Atlantic sailfish (Istiophorus albicans)

Description

Atlantic sailfish fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Atlantic sailfish description

The Atlantic sailfish (Istiophorus albicans) cuts a truly striking profile, taking its name from the large and distinctive dorsal fin which runs along the length of its body ^{(3) (4)}. When extended, the dorsal fin is taller than the width of the body ⁽³⁾, and, with its pronounced upper jaw that is modified into a long, circular bill ⁽²⁾, an elongate torso and a strongly forked tail fin ^{(3) (5)}, this fish is one of the most magnificent of all ocean creatures.

Body colouration changes depending on level of excitement ⁽³⁾, but normally the Atlantic sailfish is dark blue along the back and silvery blue/white with brown spots underneath. On each side are 20 rows of longitudinal stripes made up of many light blue dots ^{(2) (3)}. The fins are usually blackish-blue, and the base of the first and second anal fins are tipped silvery-white. The sail (first dorsal fin) is scattered with many small, round black dots ^{(2) (3) (4) (6)}.

There is debate amongst scientists over whether or not the Atlantic sailfish (Istiophorus albicans) and the Indo-Pacific sailfish (Isiophorus platypterus) are separate species. Because of this, the Atlantic sailfish is also sometimes referred to as Istiophorus platypterus ^{(2) (4) (7) (8)}. There is very little genetic evidence to separate Atlantic from Indo-Pacific populations, but it is commonly accepted that there are marked morphological differences between the two, with the Atlantic sailfish typically reaching far smaller sizes than its Indo-Pacific counterpart ^{(2) (7)}.

Size

Length: 3.15 m ⁽²⁾

Weight

up to 58 kg ⁽²⁾

Atlantic sailfish biology

A voracious and opportunistic predator, the Atlantic sailfish is able to depress its pelvic fins into grooves along the side of the body, reducing drag as it moves through the water and making it one of the fastest recorded fish, capable of attaining speeds of up to 110 kilometres per hour ^{(2) (3) (4)}. The Atlantic sailfish feeds primarily on fish, as well as consuming some squid and octopuses ^{(3) (4) (9)}. Young of the Atlantic sailfish feed mostly on copepods ^{(2) (9)}. When feeding, the Atlantic sailfish will often herd shoals of fish into a tight group, known as a ‘bait ball’, using its dorsal fin. The sailfish will then thrash from side to side at great speed using its bill to stun the schooling fish on impact, before leisurely picking off those that are injured ⁽³⁾.

Breeding typically occurs in inshore shallow waters. The female, accompanied by one or more males, will swim slowly with the dorsal fin extended above the water, spawning close to the surface ^{(2) (3)}. In the western Atlantic, spawning occurs primarily during the summer while in the eastern Atlantic spawning can occur all year round, peaking in the summer months ^{(3) (4) (8)}. A large female may typically release between 4.5 and 4.8 million eggs in a single spawning, usually in three batches ^{(2) (4)}. Fertilisation of the eggs occurs in the water, and the eggs hatch within 36 hours ⁽³⁾. Atlantic sailfish young lack the characteristic elongated jaw of the adults, and measure approximately 0.3 centimetres at hatching. At a body length of around 0.6 centimetres the bill starts to elongate, and by the time the young juvenile reaches 20 centimetres it displays all the physical features of an adult sailfish ^{(3) (4) (8)}.

Atlantic sailfish range

The Atlantic sailfish is widely distributed throughout the coastal tropical and subtropical waters of the Atlantic Ocean, with occasional sightings offshore in more temperate waters and in the Mediterranean Sea ^{(2) (6) (9)}. In the west, the Atlantic sailfish is most abundant along the coast of Florida, the Gulf of Mexico and the Caribbean Sea, and south along the Brazilian coast ^{(2) (3) (6)}. In the east, important populations of the Atlantic sailfish are known from the coast of Senegal to the Gulf of Guinea ⁽⁶⁾. During the winter, the Atlantic sailfish is restricted to the warmer parts of its range, migrating away from the tropics with the expansion of warm water currents during the summer ^{(2) (3) (9)}. Although a migratory species, very few trans-Atlantic movements have ever been recorded, suggesting that populations do not mix between east and west ^{(9) (10) (11)}.

Atlantic sailfish habitat

The Atlantic sailfish is the least oceanic of all billfish species, and although capable of descending into deep water, most of its time is spent above the thermocline, at depths of 10 to 20 metres ^{(2) (9) (11)}. Preferentially sticking to shallow coastal waters, the Atlantic sailfish can usually be found in the warmer, upper layers within a temperature range of 21 to 28 degrees Celsius ^{(2) (4) (9)}.

Atlantic sailfish status

The Atlantic sailfish has not yet been classified on the IUCN Red List.

Atlantic sailfish threats

Possibly the biggest threat to the Atlantic sailfish is incidental catch in longline and gillnet fisheries. The species itself is not commercially fished because of its tough meat, but is often discarded as bycatch when caught up in commercial fishing lines. The Atlantic sailfish is also highly sought after by recreational fishermen, putting it at risk from overfishing ^{(3) (12)}. A 2009 assessment of sailfish stocks in both the eastern and western Atlantic indicated that it is currently overfished in both regions, but particularly in the east ⁽¹¹⁾.

Atlantic sailfish conservation

The Atlantic sailfish comes under the remit of the Highly Migratory Species Division of the United States National Marine Fisheries Service (NMFS), which manages Atlantic highly migratory species (HMS) including tuna, shark, swordfish and billfish ⁽³⁾, and it is also included in the NMFS U.S. Fishery Management Plan for the Atlantic Billfishes. In 1998, the Atlantic sailfish was added to the NMFS list of overfished species ⁽¹²⁾. Commercial fishing vessels in the U.S. are prohibited from possessing Atlantic sailfish, and vessels that are used to fish recreationally are required to possess a HMS Angling permit from NMFS. Under this permit, recreational fishermen are not permitted to sell, barter, or trade Atlantic HMS, including the Atlantic sailfish, and most recreational fishing is done entirely by catch and release, with individuals released back into the ocean soon after being caught ^{(3) (11)}.

Very little information is available regarding the population status of the Atlantic sailfish. Assessment of recent trends suggests that in the east, Atlantic sailfish populations have declined and currently show very few signs of recovery. In the west, the Atlantic sailfish has also declined, but populations appear to have remained relatively stable since the 1980s. Based on these observations, the International Commission for the Conservation of Atlantic Tunas (ICCAT) have recommended that catch levels should be reduced in the eastern Atlantic, and should not exceed current levels in the west ⁽¹¹⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For more information on the Atlantic sailfish:

• The Littoral Society:
  http://www.littoralsociety.org/userfiles/doccenter/Species%20Spotlight%20Atlantic%20Sailfish.pdf

To find out more about conservation of the Atlantic sailfish and other billfish species:

• The Billfish Foundation:
  http://www.billfish.org

Authentication

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Glossary

Anal fin

In fish, an unpaired fin on the under surface of a fish, behind the anus.

Bycatch

In the fishing industry, the part of the catch made up of non-target species.

Copepod

Large and diverse group of minute marine and freshwater crustaceans belonging to the subclass Copepoda. They usually have an elongated body and a forked tail.

Dorsal fin

The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.

Fertilisation

The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.

Morphological

To the visible or measurable characteristics of an organism.

Pelvic fin

In fish, the pair of fins found on the underside of the body.

Spawning

The production or depositing of large quantities of eggs in water.

Thermocline

The region in water at which temperature rapidly decreases with depth, and which separates the layers of warmer surface water above from the colder, deeper water below.

References

1. UNEP-WCMC Species Database (July, 2010)
   http://www.unep-wcmc.org/
2. Nakamura, I. (1985) FAO species catalogue. Vol. 5. Billfishes of the world. An annotated and illustrated catalogue of marlins, sailfishes, spearfishes and swordfishes known to date. FAO Fisheries Synopsis No.125, Vol.5. Food and Agriculture Organisation of the United Nations, Rome. Available at:
   ftp://ftp.fao.org/docrep/fao/009/ac480e/AC480E00.pdf
3. The Littoral Society: Species Spotlight: Atlantic Sailfish (Istiophorus albicans) (July, 2010)
   http://www.littoralsociety.org/userfiles/doccenter/Species%20Spotlight%20Atlantic%20Sailfish.pdf
4. MarineBio (July, 2010)
   http://marinebio.org/species.asp?id=146
5. Marine Species Identification Portal (July, 2010)
   http://species-identification.org/species.php?species_group=fnam&id=1916
6. Arocha, F. and Ortiz, M. (2006) ICCAT Manual, Chapter 2.1.8.1. Sailfish (SAI). International Commission for the Conservation of Atlantic Tunas, Madrid. Available at:
   http://www.iccat.int/Documents/SCRS/Manual/CH2/2_1_8_0_SAI_ENG.pdf
7. Collette, B.B., McDowell, J.R. and Graves. J.E. (2006)Phylogeny of recent billfishes (Xiphioidei). Bulletin of Marine Science, 79(3): 455-468.
8. FishBase (July, 2010)
   http://www.fishbase.org/Summary/SpeciesSummary.php?ID=78
9. NMFS (2008). Stock Assessment and Fishery Evaluation (SAFE) Report for Atlantic Highly Migratory Species 2008. National Marine Fisheries Service, Maryland, United States. Available at:
   http://www.nmfs.noaa.gov/sfa/hms/Safe_Report/2008/HMS_SAFE_Report_2008_FINAL_FULL_DOCUMENT.pdf
10. McDowell, J.R. and Graves, J.E. (2002) A genetic perspective on Atlantic sailfish stock structure. Collective Volume of Scientific Papers ICCAT, 54(3): 805-810. Available at:
    http://www.iccat.int/Documents/CVSP/CV054_2002/no_3/CV054030805.pdf
11. ICCAT (2009). Report of the 2009 Sailfish Assessment. International Commission for the Conservation of Atlantic Tunas, Madrid. Available at:
    http://www.iccat.int/Documents/Meetings/Docs/2009_SAI_ASSESS_ENG.pdf
12. White Marlin Biological Review Team (2007) Atlantic White Marlin Status Review. National Marine Fisheries Service, Southeast Regional Office, United States. Available at:
    http://www.nmfs.noaa.gov/pr/pdfs/statusreviews/whitemarlin.pdf