Black marlinBLM

~180 cm LJFL

Characteristic features:

  • 2 keels on either side of caudal peduncle
  • Interdorsal space narrow
  • Second dorsal fin slightly anterior to second anal fin
  • Pelvic fins narrow and long, but not reaching to near anus
  • Bill stoutest of the 3 marlins, covered in large sharp denticles
  • Lower jaw short and stocky, often turned downward at tip
  • Flesh pinkish white to greyish
  • Height of anterior portion of first dorsal fin lower than body depth, dropping even lower level with pectoral fin-base (tall for much of its length in individuals <50 kg)
  • Pectoral fins sickle shaped, rigid and not able to be folded against body (although more flexible in juveniles and individuals <15 kg)
  • Single lateral line (only obvious in individuals <25 kg)

Colour:

Upper surfaces blackish to dark blue; bronze sheen along sides; silver below. All fins dark except anal fin which is pale. Juveniles sometimes show vertical stripes similar to that of striped marlin. Colours fading after death as condition is lost.

Size:

To 450 cm TL and up to 700 kg in weight.1

Important conditions and life stages:

juvenile
Juvenile Istiompax indica
~85 cm LJFL
  • First dorsal fin tall for much of its length
  • Vertical stripes sometimes present
  • Pectoral fins flexible in individuals less than around 15 kg, otherwise rigid, unable to be folded against body

Distribution:

Tropical and subtropical waters of the Indo–Pacific.

No FAO distribution map available.

Habitat:

Epipelagic in oceanic waters, found at depths from the surface to at least 915 m.2

Biology:

Highly migratory; most densely distributed in waters close to coasts and islands. Feeds mostly on small tuna but also other small fishes, crustaceans, and cephalopods. Size at 50% maturity estimated at 195 cm EFL, corresponding to 5.4 years of age for female black marlin off Taiwan.3 Maximum estimated age is 5–7 years for males and 11–13 years for females.4,5

Indonesian fisheries:

Caught predominantly by longlining and set netting, but also by gill netting.

Similar species:

Istiophorus platypterus
Sailfish
Istiophorus platypterus differs in having a sail-like dorsal fin, taller than maximum body depth along the majority of its length, tallest at mid-fin (vs. anterior portion of dorsal fin lower than body depth, posterior portion low) and pelvic-fin rays very long, almost reaching the anus (vs. short, far from reaching anus).

 

Kajikia audax
Striped marlin
Kajikia audax differs in having pectoral fins which are leaf shaped (vs. curved/sickle-shaped) and are able to be folded against the sides of body (vs. rigid, unable to be folded against sides of body); first dorsal fin with a pointed tip (vs. slightly rounded); anterior portion of first dorsal fin equal to or greater than body depth (vs. height about half body depth); second dorsal fin slightly posterior to second anal fin (vs. second dorsal fin slightly anterior to second anal fin) and flesh orange (vs. pinkish white to greyish).

 

Makaira nigricans
Blue marlin
BUM
Makaira nigricans differs in having pectoral fins which are strap like (vs. curved/sickle shaped) and flexible, able to be folded flat against sides of body (vs. rigid, unable to be folded against sides of body) and second dorsal fin slightly posterior to second anal fin (vs. second dorsal fin slightly anterior to second dorsal fin).

 

Tetrapturus angustirostris
Shortbill spearfish
tetrapturus angustirostris
Tetrapturus angustirostris differs in having a short bill, only slightly longer than lower jaw (vs. much longer than lower jaw); the anus located well anterior of first anal fin by a distance greater than the length of the first anal-fin base (vs. slightly anterior of the first anal fin by a distance less than length of the first anal-fin base) and a nape low to flat (vs. steep).

 

Xiphias gladius (Xiphiidae)
Broadbill swordfish
Xiphias gladius differs in having a bill that is flat-oval in cross section (vs. rounded); pelvic fins absent (vs. present); 1 median keel on caudal peduncle (vs. 2 keels) and a deep notch on both upper and lower profiles on caudal peduncle (vs. shallow notches).

Internal links:

Istiompax indica interactive learning
Istiompax indica market gallery

External links:

FishBase
The IUCN Red List of Threatened SpeciesTM

References

1.
IGFA. Database of IGFA angling records until 2001. IGFA Fort Lauderdale, USA; 2001.
2.
Nakamura I. FAO Fisheries catalogue Vol. 5. Billfishes of the world: An annotated and illustrated catalogue of marlins, sailfishes, spearfishes and swordfishes known to date. Food and Agriculture Organization of the United Nations; 1985.
3.
Sun C-L, Chang H-Y, Liu T-Y, Yeh S-Z, Chang Y-J. Reproductive biology of the black marlin, Istiompax indica, off southwestern and eastern Taiwan. Fisheries Research. 2015;166:12–20.
4.
Speare P. Age and growth of black marlin, Makaira indica, in east coast Australian waters. Marine and Freshwater Research. 2003;54(4):307–14.
5.
Sun C-L, Yeh S-Z, Liu C-S, Su N-J, Chiang W-C. Age and growth of Black marlin (Istiompax indica) off eastern Taiwan. Fisheries Research. 2015;166:4–11.