Invasion History

First Non-native North American Tidal Record: 2012
First Non-native West Coast Tidal Record: 2012
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Palaemon kadiakensis is native to the interior basin of North America, from the southern Great Lakes region (Lakes Erie, Ontario, southern Lake Michigan) to the Gulf of Mexico (western Florida to northeastern Mexico) (Holthuis 1949a; Strenth 1976; Holthuis 1980). It has undergone a recent range expansion in the Ohio River, from former limits at the Ohio-Indiana border to the vicinity of Pittsburgh, Pennsylvania (Weisberg 2006; USGS Nonindigenous Aquatic Species Program 2015). This spread could be due to natural expansion, transport by fishermen, aquarium releases, or transport in barge ballast. In 2005, this shrimp was found in the Cosumnes River Preserve, California, at the northeastern edge of the Sacramento-San Joaquin Delta region, and by 2012 it was caught in the San Joaquin River and Georgiana Slough, where it is considered probably established (Brown and Hieb 2014).

North American Invasion History:

Invasion History on the West Coast:

Palaemon kadiakensis was found in 2005, in the Cosumnes River Preserve, California, at the northeastern edge of the Sacramento-San Joaquin Delta region. In 2012, a single specimen was caught in the San Joaquin River, and several specimens were reported in the tidal Georgiana Slough, where it is considered probably established. This shrimp is sold in the aquarium trade, which is considered the likeliest vector for its introduction (Brown and Hieb 2014).


Infraorder characteristics for Palaemon kadiakensis include chelae (movable claws) on the first two pairs of walking legs, and a third thoracic segment overlapping the second segment. Palaemon kadiakensis has a translucent body, a long toothed rostrum and large chelae on the second pereiopods (walking legs). The rostrum is as long as, or shorter than, the carapace and lacks an elevated basal crest. The rostrum has 7 dorsal teeth and 3 ventral teeth. Palaemon kadiakensis is also distinguished from P. modestus and P. macrodactylus by the lack of a mandibular palp, and from P. macrodactylus by the lack of a gastric spine. Maximum length of P. kadiakensis is 53 mm, smaller than P. modestus and P. macrodactylus (at 70-76 mm). Description based on: Holthuis 1949a and Brown and Hieb 2014.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Malacostraca
Subclass:   Eumalacostraca
Superorder:   Eucarida
Order:   Decapoda
Suborder:   Pleocyemata
Infraorder:   Caridea
Family:   Palaemonidae
Genus:   Palaemon
Species:   kadiakensis


Palaemonetes kadiakensis (Rathbun, 1902)

Potentially Misidentified Species

Paleemon modestus
Siberian Prawn, freshwater shrimp (=Exopalaemon modestus), introduced to West Coast rivers

Palemon macrodactylus
Oriental Prawn, NW Pacific native, introduced to East and West coasts of North America

Syncaris pacifica
Native freshwater shrimp found in central California, two dorsal teeth, six ventral teeth on rostrum. Endangered species. (Emmett et al. 2002; Brown and Hieb 2014).



Life History: In caridean shrimps, the copulating pair is usually oriented at right angles to one another, with the genital regions opposing each other. The modified first and second pairs of pleopods are used to transfer a spermatophore to a receptacle between the thoracic legs of the female (Barnes 1983). After mating, female palaemonid shrimps carry broods of fertilized eggs on their abdomen. These hatch into planktonic larvae with feathery appendages, called zoeae. Zoeae of shrimps lack the prominent spines seen in brachyuran crabs, and look quite shrimplike (Borad and Hubschman 1963). They go through several molts and metamorphose into postlarvae, which have well-developed walking legs. After a subsequent molt, the body takes on the adult shape.

Palaemon kadiakensis has 6 zoeal stages. At temperatures varying from 19.5 to 24C, development to the postlarval stage took 16 to 30 days. The first postlarval stage is a well-formed juvenile shrimp, with well-developed walking legs and pleopods (swimmerets).

Ecology: Palaemon kadiakensis is a widespread freshwater shrimp (Holthuis 1949a; Holthuis 1980), but we have found no reports of its occurrence in brackish waters. Strenth (1976) found that adult P.kadiakensis tolerated salinities up to 20 PSU, and suggested that local dispersal between tributaries through coastal waters was possible, but long-range dispersal through the ocean was unlikely. Larvae developed well in fresh water, but did not progress beyond zoea Stage 3 at 3.5 PSU (Hubschman 1975).


algae, vascular plants, invertebrates



Trophic Status:




General HabitatNontidal FreshwaterNone
General HabitatFresh (nontidal) MarshNone
General HabitatGrass BedNone
General HabitatSwampNone
General HabitatTidal Fresh MarshNone
Salinity RangeLimnetic0-0.5 PSU
Salinity RangeOligohaline0.5-5 PSU
Tidal RangeSubtidalNone
Vertical HabitatEpibenthicNone
Vertical HabitatNektonicNone

Tolerances and Life History Parameters

Maximum Temperature (ºC)40Critical temperature maximum (CTM) for animals acclimated to 32 F (Nelson and Hooper 1982)
Minimum Salinity (‰)0This is a freshwater species.
Maximum Salinity (‰)20Experimental (80% survival for 1 week, Strenth 1976)
Minimum Reproductive Salinity0This is a freshwater species.
Maximum Reproductive Salinity0Experimental. Development stopped at Zoea Stage 3 at 3,5 PSU (Hubschman 1975). The limits for reproduction are somewhere between 0 and 3.5 PSU.
Minimum Duration19Larval development,19-24 C (Broad and Hubschman 1963)
Maximum Duration30Larval development,19-24 C (Broad and Hubschman 1963)
Maximum Length (mm)50Holthuis 1949a

General Impacts

There are no known ecological impacts of introduced Palaemon kadiakensis. However, this shrimp is a potential competitor with a native freshwater shrimp (Syncaris pacifica), found in some freshwater streams in the San Francisco Bay drainage (Brown and Hieb 2014).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
P090 San Francisco Bay 2012 Def Estab
GL-III Lake Ontario 0 Native Estab
GL-II Lake Erie 0 Native Estab
GL-I Lakes Huron, Superior and Michigan 0 Native Estab
G080 Suwannee River 0 Native Estab
G086 _CDA_G086 (Econfina-Steinhatchee) 0 Native Estab
G090 Apalachee Bay 0 Native Estab
G100 Apalachicola Bay 0 Native Estab
G110 St. Andrew Bay 0 Native Estab
G120 Choctawhatchee Bay 0 Native Estab
G130 Pensacola Bay 0 Native Estab
G130 Pensacola Bay 0 Native Estab
G140 Perdido Bay 0 Native Estab
G150 Mobile Bay 0 Native Estab
G160 East Mississippi Sound 0 Native Estab
G170 West Mississippi Sound 0 Native Estab
G180 Breton/Chandeleur Sound 0 Native Estab
G190 Mississippi River 0 Native Estab
G200 Barataria Bay 0 Native Estab
G210 Terrebonne/Timbalier Bays 0 Native Estab
G220 Atchafalaya/Vermilion Bays 0 Native Estab
G230 Mermentau River 0 Native Estab
G240 Calcasieu Lake 0 Native Estab
G250 Sabine Lake 0 Native Estab
G260 Galveston Bay 0 Native Estab
G270 Brazos River 0 Native Estab
G280 Matagorda Bay 0 Native Estab
G290 San Antonio Bay 0 Native Estab
G300 Aransas Bay 0 Native Estab
G310 Corpus Christi Bay 0 Native Estab
G320 Upper Laguna Madre 0 Native Estab
G330 Lower Laguna Madre 0 Native Estab
P020 San Diego Bay 2012 Def Unk

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Barnes, Robert D. (1983) Invertebrate Zoology, Saunders, Philadelphia. Pp. 883

Broad, A. C.; Hubschman, Jerry H. (1963) The larval development of Palaemonetes kadakiensis M. J. Rathbun in the laboratory, Transactions of the American Microscopical Society 82(2): 185-197

Brown, Tiffany; Hieb, Kathryn A. (2014) Status of the Siberian Prawn, Exopalaemon modestus, in the San Francisco Estuary, San Francisco Estuary and Watershed Science 12(1): Published online

de Grave, Sammy; Ashelby, Christopher W. (2013) A re-appraisal of the systematic status of selected genera in Palaemoninae (Crustacea: Decapoda: Palaemonidae), Zootaxa 3734(3): 331-344

Holthuis, L. B. (1949a) Species of Palaemonetes (Crustacea: Decapoda) found in the United States of America, Koninklijke Nederlandsche Akademie van Wederschappen 52(1): 87-95

Holthuis, L. B. (1980) FAO Species Catalogue: Vol. 1. Shrimps and Prawns of the World., Food and Agricultural Organization, Rome. Pp. <missing location>

Hubschman, Jerry H. (1975) Larval development of the freshwater shrimp Palaemonetes kadiakensis under osmotic stress, Physiological Zoology 48(1): 97-104

Mastrototaro, F.; Gasparini, F.; Montesanto, F. (2022) The clubbed tunicate Styela clava has arrived in the Lagoon of Venice, European Journal of Zoology 89(1): 502-509

Mastrototaro, F.; Gasparini, F.; Montesanto, F. (2022) The clubbed tunicate Styela clava has arrived in the Lagoon of Venice, European Journal of Zoology 89(1): 502-509

Nelson, David, Hooper, Deborah K. (1982) Thermal tolerance and preference of the freshwater shrimp Palaemonetes kadiakensis, Journal of Thermal Biology 7: 183-187

Strenth, Ned E. (1976) A review of the systematics and zoogeography of the freshwater species of Palaemonetes Heller of North America (Crustacea: Decapoda), Smithsonian Contributions to Zoology 228: 1-26

2003-2022 Nonindigenous Aquatic Species Database. Gainesville, FL.

Weisberg, Deborah (8/23/2006) Shrimp- that's right, shrimp! -- found in Monongahela River, Pittsburgh Post-Gazette Published online: <missing location>