Navigating the Balance: Mapping Shipless, Preservation, and Mitigation Areas for Marine Biodiversity
Written by Frederico Mestre, Marcello D’Amico, Vinicius Augusto Galvão Bastazini, Jorge Assis, David Jacinto, Ana Marçalo & Fernando Ascensão
October 23, 2025
Image from Alan Bedding from Pixabay
The Rising Conflict Between Shipping and Biodiversity
Maritime shipping underpins global trade, carrying 80–90% of the world’s goods. While vital for economies and livelihoods, its ecological consequences are increasingly evident. Wildlife-vessel collisions, underwater noise, oil pollution, and artificial light at night all pose threats to marine megafauna, including cetaceans (whales and dolphins), sea turtles, pinnipeds (seals, sea lions, and walruses), and seabirds. These species are crucial for marine ecosystems yet highly vulnerable to shipping impacts. With maritime traffic steadily increasing since the 1990s and new trade routes opening in the Arctic, there is an urgent need to assess how shipping overlaps with biodiversity to guide conservation and management strategies.
Our study provides the global mapping of “shipless areas” — regions with minimal maritime traffic — and identifies conflict zones where shipping density and biodiversity hotspots overlap. By distinguishing between Priority Preservation Areas (PPAs), where biodiversity is high but vessel traffic is low, and Priority Mitigation Areas (PMAs), where both biodiversity and shipping are high, we offer a framework to inform marine spatial planning and the global 30×30 biodiversity target.
Mapping Shipless and Conflict Zones
The analysis combined biodiversity layers (Figure 1): the distribution data for 85 cetacean species, 32 pinnipeds, 7 sea turtles, and 370 seabirds, with shipping density obtained from Automatic Identification System data from the Global Maritime Traffic Density Service at 1 km² resolution (2012–2023).
Figure 1 – Map depicting the combined values of species richness and shipping density. The areas shaded white have relatively low shipping traffic and low species richness, and areas in brown have high shipping traffic and high species richness.
We classified species richness and vessel density into three categories (low, medium, high), with their overlap producing a map where we identified three typologies of areas: a) shipless areas - the lowest tercile of vessel density; b) PPAs - high species richness and low vessel density; and c) PMAs - high species richness and high vessel density (Figure 2).
Figure 2 – Priority Preservation Areas (PPAs): locations with high species richness and low vessel density (shown in yellow); and Priority Management Areas (PMAs): locations with high species richness and high vessel density (shown in red).
Global Distribution of Shipless Areas and Conflict Zones
Shipless areas are mainly confined to polar and remote regions, especially the Southern Ocean and high-latitude areas of the North Pacific and Atlantic Oceans (Figure 3). Smaller shipless pockets also occur near island groups such as Polynesia, Hawaii, and the Maldives. Biodiversity hotspots include continental coasts (e.g., western North America, North Sea, Yellow Sea, Azores) and southern basins of the Pacific, Atlantic, and Indian Oceans.
Figure 3 – Shipless areas (shown in light blue) and larger (>100,000 ha) Marine Protected Areas (shown in green).
By overlaying biodiversity with shipping density, we were able to reveal that PPAs concentrated at high southern latitudes, often near Antarctica, and PMAs clustered along busy coasts and shipping routes, particularly the mid-Pacific near Hawaii, the southern Indian Ocean, and the South Atlantic west of Africa.
Only 12.1% of shipless areas, 15.2% of PPAs, and 16.2% of PMAs are currently within Marine Protected Areas, with even lower protection under no-take reserves (5–9%).
At the country level, New Zealand’s Economic Exclusive Zone, for example, harbours large PPAs, while South Africa’s contains extensive PMAs. On the High Seas, outside the coastal regions defined by the Economic Exclusive Zones, biodiversity-rich PPAs and PMAs are found across the South Pacific, South Atlantic, and Indian Oceans, suggesting international cooperation is critical.
Conservation Opportunities and Challenges
The findings highlight two complementary priorities: a) preserve shipless areas and PPAs as refuges with little human pressure, particularly in polar and remote regions. Expanding the Marine Protected Area network here would strengthen ecological resilience and help achieve 30×30 goals.; and b) mitigate impacts in PMAs, where high biodiversity faces intense vessel activity. Strategies include rerouting traffic, imposing speed limits, reducing noise, and enforcing safe distances from sensitive sites.
However, the spatial distribution of these zones is dynamic. Events such as geopolitical crises (e.g., rerouting around South Africa during Red Sea disruptions) and climate change (e.g., opening Arctic passages) are already reshaping global shipping. On the other hand, climate change will also induce changes in species ranges, therefore changing the species’ richness distribution across the globe. These factors will contribute to potential changes in the distributions of conflict areas. This framework provides a flexible, scalable tool for adaptive planning.
Next steps for conserving biodiversity and managing maritime traffic
Our study delivers a global 2025 baseline for shipless and potential vessel-wildlife conflict zones for a wide pool of species, providing essential guidance for conservation planning at a time of accelerating maritime trade. By distinguishing low- and high-conflict areas, it identifies opportunities for preservation, highlights urgent mitigation needs, and aligns with global biodiversity targets. The work demonstrates that balancing shipping and marine conservation is achievable with strategic, evidence-based management.
Author information
Frederico Mestre
CCMAR—Algarve Centre of Marine Sciences, University of Algarve, Faro, Portugal.
Frederico Mestre’s research focuses on investigating how global environmental change and human activities shape species distributions and interactions.
Marcello D'Amico
Department of Conservation Biology and Global Change, Doñana Biological Station CSIC
Marcello D’Amico is a conservation biologist studying the effects of global change, with a focus on the relationship between infrastructure, such as roads and power lines, and biodiversity.
Vinicius Augusto Galvão Bastazini
Independent Researcher, Belgium
Vinicius Bastazini is interested in ecological and evolutionary dynamics and exploring species interactions and diversity.
Jorge Assis
CCMAR—Algarve Centre of Marine Sciences, University of Algarve, Faro, Portugal.
Jorge Assis is a marine macroecologist and data scientist studying global marine biodiversity and climate change impacts and informing conservation and policy.
David Jacinto
MARE - Marine and Environmental Sciences Centre, University of Évora, Sines, Portugal.
David Jacinto is a researcher in marine ecology, focusing on biodiversity conservation in temperate rocky shore ecosystems.
Ana Marçalo
CCMAR—Algarve Centre of Marine Sciences, University of Algarve, Faro, Portugal.
Ana Marçalo’s research focuses on fisheries science, marine mammal and sea turtle strandings, and the conservation of protected species, particularly through bycatch reduction and mitigation strategies.
Fernando Ascensão
CE3C - Centre for Ecology, Evolution and Environmental Changes & CHANGE - Global Change and Sustainability Institute, University of Lisbon, Lisbon, Portugal
Fernando Ascensão is an assistant professor at the University of Lisbon, in Conservation Biology, focusing on how transport and energy infrastructures affect ecological processes and population dynamics.
Editor:
Rodney van der Ree
Cite this summary:
Mestre, F., D'Amico, M., Bastazini, V. A. G., Assis, J., Jacinto, D., Marçalo, A., & Ascensão, F. (2025). Mapping global shipless areas and conflict zones between shipping and large marine vertebrates. Biological Conservation, 311, 111431. DOI: https://doi.org/10.1016/j.biocon.2025.111431