Overview

Comprehensive Description

Euthynnus alletteratus (Rafinesque, 1810)

Aegean Sea : 23300-462 (1 spc.) ; 23300-451 (1 spc.), 30.01.1969 , Bodrum Fish Market , M. Demir .

  • Nurettin Meriç, Lütfiye Eryilmaz, Müfit Özulug (2007): A catalogue of the fishes held in the Istanbul University, Science Faculty, Hydrobiology Museum. Zootaxa 1472, 29-54: 51-51, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:428F3980-C1B8-45FF-812E-0F4847AF6786
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Biology

Found in neritic waters close inshore (Ref. 13628). This schooling species is an opportunistic predator which feeds on virtually everything within its range, i.e. crustaceans, fishes (mainly clupeoid), squids, heteropods and tunicates. Eggs and larvae are pelagic (Ref. 6769). Specialized traps (madragues) are used in Tunisia and Morocco. Diving bird flocks may indicate large schools (Ref. 9710). Utilized fresh, dried-salted, smoked, canned and frozen (Ref. 9987). A popular game fish (Ref. 9710).
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Distribution

National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Atlantic Ocean: in tropical and subtropical waters, including the Mediterranean, Black Sea, Caribbean Sea and Gulf of Mexico
  • North-West Atlantic Ocean species (NWARMS)
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Range Description

This species is present in the Atlantic Ocean in tropical and subtropical waters, including the Mediterranean, Black Sea, Caribbean Sea, Gulf of Mexico, Gulf of Guinea and west Africa.

Oray and Karakulak (2005) observed in the eastern Mediterranean basin zone high concentrations of E. alletteratus larvae. It is found at least to 10°S in Brazil (Lessa pers comm. 2010), and to the border of Argentina (Figueiredo and Menezes 2000).
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Atlantic Ocean: in tropical and subtropical waters, including the Mediterranean, Black Sea, Caribbean Sea and Gulf of Mexico. Highly migratory species, Annex I of the 1982 Convention on the Law of the Sea (Ref. 26139).
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Western Baltic Sea, North Sea, Mediterranean Sea, Black Sea, tropical and subtropical Atlantic.
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Physical Description

Morphology

Dorsal spines (total): 15 - 16; Dorsal soft rays (total): 11 - 13; Analspines: 0; Analsoft rays: 11 - 15; Vertebrae: 39
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Size

Maximum size: 1220 mm TL
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Max. size

122 cm TL (male/unsexed; (Ref. 26340)); max. published weight: 16.5 kg (Ref. 40637); max. reported age: 10 years (Ref. 28173)
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Diagnostic Description

Anterior spines of first dorsal fin much higher than the those mid-way, giving the fin a strongly concave outline. Interpelvic process small and bifid. Body naked except for corselet and lateral line. Swim bladder absent. Incipient protuberances on 33rd and 34th vertebrae. Back with broken oblique stripes (Ref. 168). Caudal peduncle with 7-8 finlets. Dark stripes on the back and with 3-7 dark spots between pelvic and pectoral fins (Ref. 35388).
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Ecology

Habitat

Habitat Type: Marine

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nektonic
  • North-West Atlantic Ocean species (NWARMS)
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Found in neritic waters close inshore.
  • North-West Atlantic Ocean species (NWARMS)
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Habitat and Ecology

Habitat and Ecology
This is a reef-associated and oceanodromous species found in neritic waters close inshore (Cervigón 1994). It is found in surface waters, mainly on the continental shelf. Less migratory than Katsuwonus pelamis or other tunas, it is usually found in coastal areas with swift currents, near shoals and offshore islands. In the Mediterranean it is also found far offshore. This schooling species is an opportunistic predator which feeds on primarily on fishes (mainly clupeoid), but also on crustaceans, squids, hyperiid amphipods, heteropods and tunicates (Bahou et al. 2007, Falautano et al. 2007). Eggs are shed in several batches when the water is warmest.

Little Tunny spawns extensively, both geographically and temporally, throughout its respective range (Schaefer 2001). Eggs are shed in several batches when the water is warmest. Although spawning distributions of all three Euthynnus species have been reported to be restricted primarily to peripheral areas and around islands within their respective ocean basins (Yoshida 1979, Nishikawa et al. 1985), spawning in the eastern tropical Pacific has been shown to be widely distributed from coastal to oceanic waters (Schaefer 1987).

In Tunisia, the sex ratio is 57.77% females (Hajjej et al. 2011). GSI indicated spawning June–Sept. Size at first maturity 43.13 cm fork length (FL) for females, 42.12 for males. Length-weight Wt = 0.0329.FL2.8101 for females, 0.0368.FL2.7832 for males.

This species has an estimated longevity of between eight and 10 years (Cayre and Diouf 1983, Landau 1965), with an estimated age of first maturity of two or three years (Landau 1965, Hattour 2000, Kahraman et al. 2008). Generation length is therefore estimated to be approximately four years.

Maximum size is 100 cm FL. The all-tackle gamefish record is a 16.32 kg fish taken in Washington Canyon, New Jersey in 2006 (IGFA 2011).

Systems
  • Marine
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Environment

reef-associated; oceanodromous (Ref. 51243); brackish; marine; depth range 1 - 150 m (Ref. 28173)
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Depth range based on 269 specimens in 2 taxa.
Water temperature and chemistry ranges based on 216 samples.

Environmental ranges
  Depth range (m): 0 - 4050
  Temperature range (°C): 2.291 - 27.353
  Nitrate (umol/L): 0.172 - 28.342
  Salinity (PPS): 34.898 - 36.527
  Oxygen (ml/l): 3.063 - 6.374
  Phosphate (umol/l): 0.088 - 1.906
  Silicate (umol/l): 0.805 - 28.876

Graphical representation

Depth range (m): 0 - 4050

Temperature range (°C): 2.291 - 27.353

Nitrate (umol/L): 0.172 - 28.342

Salinity (PPS): 34.898 - 36.527

Oxygen (ml/l): 3.063 - 6.374

Phosphate (umol/l): 0.088 - 1.906

Silicate (umol/l): 0.805 - 28.876
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Depth: 1 - 150m.
From 1 to 150 meters.

Habitat: pelagic.
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Migration

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Oceanodromous. Migrating within oceans typically between spawning and different feeding areas, as tunas do. Migrations should be cyclical and predictable and cover more than 100 km.
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Trophic Strategy

Found in neritic waters close inshore (Ref. 13628). This schooling species is an opportunistic predator which feeds on virtually everything within its range, i.e. crustaceans, fishes (mainly clupeoid), squids, heteropods and tunicates. School by size together with other scombrids but have a tendency to scatter during certain periods of the year. Varied diet and target in all prey although with a certain preference for pelagic species (Ref. 28173).
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Diseases and Parasites

Caligus Infestation 2. Parasitic infestations (protozoa, worms, etc.)
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Life History and Behavior

Behavior

Diet

This schooling species is an opportunistic predator which feeds on virtually everything within its range, i.e. crustaceans, fishes (mainly clupeoid), squids, heteropods and tunicates
  • North-West Atlantic Ocean species (NWARMS)
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Life Cycle

Eggs are shed in several batches when the water is warmest.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Euthynnus alletteratus

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 47
Specimens with Barcodes: 124
Species With Barcodes: 1
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Barcode data: Euthynnus alletteratus

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 13 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

CATGCCTTCGTAATGATTTTCTTTATAGTAATGCCAATTATGATTGGAGGGTTTGGAAACTGACTCATCCCTCTTATG---ATCGGAGCTCCAGACATAGCATTCCCTCGAATAAATAACATGAGCTTCTGACTTCTTCCCCCATCTTTCCTTCTACTCCTAGCTTCTTCAGGAGTTGAGGCCGGTGCCGGAACTGGTTGAACAGTCTACCCTCCGCTTGCCGGAAATCTGGCCCATGCCGGAGCATCCGTTGACTTA---ACCATTTTCTCCCTCCATCTAGCAGGTGTTTCCTCAATTCTTGGGGCAATTAACTTCATTACGACAATTATCAACATGAAGCCTGCCGCTATTTCTCAGTATCAAACCCCTCTATTCGTATGAGCTGTACTAATTACGGCCGTTCTTCTTCTACTATCCCTCCCAGTCCTTGCCGCT---GGCATTACAATGCTCCTGACAGACCGAAACTTAAATACAACCTTCTTCGACCCTGCAGGCGGGGGAGATCCAATCCTTTACCAACACCTATTCTGATTCTTCGGCCACCCAGAAGTATACATTTTAATTCTACCAGGATTCGGAATGATCTCTCACATTGTTGCCTACTACGCCGGTAAAAAA---GAACCTTTCGGCTATATGGGTATGGTGTGAGCCATGATGGCCATCGGCCTACTAGGGTTCATTGTATGAGCCCATCACATGTTCACAGTAGGAATGGACGTAGACACACGAGCCTACTTCACATCCGCAACAATAATTATCGCAATTCCAACAGGTGTAAAAGTATTTAGCTGGCTT---GCAACCCTTCACGGGGGA---GCCGTTAAATGAGAAACTCCTCTGCTATGAGCCATCGGCTTCATTTTCCTCTTTACAGTCGGGGGCCTGACAGGAATTGTCCTAGCCAATTCATCTCTAGACATTGTACTCCATGACACCTACTACGTCGTAGCCCACTTCCACTACGTT---CTGTCTATGGGTGCTGTATTTGCCATTGTTGCT---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------GCT
-- end --

Download FASTA File
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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: NNR - Unranked

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NatureServe Conservation Status

Rounded Global Status Rank: GNR - Not Yet Ranked

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2011

Assessor/s
Collette, B., Amorim, A.F., Boustany, A., Carpenter, K.E., de Oliveira Leite Jr., N., Di Natale, A., Fox, W., Fredou, F.L., Graves, J., Viera Hazin, F.H., Juan Jorda, M., Kada, O., Minte Vera, C., Miyabe, N., Nelson, R., Oxenford, H., Teixeira Lessa, R.P. & Pires Ferreira Travassos, P.E.

Reviewer/s
Russell, B. & Polidoro, B.

Contributor/s

Justification
This is a widespread species in the Atlantic. There is no direct fishery but it is routinely taken by a variety of gears including seines and gill nets in commercial, artisanal and recreational fisheries. Although worldwide catches are relatively stable, there are likely regional declines. Based on available data, this species is listed as Least Concern. However, close monitoring of catches should continue.
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Population

Population
This species is caught in relatively small quantities throughout its range. Reported worldwide landings range from 3,592 t in 1950, to 10,308 t in 2006, with a peak of over 26,000 t reported in 1983 and in 1990 (FAO 2009).

In the 1980s there was a marked increase in reported landings of all small tuna species combined compared to previous years, reaching a peak of about 139,412 t in 1988. Reported landings for the 1989–1995 period decreased to approximately 92,637 t, and since then values have oscillated, with a minimum of 69,895 t in 1993 and a maximum of 123,600 t in 2005. Declared catches were 79,228 t in 2006 and 74,087 t in 2007. A preliminary estimate of the total nominal landings of small tunas in 2008 is 55,876 t. The 2008 preliminary catch of small tuna amounted to 55,876 t, of which 11,552 t was Euthynnus alletteratus (STECF 2009). There are more than 10 species of small tunas, but only five of these account for about 88% of the total reported catch by weight. These five species are: Atlantic Bonito (Sarda sarda); Frigate Tuna (Auxis thazard), which may include some catches of Bullet Tuna (Auxis rochei); Little Tunny (Euthynnus alletteratus); King Mackerel (Scomberomorus cavalla); and Atlantic Spanish Mackerel (Scomberomorus maculatus) (ICCAT 2009).

In the Mediterranean, the International Commission for the Conservation of Atlantic Tunas (ICCAT) statistics are very weak for this species with many countries not reporting catches for many years. Landings reported for the period of 1997–2002 fluctuated around 2,500 t. This species is sporadically caught and larger specimens are becoming more available in recent years (Di Natale pers. comm 2008).

In the Caribbean, landings for this species are aggregated as small tuna (Oxenford pers. comm. 2010, Mahon 1996). This species is caught in small quantities in Brazil by several artisanal fisheries in northeast Brazil (Lessa et al. 2009). In northeast Brazil, this species comprised 59.4% of total catch in a survey in Ceara state; 16.4% in Piaui and (15.6%) norte da Bahia (Norbrega et al. 2009).

Population Trend
Stable
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Threats

Major Threats
This is a commercial species that is part of a multispecies fishery. In open waters it is fished with purse seines and trolling lines; juveniles are also taken with beach seines.

Almost all the commercial catches (99%) are taken by purse-seiners (2,067 t retained and 1,434 t discarded) (STECF 2009). Specialized traps (madragues) are used in Tunisia and Morocco. This species is caught in the artisanal gillnet fishery in northeast Brazil (Nobrega et al. 2009). It is an important resource in Venezuela where they are caught in beach nets, hook and line (Ramirez-Arredondo 1990). Because of its abundance in inshore waters it is a popular sportfish on light tackle, commonly taken by trolling feather jigs, spoons, or strip bait. It is also popular and very effective as live bait for sailfish.

Overall trends in the small tuna catch may mask declining trends for individual species because annual landings are often dominated by the landings of a single species. These fluctuations seem to be partly related to unreported catches, as these species generally comprise part of the bycatch and are often discarded, and therefore do not reflect the real catch. The ICCAT Standing Committee on Research and Statistics (SCRS) pointed out the relative importance of small tuna fisheries in the Mediterranean and the Black Sea, which account for 28% of the total reported catch from 1980–2007. Several countries from the Mediterranean and Black Sea are not reporting catches to the International Commission for the Conservation of Atlantic Tunas (ICCAT). It is commonly believed that catches of small tunas are strongly affected by unreported or underreported data in all areas. Small tunas are exploited mainly by coastal fisheries and often by artisanal fisheries, although substantial catches are also made, either as target species or as bycatch, by purse seiners, mid-water trawlers, handlines, troll lines, driftnets, surface drifting long-lines and small scale gillnets. Several recreational fisheries also target small tunas. Since 1991, the use of fish aggregating devices (FADs) by tropical purse-seiners may have led to an increase in fishing mortality of small tropical tuna species (STECF 2009). There is a general lack of information on the mortality of these species as bycatch, exacerbated by the confusion regarding species identification (ICCAT 2009).
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Least Concern (LC)
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Management

Conservation Actions

Conservation Actions
It is a highly migratory species listed under Annex I of the 1982 Convention on the Law of the Sea (FAO Fisheries Department 1994). In Turkey there is a minimum landing size of 45 cm.

Data on the catch composition, biology and trends are now available from the Mediterranean and the Black Sea (International Commission for the Conservation of Atlantic Tunas (ICCAT)/General Fisheries Commission for the Mediterranean (GFCM) joint expert group 2008). More information, particularly on specific fishing effort, is needed from all areas. The small tuna fishery seems to be quite important for the coastal communities, both economically and as a source of proteins. No management recommendations have been presented by ICCAT due to the lack of proper data, historical series and analyses. In 2008, the ICCAT Standing Committee on Research and Statistics (SCRS) reiterated its recommendation to carry out studies to determine the state of these stocks and the adoption of management solutions. ICCAT/SCRS in 2009 noted that there is an improvement in the availability of catch and biological data for small tuna species particularly in the Mediterranean and Black Sea. However, biological information, catch and effort statistics for small tunas remain incomplete for many of the coastal and industrial fishing countries. Given that, many of these species are of high importance to coastal fishermen, especially in some developing countries, both economically and often as a primary source of proteins, therefore the SCRS recommends that further studies be conducted on small tuna species due to the limits of information available (STECF 2009).
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Relevance to Humans and Ecosystems

Benefits

Importance

fisheries: commercial; gamefish: yes
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Wikipedia

Little tunny

The little tunny (Euthynnus alletteratus) is the most common tuna in the Atlantic Ocean. It is found in warm temperate and tropical waters of the Atlantic and the Mediterranean; in the western Atlantic, it ranges from Brazil to the New England states. It is found regularly in offshore and inshore waters, and is classified as a highly migratory species by UNCLOS.[1] Occurring in large schools and weighing up to 36 pounds, it is the smallest member of the tuna Scombridae family, and is one of the finest small game-fish in the Atlantic.

Commonly called false albacore or little tuna, it resembles the Atlantic bonito, skipjack tuna and species of mackerel.[2] The little tunny feeds primarily on pelagic fish. It is best identified by the dark spots appearing between its pectoral and ventral fins and "worm-like" markings on its back.[3] Commercially, the fish is used as bait for sharks and marlin due to its high oil content and hook retention. It is considered by many to be a trash fish because of its limited nutritional value; there have even been reports of ciguatera poisoning related to its consumption. However, the little tunny is commercially important in many locations including the West Indies. It is marketed fresh, dried, canned, smoked, and frozen. It is sought after as a sport fish due to its line stripping 40 miles per hour (64 km/h) runs and hard fighting ability when hooked. By trolling with lures near reefs, it can be caught on hook and line.[4]

Contents

Taxonomy

Constantine Samuel Rafinesque identified the little tunny in 1810 and gave the fish its current name: Euthynnus alletteratus. Synonyms for used for the name include E. alleteratus alleteratus, E. alliteratus, E. thunina, and E. alletteratus aurolitoralis.[5] The little tunny is not part of the Thunnus genus like many tuna, but it is part of the Thunnini tribe.

Etymology

The genus Euthynnus is derived from the Ancient Greek: εὖ (eu) "good, well", and θύννος (thýnnos), "tunny-fish" – which is in turn derived from θύνω (thynō), "to rush; to dart".[6]

Physical description

The little tunny is small in body size compared to other tuna species. It has a compact and stream-lined body built to facilitate bursts of speed as well as endurance while swimming. Its torpedo-shaped, robust body is made for powerful swimming.[7] It has a large mouth with rigid jaws and a slightly protruding lower jaw, with a single row of small, inwardly-curved, cone-shaped teeth on the palatines.[8] Teeth are absent on the vomer, the small bone in the roof of the mouth,[9] and the tongue has two longitudinal ridges.[10]

An image of a little tunny.
A little tunny.

The snout is shorter than the rest of the head. The little tunny has a dorsal fin with 10 to 15 tall, descending spines, as well as a much smaller second dorsal fin followed by 8 finlets. At the base, the two dorsal fins are separated by a small interspace.[11] The anal fin has 11 to 15 slightly defined rays, and is followed by 7 finlets. The pectoral fins are short and do not reach the end of the first dorsal fin and are joined to the pelvic fins by interpelvic processes.[12] There are 37-45 gill rakers, bony projections off the gills, on the first arch. There are no scales on the body of the little tunny except along the lateral line and on the corselet: a thick band of scales circling the body.[13]

The coloration of the little tunny is typically metallic blue or blue-green with dark wavy stripes above the lateral line. These "worm-like" lines are within a well marked border that never extends farther forward than the middle of the first dorsal fin.[14] The belly is bright white with 3–7 dark, fingerprint-like spots around the pectoral and pelvic fins. The little tunny is commonly confused with the Atlantic bonito because of coloration, but the two fish differ in their color patterns and overall body size.

The little tunny's markings allow it to easily be distinguished from similar species. The little tunny is often confused with the skipjack tuna, the frigate tuna, the Atlantic bonito, and the bullet tuna. Close relatives also include the kawakawa and the black skipjack. The scattering of dark, fingerprint-like spots between the pectoral and pelvic fins cannot be found on any related Atlantic species. The first dorsal fin of the Atlantic bonito is also lower and sloping. Its lack of teeth on the vomer can set it apart from its close Pacific relatives, the kawakawa and the black skipjack. The dorsal fins of the bullet and frigate mackerel are set apart. Unlike the little tunny, the skipjack tuna lacks markings on the back and has broad, straight stripes on the underside.[15]

Little tunny reach a maximum weight of 12 kilograms (26 lb) in the Mediterranean, and averages about 7 kilograms (15 lb) through its entire range. The maximum fork length (distance from the tip of the snout to the fork of the tail) of the little tunny in the Mediterranean is about 100 centimetres (39 in) and in the Atlantic is about a 90 centimetres (35 in).[16] Average fork length for an adult fish throughout the entire range is about 85 centimetres (33 in) .[17] Some little tunnies may reach the length of 40 inches (100 cm) or more, but most commonly they are around 25 inches (64 cm). The largest little tunny on record is 48 inches (120 cm) and 36.5 pounds (17 kg).[18] Females reach sexual maturity at 10.6 to 14.6 inches (27–37 cm) in fork length length while males mature at approximately 15.7 inches (40 cm).[19]

Anatomy

The little tunny has some anatomical variations when compared to other species of Euthynnus. E. alletteratus lacks a swim bladder, like most other tuna, so it must constantly keep moving to stay afloat. The pectoral fins are crucial to the little tunny in maintaining its position in the water column. The little tunny's liver is very disproportionate, with the right lobe much longer than the left or middle lobes. The stomach of the little tunny is a long sac that stretches almost the entire length of its body. The intestinal tract is fairly short, coming from the left and right sides of the stomach, and extending without looping down the length of the tuna's body. The different sections are characterized by their diameter and color.[20] The ventral vertebral column of the little tunny has unique trelliswork, which is important to its family (Scombridae.) Divided haemapophyses, or parts of the vertebrate, forming a long canal enclose the large ventral blood vessel.[21]

Feeding habits

A school of fish feeding at the surface.
A school of little tunny feeding.

In coastal waters along the North American eastern seaboard, little tunny are carnivorous, and primarily feed on small fish and invertebrates that occur in schools. The diet of the Little Tunny consists mostly of fish, they particularly like the Atlantic Bigeye and largehead hairtail. Second to fish, the Little Tunny consumes a good deal of crustaceans, and lastly cephalopods and gastropods make up a small part of the Little Tunny's diet. Sardines, scad, and anchovies are common in the diet along with squid, stomatopods, and organisms from the diogenidae family. The diet of the fish is also relative to its size. A smaller fish's diet typically consists of clupeiform, and larvae, while the larger fish mostly eat maurolicus muelleri. The typical diet is very similar to that of the king mackerel because the fish are of a similar size and live in the same area of the water column.[2] It mostly feeds on pelagic fish. The little tunny is an opportunistic predator, feeding on crustaceans, clupeid fishes, squids, and tunicates. The Little Tunny's diet also responds to seasonal changes in food availability. It has been observed that the Little Tunny has nocturnal feeding habits, and are specialist feeders. It often feeds on herring and sardines in inshore waters near the surface of the water.[22] The little tunny commonly feeds in large schools because their primary food sources (small fish and the larval forms of crustaceans) are typically in schools as well.

Distribution and habitat

The little tunny is found in the neritic waters of the temperate and tropical zones in the Atlantic ocean. It can also be found in the waters of the Mediterranean Sea and the Black Sea. In the eastern Atlantic, the little tunny has been found from Skagerrak to South Africa. Although found it this broad range of latitudes, it is rare north of the Iberian Peninsula or farther south than Brazil. On the Atlantic coast of the United States, they can be caught as far north as Cape Cod, Massachusetts, and as far south as the tip of Florida, as well as throughout the waters of the Gulf of Mexico.[23]

The little tunny's habitat tends to be near-shore waters, much closer to shore than most other tunas. They live in and around inlets, points, jetties, and sandbars. All of these places are where bait fish like sardine and menhaden, both favorites of the little tunny, form large schools, which are very helpful to the little tunny's feeding style. While the little tunny is abundant in offshore ocean waters, it is unusual to find it in brackish water of estuaries. The very young will enter estuaries in South Africa.[24] The little tunny prefers relatively warm water, from 24° to 30° Celsius. The little tunny migrates south in the winter and fall, and northward in the spring, through coastal waters. It is not as migratory as other tuna species.[25]

The little tunny is typically a schooling species.[26] It lives in schools based primarily on fish size rather than species, so other members of the Scombridae family, like the Atlantic bonito, may be present. These schools cover areas up to 2 miles long. Little tunny that have not yet reached adulthood form tight schools offshore. Larger schools are more common offshore whereas smaller groups may wander far inshore.

Reproduction

Little tunny spawn in water that is at least 25 °C (77 °F) in the months of April through November in the Atlantic Ocean. The spawning season of the little tunny in the Mediterranean is generally between May and September, but the most intensive spawning occurs between July and August. The major spawning areas are offshore, in waters that are 100 to 130 feet deep. The females are prolific fish, and can release 1.75 million eggs, in multiple clutches over a mating season.[27] The eggs are fertilized in the water column after the males release sperm. The eggs are buoyant, spherical, transparent, and pelagic. A droplet of oil within the egg adds to its buoyancy. The diameter of the eggs can be anywhere from 0.8 mm to 1.1 mm, and they are light amber. Larvae are released 24 hours after fertilization and are approximately 3 mm in size. Pigmentation in the eyes appear 48 hours after hatching. The teeth and fins develop at sizes of 3.7–14 mm. Once the larvae are 14 mm to 174 mm long, they take on the adult appearance; the body becomes more elongated.[28] Studies have found that it takes approximately 3 years for the little tunny's gonads to reach sexual maturity. The average size of a sexually mature individual is 15 inches (38 cm) in fork length.[29]

Predators and parasites

Bony fish, Marlins, sea birds, sharks, and rays prey on the little tunny.[30] Other tunas, including conspecifics and yellowfin tuna (Thynnus albacares) are predators of the little tunny. Fish such as the dolphin fish (Coryphaena hippurus), wahoo (Acanthocybium solandri), Atlantic sailfish (Istiophorus albicans), swordfish (Xiphias gladius), and various sharks as well as other large marine carnivores all prey on the little tunny. Among those sharks is the whale shark, who feeds on the little tunny's recently spawned eggs. Seabirds prey on small little tunny.[31]

Parasites of the little tunny include the copepods Caligus bonito, Caligus coryphaenae, and Caligus productus, all found on the body surface as well as on the wall of the branchial cavities. Another copepod, Pseudocycnoides appendiculatus, has been documented as parasitic on the gill filaments. Other parasites include digenea (flukes), monogenea (gillworms), cestoda (tapeworms), and isopods.[32]

Fishing and preparation

As with many inshore gamefish like bluefish and striped bass, schools of little tunny are usually indicated by flocks of birds diving in coastal waters. Fishermen targeting them often troll bait, cast lures, and float fish. When trolling for Little Tunny, fishermen often use small lures baited with either mullet or ballyhoo or lures dressed with colored feathers. When float fishing, popular baits are Spot, Bluefish, or Pinfish. Popular lures include deadly dicks, maria jigs, and other slender-profiled, brightly-colored metal lures that can be cast far and retrieved quickly that imitate the small baitfish the little tunny are often feeding on. Some anglers use little tunny for strip bait to catch other species, but most fish are released as the Little Tunny is not commonly thought of as a food fish. There is little regulation of the fishery, no size or bag limits, and no closed season. The flesh of the Little Tunny is coarse in texture, strong in flavor, and dark in color if compared to bluefin or yellowfin tuna.[33]

In preparing Little Tunny for consumption, it should be bled and iced as soon as possible after being caught. There are many ways to eat the Little Tunny, such as Tuna Salad. To do this, the fillets are first baked, then chilled and flaked, then mixed in with the salad. Removing the dark strips of meats that extend the length of each fillet helps to reduce the naturally fishy flavor.[34] Another way to prepare the Little Tunny is first to bleed it, barbecue it in foil, remove the meat from the bone, and then let it chill overnight. Various seasonings can be used to enhance the flavor. Fresh steaks can be quiet good if seasoned with salt, pepper and lemon, and thinly sliced tunny makes good sashimi. It is commonly eaten as such in Japan.

References

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