Argopecten irradians

Invasion History

First Non-native North American Tidal Record: 2007
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 2007

---

General Invasion History:

Argopecten irradians is native to the Northwest Atlantic from southern Massachusetts Bay to the Gulf of Mexico in shallow coastal waters. Specimens are known from Sable Island, Nova Scotia (Academy of Natural Sciences of Philadelphia 2011), but this bivalve is not established there (Abbott 1974; Morris 1975; Gosner 1978).

North American Invasion History:

Invasion History on the West Coast:

Argopecten irradians is known from the West Coast only from 'old and broken valves' found in South San Francisco Bay in 1963 and 1973 (Wicksten 1976, cited by Carlton 1979), and from a museum specimen from Newport Beach, Oregon in 1923 (Academy of Natural Sciences of Philadelphia 2011). Live animals or dead shells of this bivalve were probably introduced with oysters planted in San Francisco Bay and Oregon waters, from Long Island Sound, in the late 1800s - early 1900s (Carlton 1979; Miller 2000). Alternatively, especially for the Oregon specimen, discarded shells or whole scallops from seafood restaurants are a possibility. There is no evidence that a breeding population existed in San Francisco Bay or Oregon.

Invasion History on the East Coast:

In 1979 and 1989, batches of A. irradians were transported to hatcheries in Nova Scotia, for the development of a 'put and take' scallop fishery. Bay scallops do not survive the winter, but are kept, bred, and reared in hatcheries, then released in Prince Edward Island waters for 'grow-out' in the spring and harvesting in the fall (Whyte et al. 1993; Minchin 2003). In 2007, young Bay Scallops were found settling in Pomquet Harbor, Nova Scotia. Marked scallops survived the winter, and by 2013, a population was apparently established (Williams et al. 2015).

Invasion History Elsewhere in the World:

Argopecten irradians has been introduced to aquaculture facilities in China (Minchin 2003; Zheng et al. 2004). We do not know if it has been released or is established in natural waters.

---

Description

Argopecten irradians, the Bay Scallop, is round with nearly symmetrical 'wings' on each side of the beak, prominent ribs radiating from the triangular beak, and scalloped edges. The lower valve (left) and upper valve (right) are equally convex. Color patterns of the shells are variable, often with bands of light and dark along the growth lines, and varying among grey, brown, and white. Adult shells typically range from 50 to 75 mm. The adult live animal is marked by the many blue eyes visible when the shell is open and by the rapid, jerky swimming caused by opening and closing its shell. (Description from: Abbott 1974; Morris 1975; Gosner 1978)

---

Taxonomy

Ecology

General:

Juvenile Argopecten irradians use byssus threads to attach to substrates such as gravel and eelgrass, but move freely as adults, swimming when disturbed. They range through estuarine habitats, but depend on eelgrass for shelter from predators (Gosner 1978; Minchin 2003). These scallops are hermaphroditic, but the eggs are fertilized externally (Zheng et al. 2004). The veliger larvae are planktotrophic.

Food:

Phytoplankton

Consumers:

Humans

Trophic Status:

Suspension Feeder

SusFed

---

Habitats

General Habitat	Grass Bed	None
General Habitat	Oyster Reef	None
General Habitat	Unstructured Bottom	None
Salinity Range	Mesohaline	5-18 PSU
Salinity Range	Polyhaline	18-30 PSU
Salinity Range	Euhaline	30-40 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Epibenthic	None

---

---

Tolerances and Life History Parameters

Maximum Depth (m)	36	Field (Castagna and Chanley 1973)
Minimum Salinity (‰)	14	Experimental, field (Castagna and Chanley 1973)
Minimum Duration	10	Larval duration, at 28 C (Minchin 2003)
Maximum Duration	19	Larval duration, at 20 C (Minchin 2003)
Minimum Length (mm)	25	Morris 1975; Gosner 1978
Maximum Length (mm)	75	Morris 1975; Gosner 1978
Broad Temperature Range	None	Cold temperate-Tropical
Broad Salinity Range	None	Polyhaline-Euhaline

General Impacts

Argopecten irradians is a highly prized food item, because of the delicious taste and firm texture of its adductor muscle meat. Fisheries on the East Coast are limited, and declining, because of poor water quality, and the loss of eelgrass (Zostera marina) beds in many estuaries. The high status and price of this scallop has led to introductions for aquaculture in China, and a hatchery-dependent 'put and take' fishery in Atlantic Canada (Minchin 2003). No impacts have been reported for this species in its introduced range.

---

Regional Impacts

NA-S3	None		Economic Impact	Fisheries
Although it does not survive the winter in the Gulf of St. Lawrence, and is dependent on hatcheries for survival and reproduction, A. irradians sustains a 'put and take' fishery in estuaries of Prince Edward Island (Whyte et al. 1993; Minchin 2003). Discovery of a protozoan parasite, Perkinsus karlsoni in the scallops caused a 2-year suspension of Bay Scallop stocking, before experiments showed that this organism was not transmissible to other shellfish (Whyte et al. 1993).
NWP-4a	None		Economic Impact	Fisheries
Argopecten irradians is an important aquaculture organism in China, because of the high quality of its meat and its rapid growth. Selective breeding is underway (Minchin 2003; Zheng et al. 2004). We do not know if 'wild' populations occur in Chinese waters.
NWP-3a	None		Economic Impact	Fisheries
Argopecten irradians is an important aquaculture organism in China, because of the high quality of its meat and its rapid growth. Selective breeding is underway (Minchin 2003; Zheng et al. 2004). We do not know if 'wild' populations occur in Chinese waters.

References

Abbott, R. Tucker (1974) American Seashells, Van Nostrand Reinhold, New York. Pp. <missing location>

Academy of Natural Sciences of Philadelphia 2002-2024a Malacology Collection Search. <missing URL>



Carlton, James T. (1979) History, biogeography, and ecology of the introduced marine and estuarine invertebrates of the Pacific Coast of North America., Ph.D. dissertation, University of California, Davis. Pp. 1-904

Carlton, James T. (1999) Molluscan invasions in marine and estuarine communities., Malacologia 41(2): 439-454

Castagna, M.; Chanley, P. (1973) Salinity tolerance of some marine bivalves from inshore and estuarine environments in Virginia waters on the western mid-Atlantic coast., Malacologia 12(1): 47-96

Gosner, Kenneth L. (1978) A field guide to the Atlantic seashore., In: (Eds.) . , Boston. Pp. <missing location>

Lutaenko, Konstantin A.; Furota,Toshio; Nakayama, Satoko; Shin, Kyoungsoon; Xu, Jing (2013) <missing title>, Northwest Pacific Action Plan- Data and Information Network Regional Activity Center, Beijing, China. Pp. <missing location>

Miller, Alexander Whitman (2000) <missing title>, University of California at Los Angeles, Los Angeles. Pp. <missing location>

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

Morris, Percy A. (1975) A field guide to shells of the Atlantic, Houghton-Mifflin, Boston. Pp. <missing location>

Whyte, S. K.; Cawthorne, R. J.; McGladdery, S. E.; McMillan, R. J;, Montgomery, D. M. (1993) Cross-transmission studies of Perkinsus karlssoni(Apicomplexa) from bay scallops Argopecten irradians to native Atlantic Canadian shellfish species., Diseases of Aquatic Organisms 17: 33-39

Williams, Jim; Polk, Zephyr C. S.; Smit, Laura A.; Macinnis, Gina (2015) Establishment and overwintering of Bay Scallops (Argopecten irradians Lamarck) in a Gulf of St. Lawrence estuary, Journal of Shellfish Research 34(3): 737-741

Zheng, Huaiping; Zhang, Guofan; Liua,Xiao; Zhang, Fusui; Guo, Ximing (2004) Different responses to selection in two stocks of the bay scallop, Argopecten irradians irradians Lamarck (1819)., Journal of Experimental Marine Biology and Ecology 313: 213-223

---