Sharks are one of the most evolutionarily distinct and functionally diverse vertebrate radiation. The International Union for Conservation of Nature es- timated that one-quarter of sharks are threatened with extinction, making them the most threatened vertebrate lineage after amphibians. Conservation efforts for this group have historically been hindered by the paucity of data regarding their ecology and biology, imputable to resource limitations and in- herent intricacies related to researching highly-migratory species in the marine environment. As a result, almost half of global sharks and rays are classi- fied as Data Deficient by the IUCN, hence excluded by the list of priorities of many regional conventions and fisheries commissions, which are a fundamen- tal precursor to potential species-specific protection. Carcharhinus humani, is a newly described and data deficient species of whaler shark, occurring in the Western Indian Ocean. This research project aimed at building base- line ecological data on this species within the iSimangaliso Marine Protected Area (KZN, South Africa), using Baited Remote Underwater Video Surveys (BRUVs). Spatiotemporal structuring of C. humani population was inspected for the first time incorporating sexual-based segregation over a study period of two years. Average lengths of individuals occurring in this area were measured. Preferences of substrate type and depth ranges were surveyed and included in a mixed-model analysis assessing the effect of the different protection levels present in the MPA. This study revealed that C. humani constitutes a res- ident population within the iSimagaliso MPA, as females can be sighted all year around. Males seem to arrive in the area during the warmer months, sup- porting the hypothesis that this species mates in summer. Preferences were displayed for sandy substrates, and individuals were more commonly sighted at depth ranges of 26-35 m. Finally, protection level was one of the main factors influencing Human’s whaler sharks distribution, as they tended to aggregate in no-take zones, especially during the alleged mating season. This study rep- resented the first step in the process of departing C.humani from the Data Deficient classification, setting the basis for future research on this species.

Sharks are one of the most evolutionarily distinct and functionally diverse vertebrate radiation. The International Union for Conservation of Nature es- timated that one-quarter of sharks are threatened with extinction, making them the most threatened vertebrate lineage after amphibians. Conservation efforts for this group have historically been hindered by the paucity of data regarding their ecology and biology, imputable to resource limitations and in- herent intricacies related to researching highly-migratory species in the marine environment. As a result, almost half of global sharks and rays are classi- fied as Data Deficient by the IUCN, hence excluded by the list of priorities of many regional conventions and fisheries commissions, which are a fundamen- tal precursor to potential species-specific protection. Carcharhinus humani, is a newly described and data deficient species of whaler shark, occurring in the Western Indian Ocean. This research project aimed at building base- line ecological data on this species within the iSimangaliso Marine Protected Area (KZN, South Africa), using Baited Remote Underwater Video Surveys (BRUVs). Spatiotemporal structuring of C. humani population was inspected for the first time incorporating sexual-based segregation over a study period of two years. Average lengths of individuals occurring in this area were measured. Preferences of substrate type and depth ranges were surveyed and included in a mixed-model analysis assessing the effect of the different protection levels present in the MPA. This study revealed that C. humani constitutes a res- ident population within the iSimagaliso MPA, as females can be sighted all year around. Males seem to arrive in the area during the warmer months, sup- porting the hypothesis that this species mates in summer. Preferences were displayed for sandy substrates, and individuals were more commonly sighted at depth ranges of 26-35 m. Finally, protection level was one of the main factors influencing Human’s whaler sharks distribution, as they tended to aggregate in no-take zones, especially during the alleged mating season. This study rep- resented the first step in the process of departing C.humani from the Data Deficient classification, setting the basis for future research on this species.

Spatiotemporal abundances and habitat use of the new species of shark Carcharhinus humani within the iSimangaliso Marine Protected Area (Kwa-Zulu Natal, South Africa), with considerations on zonation effect

TERRACCIANO, BEATRICE
2021/2022

Abstract

Sharks are one of the most evolutionarily distinct and functionally diverse vertebrate radiation. The International Union for Conservation of Nature es- timated that one-quarter of sharks are threatened with extinction, making them the most threatened vertebrate lineage after amphibians. Conservation efforts for this group have historically been hindered by the paucity of data regarding their ecology and biology, imputable to resource limitations and in- herent intricacies related to researching highly-migratory species in the marine environment. As a result, almost half of global sharks and rays are classi- fied as Data Deficient by the IUCN, hence excluded by the list of priorities of many regional conventions and fisheries commissions, which are a fundamen- tal precursor to potential species-specific protection. Carcharhinus humani, is a newly described and data deficient species of whaler shark, occurring in the Western Indian Ocean. This research project aimed at building base- line ecological data on this species within the iSimangaliso Marine Protected Area (KZN, South Africa), using Baited Remote Underwater Video Surveys (BRUVs). Spatiotemporal structuring of C. humani population was inspected for the first time incorporating sexual-based segregation over a study period of two years. Average lengths of individuals occurring in this area were measured. Preferences of substrate type and depth ranges were surveyed and included in a mixed-model analysis assessing the effect of the different protection levels present in the MPA. This study revealed that C. humani constitutes a res- ident population within the iSimagaliso MPA, as females can be sighted all year around. Males seem to arrive in the area during the warmer months, sup- porting the hypothesis that this species mates in summer. Preferences were displayed for sandy substrates, and individuals were more commonly sighted at depth ranges of 26-35 m. Finally, protection level was one of the main factors influencing Human’s whaler sharks distribution, as they tended to aggregate in no-take zones, especially during the alleged mating season. This study rep- resented the first step in the process of departing C.humani from the Data Deficient classification, setting the basis for future research on this species.
2021
Spatiotemporal abundances and habitat use of the new species of shark Carcharhinus humani within the iSimangaliso Marine Protected Area (Kwa-Zulu Natal, South Africa), with considerations on zonation effect
Sharks are one of the most evolutionarily distinct and functionally diverse vertebrate radiation. The International Union for Conservation of Nature es- timated that one-quarter of sharks are threatened with extinction, making them the most threatened vertebrate lineage after amphibians. Conservation efforts for this group have historically been hindered by the paucity of data regarding their ecology and biology, imputable to resource limitations and in- herent intricacies related to researching highly-migratory species in the marine environment. As a result, almost half of global sharks and rays are classi- fied as Data Deficient by the IUCN, hence excluded by the list of priorities of many regional conventions and fisheries commissions, which are a fundamen- tal precursor to potential species-specific protection. Carcharhinus humani, is a newly described and data deficient species of whaler shark, occurring in the Western Indian Ocean. This research project aimed at building base- line ecological data on this species within the iSimangaliso Marine Protected Area (KZN, South Africa), using Baited Remote Underwater Video Surveys (BRUVs). Spatiotemporal structuring of C. humani population was inspected for the first time incorporating sexual-based segregation over a study period of two years. Average lengths of individuals occurring in this area were measured. Preferences of substrate type and depth ranges were surveyed and included in a mixed-model analysis assessing the effect of the different protection levels present in the MPA. This study revealed that C. humani constitutes a res- ident population within the iSimagaliso MPA, as females can be sighted all year around. Males seem to arrive in the area during the warmer months, sup- porting the hypothesis that this species mates in summer. Preferences were displayed for sandy substrates, and individuals were more commonly sighted at depth ranges of 26-35 m. Finally, protection level was one of the main factors influencing Human’s whaler sharks distribution, as they tended to aggregate in no-take zones, especially during the alleged mating season. This study rep- resented the first step in the process of departing C.humani from the Data Deficient classification, setting the basis for future research on this species.
stereo-BRUVs
Seasonal occurrence
Shark ecology
Data-deficient
Carcharhinus humani
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12608/40969