
pp. 581-583 ◽  
Author(s):  
Taylor K. Chapple ◽  
Salvador J. Jorgensen ◽  
Scot D. Anderson ◽  
Paul E. Kanive ◽  
A. Peter Klimley ◽  
...  
Keyword(s):  
Conservation Status ◽  
White Shark ◽  
Carcharodon Carcharias ◽  
Central California ◽  
Photo Identification ◽  
Marine Predators ◽  
Northeastern Pacific ◽  
The Status ◽  
Credible Intervals ◽  
Guadalupe Island

The decline of sharks in the global oceans underscores the need for careful assessment and monitoring of remaining populations. The northeastern Pacific is the home range for a genetically distinct clade of white sharks ( Carcharodon carcharias ). Little is known about the conservation status of this demographically isolated population, concentrated seasonally at two discrete aggregation sites: Central California (CCA) and Guadalupe Island, Mexico. We used photo-identification of dorsal fins in a sequential Bayesian mark–recapture algorithm to estimate white shark abundance off CCA. We collected 321 photographs identifying 130 unique individuals, and estimated the abundance off CCA to be 219 mature and sub-adult individuals ((130, 275) 95% credible intervals), substantially smaller than populations of other large marine predators. Our methods can be readily expanded to estimate shark population abundance at other locations, and over time, to monitor the status, population trends and protection needs of these globally distributed predators.

Current status of special planetary and lunar theories and ephemerides

1966 ◽  
Vol 25 ◽  
pp. 266-267
Author(s):  
R. L. Duncombe
Keyword(s):  
Observational Data ◽  
Current Status ◽  
Numerical Errors

An examination of some specialized lunar and planetary ephemerides has revealed inconsistencies in the adopted planetary masses, the presence of non-gravitational terms, and some outright numerical errors. They should be considered of temporary usefulness only, subject to subsequent amendment as required for the interpretation of observational data.

July 11, 1991 Eclipse Corona Photometry by the Results of Electropolarimetric and CCD-Matrix Observations

1994 ◽  
Vol 144 ◽  
pp. 567-569
Author(s):  
V. Kulidzanishvili ◽  
D. Georgobiani
Keyword(s):  
Solar Corona ◽  
Observational Data ◽  
Solar Limb ◽  
Ccd Matrix

AbstractThe observational data of July 11, 1991 eclipse solar corona obtained by both electropolarimeter (EP) and CCD-matrix were processed. Using these data, the solar corona photometry was carried out. The results of EP data are compared with the ones of CCD data. It must be noted here that the CCD data give us only characteristics of the inner corona, while the EP data show the features of both the inner and middle corona up to 4R⊙. Standard flattening indexϵis evaluated from both data. The dependence of the flattening index on the distance from the solar limb is investigated. The isophotes in Na and Ca lines are plotted. Based on these data some ideas and conclusions on the type of the solar corona are presented.

On The Radii of Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 49-55 ◽  
Author(s):  
F.A. Catalano ◽  
G. Strazzulla
Keyword(s):  
Observational Data ◽  
Line Width ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

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