Behavioral and visual stress-induced proxies in elasmobranchs

Wosnick, Natascha; Leite, Renata Daldin; Balanin, Samuel; Chaves, Ana Paula; Gastal, Eduardo Rufino de Senna; Hauser‐Davis, Rachel Ann; Giareta, Eloísa Pinheiro

doi:10.1007/s11160-023-09757-8

Cited by 4 publications

(2 citation statements)

References 107 publications

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“…This result suggests that, overall, the shark populations on Madeira Island are not disturbed by the coastal activities practiced by its residents [79]. However, in the case of C. obscurus, there were only sighting reports where the agonistic behaviour was seen, reflecting a stress triggered response, which can affect the feeding, resting, and reproductive behaviour [52,79]. Nevertheless, more data are required to evaluate the reliability of this hypothesis.…”

Section: Behaviourmentioning

confidence: 90%

“…Considering behaviour, almost every species, apart from C. obscurus, had sighting reports displaying milling behaviour, with this being the most frequent behaviour for M. mustelus and G. galeus. This result suggests that, overall, the shark populations on Madeira Island are not disturbed by the coastal activities practiced by its residents [79]. However, in the case of C. obscurus, there were only sighting reports where the agonistic behaviour was seen, reflecting a stress triggered response, which can affect the feeding, resting, and reproductive behaviour [52,79].…”

Section: Behaviourmentioning

confidence: 93%

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Human–Shark Interactions: Citizen Science Potential in Boosting Shark Research on Madeira Island

Berimbau,

Larrea,

Costa

et al. 2023

Diversity

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Sharks are regularly considered to be an indicator of the ocean ecosystem’s health and are generally difficult to study in their natural environment. Citizen science has been increasing, being a cost-effective method for particularly important species that have low encounter rates or are logistically challenging to sample. Madeira Island has a considerable gap in terms of its coastal shark species data and studies, which this work aims to complement. To achieve this goal, online questionnaires to citizens and specific interviews of spearfishers were conducted, with questions related to species size, distribution, and behaviour. Exactly 129 reports of shark sightings were obtained, including seven different species exhibiting four different types of behaviour around the coastal areas of the different municipalities of Madeira Island. Individuals seem to aggregate around the east and west edges of the island due to localised upwelling phenomena. Also, a relation was found between size and distance to coast and depth, as smaller sharks tend to stay close to the shore, probably reflecting the role of Madeira as a nursery area, but further studies are necessary to confirm the reliability of this hypothesis.

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Section: Behaviourmentioning

confidence: 90%

Section: Behaviourmentioning

confidence: 93%

Human–Shark Interactions: Citizen Science Potential in Boosting Shark Research on Madeira Island

Berimbau,

Larrea,

Costa

et al. 2023

Diversity

View full text Add to dashboard Cite

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A tangled web: global review of fishing interactions with rhino rays

Pytka,

Kyne,

Carlson

et al. 2023

Rev Fish Biol Fisheries

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Rhino rays (Order Rhinopristiformes) are one of the most threatened vertebrate groups. Despite overfishing being recognised as the greatest threat to this group, a comprehensive assessment of the fisheries and types of fishing gear that rhino rays interact with is lacking. We reviewed published and grey literature (n = 116 references) to evaluate interactions between rhino rays and fisheries, determine gear types most responsible for their capture, and species for which most interactions occur by region. Interactions (n = 420) were reported from 37 of 88 range states, for 52 of 68 known species. Combined, 59% of the literature reported interactions from trawlers and gillnets. Wedgefishes (Rhinidae) were the most reported family (29%) and bowmouth guitarfish (Rhina ancylostomus) the most reported species (9.5%). Asia accounted for half of interactions (n = 211), with 67% of the literature from unspecified gear (e.g., mixed landings), masking gear-specific interactions. Data quality was variable, with the highest resolution in countries with lower species diversity and where species are least imperiled (e.g., Australia). Discard mortality and physiological effects of capture are poorly known with data available for 25% of species (almost exclusively from Australia and the Americas). While additional data are urgently required to quantify the true extent of rhino ray catch globally, reducing fisheries mortality is a priority and key to address declining populations. Recommendations include prioritizing spatial management in critical habitats (e.g., nursery areas), expansion in the use of proven bycatch reduction devices, encouraging safe release and handling, and addressing drivers of retention and trade.

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