Movements and diving behaviour of white‐chinned petrels: Diurnal variation and implications for bycatch mitigation

Frankish, Caitlin K.; Manica, Andrea; Navarro, Joan; Phillips, Richard A.

doi:10.1002/aqc.3573

Cited by 6 publications

(4 citation statements)

References 86 publications

(145 reference statements)

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“…Beyond sea turtles, we expect that our methods will aid in understanding the three-dimensional movements of diverse species. Examples include (1) pinnipeds that are often tagged in a similar manner to sea turtles and have diverse dive types (Davis et al, 2003); (2) migratory fishes such as tuna where studies have used manual classification techniques to parse out dive classes (Wilson & Block, 2009); (3) birds that have aerial classes of movement and in some species diving behaviors (Frankish et al, 2021); and (4) arboreal mammals, which have vertical movement within forest canopies (Allan et al, 2019;Scheffers et al, 2017). In summary, the application of DTW and CNN approaches to movement data may be useful for species with three-dimensional and cryptic behaviors.…”

Section: Discussionmentioning

confidence: 99%

Clustering and classification of vertical movement profiles for ecological inference of behavior

et al. 2023

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Vertical movements can expose individuals to rapid changes in physical and trophic environments—for aquatic fauna, dive profiles from biotelemetry data can be used to quantify and categorize vertical movements. Inferences on classes of vertical movement profiles typically rely on subjective summaries of parameters or statistical clustering techniques that utilize Euclidean matching of vertical movement profiles with vertical observation points. These approaches are prone to subjectivity, error, and bias. We used machine learning approaches on a large dataset of vertical time series (N = 28,217 dives) for 31 post‐nesting leatherback turtles (Dermochelys coriacea). We applied dynamic time warp (DTW) clustering to group vertical movement (dive) time series by their metrics (depth and duration) into an optimal number of clusters. We then identified environmental covariates associated with each cluster using a generalized additive mixed‐effects model (GAMM). A convolutional neural network (CNN) model, trained on standard dive shape types from the literature, was used to classify dives within each DTW cluster by their shape. Two clusters were identified with the DTW approach—these varied in their spatial and temporal distributions, with dependence on environmental covariates, sea surface temperature, bathymetry, sea surface height anomaly, and time‐lagged surface chlorophyll a concentrations. CNN classification accuracy of the five standard dive profiles was 95%. Subsequent analyses revealed that the two clusters differed in their composition of standard dive shapes, with each cluster dominated by shapes indicative of distinct behaviors (pelagic foraging and exploration, respectively). The use of these two machine learning approaches allowed for discrete behaviors to be identified from vertical time series data, first by clustering vertical movements by their movement metrics (DTW) and second by classifying dive profiles within each cluster by their shapes (CNN). Statistical inference for the identified clusters found distinct relationships with environmental covariates, supporting hypotheses of vertical niche switching and vertically structured foraging behavior. This approach could be similarly applied to the time series of other animals utilizing the vertical dimension in their movements, including aerial, arboreal, and other aquatic species, to efficiently identify different movement behaviors and inform habitat models.

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Section: Discussionmentioning

confidence: 99%

Clustering and classification of vertical movement profiles for ecological inference of behavior

et al. 2023

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“…Similar mechanistic studies of weighted hooks to be used in fisheries in other regions that encounter different seabird species complexes need to account for differences in the depth to which seabirds can access baited hooks. If the fishery being studied overlaps with species of shearwaters and Procellaria petrels, which are relatively proficient divers, rapidly attaining maximum depths of 10–20 m and 15–25 m, respectively 22 , 57 , and if secondary interactions occur 17 , 25 , then sink rate assessments would need to be conducted to substantially deeper depths than assessed here for the US central North Pacific tuna longline fishery.…”

Section: Discussionmentioning

confidence: 99%

Investigating weighted fishing hooks for seabird bycatch mitigation

Gilman

Musyl²,

Wild³

et al. 2022

Sci Rep

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Fisheries bycatch threatens the viability of some seabird populations and reduces fishing efficiency. Albatross bycatch in a US North Pacific tuna longline fishery has increased over the past decade and now exceeds 1000 annual captures. Seabirds interacting with this fishery reach hooks at depths up to 1 m. A branchline weight’s mass and distance from the hook affect seabird catch rates. We conducted experimental fishing to compare the commercial viability of a weighted hook relative to conventional gear with weights attached 0.75 m from the hook. We used a Bayesian random effects meta-analytic regression modelling approach to estimate pooled expected species-specific log relative risk of capture on conventional versus experimental gear. There was a significant 53% (95% HDI: − 75 to − 25%) decrease in retained species’ catch rates on experimental hooks, indicating an unacceptable economic cost, and no significant effect for discarded species. Using a Bayesian general linear mixed regression modelling approach, experimental hooks sank to 85 cm ca. 1.4 times (95% HDI: 1.37–1.48) faster than control hooks. Given their potential to reduce seabird catch rates, eliminate safety risks from bite-offs and facilitate robust compliance monitoring, it is a priority to find a weighted hook design with acceptable catch rates.

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“…Specifically, stronger regulations for West Coast inshore trawl and small-vessel surface-longline fisheries as they pose the greatest threat to Westland petrels (Richard et al, 2020). Better management of these fisheries would include stricter rules on offal discards and implementing bird-scaring technologies such as Tori lines (Frankish et al, 2021;Jiménez et al, 2020). In South Georgia, the implementation of these management strategies saw a significant reduction in fishery mortality for white-chinned petrels (Frankish et al, 2021).…”

Section: Recommendation For Managementmentioning

confidence: 99%

“…Better management of these fisheries would include stricter rules on offal discards and implementing bird-scaring technologies such as Tori lines (Frankish et al, 2021;Jiménez et al, 2020). In South Georgia, the implementation of these management strategies saw a significant reduction in fishery mortality for white-chinned petrels (Frankish et al, 2021).…”

Section: Recommendation For Managementmentioning

confidence: 99%

Westland petrel (Procellaria westlandica) foraging behaviour: Patterns and drivers of individual variation

Rands¹

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Foraging behaviour can have a major influence on the survival and reproduction of individuals which can ultimately impact the viability of a population. Foraging is particularly challenging for procellariiformes (tube nosed seabirds) who feed on patchily distributed prey in the highly dynamic marine environment. During the breeding season procellariiformes must also increase their foraging effort to raise their chick whilst having a reduced foraging range. As a result, procellariiformes have adopted various foraging strategies, such as dual foraging and sexual foraging dimorphism, to cope with this energy demanding lifestyle. Westland petrels (Procellaria westlandica) are an endangered winter breeding procellariform endemic to the West Coast of New Zealand’s South Island. Unlike other procellariiformes, previous studies have found little evidence of Westland petrels using sexually dimorphic or dual foraging strategies. Furthermore, Westland petrels also display a high level of individual variation in foraging behaviour. To understand why there is so much variation and what factors are driving it, I first examined variation at the population, individual and within individual level to describe and categorise different foraging strategies. I then investigated how factors such as year, sex and foraging site influenced variation. Finally, I examined how oceanic variables influenced habitat selection and foraging characteristics to understand how the environment drives variation in foraging behaviour. Considerable variation was found at all levels. Most of the variation was explained by year with individuals taking shorter foraging trips in 2011 and longer trips in 2015. Females foraged further than males suggesting that there is some degree of sexual foraging segregation occurring in Westland petrels. I also found that the highest variation in foraging behaviour was exhibited by individuals within their core foraging site on the West Coast. Sea surface temperatures were highest at the West Coast foraging site and individuals within this site showed differences in habitat selection among years. Habitat selection at the West Coast site also differed between sexes suggesting that males are outcompeting females for prime foraging spots. Overall, my results indicate that foraging conditions on the West Coast are highly variable likely due to rising sea surface temperatures, marine heatwaves, and the effects of the El Nino-Southern Oscillation. As a result, it is likely that prey availability on the West Coast is unpredictable causing high variation in foraging behaviour and sexual foraging segregation. With climate change, foraging conditions on the West Coast are predicted to get more unpredictable as sea surface temperatures continue to rise and extreme weather events become more frequent. These factors will make foraging increasingly difficult for Westland petrels and could see them rely more on fishery discards as a source of food, increasing their risk of incidental mortality. Conservation management should focus on protecting the petrels core foraging area around the Hokitika canyon to help limit the effects of climate change. Fishery management should also focus on limiting or prohibiting offal discards to prevent the incidental mortality of Westland petrels.

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Movements and diving behaviour of white‐chinned petrels: Diurnal variation and implications for bycatch mitigation

Cited by 6 publications

References 86 publications

Clustering and classification of vertical movement profiles for ecological inference of behavior

Clustering and classification of vertical movement profiles for ecological inference of behavior

Investigating weighted fishing hooks for seabird bycatch mitigation

Westland petrel (Procellaria westlandica) foraging behaviour: Patterns and drivers of individual variation

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