Isotopic trajectories and interspecific niche partitioning in tropical pelagic sharks

Li, Zezheng; Chen, Ziang; Costa-Pereira, Raul; Hussey, Nigel E.; Zhang, Yanxuedan; Li, Yunkai

doi:10.1016/j.gecco.2023.e02772

Cited by 1 publication

(1 citation statement)

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“…It is likely that annual isotope values (i.e., one season) derived from vertebral bands do not reflect true variation in diet as revealed by faster turnover tissues such as plasma. Moreover, the observation of variable, but not directional δ 15 N values over ontogeny matches that recorded for five pelagic shark species sampled from the same region (Li et al, 2024).…”

Section: Habitat Shifts With Agesupporting

confidence: 75%

Vertebral microchemistry as an indicator of habitat use of the oceanic whitetip shark Carcharhinus longimanus in the central and eastern Pacific Ocean

Shen,

Hussey,

David

et al. 2024

Journal of Fish Biology

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The oceanic whitetip shark, Carcharhinus longimanus, is a highly migratory, epipelagic top predator that is classified as critically endangered. Although this species is widely distributed throughout the world's tropical oceans, its assumed mobility and pelagic behavior limit studies to derive required lifetime data for management. To address this data deficiency, we assessed variation in the habitat use of C. longimanus by oceanic region and over ontogeny through time series trace element and stable isotope values conserved along the vertebral centra (within translucent annulus bands) of 13 individuals sampled from the central and eastern Pacific Ocean. Elemental ratios of Mg:Ca, Mn:Ca, Fe:Ca, Zn:Ca, and Ba:Ca varied significantly among individuals from both sampling regions while principal component analysis of combined standardized elements revealed minimal overlap between the two areas. The limited overlap was also in agreement with stable isotope niches. These findings indicate that C. longimanus exhibit a degree of fidelity to sampling regions but also connectivity in a proportion of the population. The relatively stable Sr:Ca ratio supports its occurrence in oceanic environments. The decreasing trends in Ba:Ca, Mn:Ca, and Zn:Ca ratios, as well as in carbon and nitrogen isotope values along vertebral transects, indicate that C. longimanus undergo a directional habitat shift with age. Combined elemental and stable isotope values in vertebral centra provide a promising tool for elucidating lifetime data for complex pelagic species. For C. longimanus, management will need to consider subpopulation movement behavior in the Pacific to minimize the potential for localized depletions. Further work is now required to sample individuals across the entire Pacific and to link these findings with genetic and movement data to define population structure.

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Section: Habitat Shifts With Agesupporting

confidence: 75%