Soft-shell mud crab of Indo-Pacific

Scylla serrata

Common Name(s)

Mud crab, Swamp crab, Mangrove crab, Giant mangrove crab

Medium Risk

Stable, not optimal but not poor status. AND Actions identified to reduce environmental impact and/or improve management or stock status. May be data deficient with stable catches.


Kepiting-bakau besar


Cua bùn


'Gur Yuen Ching Hai' (鋸緣青蟹), ‘Ching Hai' (青蟹)

Date of Assessments

October 2021 (Peer reviewed September and November 2022)

Peer Reviewer

Dr. Mojibar Rahman, Bangladesh Agricultural University

Eddy Nurcahyono, Balai Besar Perikanan Budidaya Air Payau Jepara (BBPBAP Jepara)

Assessment Organisation

The University of Hong Kong


Production of soft-shell crabs is year-round, and exports of the crabs are mostly frozen. However, there are no-fishing seasons for the species in some countries which may affect access to live animals.



  • Indo-Pacific mud crab (Scylla serrata) is widely distributed in mangrove forests throughout the Indo-West-Pacific region.
  • Indo-Pacific mud crab can grow into about 24 cm carapace width and mature at about 12 cm carapace width. The species spawns throughout the year offshore, with a peak around the rainy season.
  • Soft-shell crabs are formed after individuals have moulted and before their shell hardens.
  • Indo-Pacific mud crab are commercially important, collected and sold as hard- or soft-shell crabs. Mud crab traps and baited bamboo traps are used to collect the crabs.
  • Crab collection is indiscriminate for size. Collected crabs are put in pens and cages in mangroves for fattening and moulting. Collected crabs are fed with low-priced fish, gastropods and chicken trash for grow-out. Although hatcheries for mud crabs are currently available, farming and production of soft-shell crabs are still highly dependent on wild-caught juveniles of the species. This is a practice known as ‘capture-based aquaculture’ and needs to be managed both as a fishery as well as using good aquaculture practices according to the Food and Agriculture Organization (FAO) of the United Nations.
  • In the latest estimation from FAO statistics, the global production (direct wild capture and aquaculture) of soft-shell crabs reached almost 184,000 tonnes (including about 51,000 tonnes of wild capture) in 2019. The top source countries of Scylla serrata soft-shell crab are China, Indonesia and Vietnam (Hungria et al. 2017).

Hook and Line

Hook and line is one of the best methods of fishing with regards to sustainability. This can involve one person and a rod, or alternatively using a basic winch with a line of hooks. The hook and line fishing method has little impact on the surrounding environment and the catch can be selective. For example, any fish too small, or not the right species can be placed back into the water, with limited harm.

Traps and pots

Traps and pots made of wood, metal wire or plastic are placed on the seafloor to catch fish, sometimes by using bait. The captured animals are usually still alive in the traps and pots when they are harvested. Traps and post are commonly used to catch lobsters and crabs.

  •  The Latin species name
  • Evidence of the country of origin and production method (hatchery or wild sourced)
  • Evidence that the species is caught according to national guidelines (e.g., compliant with minimum sizes, etc.) and regulations for the species, for both the fishery and aquaculture (i.e., grow-out) operation components.
  • Evidence that the Hong Kong importer has complied with trade regulations


In Indonesia, fishery improvement programme under the Mud Crab Fishery Management Plan by the Learning Center for Fisheries Management Ecosystem Approach (EAFM) in preparation according to the EAFM Assessment for Mud Crab Fisheries and Proposed Intervention Management Actions in Selected Area of FMA 713.

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  • The soft-shell form of Indo-Pacific mud crab (Scylla serrata) from Indonesia can be considered at medium risk.
  • The latest assessment of Indo-Pacific swamp crab fishery in Indonesia in 2018 indicated the stock biomass was below (B/Bmaximum sustainable yield = about 0.7) and fishing effort exceeded (F/FMSY = about 1.2) sustainable levels (Tetelepta et al. 2019).
  • Catch of Scylla crabs under 12 cm carapace length in spawning condition is prohibited. However, implementation of the restriction is ineffective in the country.
  • The soft-shell form of the Indo-Pacific mud crab (Scylla serrata) from Thailand can be considered at medium risk.
  • The latest available assessment in 2013 indicated Scylla crabs were already overexploited in the Gulf of Thailand by 1996 according to catch data (Koolkalya et al. 2017).
  • In Thailand, there are management measures that restrict collection of egg-bearing Scylla females in the wild from October to December each year and regular restocking of mud crabs in their natural habitats is conducted. However, no assessments on the effectiveness of these measures have been conducted or are available for review.
  • The soft-shell form of the Indo-Pacific swamp crab (Scylla serrata) from Bangladesh can be considered at medium risk.
  • Production and farming of soft-shell crab in the country is heavily dependent on the wild capture of juveniles of the species (Rahman et al. 2020)
  • In Bangladesh, relevant management measures include: (1) only line hooks are allowed for collection of wild crabs; (2) mud crab collection from wild sources prohibited during January to February each year; (3) any sorts of fishing including crabs prohibited from June to August each year in Sundarbans mangrove forests. However, implementation of the measures is poorly done and the level of awareness of the crab collectors is poor with no knowledge of existing fisheries rules and regulations (Rahman et al., 2020). Illegal, unreported and unregulated (IUU) harvesting and trade are common in the country.