Resilience of Sphyrna lewini, Rhizoprionodon longurio, and Carcharhinus falciformis at the entrance to the Gulf of California after three decades of exploitation

Abstract

Resilience of Sphyrna lewini, Rhizoprionodon longurio, and Carcharhinus falciformis at the entrance to the Gulf of California after three decades of exploitation Resiliencia de Sphyrna lewini, Rhizoprionodon longurio y Carcharhinus falciformis en la entrada del golfo de California después de tres décadas de explotación

The biology and ecology of the Pacific sharpnose shark Rhizoprionodon longurio

“…Litter sizes are thought to range between 1 and 12 embryos, with an average 7.4 embryos per litter (Márquez-Farias et al, 2005;Mejía Salazar, 2007). This is much higher than fecundity estimates for other Rhizoprionodon species (Capapé et al, 2006;Carlson & Baremore, 2003), and likely the major factor contributing to the resilience of the species to overfishing (Corro-Espinosa et al, 2011;Furlong-Estrada et al, 2015). No relationship between litter size and maternal size is known (Mejía Salazar, 2007), lending further credence to the absence of strong selection on female size at maturity.…”

“…better understanding about the spatial ecology of Rhizoprionodon species, which given their ecological and commercial importance (Corro-Espinosa et al, 2011;Pérez-Jiménez et al, 2015) should be a priority. In particular, effort should be made to characterise habitat usage of R. longurio in the Southern parts of its range, which as of yet remains entirely unknown.…”

“…Until recently, R. longurio was considered data deficient (Pinhal et al, 2012 ) and only in recent years has literature focussing on the species increased substantially. R. longurio is significantly more vulnerable to extinction than R. terraenovae on the basis of current IUCN estimates (Carlson et al, 2021 ; Pollom et al, 2020 ) and the species is subject to greater fishing pressure than R. terraenovae over much of its range (Corro‐Espinosa et al, 2011 ; Pérez‐Jiménez et al, 2015 ). For these reasons, improving our understanding of R. longurio biology and ecology is vital so that we may provide biologically informed conservation measures and maintain ecological function.…”

“…In addition to the uncertainties regarding migratory behaviour, nothing is known about diel and vertical movements of this species besides vague speculation based on trophic studies (Alatorre‐Ramirez et al, 2013 ; Osuna‐Peralta et al, 2014 ). Future studies utilising acoustic and satellite telemetry data will provide better understanding about the spatial ecology of Rhizoprionodon species, which given their ecological and commercial importance (Corro‐Espinosa et al, 2011 ; Pérez‐Jiménez et al, 2015 ) should be a priority. In particular, effort should be made to characterise habitat usage of R. longurio in the Southern parts of its range, which as of yet remains entirely unknown.…”

Population structure and genetic connectivity of the scalloped hammerhead shark (Sphyrna lewini) across nursery grounds from the Eastern Tropical Pacific: implications for management and conservation

“…The scalloped hammerhead shark Sphyrna lewini (Griffith and Smith, 1834), is a large (up to 420 cm total length, TL), viviparous, coastal semi-oceanic species found worldwide in tropical and sub-tropical waters (9). As occurs with many other shark species, S. lewini , has low resilience to overfishing due to its slow growth, late sexual maturity, and long gestation periods (10–12). Throughout its distribution, S. lewini has experienced severe population declines (7,13–16), leading to its listing as Critically Endangered by the International Union for the Conservation of Nature (IUCN) Red List (17).…”