Habitat Bio
Depth Zone: Abyssal ( >1000m). Horizontal Dist: Oceanic. Vertical Dist: Pelagic.
Geo Dist
Geo Dist: Highly migratory
Aq Res Struct
Biological Stock: Yes
Swordfish tend to inhabit waters further below the surface during the day than at night, and they tend to inhabit current frontal zones. Several of these fronts occur in the eastern Pacific Ocean (EPO), including areas off California and Baja California, off Ecuador, Peru, and Chile, and in the equatorial Pacific. Swordfish tolerate temperatures of about 5° to 27°C, but their preferred range is about 18° to 22°C, while larvae have been found only at temperatures exceeding 24°C.
Swordfish grow in length very rapidly, with both males and the faster-growing females reaching lower-jaw-fork lengths of more than a meter during their first year. Swordfish begin reaching maturity at about two years of age, when they are about 150 to 170 cm in length, and by age four all are mature. They probably spawn more than once per season. For fish greater than 170 cm in length, the proportion of females increases with increasing length.
There is strong evidence that swordfish in the Pacific comprise multiple stocks. Several specific spawning regions are known, and analyses of fisheries, tagging and genetic data suggest that there is only limited exchange of swordfish between geographical areas, including between the eastern and western, and the northern and southern, Pacific Ocean. As many as six stocks may exist in the Pacific Ocean, but the exact boundaries of these stocks, as well as their exchange rates—for the purposes of stock assessment—is currently uncertain. In the early 2000’s, the IATTC produced
indicators for swordfish in five areas of the EPO: two areas north of 10°N, separated at 125°W, a central area between 10°N and 5°S, and two areas south of 5°S, separated at 90°W.
Exploit
Swordfish (
Xiphias gladius) occur throughout the Pacific Ocean (PO) between about 50°N and 50°S. In the Eastern Pacific Ocean (EPO), they are caught mostly by the longline fishery—about 80% of the catch in weight on average in recent years—by distant water fleets of Far East and Western Hemisphere nations. Lesser amounts are taken by drifting gillnets (~20%), mainly in South America, and minimal amounts by other gillnets and harpoon. They are seldom caught in the recreational fishery in the EPO.
The total annual longline fishing effort for the main longline fleets in the north EPO increased from about 25 million hooks in 2007 to about 50 million hooks in 2013 and is about 43 million hooks in 2016-2020 (Figure G-1)
 |
Figure G-1: Longline fishing effort (in millions of hooks) in the North EPO for the main longline fleets for 1992-2020 (Table A-9).  |
See also fishery fact sheet:
EPO Tunas and billfishes fishery |
| Figure G-2: Retained catches of swordfish in the North EPO for 1945-2020. |
Bio Assess
Results
A
sex-specific age-structured stock assessment of swordfish in the Pacific Ocean north of the equator (from 2007) indicated that, at the level of fishing effort in 2002, there was negligible risk of the spawning biomass decreasing to less than 40% of its unfished level. In a partially overlapping region, the results of a North Pacific swordfish stock assessment completed in 2019 using data through 2016 (
ISC/18/ANNEX/16) indicated that stock biomass was 87% above SSB
MSY and fishing mortality was 45% below F
MSY, indicating that the stock is not overfished and overfishing is not occurring at current levels of fishing effort.
The last five-year average remains significantly below the 2001–2003 average of 63 million hooks. Based on the latest stock assessment for part of the north EPO, and the long period of relatively stable catches that have average 3,553 mt over the past 10 years (Figure G-2), swordfish are probably not overfished, and overfishing is most likely not occurring in the North EPO.
The IATTC staff proposed to the ISC Billfish working group that the area north of 10N be included in the next North Pacific swordfish assessment (
ISC/21/BILLWG-01), in light of recent tagging information presented during
SWO-01 on the movement of swordfish across the current assumed stock boundary for the North Pacific swordfish stock—a diagonal line from the tropics in the Central Pacific to the Northern coast of Mexico, stock area 1 in Figure S1 of
ISC/18/ANNEX/16). The ISC Billfish working group accepted the proposal and plans to assess the North Pacific stock in 2022.
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