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Billfish Working Group

Striped Marlin (Kajikia audax) --- North Pacific

◊ Biological Profile

Striped marlin is distributed across about 85° of latitude in the Pacific Ocean. Its distribution is "horseshoe-shaped", with the greatest abundances occurring in the eastern and northern Central Pacific Ocean.

This species is epipelagic, highly migratory, and the most abundant and widely distributed of the istiophorid billfishes. The relative abundance of striped marlin tends to vary seasonally by locality, including the presence of mature females and larvae.

Striped marlin are apex predators. They feed non-selectively on many types of epipelagic fishes, squids, and other organisms. Like other istiophorids, striped marlin are endothermic with a brain heater organ associated with the superior rectus muscle that warms the brain and retina and promotes visual acuity.

  • Life span : At least 11 years
  • Maximum size: About 230 cm in eye-fork
    length in the western and central Pacific Ocean
  • Maturity: About 50% at 4 years old
  • Spawning season: April-August

◊ Fisheries for Striped Marlin in the North Pacific Ocean

Catches of striped marlin by Japanese fleets greatly exceed those taken by fleets from all other nations fishing in the Western and Central North Pacific Ocean (WCNPO). For example, the 1984 catch by Chinese-Taipei and the 1994 and 1997 catches by South Korea were the only national annual totals other than Japan above 1000 mt since the start of the data series. In contrast, three Japanese fleets (Distant-water and offshore longline; Coastal longline; Large-mesh gill net) each caught >1000 mt in several different years.
Main fisheries landing striped marlin
by fishing gear and country.
alb_gear_list - Click to zoom up

The national annual catch totals from the USA, Chinese-Taipei, and South Korea are similar in magnitude at several hundred metric tons. The recreational catches in Costa Rica and Mexico are comparable to each other, but lower than the catches from the nations with longline fisheries.

Catches of WCNPO striped marlin have exhibited a long-term decline since the 1970s. Catches averaged roughly 8,100 metric ton (mt) per year during 1970-1979 and declined by roughly 50% to about 3,800 mt per year during 2000-2009.

Annual landings of striped marlin from ISC members in the North Pacific Ocean,

◊ Stock Status (From ISC13)

Female spawning biomass is currently low and averaged roughly 1,518 mt during 2007-2009 (56% of SBMSY, the female spawning biomass to produce MSY). Fishing mortality on the stock (average F on ages 3 and older) is currently high and averaged roughly F = 0.76 during 2007-2009 (24% above FMSY). Recruitment averaged about 328,000 recruits during 1994-2008, which was roughly 30% below the 1975-2010 average. Compared to MSY-based reference points, the current (average during 2007-2009) spawning biomass is 44% below SBMSY and the current fishing mortality exceeds FMSY by 24%. Therefore, overfishing is currently occurring relative to MSY and the stock is in a depleted state.

Western Central North Pacific Ocean striped marlin (Kajikia audax) Kobe plot,

◊ Conservation Advice (From ISC13)

Reducing fishing mortality would likely increase spawning stock biomass and would improve the chances of higher recruitment. Based on new projection results, fishing at FMSY would lead to a spawning biomass decrease of about 8% in 2017 under recent average recruitment. In contrast if recruitment improves to the medium or long- term average patterns, increases of roughly 45% to 73% may occur.