Investigation — Moreton Bay current claim
Local / social observation treated as a hypothesis. Independent measurements are tested. This is not a migration alert.
The claim
A strong southward-flowing current near Moreton Bay, a seasonal transition toward increased bull shark activity, possible movement south through the Gold Coast and Northern NSW, concern about rivers and estuaries, simultaneous unavailability of several northern SharkSmart acoustic stations, and a suggested elevated period of about a month.
Observer class: social / local ecological knowledge · Geography: Moreton Bay → Gold Coast → Northern NSW
Independent tests
Is southward current velocity near Moreton Bay / Gold Coast currently elevated?
UNKNOWN
EAC / OceanCurrent products are not machine-connected. Open-Meteo does not provide EAC core position. Candidate variable only — not encoded as a rule.
Is the East Australian Current unusually close to the coast?
UNKNOWN
No shelf-proximity product is ingested.
Current SST and SST anomaly?
MEASURED (centroid)
Open-Meteo marine SST 21 Sep 2026: Moreton Bay 21.1°C; Gold Coast 21.5°C; Sydney 18.0°C; Mallacoota 14.8°C; Lakes Entrance 13.9°C; Port Phillip 13.9°C. Victorian waters are a different thermal regime.
Does this hypothesis extend to Victoria?
NOT SUPPORTED
Bull-shark 0.1 thermal suitability at ~14°C is near zero. Victoria is a temperate range-edge (white shark / bronze whaler / sevengill). Represented on the corridor map; the pulse is not extrapolated to Port Phillip.
Recent Queensland and Northern NSW rainfall?
MEASURED (proxy)
Open-Meteo hourly precipitation 14–21 Sep 2026 at Moreton and Tweed shows only trace totals (tenths of a millimetre). No significant rainfall event in that window. Does not support a catchment-runoff pulse.
Major river discharge?
UNKNOWN
BOM Water / WaterNSW gauges are REQUIRES_VERIFICATION. Rainfall is not a substitute for discharge.
Estuary plume conditions?
UNKNOWN
No turbidity / plume satellite product is connected.
Recent bull shark detections?
NONE IN VSHARK
No live authorised detection feed. Absence here is not evidence of absence.
SharkSmart receiver operational status / Northern NSW coverage degraded?
UNKNOWN
The report of offline northern receivers cannot be confirmed or denied until a lawful receiver-health feed exists. Surveillance confidence is therefore low.
Do similar historical combinations correspond with increased observations?
NOT TESTED
No back-test archive of EAC + SST + discharge vs detections is in this build.
Open-Meteo marine SST (21 Sep 2026): Moreton 21.1°C (thermal 0.51); Gold Coast 21.5°C; Sydney 18°C; Mallacoota 14.8°C; Port Phillip 13.9°C (thermal 0.01). Regional grid, not a thermistor.
Supported
- Coastal SST in the low 20s °C is in a range the development thermal curve treats as increasingly relevant, not strongly peak.
Not supported (so far)
- Recent rainfall proxy does not show a major runoff event in the week to 21 Sep 2026.
- No live bull-shark detections are in vShark to corroborate a pulse.
- Victorian SST (~14°C at Mallacoota / Port Phillip on 21 Sep 2026) does not support treating Victoria as the next node of a bull-shark pulse.
Still a hypothesis
- That a strong southward current is occurring and that it precedes bull-shark movement (EAC unmeasured).
- That northern acoustic receivers are currently unavailable (health unmeasured).
- That activity will be elevated for about a month (cannot be tested without detections and history).
Evidence register
| Relationship | Strength | Model status |
|---|---|---|
| Bull sharks and SST | moderate/strong | active (continuous curve, not a hard 20°C gate) |
| Bull sharks and rainfall / runoff | moderate | active as rainfall proxy only — discharge unconnected |
| Bull sharks and river discharge | moderate | experimental / missing |
| Bull sharks and EAC / southward current | uncertain | experimental — omitted until a current product is connected |
| Bull sharks and estuary / river-mouth proximity | strong | active as node type prior, not as detection |
Local ecological knowledge generated the hypothesis. Independent evidence does not presently confirm a migration pulse. Do not encode the social-media interpretation as a rule.