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Istiompax indica  (Cuvier, 1832)

Black marlin
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Australia country information

Common names: Black marlin, Marlin, Pacific black marlin
Occurrence: native
Salinity: marine
Abundance: common (usually seen) | Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
Importance: commercial | Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
Aquaculture: never/rarely | Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
Regulations: restricted | Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
Uses: gamefish: yes;
Comments: Australian records note that black marlin extend throughout northern waters and can be found as far south as Tasmania and Albany in Western Australia. Black marlin are recorded from the western Gulf of Carpentaria to the south of Groote Eylandt, but their presence has not been confirmed in the eastern Gulf of Carpentaria. They are also reported in Torres Strait (Ref. 30354). Stock structure: The stock structure of black marlin is unclear, although there may be several stocks: the eastern Pacific, the south-west Pacific, the north-west Pacific-East China Sea and the north-east Indian Ocean stocks (Ref. 30354). The extent of movement between these stocks is not known. There is slight evidence of a relationship between the eastern Pacific population and the south-west Pacific stock (Ref. 30358, 30360). Commercial fishery: There is no domestic fishery for black marlin off eastern Australia, based on a voluntary agreement by the East Coast Longline Tunamens’ Association. Elsewhere, domestic fleets catch black marlin incidentally in longline tuna fisheries. Japanese vessels began making significant catches of black marlin in both the north-west Coral Sea and off north-western Australia in 1953. Since the commencement of operation of the 200-mile Australian Fishing Zone in 1979, access of this fleet to Australian waters is subject to bilateral agreements. In the Australian Fishing Zone, Japanese fleets fish for tunas such as yellowfin tuna (Thunnus albacares) and bigeye tuna (T. obesus) and billfish such as striped marlin (Tetrapturus audax) and broadbill swordfish (Xiphias gladius). Black marlin and blue marlin usually form an incidental catch of the Japanese drifting longline fishery. A few longliners used to target spawning and pre-spawning aggregations of black marlin in the Coral Sea during the summer. The Japanese longline boats range up to 350 t and 45 m in size and each boat generally spends about 60 days in the Australian Fishing Zone during its fishing campaign. The longlines are 70-110 km long and may carry more than 3000 hooks. One set of a single main line is made in any 24 hour period, and traditionally the line are set to fish at between 50 m and 150 m depth. Deeper sets to 250 m - which target bigeye tuna - may occasionally be made. The maximum catch rate for black marlin off north-western Australia occurs between November and April (Ref. 30354), mostly between 12°S and 24°S, peaking offshore between Exmouth and Broome. The north-west Coral Sea longline grounds, which were historically bounded by 142-150°E and 10-20°S, accounted for the major part of the south-west Pacific black marlin catch. Catch and catch rates there peaked between October and December between 14°S and 19°S in the Queensland and Townsville troughs. The present fishing grounds are much more restricted due to area closures. Black marlin in the Coral Sea longline fishery typically range from 50-120 kg (processed weight) with an average size of 85-90 kg. In this fishery, fish less than 100 kg are usually male and all fish more than 90 kg are female. This size difference suggests that immature females may not be present in the Coral Sea longline fishery - only about 10% of the total north-west Coral Sea longline catch is comprised of females. The whereabouts of immature females larger than 60 kg is unknown. The vast majority of black marlin caught by Japanese longliners is sold as processed, frozen sashimi in Japan. Domestically, black marlin is banned from sale in New South Wales because mercury and selenium levels usually exceed government health limits in the State. Although the levels are highly variable between individuals, they are correlated with size (Ref. 30363). Recreational fishery: The black marlin recreational fishery off eastern Australia is large in terms of value and interest. The game fishery off Cairns to Lizard Island occurs at the same time as the longline fishery (September-December) on the outside of the coral reefs but within several km, often hundreds of m, of the reef crests. The Cairns-Lizard Island charter boat fishery targets females of greater than 450 kg (‘thousand pounders’) associated with the spawning/pre-spawning aggregation previously targeted by the commercial fleet. The size of fish caught generally ranges from 10 kg to 500 kg (Ref. 30358). Of the total catch (including tagged fish), 47% are larger than 200 kg. Up to 1993, the largest black marlin recorded by the Gamefishing Association of Australia, caught off Cairns, was 654 kg. Most captures of black marlin in eastern Australia are made off Queensland, where a high proportion are tagged and released (the fate of about 90% of black marlin caught by charter boats and tournaments). Tagging of black marlin in New South Wales is steadily growing in popularity. Under the New South Wales Fisheries Research Institute’s gamefish tagging program, 16,412 black marlin were tagged from the end of 1973 to mid-1992 and there had been 108 recaptures. Light-tackle fisheries for 10-40 kg fish take place from July to October at Pixie Reef, Dunk Island and Cape Bowling Green. Fishing for 20-50 kg fish off Cape Moreton peaks in January-February. The range of sizes of fish caught in north-central New South Wales is 25-120 kg, with the peak season occurring from January to March. Some larger fish are caught off Bermagui further south, mostly around March (Ref. 30358). Angler clubs located in eastern Australia reported landing approximately 600 marlin (mostly black, also blue and striped) in 1988-89. There is a small fishery in Northern Territory waters concentrated around Melville Island, Cobourg Peninsula, the Wessel Islands and south of Groote Eylandt. Landed fish range in size from 50 kg to 200 kg. Resource status: The Pacific-wide catch of black marlin by the Japanese fleet has remained moderately stable since the mid 1960s although fishing effort measured as thousands of hooks set) has increased (Ref. 30364). Exclusion of the fleet from inshore areas of the Australian Fishing Zone has contributed to the reduced catch per unit effort as it denies access to the coastal habitats of black marlin. This in turn results in a change in the species targeted: the longline boats now fish primarily in cooler and deeper waters than those normally frequented by black marlin. The black marlin catch of the Taiwanese distant water fleet has been increasing over the same period, and to some extent has offset the declining Japanese catches - although the Taiwanese do not fish in Australian waters and their Coral Sea catch is small compared with that of the Japanese. The recreational fisheries of Cairns-Lizard Island and north-western Australia fish the same stock as the Japanese longline fishery. The extent of their combined pressure on the stock is unknown. Because of uncertainty in total (global) catch figures and stock structure (Ref. 30365), together with an apparently sustained total catch level over a wide range of fishing effort, stock production models have not been successfully applied to black marlin in either the Pacific or Indian oceans (Ref. 30364). There have been apparent declines in the catch per unit effort for both oceans, but the extent to which these declines have been due to reductions in stock size or to changes in targeting and area closures are unclear. Also Ref. 2334.
National Checklist:
Country Information: httpss://www.cia.gov/library/publications/resources/the-world-factbook/geos/as.html
National Fisheries Authority: https://www.csiro.au/
Occurrences: Occurrences Point map
Main Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
National Database:

Classification / Names

Actinopterygii (ray-finned fishes) > Perciformes (Perch-likes) > Istiophoridae (Billfishes)
Common names | Synonyms | Catalog of Fishes (gen., sp.) | ITIS | CoL

Common names from other countries

Main reference

Size / Weight / Age

Max length : 465 cm FL male/unsexed; (Ref. 40637); common length : 380 cm TL male/unsexed; (Ref. 30573); max. published weight: 750.0 kg (Ref. 5503)

Environment

Marine; pelagic-oceanic; oceanodromous (Ref. 51243); depth range 0 - 915 m (Ref. 43), usually 0 - 200 m (Ref. 43)

Climate / Range

Subtropical; 15°C - 30°C (Ref. 43), preferred 28°C (Ref. 107945); 44°N - 47°S, 18°E - 69°W (Ref. 43)

Distribution

Indo-Pacific: tropical and subtropical waters, occasionally entering temperate waters. Stray individuals migrate into the Atlantic Ocean by way of the Cape of Good Hope, but the existence of Atlantic breeding stocks is unlikely. Highly migratory species, Annex I of the 1982 Convention on the Law of the Sea (Ref. 26139).
Countries | FAO areas | Ecosystems | Occurrences | Introductions

Short description

Dorsal spines (total): 0; Dorsal soft rays (total): 39-50; Anal spines: 0; Anal soft rays: 16 - 21. Body elongate and not very compressed; upper jaw produced into a robust but not very long beak; two dorsal fins, the height of the first less then the greatest body depth, becoming shorter posteriorly; pectoral fins falcate and rigid, with 19 to 20 rays; body densely covered with small, embedded scales with 1 or 2 sharp points; back dark blue; belly silvery white; membrane of first dorsal fin blue black, without spots; flanks without spots (Ref. 55763). Dark blue above, silvery white below; sometimes with light blue vertical stripes; 1st dorsal fin blackish to dark blue, other fins dark brown with tinges of dark blue in some specimens.

Biology     Glossary (e.g. epibenthic)

Oceanic, usually found in surface waters above the thermocline, often near shore close to land masses, islands and coral reefs. Feed on fishes, squids, cuttlefishes, octopods, large decapod crustaceans and mostly on small tunas when abundant (Ref. 9668). The flesh is of good quality; marketed refrigerated or frozen and prepared as sashimi in Japan (Ref. 9308). Also Ref. 9692.

IUCN Red List Status (Ref. 115185)

Threat to humans

  Harmless



Human uses

Fisheries: commercial; gamefish: yes

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Estimates of some properties based on models

Phylogenetic diversity index (Ref. 82805)
PD50 = 1.0005 many relatives (e.g. carps) 0.5 - 2.0 few relatives (e.g. lungfishes)

Trophic Level (Ref. 69278)
4.5   ±0.4 se; Based on diet studies.

Resilience (Ref. 69278)
Medium, minimum population doubling time 1.4 - 4.4 years (K=0.47(?); Fec=67 million; assuming tm>2)

Vulnerability (Ref. 59153)
Very high vulnerability (78 of 100)
Price category (Ref. 80766)
Very high