Thunnus tonggol | UAE National Red List of Marine Species: Reef-building corals, cartilaginous fishes and select bony fishes

Thunnus tonggol | (Bleeker, 1851)
Countries in Assessment
United Arab Emirates
Country ISO code(s)
Does the assessment cover a marine EEZ area(s)?
Scope (Assessment)
Taxonomic Group
Taxonomic Group Level 2
Assessed taxon level
Taxon distribution as listed in assessment
This species occurs throughout UAE waters. Globally, itis widely distributed in the Indo-West Pacific.
Habitats and Ecology
Ecological system type
Terrestrial system
Freshwater system
Marine system
Habitat details as listed in assessment
This pelagic species primarily occurs on the continental shelf, but can also occur in the open-ocean, and avoids very turbid waters and areas with reduced salinity such as estuaries. It may form schools of varying size. It feeds on a variety of fishes, cephalopods, and crustaceans, particularly stomatopod larvae and prawns. This species probably spawns more than once a year and is reported to be confined to coastal waters (Nishikawa and Ueyanagi 1991). Maximum fork length (FL) is 145 cm. Very few life history studies have been conducted, but in the Indian Ocean, longevity is about 20 years, males and females reach maturity at about 40 cm fork length and age at first maturity is not known (IOTC 2018). In Australia, longevity is estimated to be about 10 years (Wilson 1981), and age at first maturity in Thailand is estimated to be 2 years (Boonragsa 1987). It may live as long as 18 years in the central Indo-Pacific (Griffiths et al. 2009). Natural mortality in a study conducted across Iranian waters was 0.49 year<sup>-1</sup> (Darvishi et al. 2018).
Is there a map available in assessment?
Assessed status
Asessment status in full
Data deficient
Assessment status abreviation
Assessment rationale/justification
This pelagic species occurs throughout UAE waters, but may be less common there due to its preference for deeper waters such as areas off Iran. It is targeted by commercial fisheries that operate throughout the Indian Ocean, including the Gulf and Sea of Oman, and the Indian Ocean is considered a single stock by the Indian Ocean Tuna Commission (IOTC). According to the 2018 IOTC stock assessment, this species is overfished with overfishing occurring due to unsustainable fishing pressure. A recent assessment conducted off Iran also reported it as overfished. Catch has been declining since 2012, or over the past five years, but effort data are largely unavailable. In addition, the lack of life history studies prevents an estimation of generation length at this time. Conservation measures are likely insufficient to reduce fishing effort. Due to the lack of population and life history data, and acknowledging the ongoing major threat from overfishing across the Indian Ocean and in Iran, this species is listed as Data Deficient in the UAE. It is recommended to improve fisheries monitoring and determine generation length, specifically age at first maturity.
About the assessment
Assessment year
Assessors/contributors/reviewers listed
UAE National Red List Workshop
Affliation of assessor(s)/contributors/reviewers listed on assessment
Assessor affiliation specific
Criteria system
Criteria system specifics
IUCN v3.1 + Regional Guidelines v4.0
Criteria system used
Criteria Citation
IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1, Second edition. IUCN, Gland, Switzerland and Cambridge, UK. iv + 32pp pp. And IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN. iii + 41pp.
Endemic to region
Endemism Notes
Is an endemic?: Not_assigned
Threats listed in assessment
Overfishing is a major threat to this species in the UAE in part due to its overfished status across the Indian Ocean stock, in which the Arabian Gulf and Sea of Oman are included (IOTC 2018).
Conservation Measures

Conservation measures:
Conservation measures notes:
Required conservation measures:

Scientific Name Kingdom Phylum Class Order Family Genus
Thunnus tonggol Animalia Chordata Actinopterygii Perciformes Scombridae Thunnus