Understanding the Stock
Stock condition
The latest scientific assessment concludes that Southwest Pacific swordfish are in healthy condition relative to the conventional maximum‑sustainable‑yield (MSY) yardsticks. Across a very large ensemble of model runs, the stock’s recent spawning biomass is well above the level that would produce MSY (median SBrecent/SBMSY ≈ 2.37) and recent fishing mortality is well below the MSY threshold (median Frecent/FMSY ≈ 0.27). Put simply: the stock is not overfished and overfishing is not occurring. While biomass has trended downward since a mid‑2010s bump, it remains comfortably above MSY‑based limits.
Current fishery status
Longline fleets catch swordfish widely across the South Pacific. Catches climbed through the 2000s, peaked around 9,000–10,000 tonnes in the early 2010s, and have eased in recent years to about 5,000–,6,000 tonnes annually within the Southwest Pacific assessment area. Fishing today is a mix of targeted swordfish longlining off eastern Australia and New Zealand, high‑seas operations further east, and bycatch in tropical bigeye tuna sets (notably by Chinese Taipei) in the north‑eastern part of the region.
Focusing on the most recent year reported in the overview: total South Pacific swordfish catch (i.e., across WCPFC and IATTC waters) was provisionally 17,572 t in 2024, largely from the EU‑Spanish high‑seas fleet, while the catch within WCPFC waters south of the equator was 4,489 t, well below peaks seen in 2012–2014.
Importance of the fishery
Swordfish is a high‑value longline product that contributes meaningful revenue to domestic fleets (e.g., Australia and New Zealand) and to Pacific small‑island economies through access arrangements and local operations. Within the broader Western and Central Pacific fisheries, longline accounts for only ~8–10% of total tuna/billfish volume, yet it rivals purse seine in landed value, reflecting the premium nature of longline markets. The WCPFC has also recognized the potential of South Pacific swordfish to provide “long‑term economic opportunities” for small island developing States when well managed.
Science
Stock status – latest assessment
In 2025, scientists rebuilt the assessment in the Stock Synthesis framework, moving to a two‑sex model and running a structured grid (360 models) plus estimation uncertainty (360,000 runs) to capture the plausible range of outcomes. Despite known data tensions (notably between CPUE series and weight/size compositions), the headline remains consistent: SBrecent/SBMSY stays well above 1 and Frecent/FMSY well below 1 across the ensemble, i.e., “green‑zone” status on both the Kobe and Majuro plots throughout the fishery’s history. The assessment also notes a gradual biomass decline since the late 2010s and emphasizes that growth, spatial structure, and the absolute scale of the population remain key uncertainties.
Scientific advice to managers
Scientists advise managers to (i) treat the stock as healthy but trending down from mid‑2010s levels; (ii) note that MSY‑based conclusions are robust to many model choices; and (iii) prioritize data improvements to reduce the biggest uncertainties. In particular, the assessment invites the Commission to consider Close‑Kin Mark‑Recapture (CKMR) to validate population size, expand age‑reading programs (otoliths) by sex and area, standardize length/weight measurements to minimize conversion‑factor noise, and continue work on alternative/diagnostic CPUE series. These steps would materially strengthen future advice.
How does the WCPFC manage the Southwest Pacific swordfish fishery?
Current management framework
WCPFC’s dedicated measure for South Pacific swordfish is CMM 2009‑03. It limits each member’s number of swordfish vessels south of 20°S to the maximum in any year from 2000–2005 and caps catches south of 20°S at the member’s maximum in 2000–2006. It also prohibits shifting effort to north of 20°S to compensate, requires nominated catch limits and annual reporting, sets compliance review through TCC, and established that the measure would be reviewed in light of new science. (CMM 2009‑03 replaced CMM 2008‑05.)
Management issues
Three strategic issues stand out:
- Geography vs. biology. The measure constrains effort/catch only south of 20°S, yet substantial fishing occurs north of that line (e.g., sub‑tropical/tropical bycatch around 2°N–10°S), and swordfish move across regional and RFMO boundaries (WCPFC/IATTC). This raises questions about alignment between the managed area and the biological unit.
- Cross‑RFMO coordination. A large share of total South Pacific swordfish is taken by the EU‑Spanish fleet in waters that include the far‑eastern Pacific high seas, underscoring the need for complementary action with IATTC, something the WCPFC itself acknowledges in the CMM preamble.
- Information gaps that matter. The assessment’s main uncertainties, such as growth, population scale, spatial structure, and composition data are management‑relevant. Recent gaps in size data from key fleets (e.g., EU‑Spanish) and documented conflicts between CPUE and weight composition signals reduce confidence in trend interpretation and harvest‑strategy design.
Improving Future Management
A practical pathway consistent with the science would include:
- Adopt a harvest‑strategy framework for Southwest Pacific swordfish, with explicit target and limit reference points (WCPFC has not yet adopted formal RP for this stock; the assessment uses default MSY‑based proxies), a monitoring strategy, and pre‑agreed harvest control rules.
- Modernize the spatial scope of the measure. Revisit the south‑of‑20°S focus and consider area‑based limits that better match where catch and movement actually occur (including the tropical/sub‑tropical “2N/1C/2C” band) while coordinating with IATTC for the east.
- Invest in the right data. Commission CKMR sampling to pin down population scale; expand sex‑specific age data across sub‑regions; standardize length/weight protocols; and continue CPUE diagnostics (including alternative indices) so that abundance signals are resilient to fleet behavior and measurement noise.
- Tighten fleet‑level monitoring where information is thin. Encourage timely size/sex submissions from all major fleets (notably EU‑Spanish), and consider electronic monitoring to bolster size composition and bycatch recording.
Summary
In short: Southwest Pacific swordfish is a healthy stock relative to MSY but has slipped from mid‑2010s highs. The fishery’s footprint spans domestic and high‑seas operations, with notable catches outside the current WCPFC control line (20°S), and a large share in adjacent IATTC waters. Management today is anchored by a 2009 cap‑and‑stabilize measure south of 20°S; the next step is to graduate to a harvest‑strategy approach, better align spatial controls with biology, and close the most important data gaps (CKMR, age/size standardization, robust CPUE), so that the fishery’s economic benefits, especially for small island economies, are secured on a robust scientific foundation.