Biology subjects

March, D.

Publications and source records attributed to March, D..

5 recordsLinked to original sources

bioRxiv2026

Predicting seabird-vessel interactions from bird-borne data alone

Seabirds often follow fishing vessels to scavenge discards and bait, benefiting from access to food but also facing the risk of bycatch. Exposure to bycatch is commonly assessed by analysing seabird-fishing interactions, typically through the spatiotemporal alignment of seabird and vessel tracking data. However, this approach may underestimate interactions when vessel tracking information is incomplete or unavailable. We tested whether seabird-vessel interactions could be identified using seabird telemetry alone and whether fishing and nonfishing vessels could be distinguished. We analysed GPS, wet-dry, accelerometer and pressure data from 273 Scopoli's shearwaters in the Northwest Mediterranean. We identified 779 vessel-attendance events using seabird GPS, Automatic Identification System (AIS) data and simulation-based tests to distinguish vessel attraction or following from chance encounters. We then trained random forest models to predict vessel-attendance from bird-borne movement and environmental metrics, testing different sensor combinations. Finally, we selected the GPS and environmental model for its performance and compatibility with GPS-only tracking data from 17 radar-equipped shearwaters, whose detectors identified nearby vessels independently of AIS. Models predicting vessel-attendance from seabird movement metrics derived from GPS, wet-dry sensors and accelerometers achieved classification rates above 90% during training. However, when tested on new individuals, 42% of their positive predictions were false-positives. Models combining environmental metrics with either GPS or GPS and wet-dry data achieved classification rates around 75% during training and generalised consistently across individuals, maintaining classification rates of 70% or above. Attendance events involving fishing (n = 482) and nonfishing vessels (n = 297) could not be reliably distinguished. Across 45 trips of radar-equipped shearwaters, the GPS and environmental model discriminated vessel-attendance in hourly bins against AIS detections (AUC = 0.85), supporting assessment of spatiotemporal attendance patterns. At the event level, only 17% of 227 predicted vessel-attendance events were supported by AIS or radar detections. However, radar detected nearby vessels during 19 predicted events lacking AIS support, highlighting the value of complementary vessel detection. This study presents a vessel-independent framework for assessing seabird-vessel interactions based solely on bird-borne data, complementing fisheries monitoring programmes, helping to identify gaps in vessel-tracking systems across poorly monitored marine regions, and informing future assessments of bycatch risk.

ecology↗

bioRxiv2026

A simulation-based framework to detect marine animal-vessel interactions using tracking data

Understanding how animals respond to vessels is a fundamental question in conservation, since interactions between marine animals and vessels can expose wildlife to threats such as fisheries bycatch and vessel collisions. Although animal-borne tags and vessel-tracking systems now allow both components to be monitored at fine spatiotemporal scales, distinguishing behavioural interactions from incidental co-occurrence remains challenging, particularly in areas of dense marine traffic. Here, we developed a simulation-based framework to determine whether an animal is attracted to or follows a vessel, or instead moves independently. We applied the framework to concurrent GPS data from 2,705 foraging trips by Scopolis shearwaters (Calonectris diomedea) and Automatic Identification System (AIS) trajectories from fishing and nonfishing vessels in the northwestern Mediterranean. Candidate association events (n = 1,567) were first identified using spatiotemporal proximity and subsequently tested against simulated seabird trajectories representing movement in the absence of a vessel response. The framework classified apparent associations arising when vessels approached stationary birds or when independently moving trajectories crossed by chance as independent movement. Overall, 53.5% of association events showed evidence of vessel attraction, following, or both, whereas the remainder were consistent with independent movement. Although only approximately 3% of the vessels recorded by AIS were fishing vessels, they accounted for 69% of attraction events and 74% of following events, whereas most associations with nonfishing vessels were consistent with incidental proximity. Attraction and following became less likely as birds spent more time stationary and were more likely during daytime, while following was less likely for nonfishing than fishing vessels. These ecologically coherent patterns support the biological relevance of the interactions identified by the simulation-based approach. Sensitivity analyses showed that the number of associations detected by conventional threshold methods increased markedly with broader proximity criteria, whereas inference of attraction and, particularly, following remained comparatively stable. Implemented in the R package intersimR, the framework provides an accessible, reproducible, and scalable approach for separating behavioural responses from incidental co-occurrence at the event level and identifying the animal-vessel interactions most relevant to conservation and management.

ecology↗

bioRxiv2026

Threatened species bycatch hotspots in the tropical Atlantic Ocean

Predicting bycatch patterns in tropical tuna purse seine fisheries remain challenging due to low variance explained by existing models, limiting their use for management purposes. To address this limitation, we combined ecological network analyses and community detection methods to characterize recurring bycatch assemblages in tropical tuna purse seine fisheries. Ecological network analyses consistently revealed two key bycatch communities: one dominated by bony fishes with low conservation concern, and another by IUCN-listed threatened species (NT-CR; sharks, rays, sea turtles). By focusing on sets with high numbers of threatened species, we identified bycatch hotspots near Mauritania, Gabon and Angola. These hotspots result from seasonal fishing patterns and specific bycatch compositions, with specific composition in terms of sex and age, compared to the rest of the Atlantic. We suggest that the Mauritanian region is a potential candidate for shark nursery and sea turtle foraging grounds. These insights can guide the development of bycatch reduction strategies based on predictable spatio-temporal or community-specific features and provide a basis for targeted management actions.

ecology↗

bioRxiv2025

Predicting Potential Spawning Areas: a novel framework for elasmobranch conservation and spatial management

Defining and protecting critical habitats for elasmobranchs (sharks and rays), such as spawning areas, is essential for mitigating anthropogenic pressures that threaten their populations, primarily driven by fisheries and habitat degradation. This study presents a novel modelling-based framework to identify Potential Spawning Areas (PSAs) - habitats offering optimal conditions for oviposition. Using fisheries-dependent trawl bycatch data combined with environmental and anthropogenic predictors, we applied machine-learning models to delineate PSAs for the smallspotted catshark (Scyliorhinus canicula) and skates (Raja spp.) in the western Mediterranean. Static environmental predictors, including depth and slope, were primary drivers, while dynamic predictors, including sea bottom temperature and salinity played seasonally relevant roles. Trawl fishing pressure also influenced importantly the distribution of PSAs, revealing a concerning positive feedback loop between exploitation and habitat degradation. While PSAs experienced lower fishing effort than the rest of the study area, a substantial proportion of egg case bycatch still occurs within them. The current network of Marine Protected Areas in the region fails to adequately safeguard these habitats due to limited coverage and enforcement. Our findings underscore significant gaps in spatial management and the urgent need for targeted conservation measures. The PSA framework provides a robust, scalable tool for identifying critical habitats across regions and species, offering actionable insights for marine spatial planning and ecosystem-based management. This adaptable approach can support global conservation efforts for elasmobranchs and their ecosystems. SignificanceSharks and rays are vital to marine ecosystems but face alarming extinction risks due to overfishing and habitat loss. Identifying critical reproductive habitats, such as spawning areas, is essential for protection but remains a significant challenge. This study introduces a novel framework for identifying Potential Spawning Areas (PSAs) - habitats offering optimal conditions for oviposition - using machine-learning and fisheries bycatch data. Applied in the western Mediterranean for the smallspotted catshark and skates, it demonstrates how environmental factors and fishing pressures shape these habitats, highlighting significant management gaps. The PSAs framework offers a scalable approach to guide the establishment of marine protected areas and fisheries management plans, providing a novel approach for conserving vulnerable marine species and their habitats.

ecology↗

bioRxiv2020

Disease Risk Analysis in sea turtles: A baseline study to inform conservation efforts

The impact of a range of different threats has resulted in the listing of six out of seven sea turtle species on the IUCN Red List of endangered species. Disease risk analysis (DRA) tools are designed to provide objective, repeatable and documented assessment of the disease risks for a population and measures to reduce these risks through management options. To the best of our knowledge, DRAs have not previously been published for sea turtles, although disease is reported to contribute to sea turtle population decline. Here, a comprehensive list of health hazards is provided for all seven species of sea turtles. The possible risk these hazards pose to the health of sea turtles were assessed and "One Health" aspects of interacting with sea turtles were also investigated. The risk assessment was undertaken in collaboration with more than 30 experts in the field including veterinarians, microbiologists, social scientists, epidemiologists and stakeholders, in the form of two international workshops and one local workshop. The general finding of the DRA was the distinct lack of knowledge regarding a link between the presence of pathogens and diseases manifestation in sea turtles. A higher rate of disease in immunocompromised individuals was repeatedly reported and a possible link between immunosuppression and environmental contaminants as a result of anthropogenic influences was suggested. Society based conservation initiatives and as a result the cultural and social aspect of interacting with sea turtles appeared to need more attention and research. A risk management workshop was carried out to acquire the insights of local policy makers about management options for the risks relevant to Queensland and the options were evaluated considering their feasibility and effectiveness. The sea turtle DRA presented here, is a structured guide for future risk assessments to be used in specific scenarios such as translocation and head-starting programs.

ecology↗