Invasion History

First Non-native North American Tidal Record: 1989
First Non-native West Coast Tidal Record: 1989
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Mizuhopecten yessoensis is native to the Northwest Pacific, from Tokyo Bay, Japan and the northern part of the Korean Peninsula to southern Sakhalin and the Kurile Islands, Russia (Scarlato, in Golikov et al. 1976; Gillespie et al. 2012). They have been introduced for aquaculture to China (Yellow Sea), Western Canada (British Columbia), Denmark, France, and Morocco (Minchin 2003). Culture operations in China and British Columbia have been commercially successful, but are dependent on hatcheries for reproduction (Gillespie et al. 2012), although some wild reproduction occurs in China (Liu et al. 2010). Other introductions have not resulted in commercially viable culture, or established populations (Minchin 2003; Gillespie et al. 2012).

North American Invasion History:

Invasion History on the West Coast:

Mizuhopecten yessoensis was imported to British Columbia (BC), and reared in hatcheries, under quarantine conditions, until 1988-1989, when culture began in open waters. Attempts at growing-out hatchery-reared scallops were unsuccessful because of predation. Consequently, scallops were reared in cages, suspended from rafts (Gillespie et al. 2012). Cultured M. yessoensis had high mortality due to the protozoan parasite Perkinsus pugwadi. Hybrids between M. yessoensis and the native Weathervane Scallop (Patinopecten caurinus) proved resistant to infection (Bower et al. 1999), and are now the predominant form cultured in BC waters (Gillespie et al. 2012). Scallop culture operations have occurred in all of BC’s Shellfish Transfer Zones, including Haida Gwaii (Queen Charlotte Islands) (Sloan et al. 2004), the north central Coast, Queen Charlotte Strait, Georgia Strait, and the west coast of Vancouver Island. While commercial, hatchery based culture of the scallops have been successful, no reproduction has been reported (Gillespie et al. 2012).

Invasion History Elsewhere in the World:

Culture of Mizuhopecten yessoensis has been attempted at many locations around the world, owing to this scallop's large size and high food quality. Culture in China began in 1982, using hatchery-produced spat. By 2010, natural reproduction was occurring at some sites in Dalian, China, in the Yellow Sea (Liu et al. 2010). Culture of M. yessoensis continues to be commercially successful, although climate variability can sometimes contribute to high mortality (Liu et al. 2014). Culture attempts in Denmark (in 1985), France (in 1986-1988), Ireland (in 1990), and Morocco have been commercially unsuccessful, and have not resulted in documented reproduction (Goulletquer at al. 2002; Minchin 2003; Gillespie et al. 2012).


Mizuhopecten yessoensis, has a large, rounded shell, which is a little wider than it is tall. It has prominent auricles ('wings') flanking the triangular beak. The right valve has a shallow, rounded byssal notch at the base of the auricle. The shell has 21-23 radial ribs, with rounded cross-sections on the right valve, and narrower ribs on the left valve. The left (upper) valve is flattened, while the right (lower) valve is more convex. Fine radial ribs are present on the auricles of the left valve. The shell can reach lengths and heights of 180-200 mm. The upper valve is dark brown or violet-brown, while the lower valve is yellowish-gray. The upper valve can become heavily encrusted with algae, barnacles, hydroids, and other epibiota. Description based on Skarlato, in Golikov et al. 1976, Coan et al. 2000, and Gillespie et al. 2012.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Mollusca
Class:   Bivalvia
Subclass:   Pteriomorphia
Order:   Ostreoida
Family:   Pectinidae
Genus:   Mizuhopecten
Species:   yessoensis


Patinopecten yessoensis (Jay, 1857)
Pecten brandti (Schrenck, 1861)
Placopecten yessoensis (Jay, 1857)
Pecten yessoensis (Jay, 1857)

Potentially Misidentified Species

Patinopecten caurinus
Weathervane Scallop, native to Northeast Pacific from the Aleutian Islands to California. The right valve has a deep notch at the base of the auricle, and the auricles are smaller than those of M. yessoensis (Coan et al. 2000).





Fishes, crabs, predatory snails, starfish

Trophic Status:

Suspension Feeder



General HabitatUnstructured BottomNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Vertical HabitatEpibenthicNone
Vertical HabitatNektonicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)2Field (Gillespie et al. 2012)
Maximum Temperature (ºC)26Field (Gillespie et al. 2012)
Minimum Salinity (‰)28Field (Gillespie et al. 2012)
Maximum Salinity (‰)40Field (Gillespie et al. 2012)
Minimum Duration15Lab, at 17-19 C (Motavkin 1986, cited by Gillespie et al. 2012)
Maximum Duration35Lab, 22-35 days at 7-13 C (Motavkin 1986, cited by Gillespie et al. 2012)
Minimum Length (mm)95Maturity is reached at 95-110 mm, at 3 years of age (Golikov and Skarlato 1970, cited by Gillespie et al. 2012).
Maximum Length (mm)200Skarlato, in Golikov et al. 1976; Coan et al. 2000; Gillespie et al. 2012)
Broad Temperature RangeNoneCold-temperate
Broad Salinity RangeNonePolyhaline-euhaline

General Impacts

Regional Impacts

NEP-IIIAlaskan panhandle to N. of Puget SoundEconomic ImpactFisheries
Aquaculture operations for purebred M. yessoensis and M. yessoensis X native P. caurinus hybrids have been successful, though no reproduction has been reported (Minchin 2003; Sloan et al. 2004; Gillespie et al. 2012).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NWP-5 None 0 Native Estab
NWP-4a None 0 Native Estab
NWP-4b None 0 Native Estab
NWP-3b None 0 Native Estab
NEP-III Alaskan panhandle to N. of Puget Sound 1989 Def Unk
NEA-II None 1985 Def Failed
NEA-IV None 0 Def Failed
WA-I None 1998 Def Failed
NWP-3a None 0 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Bower, Susan M.; Blackbourn, Janice; Meyer, Gary R.; Welch, David W. (1999) Effect of Perkinsus qugwadi on various species and strains of scallops, Diseases of Aquatic Organisms 36: 143-151

Coan, Eugene V.; Valentich-Scott, Paul; Bernard, Frank R. (2000) Bivalve Seashells of Western North Ameira, Santa Barbara Museum of Natural history, Santa Barbara CA. Pp. <missing location>

Collado-Vides, L. (2002) Morphological plasticity of Caulerpa prolifera (Caulerpales, Chlorophyta) in relation to growth form in a coral reef lagoon, Botanica Marina 45: 123-129

Gillespie, Graham E.; Bower, Susan M.; Marcus, Kerry L.; Kieser, Dorothee (2012) <missing title>, Canadian Science Advisory Secretariat, Fisheries and Oceans Canada, Ottawa, Ontario. Pp. 1-97

Golikov, A. N. and 7 other editors. (1976) <missing title>, Nauk, Leningrad. Pp. <missing location>

Gordon, Dennis P. (2016) Bryozoa of the South China Sea: an overview, Raffles Bulletin of Zoology 34: 604-618

Goulletquer, Philippe; Bachelet, Guy; Sauriau, Pierre; Noel, Pierre (2002) Invasive aquatic species of Europe: Distribution, impacts, and management, Kluwer Academic Publishers, Dordrecht. Pp. 276-290

Harvard Museum of Comparative Zoology 2008-2021 Museum of Comparative Zoology Collections database- Malacology Collection. <missing URL>

Lin, Xuezheng; Huang, Xiaohang (2007) Introduced marine species in China from Japan, and their impacts, Nippon Suisan Gakkaishi 73(6): 1138-1146

Liu, Wei-Dong and 6 authors (2010) Genetic differentiation between natural and hatchery stocks of Japanese scallop (Mizuhopecten yessoensis) as revealed by AFLP analysis, International Journal of Molecular Science 11: 3933-3941

Liu, Yang; Saitoh, Sei-Ichi; Radiarta, I Nyoman; Igarashi, Hiromichi; Hirawake, Toru (2014) Spatiotemporal variations in suitable areas for Japanese scallop aquaculture in the Dalian coastal area from 2003 to 2012, Aquaculture Published online: <missing location>

Minchin, Dan (2003) Introductions: some biological and ecological characteristics of scallops., Aquatic Living Resources 16: 521-532

Museum of Comparative Zoology 2008-2015 Invertebrate Zoology Collections Database <missing URL>

Nam, Myung-Mo; Lee, Chu; Moon, Tae Seok; Hu, Man, Kyu (2012) Genetic diversity and populatiuon structure of the scallop Patinopecten yessoensis in Korea, China, and Japan by random polymorphic DNA Markers, Journal of Life Science 22(4): 466-471

Riedel, Arthur; Monro, Keyne; Blows, Mark W.; Marshall, Dusttin J. (2014) Relative influence of resident species and environmental variation on community assembly, Marine Ecological Progress Series 499: 103-113

Ruiz, Gregory M.; Geller, Jonathan (2018) Spatial and temporal analysis of marine invasions in California, Part II: Humboldt Bay, Marina del Re, Port Hueneme, and San Francisco Bay, Smithsonian Environmental Research Center & Moss Landing Laboratories, Edgewater MD, Moss Landing CA. Pp. <missing location>

Sloan, N. A., Bartier, P. M. (2004) Introduced marine species in the Haida Gwaii region, British Columbia., Canadian Field-Naturalist 118(1): 77-84

U.S. National Museum of Natural History 2002-2021 Invertebrate Zoology Collections Database.