North Atlantic shark distribution signals and data gaps

Synthesis

The clearest recent North Atlantic shark/ray signal in the local evidence is Dipturus batis: 198 of 270 filtered post-2015 shark records across the North Atlantic bbox, all with depth, with most records in epipelagic depths and a smaller surface/mesopelagic tail. Secondary, much weaker signals are Scyliorhinus stellaris with 32 records and Mustelus mustelus with 15 records; Dipturus intermedius and Galeorhinus galeus are present but thin at 6 records each.

Consistency is not confirmed across all three evidence streams. The occurrence-record signal is strong for Dipturus batis and moderate for Scyliorhinus stellaris / Mustelus mustelus, but the vault/paper searches did not return matching North Atlantic shark survey-note or tag-derived evidence. The harness should treat these as occurrence-led distribution signals, not fully triangulated survey + tag signals. Main data caveats: only 270 post-2015 shark-filtered records, 3 datasets, and major imagery/vault-note gaps for the leading taxa.

WHAT NEXT: pull dataset coverage for the three source datasets, or traverse Dipturus batis / Scyliorhinus stellaris into adjacent papers and gaps.

The strongest gap is not depth metadata: the local North Atlantic shark packet has 1,856/1,856 records with depth, but it is thin in coverage, imagery, and taxonomic curation. Across 187 shark taxa, only 7 datasets contribute records, 1,469 records lack imagery, 237 lack IUCN status, and several leading taxa have no vault note, including Dipturus batis, Carcharias taurus, Carcharhinus acronotus, Carcharhinus falciformis, and Carcharhinus longimanus.

Spatially, the clearest nursery/coastal gap is the western North Atlantic shelf and subtropical margin: the shallow-water packet from 20-60°N, 85-45°W has only 319 shark records, 19 taxa, and 2 datasets. It is dominated by Carcharias taurus at 122 records, Leucoraja ocellata at 108, and Carcharhinus acronotus at 45. That makes sand tiger and skate nursery/coastal habitat a high-priority validation target.

Deepwater is broader but sparse: the >200 m North Atlantic packet has 326 records, 113 taxa, and 3 datasets, with median depth 1,187.4 m. Top taxa are low-count and taxonomically scattered: Carcharhinus falciformis 21, Carcharhinus longimanus 18, Centrophorus granulosus 13, Cetorhinus maximus 13, Gymnura sereti 11. The deep gap is strongest along slope, basin, and ridge habitats where many taxa appear as single-digit records.

Seasonal and boundary-zone inference is weak from the current packet. The index spans 1809-2024, but the visible evidence does not expose month/season bins, and dataset coverage drops sharply in focused habitats. Treat migration corridors and EEZ/national-boundary crossings as priority gaps until month-tagged records, tagging tracks, or repeated seasonal surveys are joined in.

WHAT NEXT: run corridor-specific packets for Gulf Stream, Mid-Atlantic Ridge/Azores, and US-Canada shelf break; or build a month-by-month shark gap layer.

The best-supported signal is fishing footprint plus bycatch, not temperature alone. In the North Atlantic shark packet, the local OBIS GeoParquet index shows only 1,509 shark/ray records across 160 taxa in the bbox, but the status mix is heavily depleted: 525 CR, 522 EN, 282 VU, 180 unrated. The dominant taxa are shelf and slope species such as *Dipturus batis* 253, *Leucoraja ocellata* 234, *Carcharias taurus* 101, *Galeorhinus galeus* 65, and *Cetorhinus maximus* 50. That pattern fits fisheries exposure: demersal trawls/longlines/gillnets remove or displace shelf elasmobranchs and create bycatch mortality hotspots. Vault evidence includes bycatch, and the paper hit Catch Efficiency Benefits and Bycatch Risks of Baited Drift Gillnets (2026, DOI 10.3390/su18104675) is the most relevant current literature signal visible here.

Second-order signals are warming waters, prey redistribution, and habitat compression. The depth profile is mostly shelf/upper-ocean: median 71 m, with 425 surface, 683 epipelagic, and 198 mesopelagic records. That makes these taxa sensitive to warming-driven poleward and depth shifts, especially where prey fields move faster than predator recovery. Habitat compression is strongest where shallow shelf habitat, oxygen/temperature limits, fishing gear, and coastal development overlap, forcing sharks into narrower thermal-depth corridors.

Ranked explanation: 1. fishing pressure/bycatch exposure, 2. warming-driven range and depth shifts, 3. prey-field movement, 4. habitat compression, with the latter three acting as amplifiers of the fisheries signal. Evidence caveat: map imagery/vault coverage is thin, with 1,132 missing-image records and missing vault notes for leading taxa, so this is a threat-signal read, not a full causal attribution.

WHAT NEXT: compare *Dipturus batis* vs *Leucoraja ocellata*, run a North Atlantic bycatch-gap scan, or focus the map on endangered shark records.

For North Atlantic shark/ray distribution gaps and fishing/bycatch pressure, the best named fit is The Shark Trust: donate at https://www.sharktrust.org/donate, join the Great Eggcase Hunt at https://www.sharktrust.org/great-eggcase-hunt, and track their Atlantic shortfin-mako, angel-shark, CITES, and ICCAT bycatch/trade campaigns.

Project AWARE is the strongest diver citizen-science option: donate at https://www.projectaware.org/donate and use Dive Against Debris at https://www.projectaware.org/dive-against-debris. It is not shark-only, but the vault note ties it to shark-conservation policy plus standardized underwater debris records.

Shark Stewards is shark-specific advocacy: donate at https://sharkstewards.org/donate/. Its documented focus is endangered sharks/rays, shark-fin trade, MPAs, and shark sanctuaries; the local note emphasizes US/Pacific policy more than North Atlantic shelf/slope work, so treat it as adjacent rather than the primary North Atlantic campaign vehicle.

Other vault hits worth checking next, but not yet read in this evidence loop: Sea Shepherd Conservation Society for fisheries enforcement/bycatch campaigns and Ocean Conservancy for policy/citizen-science programs.

WHAT NEXT: read Sea Shepherd and Ocean Conservancy notes, or run a fresh web-capable pass for current 2026 campaign pages.

What you can do:

• Open the cited vault notes and paper records for review.
• Use the map filter for the cited taxon or region to inspect occurrence coverage.
• Re-run the dossier with a narrower monitoring question if deeper synthesis is needed.

Threads

1. Which North Atlantic shark taxa show the clearest recent distribution signals across shelf, slope, and pelagic habitats, and are those signals consistent across occurrence records, survey notes, and tag-derived evidence?

The clearest recent North Atlantic shark/ray signal in the local evidence is Dipturus batis: 198 of 270 filtered post-2015 shark records across the North Atlantic bbox, all with depth, with most records in epipelagic depths and a smaller surface/mesopelagic tail. Secondary, much weaker signals are Scyliorhinus stellaris with 32 records and Mustelus mustelus with 15 records; Dipturus intermedius and Galeorhinus galeus are present but thin at 6 records each.

Consistency is not confirmed across all three evidence streams. The occurrence-record signal is strong for Dipturus batis and moderate for Scyliorhinus stellaris / Mustelus mustelus, but the vault/paper searches did not return matching North Atlantic shark survey-note or tag-derived evidence. The harness should treat these as occurrence-led distribution signals, not fully triangulated survey + tag signals. Main data caveats: only 270 post-2015 shark-filtered records, 3 datasets, and major imagery/vault-note gaps for the leading taxa.

WHAT NEXT: pull dataset coverage for the three source datasets, or traverse Dipturus batis / Scyliorhinus stellaris into adjacent papers and gaps.

Cited: paper/occurrence-of-heavy-metals-in-sediments-and-bioaccumulation-factor-in-ra-c60a861b, paper/deriving-water-quality-criteria-for-three-emerging-pesticides-chlorothal-04f52e7c, paper/sirovic-2015-blue-whale-acoustic, paper/bettridge-2015-humpback-recovery, paper/pace-2017-nare-pop-status, species/carcharhinus-leucas, species/eubalaena-glacialis, species/dipturus-lamillai, species/mustelus-asterias, species/navicula-pelagica, species/pronoctiluca-pelagica, species/scyliorhinus-canicula, species/carcharhinus-albimarginatus, species/carcharhinus-amblyrhynchos, species/carcharhinus-amboinensis, species/carcharhinus-brachyurus, species/carcharhinus-fitzroyensis

2. Where are the strongest spatial, seasonal, or taxonomic gaps in North Atlantic shark observations, especially around nursery areas, deepwater habitats, migration corridors, and national boundary zones?

The strongest gap is not depth metadata: the local North Atlantic shark packet has 1,856/1,856 records with depth, but it is thin in coverage, imagery, and taxonomic curation. Across 187 shark taxa, only 7 datasets contribute records, 1,469 records lack imagery, 237 lack IUCN status, and several leading taxa have no vault note, including Dipturus batis, Carcharias taurus, Carcharhinus acronotus, Carcharhinus falciformis, and Carcharhinus longimanus.

Spatially, the clearest nursery/coastal gap is the western North Atlantic shelf and subtropical margin: the shallow-water packet from 20-60°N, 85-45°W has only 319 shark records, 19 taxa, and 2 datasets. It is dominated by Carcharias taurus at 122 records, Leucoraja ocellata at 108, and Carcharhinus acronotus at 45. That makes sand tiger and skate nursery/coastal habitat a high-priority validation target.

Deepwater is broader but sparse: the >200 m North Atlantic packet has 326 records, 113 taxa, and 3 datasets, with median depth 1,187.4 m. Top taxa are low-count and taxonomically scattered: Carcharhinus falciformis 21, Carcharhinus longimanus 18, Centrophorus granulosus 13, Cetorhinus maximus 13, Gymnura sereti 11. The deep gap is strongest along slope, basin, and ridge habitats where many taxa appear as single-digit records.

Seasonal and boundary-zone inference is weak from the current packet. The index spans 1809-2024, but the visible evidence does not expose month/season bins, and dataset coverage drops sharply in focused habitats. Treat migration corridors and EEZ/national-boundary crossings as priority gaps until month-tagged records, tagging tracks, or repeated seasonal surveys are joined in.

WHAT NEXT: run corridor-specific packets for Gulf Stream, Mid-Atlantic Ridge/Azores, and US-Canada shelf break; or build a month-by-month shark gap layer.

3. Which current threat signals best explain North Atlantic shark distribution changes, including fishing pressure, bycatch exposure, warming waters, prey shifts, and habitat compression?

The best-supported signal is fishing footprint plus bycatch, not temperature alone. In the North Atlantic shark packet, the local OBIS GeoParquet index shows only 1,509 shark/ray records across 160 taxa in the bbox, but the status mix is heavily depleted: 525 CR, 522 EN, 282 VU, 180 unrated. The dominant taxa are shelf and slope species such as *Dipturus batis* 253, *Leucoraja ocellata* 234, *Carcharias taurus* 101, *Galeorhinus galeus* 65, and *Cetorhinus maximus* 50. That pattern fits fisheries exposure: demersal trawls/longlines/gillnets remove or displace shelf elasmobranchs and create bycatch mortality hotspots. Vault evidence includes bycatch, and the paper hit Catch Efficiency Benefits and Bycatch Risks of Baited Drift Gillnets (2026, DOI 10.3390/su18104675) is the most relevant current literature signal visible here.

Second-order signals are warming waters, prey redistribution, and habitat compression. The depth profile is mostly shelf/upper-ocean: median 71 m, with 425 surface, 683 epipelagic, and 198 mesopelagic records. That makes these taxa sensitive to warming-driven poleward and depth shifts, especially where prey fields move faster than predator recovery. Habitat compression is strongest where shallow shelf habitat, oxygen/temperature limits, fishing gear, and coastal development overlap, forcing sharks into narrower thermal-depth corridors.

Ranked explanation: 1. fishing pressure/bycatch exposure, 2. warming-driven range and depth shifts, 3. prey-field movement, 4. habitat compression, with the latter three acting as amplifiers of the fisheries signal. Evidence caveat: map imagery/vault coverage is thin, with 1,132 missing-image records and missing vault notes for leading taxa, so this is a threat-signal read, not a full causal attribution.

WHAT NEXT: compare *Dipturus batis* vs *Leucoraja ocellata*, run a North Atlantic bycatch-gap scan, or focus the map on endangered shark records.

Cited: paper/catch-efficiency-benefits-and-bycatch-risks-of-baited-drift-gillnets-55ffb93c, paper/deriving-water-quality-criteria-for-three-emerging-pesticides-chlorothal-04f52e7c, paper/ecological-assessment-of-macrobenthic-invertebrates-in-a-tidally-influen-eb188aae, paper/microplastic-concentration-and-composition-in-surface-waters-and-in-stre-9a91940e, paper/occurrence-of-heavy-metals-in-sediments-and-bioaccumulation-factor-in-ra-c60a861b, paper/optimizing-the-depressurization-rate-to-balance-ch4-hydrate-dissociation-ddb96880

4. What specific organizations, donation pages, citizen-science programs, or active campaigns address this question? Name them. Use web_search.

For North Atlantic shark/ray distribution gaps and fishing/bycatch pressure, the best named fit is The Shark Trust: donate at https://www.sharktrust.org/donate, join the Great Eggcase Hunt at https://www.sharktrust.org/great-eggcase-hunt, and track their Atlantic shortfin-mako, angel-shark, CITES, and ICCAT bycatch/trade campaigns.

Project AWARE is the strongest diver citizen-science option: donate at https://www.projectaware.org/donate and use Dive Against Debris at https://www.projectaware.org/dive-against-debris. It is not shark-only, but the vault note ties it to shark-conservation policy plus standardized underwater debris records.

Shark Stewards is shark-specific advocacy: donate at https://sharkstewards.org/donate/. Its documented focus is endangered sharks/rays, shark-fin trade, MPAs, and shark sanctuaries; the local note emphasizes US/Pacific policy more than North Atlantic shelf/slope work, so treat it as adjacent rather than the primary North Atlantic campaign vehicle.

Other vault hits worth checking next, but not yet read in this evidence loop: Sea Shepherd Conservation Society for fisheries enforcement/bycatch campaigns and Ocean Conservancy for policy/citizen-science programs.

WHAT NEXT: read Sea Shepherd and Ocean Conservancy notes, or run a fresh web-capable pass for current 2026 campaign pages.

Cited: organization/shark-trust, organization/shark-stewards, organization/sea-shepherd, organization/wdc, organization/ci-oceans, organization/project-aware, organization/reef-check, organization/5gyres, organization/ocean-conservancy, organization/surfrider