Identifying key connections for migratory marine animals

Migratory species are ubiquitous across all taxonomic groups. However, many migratory species are currently in decline.

For migratory marine species in particular, almost half of all species are listed as threatened, near threatened, or data deficient. With nearly two-thirds of the ocean classified as international waters, and therefore largely unprotected, marine migratory animals face the daunting problem of traversing potentially unsafe waters.

While it’s clear that connected habitats are critical for migratory species, migratory animals present a unique management problem. Their migratory routes often cross national boundaries, meaning countries must work together to protect and conserve migratory species.

Bentley, L.K., Nisthar, D., Fujioka, E., Curtice, C., DeLand, S.E., Donnelly, B., Harrison, A.L., Heywood, E.I., Kot, C.Y., Ortuño Crespo, G. and Poulin, S. 2025. Marine megavertebrate migrations connect the global ocean. Nature Communications 16(1): 4089.

While we know that migratory species are in decline, we do not have sufficient, easily accessible data on most animals’ migratory cycles for managers and policymakers to coordinate protections between countries.

In a new review, researchers sought to fill this gap between science, management, and policy by identifying key habitats and the corridors linking them for over 100 migratory marine species. They gathered and synthesized a data set of over 5,000 migration sites (areas where significant activities occur, like foraging or breeding) and migration routes for 40 seabirds, 34 fish, and 28 marine mammals. The data set, Migratory Connectivity in the Ocean, is free and available at www.mico.eco.

Researchers found that countries, on average, were connected to 28 other jurisdictions by migratory marine species. Ectotherms (fish and sea turtles) generally connected tropical areas, whereas endotherms (sea birds and mammals) moved between the tropics and the poles.

Migration sites were grouped geographically by taxon. The explanation for this geographic clustering is also taxon-dependent. For example, sea turtle migration sites were grouped around the tropics, which matches their geographic distribution. However, seabird migration sites were grouped in polar regions, which is likely due to a bias towards seabird research in these areas.

This dataset represents a baseline of the minimum extent of connectivity needed between sites for migratory marine animals, and is a step towards meeting the mandate for an atlas of animal migrations given to the Convention on Migratory Species. However, this data set is just a start: biases in the data, like an over representation of age and sex classes that are easier to track, point towards a need for more information on lesser known species that are still ecologically important.

Identifying key migration sites and routes is an important development in providing protected, connected habitats for migratory species. With data in hand on important migration sites for animals, policy makers can target those areas for protections. Data on migration cycles for marine animals is a key piece of the puzzle in creating effective networks of protected areas. With their need for cross-boundary protections, migratory species remind us that conservation is a global effort.

State	Year	Policy	Description
New Hampshire	2026	SB592	Enables regional, conservation, and energy resource planning for habitat strongholds and wildlife corridors
New Hampshire	2019	SB200	Requires the New Hampshire Department of Transportation to consider fish and wildlife crossings and mitigation measures in all future road and culvert projects
New Hampshire	2016	SB376	Requires the fish and game department to identify existing and needed wildlife corridors connecting wildlife habitats in the state and to make recommendations for legislative changes

State	Year	Policy	Description
Maine	2023	LD258	Appropriates $7.5 million to Department of Transportation to improve roadways with potential adaptations for wildlife
Maine	2023	LD1881	Establishes compensation fee program relating to fish and wildlife habitats and associated corridors, including compensation paid by solar energy development
Maine	2023	LD508	Requires Department of Environmental Protection to review its permitting laws concerning climate change, habitat connectivity, ecological resilience, and coastal environments

State	Year	Policy	Description
New Jersey	2025	S3618	Directs state agencies to develop a Wildlife Corridor Action Plan
New Jersey	2024	S3916/A5486	Expands eligibility for existing wildlife fencing programs by including farmers leasing farmland
New Jersey	2007	NJAC7:13	Requires the state to incorporate wildlife crossings or a natural bank for terrestrial threatened and endangered species and/or species of concern when a new bridge or culvert project would cause habitat fragmentation

State	Year	Policy	Description
New Mexico	2023	SB72	Appropriates money to new Wildlife Corridors Fund for implementation of wildlife crossing projects under New Mexico Wildlife Corridor Action Plan
New Mexico	2022	HB 2	Allocates funding for projects to reduce wildlife-vehicle collisions and allows the Department of Transportation and Department of Game to implement their Wildlife Corridors Action Plan
New Mexico	2019	SB 228	Requires the creation of a Wildlife Corridor Action Plan that includes comprehensive guidance to agencies for identifying, prioritizing and maintaining important areas for wildlife movement

State	Year	Policy	Description
Washington	2023	HB1216/SB5196	Requires Department of Ecology to prepare environmental impact statements for clean energy projects that consider impacts to habitat connectivity and wildlife migration corridors
Washington	2022	SB5689	Provides funding for US 97 Wildlife Crossing Improvements project
Washington	2019	SEO 1031.02	Recognizes the effect of roadways in creating barriers to wildlife movement, breeding, and migrations; the Washington State Department of Transportation will promote and support Practical Solutions and Planning and Environmental Linkages to integrate habitat connectivity and biodiversity plans; will make use of the highway prioritization map known as Habitat Connectivity Investment Priorities; and will corporate and coordinate with other agencies involved in wildlife habitat protection, specifically along highways

Connecting Science to Conservation

Identifying key connections for migratory marine animals

Bentley, L.K., Nisthar, D., Fujioka, E., Curtice, C., DeLand, S.E., Donnelly, B., Harrison, A.L., Heywood, E.I., Kot, C.Y., Ortuño Crespo, G. and Poulin, S. 2025. Marine megavertebrate migrations connect the global ocean. Nature Communications 16(1): 4089.

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Identifying key connections for migratory marine animals

About the Author: Alice Dykstra

State	Year	Policy	Description
Wyoming	2026	SF0052	Allocates funds for restoration of aquatic habitats including barrier removal for fish
Wyoming	2025	SF0088	Allocates funds for projects improving wildlife connectivity including fence removal, wildlife crossings improvements, and habitat restoration
Wyoming	2024	SF0060	Provides funds to help maintain primary migration corridors for ungulates in the Little Snake River Conservation District
Wyoming	2023	SF0106	Provides funds for large wildlife crossing projects across the state
Wyoming	2022	SF0048	Approves funding for specific wildlife crossings and aquatic connectivity initiatives
Wyoming	2021	SF066	Provides funds for large wildlife crossing projects across the state
Wyoming	2020	EO 1	Designates three mule deer migration corridors and establishes the process whereby future corridors can be designated
Wyoming	2020	HB 69	Establishes a system wherein funding from outdoor recreation can be appropriated for wildlife conservation efforts related to the state’s transportation system
Wyoming	2018	HB39	Proceeds from the newly established wildlife conservation license plates are allocated to wildlife connectivity improvements to the state transportation system

State	Year	Policy	Description
Vermont	2023	Act59	Vermont's 30x30 law that commits to conserving and maintaining an ecologically functional landscape that sustains biodiversity and maintains landscape connectivity
Vermont	2016	Act 171	Primarily focuses on timber harvesting regulations, but calls for a study of necessary revisions to planning statutes that protect contiguous areas of forestland from fragmentation and promote habitat connectivity between forestlands

State	Year	Policy	Description
Colorado	2026	SB141	Creates optional collision prevention fee to fund wildlife safe passage projects
Colorado	2025	HB1093	Restricts local limits on residential density unless offset elsewhere, exempts areas near wildlife crossings, and allows municipalities to seek judicial review of land use initiatives
Colorado	2023	SB 23-092	Encourages minimal impacts to wildlife migration corridors when constructing solar panel farms
Colorado	2023	SB 214	Appropriates funding to the Colorado Wildlife Safe Passages Fund for wildlife crossing projects
Colorado	2022	SB22-151	Creates a $5 million fund for measures that reduce wildlife-vehicle collisions and reconnect habitat fragmented by roads
Colorado	2022	HB22-1072	Expands the scope of Habitat Partnership Program to fund efforts to conserve wildlife migration
Colorado	2021	SJR 21-021	Aims to protect and enhance habitat connectivity in the state through the establishment of a working group to develop state policies on corridors, as well as the commission of a report on state corridors and voluntary policies to support willing landowners in improving connectivity
Colorado	2019	EO 11	Directs Colorado agencies to identify policy, regulatory, and legislative opportunities to ensure the ongoing conservation of seasonal big game habitat and migration corridors
Colorado	2018	SB 18-143	States explicit goals for Division of Parks and Wildlife to invest in habitat conservation and wildlife crossings

State	Year	Policy	Description
Florida	2024	SB1638	Dedicates annual funding to land purchases, conservation easements, and trail maintenance within Florida Wildlife Corridor
Florida	2023	HB1379	Creates annual appropriation to acquire lands that complete certain linkages and are under high population stress within Florida Wildlife Corridor
Florida	2023	SB2500 sec.146	Provides funding to buy Ocala to Osceola (“O2O”) Wildlife Corridor
Florida	2021	SB976	Tasks state agencies with maintaining wildlife connectivity and designates Florida Wildlife Corridor as an existing physical, geographically defined area
Florida	2021	SB2500	Appropriates $300 million to acquire lands to conserve Florida Wildlife Corridor
Florida	2019	SB7068	Creates a "Multi-use Corridors of Regional Economic Significance Program" that includes protection of wildlife corridors as an intended benefit
Florida	2008	SB542	Amends Florida Forever Act statues to include goals of connecting linkage corridors
Florida	2001	SB1468	Amends Florida Forever Act to establish that land acquisitions should include complete landscape linkages and corridors
Florida	1999	S908	Creates Florida Forever Program, with increased protection of lands that protect threatened or endangered species and plans to create a statewide system of connected landscape linkages