Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Palaemon macrodactylus
(oriental shrimp)



Palaemon macrodactylus (oriental shrimp)


  • Last modified
  • 20 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Natural Enemy
  • Preferred Scientific Name
  • Palaemon macrodactylus
  • Preferred Common Name
  • oriental shrimp
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Arthropoda
  •       Subphylum: Crustacea
  •         Class: Malacostraca
  • Summary of Invasiveness
  • P. macrodactylus, a large edible crustacean native to northeast Asia, was first recorded outside of its native range in San Francisco Bay, USA, in the 1950s. Once established in a region P. macrodactylus...

Don't need the entire report?

Generate a print friendly version containing only the sections you need.

Generate report


Top of page
Adult  Palaemon macrodactylus (oriental shrimp).
CaptionAdult Palaemon macrodactylus (oriental shrimp).
Copyright©Arjan Gittenberger/GiMaRIS-2013
Adult  Palaemon macrodactylus (oriental shrimp).
HabitAdult Palaemon macrodactylus (oriental shrimp).©Arjan Gittenberger/GiMaRIS-2013
Palaemon macrodactylus (oriental shrimp) in habitat.
CaptionPalaemon macrodactylus (oriental shrimp) in habitat.
Copyright©Arjan Gittenberger/GiMaRIS-2013
Palaemon macrodactylus (oriental shrimp) in habitat.
HabitPalaemon macrodactylus (oriental shrimp) in habitat.©Arjan Gittenberger/GiMaRIS-2013
Palaemon macrodactylus (oriental shrimp), Victoria, British Columbia, 2011
CaptionPalaemon macrodactylus (oriental shrimp), Victoria, British Columbia, 2011
Copyright©Melissa Frey/Royal BC Museum-2011 - CC-BY-NC
Palaemon macrodactylus (oriental shrimp), Victoria, British Columbia, 2011
AdultPalaemon macrodactylus (oriental shrimp), Victoria, British Columbia, 2011©Melissa Frey/Royal BC Museum-2011 - CC-BY-NC
Palaemon macrodactylus, showing detail  of rostrum.
CaptionPalaemon macrodactylus, showing detail of rostrum.
Copyright©Melissa Frey/Royal BC Museum-2011 - CC-BY-NC
Palaemon macrodactylus, showing detail  of rostrum.
RostrumPalaemon macrodactylus, showing detail of rostrum.©Melissa Frey/Royal BC Museum-2011 - CC-BY-NC


Top of page

Preferred Scientific Name

  • Palaemon macrodactylus Rathbun, 1902

Preferred Common Name

  • oriental shrimp

International Common Names

  • English: Korean grass shrimp; migrant prawn; oriental shrimp

Local Common Names

  • France: bouquet migrateur; crevette asistique
  • Netherlands: rustreepsteurgarnaal
  • Spain: camaron emigrante; camaron oriental

Summary of Invasiveness

Top of page

P. macrodactylus, a large edible crustacean native to northeast Asia, was first recorded outside of its native range in San Francisco Bay, USA, in the 1950s. Once established in a region P. macrodactylus spreads to other nearby areas with apparent ease. P. macrodactylus has wide environmental tolerances (e.g. temperature, salinity, hypoxia), comparatively long breeding seasons and high fecundity. It is largely carnivorous but can exploit a wide variety of food sources and can be cannibalistic in crowded laboratory conditions. In San Francisco Bay it is thought to be out-competing native Crangon species but evidence for its impact on native species in other regions is lacking. In China, it is listed in their Red Data Book as a threatened species.

Taxonomic Tree

Top of page
  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Crustacea
  •                 Class: Malacostraca
  •                     Subclass: Eumalacostraca
  •                         Order: Decapoda
  •                             Suborder: Natantia
  •                                 Unknown: Palaeomonoidea
  •                                     Family: Palaemonidae
  •                                         Genus: Palaemon
  •                                             Species: Palaemon macrodactylus

Notes on Taxonomy and Nomenclature

Top of page

As with many Palaemon species, Palaemon macrodactylus is often referred to the genus Leander in older literature. Some of the figures provided by Yu (1930) of the species that he described as Leander serrifer var. longidacytlus are based on P. macrodactylus but this name has not been used to refer to P. macrodactylus elsewhere.


Top of page

Description: Carapace with antennal and branchiostegal teeth and branchiostegal groove. Rostrum slender, only weakly expanded ventrally, straight or very slightly upcurved with 9-15 dorsal teeth, usually three of which are behind the posterior edge of the orbit; distance between 1st and 2nd tooth between 1.5 and 2 times as long as that between 2nd and 3rd teeth; distal portion (up to one fifth) unarmed; 3-5 ventral teeth, tip bifid; ventral margin with double row of plumose setae. Mandible usually with three-segmented palp. Dorsal flagellum of the antennula approximately equal in length to antennular peduncle, fused for about 20% of its length. Fingers of chela of pereiopod 2 about 0.7 times as long as palm. Chela of pereiopod 2 equal to or slightly longer than carpus. Dactylus of pereiopods 3-5 slender, abut 0.9 times as long as carpus. Fifth abdominal pleuron with small distoventral tooth. First pleopod of male without marginal appendix on endopod.

Length: up to 70 mm (females) and 40 mm (males)

The most detailed description and figures to date are those of Newman (1963), with supplementary figures and diagnoses given by Ashelby et al. (2004), d’Udekem d’Acoz et al. (2005), González-Ortegón and Cuesta (2006), and Li et al. (2007). The type material of P. macrodactylus is preserved in the collections of the National Museum of Natural History, Smithsonian Institution, Washington DC.

Colour pattern: Reddish to brownish or greenish to blueish-green. A whitish longitudinal dorsal stripe runs along the body in some specimens. Carapace with a weakly developed pattern of oblique stripes on a finely dotted background; no distinct transverse stripes at all or just one or two very short broad transverse marks or spots. Pleurae in ovigerous females with brown and white chromatophores, the brown ones forming distinct marks. Peduncle of antenna 1 with many large dot-like dark chromatophores. Pereiopods brownish to reddish (sometimes translucent light blueish) with a tinge of orange at articulations and a small indistinct brownish band above them. Pereiopods (esp. P2) look mottled with dark brown chromatophores. Peduncle of pleopods with an anterior longitudinal brown stripe and a posterior white stripe. Eggs brown or green. (d’Udekem d’Acoz et al., 2005).

The colour pattern noted by Walker and Poore (2003) for Australian specimens is not consistent with that of European, Californian and Asian specimens but is as follows: grey or olive-green; distinct wide, grey band across palm of pereiopod 2; diffuse longitudinal and oblique rows on carapace; diffuse transverse lines on posterior edges of abdominal articles.

Good colour photographs of this species have been provided by d’Udekem d’Acoz et al. (2005) and Jensen (1995). As with all Palaemon species, specimens of P. macrodactylus from turbid waters are usually almost translucent without a defined colour pattern.

Larvae: the larvae of P. macrodactylus have a distinctive hook-like process on their third abdominal somite in the 2nd to 8th stage zoea. This process is found in some other Asian species (P. ortmanni, P. serrifer) but not known in native larvae in any of the areas to which it has been introduced and therefore makes them easily discernable. The larval development of P. macrodactylus has been described by Little (1969) and Shy and Yu (1987).


Top of page

P. macrodactylus inhabits brackish waters throughout its range. It is native to Japan, Korea and Northern China, with southern Chinese records from Guangdong province (Li et al., 2007) requiring confirmation since the region seems too warm for a temperate species and due to the lack of records from intermediate areas. Taiwanese records (Chan and Yu, 1985) do not refer to P. macrodactylus. In western North America it is found from Malibu Lagoon and Long Beach Harbour, California to Willapa Bay, Washington (Jensen, 1995). Recently, P. macrodatylus was recorded from New York (Warkentine and Rachlin, 2010), with this being the only published occurrence in eastern North America. Likewise a record from Mar del Plata Harbour, Argentina represents the only known occurrence of the species in the south-western Atlantic.

The occurrence and distribution of P. macrodactylus in Australia is unclear. The only verified occurrence is from power station cooling water ponds in New South Wales (Buckworth, 1979). Whilst Williams et al. (1978; 1982) mentioned the occurrence of this species in South Australia, neither Pollard and Hutchings (1990) nor Wiltshire et al. (2010) could corroborate this record. It has been cited from South Australia in more recent papers (e.g. from the Gulf of St. Vincent by Wear and Tanner, 2007) but its occurrence in South Australia still requires verification. A further record from Darwin, Northern Territory (Bruce and Coombes, 1997) seems unlikely due to the high water temperatures.

P. macrodactylus also occupies a large geographic range along the Atlantic coasts of Europe (Ashelby et al., 2004; Cuesta et al., 2004; d’Udekem d’Acoz et al., 2005; González-Ortegón et al., 2006; Béguer et al., 2007; Worsfold and Ashelby, 2008; Chícharo et al., 2009), seemingly having colonised most (but not all - see Lavesque et al., 2010) suitable habitats in this region, south of the southern North Sea. There are two published occurrences of the species in the Black Sea from Romania (Micu and Nita, 2009) and Bulgaria (Raykov et al., 2010) but as yet there have been no records from the Mediterranean.

Distribution Table

Top of page

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Sea Areas

Atlantic, NortheastWidespreadIntroduced1992Ashelby et al., 2004; Cuesta et al., 2004; Udekem et al., 2005; Béguer et al., 2007; González-Ortegón et al., 2007; Worsfold and Ashelby, 2008; Chícharo et al., 2009; Lavesque et al., 2010
Atlantic, NorthwestLocalised2008Introduced2001Warkentine and Rachlin, 2010
Atlantic, SouthwestLocalisedIntroduced2000Spivak et al., 2006
Indian Ocean, EasternUnconfirmed recordWilliams et al., 1978; Williams et al., 1982; Wear and Tanner, 2007
Mediterranean and Black SeaLocalisedIntroduced2002Micu and Nita, 2009; Raykov et al., 2010
Pacific, NortheastWidespreadIntroduced1957Newman, 1963; Jensen, 1995
Pacific, NorthwestWidespreadNative Not invasive Rathbun, 1902; Yu, 1930; Kubo, 1942; Kobjakova, 1967; Kim, 1985; Li et al., 2007Native range. Type locality Aomori, Japan
Pacific, SouthwestPresentIntroducedBuckworth, 1979
Pacific, Western CentralUnconfirmed recordBruce and Coombes, 1997


ChinaPresentPresent based on regional distribution.
-GuangdongUnconfirmed recordLi et al., 2007This record requires confirmation
-JiangsuWidespreadNative Not invasive Li et al., 2007
-LiaoningWidespreadNative Not invasive Li et al., 2007
-ShandongWidespreadNative Not invasive Li et al., 2007
JapanPresentPresent based on regional distribution.
-HonshuWidespreadNative Not invasive Rathbun, 1902; Kubo, 1942Type locality: Aomori
-KyushuWidespreadNative Not invasive Rathbun, 1902; Kubo, 1942
Korea, DPRWidespreadNative Not invasive Rathbun, 1902; Kim, 1985
Korea, Republic ofWidespreadNative Not invasive Rathbun, 1902; Kim, 1985
TaiwanAbsent, invalid recordChan and Yu, 1985This record does not refer to P. macrodactylus but to P. serrifer

North America

USAPresentPresent based on regional distribution.
-CaliforniaWidespreadIntroduced1957 Invasive Newman, 1963
-ConnecticutPresentIntroduced2010Wojtas, 2010
-New YorkLocalised2010Introduced2001Warkentine and Rachlin, 2010
-OregonPresentIntroducedGonzález-Ortegón et al., 2007; Warkentine and Rachlin, 2010Cited as occurring in Oregon by González-Ortegón et al. (2007) and Warkentine and Rachlin (2010) but without any details or reference to published records. The occurrence Northwards in Washington (Jensen, 1995) and southwards in California (Newman, 1963) would suggest that it is probably present in Oregon
-VirginiaPresentIntroduced2007NEMESIS and, 2011
-WashingtonPresentIntroducedJensen, 1995

South America

ArgentinaLocalisedIntroduced2000Spivak et al., 2006


BelgiumWidespreadIntroduced1998Udekem et al., 2005; Blauwe, 2006; Soors et al., 2010; Boets et al., 2011
BulgariaLocalisedIntroduced2009Raykov et al., 2010
FranceWidespreadIntroduced1998Lavesque et al., 2010; Béguer et al., 2011
GermanyLocalisedIntroduced2004González-Ortegón et al., 2007
NetherlandsWidespreadIntroduced1999Faasse, 2005; Udekem et al., 2005; Tulp, 2006
PortugalLocalisedIntroduced2004Cuesta et al., 2004; González-Ortegón et al., 2005; Chícharo et al., 2009Only Larvae were reported in 2004 by Cuesta et al. (2004) and González-Ortegón et al. (2005); the first adults were reported in 2008 by Chicharo et al. (2009)
RomaniaLocalisedIntroduced2002Micu and Nita, 2009
Russian FederationPresentPresent based on regional distribution.
-Russian Far EastLocalisedNative Not invasive Kobjakova, 1967
SpainLocalisedIntroduced1999Cuesta et al., 2004
UKLocalisedIntroduced1992Ashelby et al., 2004; Worsfold and Ashelby, 2008


AustraliaPresentPresent based on regional distribution.
-Australian Northern TerritoryUnconfirmed recordBruce and Coombes, 1997This record from Darwin Harbour is almost certainly incorrect. Darwin exceeds P. macrodactylus’ preferred temperature range
-New South WalesPresentIntroducedBuckworth, 1979
-South AustraliaUnconfirmed recordWilliams et al., 1978; Wear and Tanner, 2007Records from South Australia require confirmation

History of Introduction and Spread

Top of page

P. macrodactylus was first noted outside of its native range in San Francisco Bay in 1957 but was possibly present in the region since 1954 (Newman, 1963). Here, its spread was facilitated by its use as a bait species (Williams, 1997) and it now occupies a range from Malibu Lagoon and Long Beach Harbour California to Willapa Bay, Washington (Jensen, 1995). It has since spread to many other areas including Australia (Buckworth, 1979), Atlantic and North Sea coasts of Europe since 1992 (Ashelby et al., 2004; Cuesta et al., 2004; d’Udekem d’Acoz et al., 2005; González-Ortegón et al., 2006; Béguer et al., 2007; Worsfold and Ashelby, 2008; Chícharo et al., 2009), Argentina in 2000 (Spivak et al., 2006) and the Black Sea in 2002 and 2009 (Micu and Nita, 2009; Raykov et al., 2010). Most recently it has been reported in rivers surrounding New York City since 2001 (Warkentine and Rachlin, 2010).

The oldest European record is from the Thames in England in 1992 (Ashelby et al., 2004). However, it is currently unclear where the original introduction to Europe occurred or whether multiple introductions are involved. Introduction to different European countries could have either been associated with shipping, aquaculture or natural spread from other European populations.

It is likely that shipping is the primary vector for transport to disparate areas with subsequent spread being via local shipping or natural spread through larval distribution. The first recognition of P. macrodactylus has rarely, if ever, been coincidental with its introduction and in virtually all areas of introduction, the occurrence of the species has been antedated by examining archived material. Populations have invariably become established and abundant prior to detection.


Top of page
Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Argentina 2000 Hitchhiker (pathway cause) Yes Spivak et al. (2006)
Belgium  1998 Hitchhiker (pathway cause) Yes Udekem et al. (2005)
Bulgaria 2009 Hitchhiker (pathway cause) Yes Raykov et al. (2010)
California Asia 1954-1957 Hitchhiker (pathway cause) Yes Newman (1963) Subsequent spread accelerated due to its use as bait
England and Wales 1992 Hitchhiker (pathway cause) Yes Ashelby et al. (2004); Worsfold and Ashelby (2008) The oldest European record is from the Thames in 1992
France 1998 Hitchhiker (pathway cause)Béguer et al. (2007)
Germany 2004 Hitchhiker (pathway cause) Yes González-Ortegón et al. (2006)
Netherlands 1999 Hitchhiker (pathway cause) Yes Udekem et al. (2005)
New South Wales Asia 1970s Buckworth (1979)
New York 2001 Hitchhiker (pathway cause) Yes Warkentine and Rachlin (2010)
Portugal 2004 Hitchhiker (pathway cause) Yes Chícharo et al. (2009); Cuesta et al. (2004); González-Ortegón et al. (2005)
Romania 2002 Hitchhiker (pathway cause) Yes Micu and Nita (2009)
Spain 1999 Hitchhiker (pathway cause) Yes Cuesta et al. (2004)

Risk of Introduction

Top of page

The potential distribution of P. macrodactylus is determined by temperature and it already occurs in most suitable regions. However, it is highly likely that P. macrodactylus will be introduced to other regions with suitable temperature regimes. This would include South Africa and New Zealand. Spread between disparate areas is most likely to occur via shipping (Dawson, 1973) and its occurrence in large harbours throughout its native and introduced range increases the opportunities and likely destinations. The fact that many harbours are situated in large estuaries, the favoured habitat of P. macrodactylus, increases the chance that an introduction would be successful.

In regions to which P. macrodactylus has been introduced it is likely that, in time, it will colonise all suitable habitats either through natural spread or infra-regional shipping. In northeast Europe the occurrence of the species in the Baltic Sea seems highly probable as has been predicted by González-Ortegón et al. (2006). It is also likely to spread to Norway and Iceland, the Mediterranean and north west Africa. Further spread along both coasts of North America, Atlantic coasts of South America and throughout southern Australia is highly probable. In California the spread of P. macrodactylus was assisted by its use as a bait species (Williams, 1997) but intentional introduction to new regions seems unlikely.


Top of page

P. macrodactylus has broad environmental tolerances but is mostly found in brackish water, in estuaries, particularly favouring protected harbours, bays, ponds and tidal creeks. It is rarely found in fully marine or fully freshwater conditions.

Habitat List

Top of page
Coastal areas Secondary/tolerated habitat Natural
Estuaries Principal habitat Natural
Lagoons Secondary/tolerated habitat Natural
Benthic zone Secondary/tolerated habitat Natural

Biology and Ecology

Top of page


Detailed genetic investigations have not been conducted for P. macrodactylus but it has been included in phylogenetic studies (Mitsuhashi et al., 2007; Ashelby et al., in prep) from which partial gene sequences for 16SrRNA, 28SrRNA, 12SrRNA, 18SrRNA and Histone are available. Microsatellite work is currently being conducted by some European researchers in order to try to determine the sequence of introductions of P. macrodactylus. There is currently no information on genetic variation within the species.

Reproductive Biology

Omori and Chida (1988a) described reproduction in P. macrodactylus in Japan. The breeding season was noted as being mid-April to early October. Second-year females carry eggs earlier than first-year females. Most 0- to 1-year-old females were found to produce less than 1000 eggs at temperatures of between 15 and 27°C. Older females were found to produce 500-2800 eggs at similar temperatures. Brood sizes of between 100 and 2000 have been noted for Californian specimens of the species (Siegfried, 1980). Each age group produces at least two cohorts per year, with five to nine being possible under controlled laboratory conditions entailing a raised temperature and hence an extended breeding season (Omori and Chida, 1988b). It has been suggested that higher salinities may also extend the breeding season of P. macrodactylus (Little, 1969).

Females may carry a second brood in their ovaries before the first brood is released (Siegfried, 1980). The larvae of P. macrodactylus are photopositive (Little, 1969); however, they become photonegative as they develop, prior to recruitment to the benthos (Siegfried et al., 1978). Photoperiod has been noted as an important parameter in controlling spawning (Siegfried, 1980). In California, ovigerous females are found mainly from May to August (Siegfried, 1980); juveniles are recruited to the benthos after May (Siegfried, 1980; 1982).

In this species, growth rate is very high in the first year and there is a spurt of growth just before spawning: little growth occurs after spawning until the following year. Sexual characteristics are noted on individuals 20 mm in length (Siegfried, 1980) and females grow faster than, and are larger than, males (Omori and Chida, 1988a).

Physiology and Phenology

P. macrodactylus is a strong osmoregulator over the salinity range of 2-150% sea water, and is known to inhabit a wide range of salinities in San Francisco Bay (Born, 1968), where it is not uncommon to capture P. macrodactylus in fresh or nearly fresh water (Siegfried, 1980). The upstream limit of its range has been noted as 1PSU, the downstream limit being set by prey availability (Siegfried, 1980). González-Ortegón et al. (2006) demonstrated that the centre of mass of the population with respect to distance from the river mouth and salinity was related to temperature with P. macrodactylus occupying a wider range at lower temperatures. The isosmotic point was 584 mmol kg-1 at 20°C (González-Ortegón et al., 2006).


Life spans of two to three years have been recorded for individuals of P. macrodactylus in Japan (Omori and Chida, 1988a, c).

Activity Patterns

P. macrodactylus moves into the water column at night and is mainly nocturnal (Siegfried, 1982). Significant migrations do not occur in this species but the centre of population moves seawards in the summer and back upstream in autumn and winter, following preferred salinity gradients (Béguer et al., 2011).

Population Size and Density

Mean population densities of 5.4 individuals 10-2 m-3 have been recorded by González-Ortegón et al. (2010) and 11.2 individuals 10-3 m-3 by Béguer et al. (2011). The maximum population density of P. macrodactylus in the Guadlaquivir Estuary, Spain, is distributed further upstream than the native P. longirostris. Béguer et al. (2011) recorded larval densities of up to 225 larvae m-3.


P. macrodactylus is omnivorous but the greater proportion of the diet is made up of animals, with Sitts and Knight (1979) recording between 75 and 93% of gut content consisting of animal fragments. It predates on mysids, copepods, amphipods, barnacles, polychaetes, small bivalves, fish larvae (Sitts and Knight, 1979) and insect larvae (Ashelby, pers obs.). There is also evidence of cannibalism when kept in crowded laboratory conditions (Newman, 1963). Whether this also occurs in nature or is extended to feeding on other carideans is not known.

Studies in California have reported P. macrodactylus as preying on Neomysis mercedis, Corophium spp., Rhithropanopeus harrissi and its own larvae.


P. macrodactylus has no obligate associations; however, as with many decapods, its eggs are susceptible to infection by the fungus Lagenidium callinectes (Fisher, 1983b). P.macrodactylus has a symbiotic bacterium, Alteromonas sp., which protects its eggs from fungal attack (Fisher 1983a, b; Gil-Turnes et al., 1989). When the bacteria are removed or the first pereiopods (used for cleaning) are removed, fungal infection normally results in death of the embryos (Fisher, 1983b; Gil-Turnes et al., 1989).

In the wild, P. macrodactylus forms loose associations with other carideans and is most abundant around rocks, submerged structures and macroalgae.

Environmental Requirements

The tolerance limits of P. macrodactylus for most environmental parameters have not been studied in detail. The values included in the tables are mostly based on sampling data included in publications of records of the species rather than laboratory studies into tolerance. They may be more indicative of preference rather than tolerance.


Natural Food Sources

Top of page
Food SourceLife StageContribution to Total Food Intake (%)Details
Macrodactylus Adult

Water Tolerances

Top of page
ParameterMinimum ValueMaximum ValueTypical ValueStatusLife StageNotes
Dissolved oxygen (mg/l) 0.3 10 Optimum
Salinity (part per thousand) 5 15 Optimum Palaemon macrodactylus is a strong regulator over the range 2-150% sea water (Born, 1968). Can tolerate 0.6-48 ppt
Turbidity (JTU turbidity) 56 4000 Optimum
Water temperature (ºC temperature) 14 26 Optimum Tolerates temperatures from 2-26°C. Neman (1963) noted that P. macrodactylus can be maintained in captivity for extended periods between 14 and 26°C.

Natural enemies

Top of page
Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Crangon franciscorum Predator Larval not specific
Morone saxatilis Predator Adult not specific

Notes on Natural Enemies

Top of page

Little information exists on the natural enemies of P. macrodactylus but, in California, it serves as an important food resource for fish, including striped bass (Ganssle, 1966; Ricketts et al., 1968) and it is likely that, as for other shrimp species, fish and birds are its main predators in all parts of its range. The larvae are prey for Crangon franciscorum (Siegfried, 1980) in California and would be also be consumed by other estuarine planktivores, elsewhere. As demonstrated by Newman (1963) there may be strong intraspecific competition and possible cannibalism, thus P. macrodactylus may become an enemy of itself.

Means of Movement and Dispersal

Top of page

Natural Dispersal (Non-Biotic)

P. macrodactylus is unlikely to reach distant locations via natural means but once introduced to a region natural spread via larval dispersal or short migrations is likely. 

Vector Transmission (Biotic)

No biotic vectors have been reported for P. macrodactylus.

Accidental Introduction

Newman (1963) presented a convincing argument that the introduction of P. macrodactylus to San Francisco Bay was coincidental with an increase in shipping to the region from Japan and Korea following the Korean War and other introductions of the species are also likely to be associated with shipping. Ballast water has been suggested as the primary vector for introduction of P. macrodactylus since many reports of the species are from the vicinity of large, international harbours (Ashelby et al. 2004; Cuesta et al. 2004; d’Udekem d’Acoz et al. 2005; Spivak et al. 2006; Béguer et al. 2007; González-Ortegón et al. 2007; Micu and Nita 2009). However other shipping associated vectors, such as the sea water systems of large vessels (Newman, 1963) have been suggested and it is important to note that the species has not actually been recorded in ballast water sampling.

Whilst shipping mediated introduction seems most likely, it should be noted that harbours are also more likely to be the subject of routine monitoring studies than other suitable habitats, increasing the likelihood of detection. Once established in a region, spread through infra-regional shipping or pleasure craft is probable.

 Intentional Introduction

 Intentional introduction of P. macrodactylus has not been reported.

Pathway Causes

Top of page
CauseNotesLong DistanceLocalReferences
Animal productionPossible but not proven Yes
FisheriesPossible but not proven Yes
HitchhikerProbably occurs but not observed Yes Lavesque et al., 2010

Impact Summary

Top of page
Economic/livelihood Positive and negative

Economic Impact

Top of page

There are no known negative economic impacts of P. macrodactylus; however, its potential effect on fisheries of native shrimp species should be monitored.

Environmental Impact

Top of page

Impact on Habitats

P. macrodactylus is known to occur in areas with statutory designations (e.g. in the UK it occurs in Sites of Special Scientific Interest, Special Areas of Conservation and Special Protection Areas) but the impact of the species on these habitats is unknown.

Impact on Biodiversity

While little data exists on competitive interactions of P. macrodactylus, Ricketts et al. (1968) observed that it eclipsed native (American) Crangon spp. in terms of numerical abundance, while Siegfried (1980) felt that careful management of water projects may be necessary to protect the native shrimp (C. franciscorum) in the Sacramento/San Joaquin Delta. Importantly, neither of these studies demonstrated detrimental effects or a decrease in the abundance of Crangon. Béguer et al. (2011) indicated that P. macrodactylus exploits niches in the Gironde Estuary that are currently under-used by the native Palaemon longirostris thus reducing competition. Likewise, Newman (1963) and Carlton (1979) noted that, in San Francisco Bay, P. macrodactylus occupied a different ecological niche to the native shrimp species, and so did not seem to have a damaging effect. However, Sitts and Knight (1979) and Siegfried (1982) found that there was dietary overlap, with size-related resource partitioning, between this species and the indigenous Crangon franciscorum, in California and González-Ortegón et al, (2010) also showed dietary overlap with P. longirostris in Spain.

Threatened Species

Top of page
Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Palaemon longirostrisNo DetailsUKCompetitionChadd and Extence, 2004

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Is a habitat generalist
  • Tolerant of shade
  • Capable of securing and ingesting a wide range of food
  • Highly mobile locally
  • Long lived
  • Fast growing
  • Has high reproductive potential
  • Gregarious
Impact outcomes
  • Modification of natural benthic communities
Impact mechanisms
  • Predation
  • Rapid growth
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect in the field


Top of page

Economic Value

Holthuis (1980) listed P. macrodactylus in his annotated catalogue of shrimps and prawns of interest to fisheries. In China, Japan and Korea P. macrodactylus is fished and sold for food; however it is regarded as low economic value (Liu, 1955; Omori and Chida, 1988a). In California, P. macrodactylus is used as bait and was first noted from commercial shrimp catches. As an edible species, it is probable that it would form part of the commercial shrimp wherever it occurs (Ashelby et al., 2004; Béguer, 2011).

Environmental Services

P. macrodactylus does not provide any major environmental services but will scavenge on carrion.

Uses List

Top of page

Animal feed, fodder, forage

  • Bait/attractant
  • Fishmeal
  • Invertebrate food


  • Research model

Human food and beverage

  • Meat/fat/offal/blood/bone (whole, cut, fresh, frozen, canned, cured, processed or smoked)


Top of page

Identification using morphological features under stereo microscopy along with comparison with voucher specimens from museums or other verified sources remains the most accurate and cost effective method of identifying the species. Partial gene sequences for 16SrRNA, 28SrRNA, 12SrRNA, 18SrRNA and Histone are available from GenBank for comparison.

Detection and Inspection

Top of page

P. macrodactylus is most likely to be caught using sweep nets or trawls around hard structures near reduced salinity ports or harbours. Early detection may be possible through examination of ballast water tanks or the sea chests of large ships but there have been no documented occurrences of P. macrodactylus larvae or adults from either of these. In the field, this species is most easily recognised by the presence of a longitudinal dorsal white stripe (but this may be missing). Larvae are easily recognised in plankton samples by the presence of a hook-like process on the abdomen. Confirmation of field identifications can be through one of the following keys: Walker and Poore (2003); Ashelby et al. (2004); d’Udekem d’Acoz et al. (2005); González-Ortegón and Cuesta (2006); Li et al. (2007).

Similarities to Other Species/Conditions

Top of page

The presence of a longitudinal white stripe along the dorsum is possibly unique to P. macrodactylus and may serve to provide a quick recognition feature in the field, but it is not always present and any such field identification should be confirmed by more detailed analysis. In its native range, P. macrodactylus may be confused with P. serrifer. They can be separated by the following features: carpus of pereiopod 1 about 1.6 times as long as chela (P. macrodactylus) vs. about 2 times as long as chela (P. serrifer); chela of pereiopod 2 with palm little longer than fingers (P. macrodactylus) vs. palm 1.2 times as long as fingers (P. serrifer); the more slender and longer dactyli of P3-5 as well as the colour pattern in living specimens.

Outside of its native range, P. macrodactylus can be distinguished from most of its congeners through the greater number of rostral teeth. Additional features and similar species are given below.

In California, there are few Palaemon species and P. macrodactylus could only really be confused with P. ritteri. In P. ritteri the branchiostegal tooth originates on the anterior margin of the carapace whereas in P. macrodactylus it originates slightly behind the margin.

In New York, P. macrodactylus co-occurs with Palaemonetesvulgaris and Palaemonetespugio but is differentiated by its substantially longer pereiopod 2, extending well beyond the rostrum and through the presence of a mandible palp in P. macrodactylus (absent in Palaemonetes).

In Europe, there is a high diversity of native Palaemon species and P. macrodactylus is most likely to be confused with P. longirostris, compounded by the fact that P. longirostris is a highly variable species and co-occurs with P. macrodactylus. It can be separated from P. longirostris by possession of a pre-anal spine (absent in P. longirostris), the extent of fusion of the dorsal flagellum of the antennula (about 20% of its length in P. macrodactylus and 30% in P. longirostris), and the double row of setae on the ventral margin of the rostrum (single row in P. longirostris).

Australian specimens should not be easily confused with any of the native fauna but are most easily distinguished by the second pereiopod being 0.7-0.9 times body length, the large number of dorsal rostral teeth and the degree of fusion of the flagellum of the antennula.

Prevention and Control

Top of page

SPS Measures

No SPS measures have been implemented for P. macrodactylus.

Early Warning Systems

No early warning systems are in place specifically for P. macrodactylus. As awareness of the species grows, early detection in routine monitoring surveys is more likely. 

Rapid Response

There are no known rapid response systems for the management of P. macrodactylus

Public Awareness 

Awareness of P. macrodactylus is still largely confined to the scientific community but, even within the scientific community, it is not widely known and is missing from most standard identification guides so may be easily overlooked. The recent occurrence of the species in the Mystic River, Connecticut was reported by News8 but the occurrence in other areas has not been publicly broadcast. Furthermore, the species is often not included in regional summaries or websites of invasive species.


There are no published accounts of attempts to eradicate this species. Once established, ecologically sound eradication is probably not possible.


No containment strategies have been suggested or trialed for P. macrodactylus. As a mobile species with pelagic larvae, containment would be difficult.


No control procedures have been developed for P. macrodactylus. As most physical, biological or chemical control measures would be non-specific their implementation would have adverse effects on native fauna as well as P. macrodactylus.

Monitoring and Surveillance

There are no monitoring programs specifically designed for detection or monitoring the spread of P. macrodactylus. Furthermore, the species may be overlooked in routine monitoring surveys where rapid assessments and in-situ identification are used and shrimp populations are not the focus. For example, in the UK, routine invertebrate sampling uses methods that would be unlikely to detect the species, while trawl and net samples are often examined for fish only.

Gaps in Knowledge/Research Needs

Top of page

Laboratory studies into tolerance limits for many environmental parameters are lacking and would provide useful insights into potential areas at risk of invasion by P. macrodactylus.

Although ballast water is frequently cited as the mode of introduction the occurrence of the species in ballast water has not been proven and other forms of potential transport should also be investigated.

The status of P. macrodactylus in Australia, particularly South Australia should be investigated.

Although negative effects of non-native species on native species and habitats are often postulated, conclusive evidence for negative impacts is lacking.

The northern and southern limits of the species in its native range require clarification. This would help predictions of its potential spread outside of its native range.


Top of page

Ashelby CW; Worsfold TM; Fransen CHJM, 2004. First records of the oriental prawn Palaemon macrodactylus (Decapoda: Caridea), an alien species in European waters, with a revised key to British Palaemonidae. Journal of the Marine Biological Association of the United Kingdom, 84:1041-1050.

Béguer M; Bergé J; Martin J; Martinet J; Pauliac G; Girardin M; Boët P, 2011. Presence of Palaemon macrodactylus in a European estuary: evidence for a successful invasion of the Gironde (SW France). Aquatic Invasions, 6(3):401-418.

Béguer M; Girardin M; Boët P, 2007. First record of the invasive oriental shrimp Palaemon macrodactylus Rathbun, 1902 in France (Gironde Estuary). Aquatic Invasions, 2(2):132-136.

Blauwe HDe, 2006. De rugstreepsteurgarnaal Palaemon macrodactylus in België. De Strandvlo, 26(1):22-23.

Boets P; Lock K; Goethals PLM, 2011. Using long-term monitoring to investigate the changes in species composition in the harbour of Ghent (Belgium). Hydrobiologia, 663:155-166.

Born JW, 1968. Osmoregulatory capacities of two caridean shrimps, Syncaris pacifica (Atyidae) and Palaemon macrodactylus (Palaemonidae). The Biological Bulletin, 134(2):235-244.

Bruce AJ; Coombes KE, 1997. An annotated check-list of the caridean shrimps (Crustacea: Decapoda) of Darwin Harbour, with descriptions of three new species of Periclimenes [Palaemonidae: Pontoniinae]. In: Proceedings of the Sixth International Marine Biological Workshop. The Marine Flora and Fauna of Darwin Harbour, Northern Territory, Australia [ed. by Hanley, J. R. \Caswell, G. \Megirian, D. \Larson, H. K.]. Darwin, Australia: Museums and Art Galleries of the Northern Territory and the Australian Marine Sciences Association, 301-337.

Buckworth R, 1979. Aspects of the population dynamics of Palaemon macrodactylus (Decapoda: Palaemonidae) in Lake Mannering, N., and in the laboratory. Thesis. Sydney, Australia: University of New South Wales.

Carlton JT, 1979. Introduced invertebrates of San Francisco Bay. In: San Francisco Bay: the urbanized estuary [ed. by Conomos TJ] San Francisco, : Pacific Division of the American Association for the Advancement of Science c/o California Academy of Science, 427-444.

Chadd R; Extence C, 2004. The conservation of freshwater macroinvertebrate populations: a community-based classification scheme. Aquatic Conservation: Marine and Freshwater Ecosystems, 14:597-624.

Chan T-Y; Yu H-P, 1985. Studies on the genus Palaemon (Crustacea: Decapoda: Palaemonidae). Journal of the Taiwan Museum, 38:119-127.

Chícharo MA; Leitão T; Range P; Gutierrez C; Morales J; Morais P; Chícharo L, 2009. Alien species in the Guadiana Estuary (SE-Portugal/SW-Spain): Blackfordia virginica (Cnidaria, Hydrozoa) and Palaemon macrodactylus (Crustacea, Decapoda): potential impacts and mitigation measures. Aquatic Invasions, 4(3):501-506.

Cuesta JA; Gonzalez-Ortegon E; Drake P; Rodriguez A, 2004. First record of Palaemon macrodactylus Rathbun, 1902 (Decapoda, Caridea, Palaemonidae) from European waters. Crustaceana, 77:377-380.

Dawson GE, 1973. Occurrence of an exotic eleotrid fish in Panama with discussion of probable origin and mode of introduction. Copeia, 1:141-144.

Faasse M, 2005. [English title not available]. (Een Aziatische Steurgarnaal in Nederland: Palaemon macrodactylus Rathbun, 1902 (Crustacea: Decapoda: Caridea).) Het Zeepaard, 65(6):193-195.

Fisher WS, 1983a. Eggs of Palaemon macrodactylus: II. Association with aquatic bacteria. Biological Bulletin, 164:201-213.

Fisher WS, 1983b. Eggs of Palaemon macrodactylus: III. Infection by the fungus, Lagenidium callinectes. Biological Bulletin, 164:214-226.

Ganssle D, 1966. Fishes and decapods of the San Pablo and Suisun Bays. California Department of Fish and Game,Fish Bulletin, 133:64-94.

Gil-Turnes MS; Hay ME; Fenical W, 1989. Symbiotic marine bacteria chemically defend crustacean embryos from a pathogenic fungus. Science (Washington), 246(4926):116-118.

González-Ortegón E; Cuesta JA, 2006. An illustrated key to species of Palaemon and Palaemonetes (Crustacea: Decapoda: Caridea) from European waters, including the alien species Palaemon macrodactylus. Journal of Marine Biology Association United Kingdom, 86(1):93-102.

González-Ortegón E; Cuesta JA; Drake P, 2005. [English title not available]. (La introducción del camarón oriental en el estuario del Guadalquivir.) Quercus, 234:20-24.

González-Ortegón E; Cuesta JA; Pascual E; Drake P, 2010. Assessment of the interaction between the white shrimp, Palaemon longirostris, and the exotic oriental shrimp, Palaemon macrodactylus, in a European estuary (SW Spain). Biological Invasions, 12(6):1731-1745.

González-Ortegón E; Cuesta JA; Schubart CD, 2007. First report of the oriental shrimp Palaemon macrodactylus Rathbun, 1902 (Decapoda, Caridea, Palaemonidae) from German waters. Helgoland Marine Research, 61(1):67-69.

González-Ortegón E; Pascual E; Cuesta JA; Drake P, 2006. Field distribution and osmoregulatory capacity of shrimps in a temperate European estuary (SW Spain). Estuarine,Coastal and Shelf Science, 67:293-302.

Holthuis LB, 1980. Shrimps and prawns of the world: an annotated catalogue of species of interest to fisheries. FAO Species Catalogue. Rome, Italy: FAO.

Jensen GC, 1995. Pacific Coast Crabs and Shrimps. Pacific Coast Crabs and Shrimps. Monterey, California, USA: Sea Challengers, 87 pp.

Kim HS, 1985. Systematic studies on Crustaceans of Korea, 1. Decapods. Proceedings of the College of Natural Sciences,Seoul National University, 10:63-94.

Kobjakova ZI, 1967. Decapoda (Crustacea, Decapoda) from the Possjet Bay (the Sea of Japan). Biocoenoses of the Possjet Bay of the Seas of Japan (Hydrobiological Investigations by Means of Aqualungs). In: Exploration of the Fauna of the Seas 5 (= old series, volume 13). Leningrad, Russia 230-247.

Kubo I, 1942. Studies on Japanese Palaemonoid Shrimps, III. Leander. Journal of the Imperial Fishery Institute,Tokyo, 35:17-85.

Lavesque N; Bachelet G; Béguer M; Girardin M; Lepage M; Blanchet H; Sorbe J-C; Modéran J; Sauriau P-G; Auby I, 2010. Recent expansion of the oriental shrimp Palaemon macrodactylus (Crustacea: Decapoda) on the western coasts of France. Aquatic Invasions, 5(Supplement 1):S103-S108.

Li X; Liu R; Liang X-Q; Chen G-X, 2007. Fauna Sinica. Invertebrata vol 44. Crustacea Decapoda Palaemonoidea. Beijing, China: Science Press, 381pp.

Little G, 1969. The larval development of the shrimp Palaemon macrodactylus Rathbun, reared in the laboratory, and the effect of eyestalk extirpation and development. Crustaceana, 17:69-87.

Liu JY, 1955. Economic shrimps and prawns of North China, 73 pp (in Chinese).

Micu D; Nita V, 2009. First record of the Asian prawn Palaemon macrodactylus Rathbun, 1902 (Caridea: Palaemonoidea: Palaemonidae) from the Black Sea. Aquatic Invasions, 4(4):597-604.

Mitsuhashi M; Sin YW; Lei HC; Chan T-Y; Chu KH, 2007. Systematic status of the caridean families Gnathophyllidae Dana and Hymenoceridae Ortmann (Crustacea: Decapoda): a preliminary examination based on nuclear rDNA sequences. Invertebrate Systematics, 21:613-622.

National Exotic Marine Estuarine Species Information System (NEMESIS), 2011. Smithsonian Environmental Research Centre.

Newman WA, 1963. On the introduction of an edible oriental shrimp (Caridea, Palaemonidae) to San Francisco Bay. Crustaceana, 5:119-132.

Omori M; Chida Y, 1988a. Life history of the caridean shrimp Palaemon macrodactylus with special reference to the difference in reproductive features among ages. Nippon Suisan Gakkaishi, 54(3):365-375.

Omori M; Chida Y, 1988b. Reproductive ecology of a caridean shrimp Palaemon macrodactylus in captivity. Nippon Suisan Gakkaishi, 54(3):377-383.

Omori M; Chida Y, 1988c. Comparison of life history between two caridean shrimps, Heptacarpus rectirostris and Palaemon macrodactylus, with different life spans. Tokyo Journal of Agricultural Research, 39(1):29-38.

Pollard D; Hutchings P, 1990. A review of exotic marine organisms introduced to the Australian region. II Invertebrate and algae. Asian Fish. Sci., 3:223-250.

Rathbun MJ, 1902. Japanese stalk-eyed Crustaceans. Proceedings of the United States National Museum, 26:23-55.

Raykov VS; Lepage M; Pérez-Domínguez R, 2010. First record of oriental shrimp, Palaemon macrodactylus Rathbun, 1902 in Varna Lake, Bulgaria. Aquatic Invasions, 5(Supplement 1):S91-S95.

Ricketts EF; Calvin J; Hedgpeth JW, 1968. Between Pacific Tides. California, USA: Stanford University Press, 614 pp.

Shy J-Y; Yu HP, 1987. Morphological observation on the development of larval Palaemon macrodactylus Rathbun, 1902 (Crustacea, Decapoda, Palaemonidae) reared in the laboratory. Journal of the Fisheries Society of Taiwan, 30:135-152.

Siegfried CA, 1980. Seasonal abundance and distribution of Crangon franciscorum and Palaemon macrodactylus (Decapoda, Caridea) in the San Francisco Bay Delta. Biological Bulletin, 159:177-192.

Siegfried CA, 1982. Trophic relations of Crangon franciscorum Stimpson and Palaemon macrodactylus Rathbun - predation on the opossum shrimp, Neomysis mercedis Holmes. Hydrobiologia, 89(2):129-139.

Siegfried CA; Knight AW; Kopache ME, 1978. Ecological studies on the western Sacramento-San Joaquin Delta during a dry year. Department of Land, Air, and Water Resources, Water Science and Engineering Paper No. 4506., USA: University of California, Davis, 121 pp.

Sitts RM; Knight AW, 1979. Predation by the estuarine shrimps Crangon franciscorum Stimpson and Palaemon macrodactylus Rathbun. Biological Bulletin, 156:356-368.

Soors J; Faasse M; Stevens M; Verbessem I; Regge Nde; Bergh Evan den, 2010. New crustacean invaders in the Schelde estuary (Belgium). Belgian Journal of Zoology, 140(1):3-10.

Spivak ED; Boschi EE; Martorelli SR, 2006. Presence of Palaemon macrodactylus Rathbun 1902 (Crustacea: Decapoda: Caridea: Palaemonidae) in Mar Del Plata Harbor, Argentina: first record from southwestern Atlantic waters. Biological Invasions, 8(4):673-676.

Tulp AS, 2006. [English title not available]. (De rugstreepsteurgarnaal Palaemon macrodactylus in meerdere Waddenhavens.) Het Zeepaard, 61(1):27-28.

Udekem d'Acoz d' C; Faasse M; Dumoulin E; Blauwe HDe, 2005. Occurrence of the Asian shrimp Palaemon macrodactylus in the southern bight of the North Sea, with a key to the Palaemonidae of north-western Europe (Crustacea: Decapoda: Caridea). Nederlandse Faunistische Mededelingen, 22:95-111.

Walker TM; Poore GCB, 2003. Rediagnosis of Palaemon and differentiation of Southern Australian species (Crustacea: Decapoda: Palaemonidae). Memoirs of Museum Victoria, 60:243-256.

Warkentine BE; Rachlin JW, 2010. The First Record of Palaemon macrodactylus (Oriental Shrimp) from the Eastern Coast of North America. Northeastern Naturalist, 17(1):91-102.

Wear RJ; Tanner JE, 2007. Spatio-temporal variability in faunal assemblages surrounding the discharge of secondary treated sewage. Estuarine, Coastal and Shelf Science, 73(3/4):630-638.

Williams GD, 1997. Annual Report, 20 September 1996 - 20 September 1997 for Los Peñasquitos Lagoon Foundation. 29 pp.

Williams RJ; Wal EJvan der; Kelly J, 1978. Draft inventory of introduced marine organisms. Australian Marine Science Bulletin, 6:12.

Williams RJ; Wal EJvan der; Kelly J, 1982. Ballast water as a dispersal vector for non-indigenous marine animals. Unpublished report to the Fishing Industry Research Committee. FIRTA 76/18. 58 pp.

Wiltshire K; Rowling K; Deveney M, 2010. Introduced marine species in South Australia: a review of records and distribution mapping. SARDI Research Report Series, 468:1-232. [SARDI Publication No. F2010/000305-1.]

Wojtas J, 2010. Mystic River research turns up big surprise. The Day, 16th June 2010. New London, CT, USA: The Day Publishing Company.

Worsfold TM; Ashelby CW, 2008. Additional UK records of the non-native prawn Palaemon macrodactylus (Crustacea: Decapoda). Marine Biodiversity Records, 1(e48). 1-3.

Yu SC, 1930. [English title not available]. (Note Sur Les Crevettes Chinoises Appartenant Au Genre Leander Desm. Avec Description De Nouvelles Especes.) Bulletin De La Societé Zoologique De France, 55:553-573.

Links to Websites

Top of page
Alien species in Swedish seas
GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gateway source for updated system data added to species habitat list.
Global register of Introduced and Invasive species (GRIIS) source for updated system data added to species habitat list.


Top of page

12/12/11 Original text by:

Christopher Ashelby, Thomson Unicomarine Ltd, 7 Diamond Centre, Works Road, Letchworth, Herts SG6 1LW, UK and CEMS, University of Hull, Scarborough Campus, Filey Road, Scarborough, Yorkshire YO11 3AZ, UK

Distribution Maps

Top of page
You can pan and zoom the map
Save map