Drivers of reef shark abundance and biomass in the Solomon Islands

Goetze, Jordan; Langlois, Tim; McCarter, Joe; Simpfendorfer, Colin A.; Hughes, Alec; Leve, Jacob Tingo; Jupiter, Stacy D.

doi:10.1371/journal.pone.0200960

Cited by 24 publications

(18 citation statements)

References 66 publications

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“…Environmental factors such as temperature, depth and habitat composition are also key drivers of elasmobranch assemblages 31,78,79 , but these drivers had little or no contribution in our study. Based on our results, there was a positive effect of depth on both elasmobranch species richness and abundance, which is consistent with findings from other studies 19,80 . Changes in temperature, light level and productivity associated to depth may explain some of the observed trends in elasmobranch assemblages 78 .…”

Section: Discussionsupporting

confidence: 93%

Monitoring elasmobranch assemblages in a data-poor country from the Eastern Tropical Pacific using baited remote underwater video stations

Espinoza

Araya‐Arce

Chaves-Zamora

et al. 2020

Sci Rep

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Understanding how threatened species are distributed in space and time can have direct applications to conservation planning. However, implementing standardized methods to monitor populations of wide-ranging species is often expensive and challenging. In this study, we used baited remote underwater video stations (BRUVS) to quantify elasmobranch abundance and distribution patterns across a gradient of protection in the Pacific waters of Costa Rica. Our BRUVS survey detected 29 species, which represents 54% of the entire elasmobranch diversity reported to date in shallow waters (< 60 m) of the Pacific of Costa Rica. Our data demonstrated that elasmobranchs benefit from no-take MPAs, yet large predators are relatively uncommon or absent from open-fishing sites. We showed that BRUVS are capable of providing fast and reliable estimates of the distribution and abundance of data-poor elasmobranch species over large spatial and temporal scales, and in doing so, they can provide critical information for detecting population-level changes in response to multiple threats such as overfishing, habitat degradation and climate change. Moreover, given that 66% of the species detected are threatened, a well-designed BRUVS survey may provide crucial population data for assessing the conservation status of elasmobranchs. These efforts led to the establishment of a national monitoring program focused on elasmobranchs and key marine megafauna that could guide monitoring efforts at a regional scale.

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Section: Discussionsupporting

confidence: 93%

Monitoring elasmobranch assemblages in a data-poor country from the Eastern Tropical Pacific using baited remote underwater video stations

Espinoza

Araya‐Arce

Chaves-Zamora

et al. 2020

Sci Rep

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“…These findings align with those of related BRUV studies: a study of tropical sharks on the Great Barrier Reef found proximity to reefs with high coral cover to be the most important factor structuring shark communities and a factor contributing to MPA success [12], while a previous analysis of the fish community in the Betty’s Bay MPA found habitat affected the diversity and species composition while protection had no effect [27]. However, in cases where fishing has had large impacts on populations of sharks and their prey, MPA presence can explain the most variation in shark abundance and community composition compared to environmental and habitat variables alone [49,50]. Our expanded analysis of chondrichthyan abundance and richness did find a limited positive effect of protection in Betty’s Bay not previously detected [27].…”

Section: Discussionmentioning

confidence: 99%

“…South Africa’s endemic catsharks may not be currently threatened, but their abundance in the region is supported by the quality of habitat located in Betty’s Bay, indicating even small MPAs could play a role in protecting coastal ecosystems and endemic species. Spatial protection has had strong effects on resident populations of more threatened sharks on tropical reefs [49,50]; thus MPAs will likely play an important conservation role for endemic South African species should fishing pressure or habitat degradation intensify.…”

Section: Discussionmentioning

confidence: 99%

Using baited remote underwater videos (BRUVs) to characterize chondrichthyan communities in a global biodiversity hotspot

Osgood

McCord²,

Baum

2019

PLoS ONE

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Threatened chondrichthyan diversity is high in developing countries where scarce resources, limited data, and minimal stakeholder support often render conservation efforts challenging. As such, data on many species, including many evolutionarily distinct endemics, is poor in these countries and their conservation status and habitat needs remain uncertain. Here, we used baited remote underwater videos (BRUVs; n = 419) conducted at 167 sites over two years to assess the frequency of occurrence (FO), relative abundance, diversity, and structure of chondrichthyan assemblages in one of the world’s chondrichthyan biodiversity and endemism hotspots, South Africa. We compared chondrichthyan assemblages across three habitat types, and between unprotected and protected areas (a small marine protected area [MPA] and a larger, seasonal whale sanctuary). Although in total we observed 18 chondrichthyan species (11 families), over half of all observations were of just two species from the same family of mesopredatory endemic catsharks; only 8.8% were larger shark species. These mesopredatory species do not appear to be threatened, but some skates and larger shark species, including some endemics, were much rarer. Overall chondrichthyan FO was high (81% of all BRUVs); FO was higher in kelp (100% of BRUVS) and reef (93%) sites than at sites in sandy habitat (63%), which had a distinct chondrichthyan community. Independent of habitat, the chondrichthyan community did not relate strongly to protection. Because sites with kelp and reef habitat were rare in the whale sanctuary, this protected area had a lower chondrichthyan FO (67% of BRUVs) than either unprotected sites (81%) or those in the small MPA (98%), as well as having lower chondrichthyan relative abundance and species richness. Our study provides evidence of the importance of distinct habitat types to different chondrichthyan species, and suggests that even small MPAs can protect critical habitats, such that they may provide safe refuge for endemic species as anthropogenic pressures increase.

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“…Baited remote underwater video stations (BRUVS) are increasingly being used to survey predator abundances on coral reefs [11][12][13]. BRUVS have been shown to have higher statistical power and consistency than unbaited videos [14].…”

Section: Introductionmentioning

confidence: 99%

“…Changes in rainfall between seasons can impact freshwater output, turbidity, and nutrient loads which may impact coastal species abundances including elasmobranchs [ 18 , 19 ]. Many BRUVS studies compare locations that are sampled at a single time point [ 12 , 20 ]. By only having a single sampling period, it is not possible to document if community composition and abundance estimates change seasonally.…”

Section: Introductionmentioning

confidence: 99%

Repeatability of baited remote underwater video station (BRUVS) results within and between seasons

et al. 2020

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Baited remote underwater video stations (BRUVS) are increasingly being used to evaluate and monitor reef communities. Many BRUVS studies compare multiple sites sampled at single time points that may differ from the sampling time of another site. As BRUVS use grows in its application to provide data relevant to sustainable management, marine protected area success, and overall reef health, understanding repeatability of sampling results is vital. We examined the repeatability of BRUVS results for the elasmobranch community both within and between seasons and years, and explored environmental factors affecting abundances at two sites in Indonesia. On 956 BRUVS, 1139 elasmobranchs (69% rays, 31% sharks) were observed. We found consistent results in species composition and abundances within a season and across years. However, elasmobranch abundances were significantly higher in the wet season. The elasmobranch community was significantly different between the two sites sampled, one site being more coastal and easily accessed by fishermen. Our results demonstrate that while BRUVS are a reliable and repeatable method for surveying elasmobranchs, care must be taken in the timing of sampling between different regions to ensure that any differences observed are due to inherent differences amongst sampling areas as opposed to seasonal dissimilarities.

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Drivers of reef shark abundance and biomass in the Solomon Islands

Cited by 24 publications

References 66 publications

Monitoring elasmobranch assemblages in a data-poor country from the Eastern Tropical Pacific using baited remote underwater video stations

Monitoring elasmobranch assemblages in a data-poor country from the Eastern Tropical Pacific using baited remote underwater video stations

Using baited remote underwater videos (BRUVs) to characterize chondrichthyan communities in a global biodiversity hotspot

Repeatability of baited remote underwater video station (BRUVS) results within and between seasons

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