There is high uncertainty about the actual stock structure of swordfish (Xiphias gladius) in the Pacific Ocean. According to (IATTC 2020), there might be as many as 6 different stocks, but the exact boundaries of these stocks, as well as their exchange rates, are currently uncertain. FishSource profiles for swordfish follow the stocks identified in (ISC 2014):

• Swordfish - Northwest Pacific, for the Western and Central North Pacific Ocean stock (WCNPO). It is managed by the WCPFC (west of 150ºN) and the IATTC (east of 150ºE).
• Swordfish - Northeast Pacific, for the Northeastern Pacific Ocean stock (North EPO), which actually stretches into the Southern hemisphere (. It is managed by the IATTC, It is managed by the IATTC, although there is a reduced overlapping area with the WCPFC below 5ºN and between 150ºW and 165ºW.
• Swordfish - Southeast Pacific, for the Southeastern Pacific Ocean stock (South EPO). It is managed by the IATTC, although there is an overlapping area with the WCPFC west of 130ºW.

This profile deals with the South EPO stock. In the stock assessment performed in 2022 (IATTC 2022), three models were developed to represent three  stock structure hypotheses. The first hypothesis (H1) assumes the stock is distributed south of 5°S and east of 150°W as in the previous assessment. In the last 10 years, catches in the equatorial region
have sharply increased; the second hypothesis (H2) considers those catches as coming from the south EPO stock and extends the latitudinal stock boundary to 10°N, and maintains the longitudinal boundary at 150°W. The third hypothesis (H3) expands the longitudinal boundary to 170°W, thus including the central Pacific catches. H2 was considered as the reference case hypothesis in (IATTC 2022).