Drivers of spatiotemporal variability in bycatch of a top marine predator: First evidence for the role of water turbidity in protected species bycatch

Luck, C.P.; Cronin, Michelle; Gosch, Martha; Healy, Kieran; Cosgrove, Ronán; Tully, Oliver; Rogan, Emer; Jessopp, Mark

doi:10.1111/1365-2664.13544

Cited by 8 publications

(7 citation statements)

References 52 publications

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“…Anomalous blooms occurring in important seabird habitat have resulted in mass die-offs due to starvation [ 33 ], with associated turbidity likely to compromise seabirds' ability to locate prey. Increased turbidity has also been linked with elevated bycatch rates of seals by static gillnet fisheries [ 44 ]. Though this connection has not been investigated in other marine predators or fisheries, turbidity could contribute to bycatch risk for other species, and this topic deserves further attention.…”

Section: Discussionmentioning

confidence: 99%

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Underwater visibility constrains the foraging behaviour of a diving pelagic seabird

et al. 2022

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Understanding the sensory ecology of species is vital if we are to predict how they will function in a changing environment. Visual cues are fundamentally important for many predators when detecting and capturing prey. However, many marine areas have become more turbid through processes influenced by climate change, potentially affecting the ability of marine predators to detect prey. We performed the first study that directly relates a pelagic seabird species's foraging behaviour to oceanic turbidity. We collected biologging data from 79 foraging trips and 5472 dives of a visually dependent, pursuit-diving seabird, the Manx shearwater ( Puffinus puffinus ). Foraging behaviour was modelled against environmental variables affecting underwater visibility, including water turbidity, cloud cover and solar angle. Shearwaters were more likely to initiate area-restricted search and foraging dives in clearer waters. Underwater visibility also strongly predicted dive rate and depth, suggesting that fine-scale prey capture was constrained by the detectability of prey underwater. Our novel use of dynamic descriptors of underwater visibility suggests that visual cues are vital for underwater foraging. Our data indicate that climate change could negatively impact seabird populations by making prey more difficult to detect, compounded by the widely reported effects of reduced prey populations.

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Section: Discussionmentioning

confidence: 99%

“…Secchi disc depth (Zsd) was used as a metric of light transmissibility through the water column, i.e. turbidity [ 10 , 44 ]. Zsd was provided in metres, where greater Zsd corresponds to clearer water, and sourced at daily temporal and 4 km spatial resolution from the Copernicus Marine Service Ocean Products database ( ).…”

Section: Methodsmentioning

confidence: 99%

Underwater visibility constrains the foraging behaviour of a diving pelagic seabird

et al. 2022

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“…MPCEIP-SRP-2021-0208-A). Onboard observers can only be efficiently placed on one of the two decks, and information is provided by the crew to complement it, underestimating bycatch estimates (Luck et al, 2020), especially when bycatch estimation is of a lower priority (Forget et al, 2021). The longline fleet is the only one monitored by fisheries observers, while other fishing gears (such as gillnets or trawls) are absent.…”

Section: Limitationsmentioning

confidence: 99%

By-catch of sea turtles in Pacific artisanal fishery: Two points of view: From observer and fishers

et al. 2022

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Fisheries bycatch is a primary driver of population declines in marine megafauna. These captures not only have environmental impacts, they also have economic consequences for fishers such as direct losses when repairing fishing gear. Therefore, evaluating the fishers’ perception of bycatch and comparing it with data from scientific fisheries observers might provide a broader view of the current situation these species face. To do this, we obtained data concerning the bycatch of 1,838 sea turtles between 2008-2018 in the Eastern Pacific Ocean as well as informative surveys from 421 artisanal fishers surveyed in 2020. There is a discrepancy between the bycatch observed and the fishers’ perceptions of it. The observers’ results identified that high rates of incidental capture of sea turtles are associated with the mahi mahi fishery that occurs during winter and is a shallow set fishery using fish as bait. The olive ridley turtle was the main species affected by bycatch. According to the fishers’ perception, bycatch was higher with the use of J-hooks and a longline (compared to circle hooks and to gill nets and trawl nets) and when the target species are pelagic fish during the winter season. In addition, the fishers’ perception showed that 39.4% considered incidental fishing as an environmental problem and 28.5% considered it as a nuisance, while 32.1% do not consider sea turtle bycatch as a problem. These findings suggest that 60% of fishers do not consider it a need to protect sea turtles. Given the different responses between fisheries observers and fishers’ perception, it is clear that more dialogue is necessary to raise awareness about the effects of bycatch on worldwide sea turtle populations. Thus, there is an enormous potential to recruit/increase fishers’ active participation for turtle protection. In this context, the idea of including the fishers’ perception into any management strategy or conservation measure should be reinforced in order to effectively reduce the bycatch of these iconic species.

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“…Seal predation and damage to fishing gear is currently not monitored, but fishers and aquaculture operators are still licensed to shoot seals interacting with fishing equipment. An additional threat to this population includes bycatch, especially in the vicinity of major colonies [141,142].…”

Section: United Kingdom and Irelandmentioning

confidence: 99%

“…Bycatch is recognised as a source of mortality in many areas, e.g., [108,141,210]; however, estimates and observer programs are limited in most regions.…”

Section: Knowledge Gapsmentioning

confidence: 99%

Harbour Seals: Population Structure, Status, and Threats in a Rapidly Changing Environment

Blanchet

Vincent

Womble

et al. 2021

Oceans

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The harbour seal (Phoca vitulina) is the world’s most widely distributed pinniped species ranging from temperate to Arctic regions (30–78.5° N in the Atlantic, 28–61.2° N in the Pacific), but no detailed overview of the species status exists. The aims of this review are to (i) provide current information on the genetic structure, population status, and threats; (ii) review potential consequences of a changing climate; and (iii) identify knowledge gaps to guide future research and monitoring. Although the species is globally abundant, wide differences exist across the species’ broad range. As climate warms, populations at the edges of the species’ distributional range are likely to be more affected. The primary climate-related drivers include: (i) changes in weather patterns, which can affect thermoregulation; (ii) decrease in availability of haul-out substrates; (iii) large-scale changes in prey availability and inter-specific competition; (iv) shifts in the range of pathogens; (v) increase in temperature favouring the biotransformation of contaminants; and (vi) increased exposure to pollutant from increased freshwater run-off. Multiple anthropogenic stressors may collectively impact some populations. Coordinated monitoring efforts across and within regions is needed. This would allow for a spatially explicit management approach including population-specific responses to known stressors.

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Drivers of spatiotemporal variability in bycatch of a top marine predator: First evidence for the role of water turbidity in protected species bycatch

Cited by 8 publications

References 52 publications

Underwater visibility constrains the foraging behaviour of a diving pelagic seabird

Underwater visibility constrains the foraging behaviour of a diving pelagic seabird

By-catch of sea turtles in Pacific artisanal fishery: Two points of view: From observer and fishers

Harbour Seals: Population Structure, Status, and Threats in a Rapidly Changing Environment

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