## Facts

- Southern bluefin tuna is a highly migratory stock subject to conservation concerns and scientific uncertainty about depletion.
- Australia and New Zealand alleged Japan conducted unilateral “experimental fishing” programs in 1998 and 1999 that exceeded agreed catch limits while CCSBT negotiations on conservation measures were ongoing.
- Australia and New Zealand claimed Japan failed to cooperate in conserving the stock, invoking UNCLOS duties concerning highly migratory species and conservation of living resources of the high seas (UNCLOS arts. 64, 116–119).
- Australia and New Zealand initiated separate Annex VII arbitrations against Japan under UNCLOS concerning southern bluefin tuna (15 July 1999).
- Pending constitution of the Annex VII tribunal, both applicants requested provisional measures from ITLOS under UNCLOS art. 290(5) (30 July 1999); ITLOS joined the parallel proceedings and held hearings (18–20 August 1999).
- Japan objected that the dispute was primarily about CCSBT interpretation and application, that CCSBT displaced UNCLOS dispute settlement, and that Part XV preconditions (including exchange of views) were not satisfied.

## Issues

1. Whether ITLOS had prima facie jurisdiction under UNCLOS art. 290(5) to prescribe provisional measures pending Annex VII arbitration.
2. Whether the existence of CCSBT and its dispute-settlement arrangements excluded recourse to UNCLOS Part XV procedures for the dispute.
3. Whether the applicants showed plausible rights under UNCLOS and urgency, including a risk of irreparable harm to the stock and the marine environment absent interim relief.

## Decision

- ITLOS found prima facie jurisdiction to prescribe provisional measures pending the Annex VII tribunal’s constitution.
- ITLOS held that CCSBT’s application between the parties did not, at the provisional-measures stage, exclude reliance on UNCLOS obligations regarding conservation and management of the stock.
- ITLOS concluded the applicants had met the Part XV, Section 1 preconditions sufficiently for purposes of provisional measures.
- ITLOS determined the applicants asserted plausible UNCLOS rights to cooperation and conservation (arts. 64, 116–119) and that continued unilateral experimental fishing posed urgency and a risk of irreparable harm given uncertainty about the stock’s condition.
- ITLOS ordered Japan to cease its unilateral experimental fishing program, directed all parties to act with prudence and caution to conserve the stock, and required the parties to refrain from acts that might aggravate or extend the dispute or make settlement more difficult.

## Legal Principles

- Under UNCLOS art. 290(5), provisional measures may be prescribed when an Annex VII tribunal is not yet constituted if prima facie jurisdiction exists and measures are needed to preserve rights or prevent serious harm pending a merits decision.
- A single dispute may implicate obligations under UNCLOS and a specialized fisheries treaty; the existence of a related treaty does not automatically displace UNCLOS duties or UNCLOS dispute-settlement procedures for provisional-measures purposes absent clear exclusion.
- Provisional measures may be justified where scientific uncertainty and alleged depletion create urgency and a risk that continued exploitation could cause harm not readily repairable within the proceedings’ timeframe.
- Parties before an international tribunal must avoid conduct that aggravates or extends the dispute or undermines the effectiveness of eventual adjudication.

## Conclusion

ITLOS granted binding provisional measures to protect the southern bluefin tuna stock by stopping Japan’s unilateral experimental fishing and requiring caution and non-aggravation while Annex VII proceedings were pending, based on prima facie UNCLOS jurisdiction and urgent risk of irreparable harm despite parallel CCSBT arrangements.


New Zealand v. Japan (S. Bluefin Tuna Cases), 1999 I.T.L.O.S. 280 (Int’l Trib. L. Sea 1999)