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ongoing rate of invasion, and our developing knowledge about past invasions, each ofthese databases is necessarily also a work in progress.Rather than rely on any one database, we attempted to review all the available data,from these databases, from published literature and from other sources, in order tocompile the relevant information to make the classification judgments needed for thetasks addressed here. The NEMESIS/California database, which was made available tous and the other research teams through a special arrangement with OST, lists“Discarded Seafood” as a possible vector for 48 introductions into California baysinvolving 14 marine species. We considered the evidence for each of these beingintroduced by the commercial trade in live marine seafood in California.Survey of Seafood WholesalersFollowing the methods of Weigle (2002, 2007) and Weigle et al. (2005), in Sept.-Dec.2011 we used online business directories (www.yellowpages.com) to compile a list ofwholesale seafood dealers located in California’s coastal counties.3 We conductedsome screening calls to eliminate duplicate entries, that is, entries of the same businessunder variant or different names or at different addresses.We prepared a survey booklet (Appendix B) and other survey materials (Appendix C)and in Mar. and Apr. 2012 conducted a mail survey using Dillman’s Total DesignMethod (Dillman 1978; Salant and Dillman 1994). Survey questions addressed thetypes and quantities of live marine seafood species sold, the source regions, whetherthe species are farmed or wild-caught, the shipping and packing materials, the disposalmethods for packing materials and for water from shipments or holding tanks, thegeographic region and proximity of facilities to coastal waters, and the geographicregions the seafood species are shipped to. The survey was conducted via the followingsteps: A first-class letter containing a cover letter, a survey booklet and a stamped returnenvelope was sent to the survey list. One week later a reminder postcard was sent to the survey list minus anyresponses received up to that point. Two weeks after the postcard was mailed a second letter consisting of a new coverletter, a replacement survey booklet and a stamped return envelope was sent tothe survey list minus any responses received up to that point. Three-and-a-half weeks after the second letter was send, a third letter consisting ofa new cover letter, a replacement survey booklet and a stamped return envelopewas sent to the survey list minus any responses received up to that point.was listed as a possible vector, the listing was either an error or is inconsistent with the rest of the vectorlistings (see Appendix F in this study and in Cohen 2012).3This included 34% of California’s counties, covered about 22% of the state’s area, and extended 15-60miles from the coast (Appendix A).Live Marine Seafood Vector4

When letters or cards were returned undelivered, we searched for the businessname on the Internet to look for an alternate address; if found, we sent new letters,surveys and cards to the alternate address. A log was kept of letters and cards mailed, letters and cards returned, letters andcards re-mailed to alternate addresses, and responses received, as well as anyresponses received by telephone or email, in order to adjust and correct the list forthe next mailing and to track response rates. Responses were entered into a spreadsheet as they were received. Whennecessary, businesses were called to clarify responses or to obtain more completeresponses. When the person contacted was amenable, we also used these calls toobtain further information on the history of and trends in live seafood imports andsales.In the data sheets, seafood species identified by variable trade or common names in theresponses were converted to scientific names and standard common names. Quantitiesreported in pounds were converted to numbers of organisms using estimates based ononline seafood websites, our observations of live seafood for sale during site visits, andother information (Appendix D). The summary sheets were formatted to automaticallycalculate summary data.Site Visits and Examination of Seafood SpeciesWe further investigated the types of live marine seafood species sold in California byvisiting retail food markets in the San Francisco Bay Area and Los Angeles/OrangeCounty area, with a focus on Chinese food markets, since previous investigations hadindicated these generally carried a wider variety of live seafood species than nonChinese food markets. We identified seafood species sold by gross visual examinationin the store or, where necessary, by purchase and examination or dissection in thelaboratory. To assist in the identification of the trade species and associated hitchhikerspecies we used standard morphological keys (e.g. Smith 1964; Gosner 1971; Kozloff1987; Pollock 1998; Carlton 2007); other relevant taxonomic literature; information orimages from the internet; and consultation with appropriate taxonomic experts.When available, we recorded relevant information from signs, including the commonname of the species, the source region and whether it was farmed or wild-caught. If theproprietors or salespeople were open to conversation we asked them about species inthe store and species that were sold by the store at other times, source regions,quantities, etc. In these conversations, we identified ourselves as researchers anddescribed the focus of our study. On some site visits we were assisted by a translatorwho was fluent in Cantonese.We investigated the hitchhiker species transported with live seafood species by grossvisual examination of the seafood species in the store, noting associated or attachedorganisms, and purchasing seafood items as needed in order to identify or confirm theLive Marine Seafood Vector5

identity of the hitchhiker species by dissecting and examining samples under amicroscope in the laboratory. All hitchhiker specimens that we collected were preservedand will be deposited with the California Academy of Sciences.We purchased several lots of the Atlantic periwinkle Littorina littorea to look forparasites. We examined the foot color of live snails, which is an indicator of infection bythe digenean trematode Cryptocotyle lingua (Willey and Gross 1957; Huxham et al.1993; Wood et al. 2007), and dissected the snails We also looked for parasites in a fewspecimens of other seafood organisms that we purchased.Live Seafood OnlineWe searched the internet for live seafood offered for sale and shipment to consumers inCalifornia, and recorded the species offered, source regions and the number ofwebsites offering each species.AnalysesWe reviewed the data and methods used by Chapman et al. (2003) to estimate theprobability of future successful introductions of bivalve species via the live seafoodtrade, corrected several data issues, and recalculated the probabilities.ResultsThe California Trade in Live Marine SeafoodResults from SurveyIn any survey errors of several types may arise, including: Miscommunication errors, i.e. a respondent understanding a question to meansomething other than what the survey designer intended, or providing an answerthat the surveyor misunderstands. Bias in the return of surveys, in “item nonresponse” (skipping some questions) orin “early termination” (ending the survey before getting to all questions) (Dillman1978), i.e. some parties not returning or completing surveys for reasons related tothe content of the survey questions (such as not wanting to disclose informationthat might lead to regulatory actions), so that the answers received do notrepresent an unbiased sample of the surveyed population. Inaccurate and misleading answers, including answers intended to discourageregulatory actions, or answers that the surveyed parties thinks the surveyor wants(“social desirability bias”—Dillman 1978).While good survey design can help to minimize these types of error, all surveys remainsubject to them to a greater or lesser degree. This should be borne in mind whenconsidering the survey results.Live Marine Seafood Vector6

We assembled an initial list of 450 businesses in California’s coastal counties from thebusinesses listed under wholesale seafood categories in an online directory. Afterscreening calls to eliminate businesses that were listed more than once under differentnames or addresses, we mailed surveys to the remaining 411 businesses. Five of thesealso turned out to be duplicates, 12 were not seafood wholesalers, five confirmed thatthey were out of business, and 53 had moved with no forwarding address (Table 2),which we took as an indication that they were out of business. Of the remaining 336, wereceived completed surveys from 127, one sent the questionnaire back with a notestating that he chose not to participate in the survey, and the rest did not respond. Theoverall response rate was 39%, which compares well with rates of 26% (Weigle 2002;Weigle et al. 2005) and 30% (Weigle 2007) in previous mail surveys of wholesalers oflive marine seafood. Response rates varied among regions from 25% to 46%. Most ofthe respondents were located the South county region (62% of the total) or Bay countyregion (31% of the total).Table 2. Breakdown of screening results by county region.Business categoryNorthBayCentralSouthAllDuplicate12025Not a seafood wholesaler023712Confirmed out of business03115Moved with no forwarding address11473153Replied340680129No Answer9487142206Refused to answer01001141102426341125%45%46%36%39%Total% repliesOf the 129 respondents to the survey, 38 (29%) reported that they sell live marineseafood. If the businesses that did not respond to the survey are similar to those thatdid, then extrapolating to the 411 businesses in the survey list suggests a total of 121wholesale businesses selling live marine seafood in California’s coastal counties. Sixtyone percent of the respondents that sell live marine seafood are located south of PointConception.The survey respondents reported selling at least 30 species of live marine seafood(Table 3), and provided a total of 121 records (respondent x species) of seafoodspecies sold. These species included one echiurid worm, 12 bivalves (clams, mussels,oysters, scallops), one cephalopod, six decapods (shrimp, crabs, lobsters) and ten fish.In addition, one surveyed business that communicated with me by email but did notsubmit a survey reported selling two snail species (“periwinkle,” probably Littorinalittorea, and “conch,” probably Busycotypus canaliculatus). The most commonlyreported species were, in order, American lobsters, Dungeness crab, spot prawn,Pacific oysters and red abalone (Table 3).Live Marine Seafood Vector7

Table 3. Reported species; number of sellers among survey respondents, by species; speciessource type according to survey respondents.Numberof sellersWildcaughtUrechis unicinctus11Red AbaloneHaliotis rufescens77Clam(unidentified)32Northern QuahogMercenaria mercenaria32Manila ClamRuditapes philippinarum33New Zealand CockleChione stutchburyi21Pacific GeoduckPanopea abrupta11Edible MusselMytilus edulis32Bay MusselMytilus sp.32New Zealand MusselPerna canaliculus21Pacific OysterCrassostrea gigas76Virginia OysterCrassostrea virginica32Kumamoto OysterCrassostrea sikamea21Flat OysterOstrea edulis1Scallop(unidentified)11Whiparm OctopusOctopus variabilis11Spot PrawnPandalus platyceros109Blue CrabCallinectes sapidus33Dungeness CrabCancer magister1817King CrabParalithodes camtschaticus22Crab(unidentified)1American LobsterHomarus americanus2222California LobsterPanulirus interruptus54Giant SculpinMyxocephalus polyacanthocephalus11Black CodNotothenia microplepidota21Ling CodOphiodon elongatus1Bastard HalibutParalicthys olivaceus33Starry FlounderPlatichthys stellatus11ThornyheadSebastolobus sp.2RockfishSebastes sp.1SheepsheadSemicossyphus pulcher1Sea UrchinStrongylocentrotus sp.1Sea CucumberStichopus japonicus1Common nameScientific nameSpoon WormFarmed11112111The source areas for these species reported by the wholesalers generally conformed toour prior understanding of where these species are primarily harvested or farmed. A fewsurprises for us were: a report of littleneck clams (Mercenaria mercenaria) importedLive Marine Seafood Vector8

from Florida (which might possibly include a related species, M. campechiensis); bluecrab (Callinectes sapidus) more often reported from Texas and Louisiana than fromMaryland; and starry flounder and king crab, species that occur in U.S. waters, reportedin part from South Korea.Table 4. Source regions of species according to survey respondents.Common nameReported source region (number of respondents reporting)Spoon WormSouth Korea (1)Clam (unidentified)CA, OR, WA (1); Southern CA (1); East Coast FL (1)Northern QuahogEast Coast (1); VA (1); FL (1)Manila ClamBritish Columbia, WA, CA (1); British Columbia, WA (2)New Zealand CockleNew Zealand (2)Pacific GeoduckSouthern CA (1)Pacific OysterBritish Columbia, WA, OR, Central CA (1); Canada, WA, OR, CA (1);Canada, WA (1); WA (1); Northern & Central CA; Central CA (1); SouthernCA (1)Virginia OysterNew Brunswick, NY, Cape Cod (1); Canada, WA, OR, CA (1); VA (1)Kumamoto OysterBritish Columbia, WA, OR, Central CA (1); Canada, WA, OR, CA (1)Flat OysterNew Brunswick (1)Scallop (unidentified)East Coast (1)New Zealand MusselNew Zealand (2)Edible MusselCanada (1); Prince Edward Island (2)Bay Mussel (Mytilus)Prince Edward Island, WA, CA (1); Canada, US, Mexico (1); Canada (1)Red AbaloneCA (1); Central CA (2); So CA (2); Baja CA (1)Whiparm OctopusSouth Korea (1)Spot PrawnCentral CA (2); Northern & Southern CA (1); Central & Southern CA (1);Southern CA (4)Blue CrabMD, LA (1); LA (1); TX (1)Dungeness CrabAK, Canada, WA, OR, Northern & Central CA (1); Canada, WA, OR, CA(1): British Columbia, WA, OR (1); WA, OR, Northern CA (1); OR (1); CA(1); Northern CA (1); Northern & Central CA (2); Central CA (4); MontereyCA (1); ME or Canada (1)King CrabAK, South Korea (1)Crab (unidentified)Southern CA (1)American LobsterNova Scotia, New Brunswick, ME, NH (1); Canada/New England (1);Canada, ME (4); East Coast (2); ME (4); ME, NY (1); ME, Boston (1); MA(1); Boston (1)California LobsterSouthern CA (3); CA, Mexico (1)Giant SculpinMexico (1)Black CodSouthern CA (1); Southern CA, Mexico (1)Ling CodCanada, Mexico (1)Bastard HalibutSouth Korea (3)Starry FlounderSouth Korea (1)Live Marine Seafood Vector9

Common nameReported source region (number of respondents reporting)ThornyheadCentral CA (1); Southern CA, Mexico (1)RockfishSouthern CA (1)SheepsheadSouthern CA, Mexico (1)Sea UrchinNorthern CA (1)Sea CucumberSouth Korea (1)Based on the survey responses, the majority of wholesalers handling live marineseafood are in the Southern California bioregion, south of Point Conception (60%), with35% in the Central California bioregion and 5% in the Northern California bioregion,north of Cape Mendocino (Table 5). The distribution of the numbers of live organismssold wholesale is similar to the distribution of wholesalers, with 65%, 34% and 1% soldby wholesalers in the Southern, Central and Northern California bioregions, respectively(Table 5). Twenty-five percent of these are exported or transshipped to locationsoutside of California (Table 6). About 80% of the live New Zealand bivalves that arrive inCalifornia are shipped on to other sites through Southern California, and 26% of the liveAmerican lobsters that arrive from the East Coast are shipped out, again throughSouthern California wholesalers. Of the live organisms that remain in the state, 64%,35% and 1% are sold to businesses in the Southern, Central and Northern Californiabioregions, respectively (Table 6). This closely parallels the distribution of thewholesalers, suggesting, at least at this gross level of analysis, that once wholesalersreceive live seafood it is rarely shipped across bioregional boundaries to retailestablishments in other regions of the state. A closer examination of the data supportsthis, especially for imported species: for example, all of the reported worms, octopus,crab, fish and sea cucumbers imported from South Korea, and all the bivalves importedfrom New Zealand that are not transshipped are received by Southern Californiawholesalers and sold to Southern California retailers; and all the flat oysters reportedfrom New Brunswick are received by Central California wholesalers and sold to CentralCalifornia retailers (Tables 5 and 6). Overall, 95% of wholesalers reported that 100% oftheir California sales were to retailers located within the same bioregion.Seventy-nine percent of the respondents that sell live marine seafood hold thosespecies in tanks of water. Thirty percent of these discharge that water into a water body,with 18% filtering or treating it first and 12% discharging it without treatment. Of thebusinesses selling live marine seafood, 39% are within 500 feet of a salt or brackishwater body.The most commonly reported packing materials that seafood organisms arrive in areice, ice packs and seawater. There are five reports of seaweed used as packing forlobsters from the East Coast and one report of seaweed packing for octopus from SouthKorea. One business located within 500 feet of a salt or brackish water body reporteddisposing of the packing materials into a water body.Live Marine Seafood Vector10

Table 5. Number of wholesalers and number of organisms handled annually, by species andbioregion.Common nameNorthernCaliforniaCentralCaliforniaSpoon WormSouthernCaliforniaAll1 (9,500)1 (9,500)Red Abalone3 (27,500)4 (569,000)7 (596,500)Clam (unidentified)2 (60,000)1 (108,000)3 (168,000)Northern Quahog2 (32,600)1 (100,000)3 (133,000)2 (716,300)1 (975,000)3 (1,690,000)2 (1,890,000)2 (1,890,000)1 (1,800)1 (1,800)Manila ClamNew Zealand CocklePacific GeoduckEdible Mussel3 (1,100,000)Bay Mussel (Mytilus)2 (60,000)New Zealand Mussel3 (1,100,000)1 (600,000)3 (660,000)2 (1,260,000)2 (1,260,000)3 (278,000)7 (779,000)Pacific Oyster4 (501,000)Virginia Oyster3 (501,000)3 (501,000)Kumamoto Oyster2 (498,000)2 (498,000)Flat Oyster1 (375,000)1 (375,000)1 (33,000)1 (33,000)Scallop (unidentified)Whiparm Octopus1 (14,000)1 (14,000)1 (17,500)9 (3,700,000)10 (3,720,000)1 (200)2 (11,000)3 (11,200)11 (119,000)5 (281,000)18 (452,500)King Crab2 (8,700)2 (8,700)Crab (unidentified)1 (2,700)1 (2,700)10 (1,380,000)22 (1,500,000)5 (32,000)5 (32,000)Giant Sculpin1 (5,300)1 (5,300)Black Cod2 (2,500)2 (2,500)Ling Cod1 (2,700)1 (2,700)Bastard Halibut3 (32,200)3 (32,200)Starry Flounder1 (460)1 (460)1 (8,700)2 (13,700)Spot PrawnBlue CrabDungeness CrabAmerican Lobster2 (52,500)2 (51,500)10 (65,000)California LobsterThornyhead1 (5,000)RockfishSheepsheadSea UrchinLive Marine Seafood Vector1 (450)1 (3,200)1 (140)Sea CucumberAll species1 (450)1 (3,200)2 (104,000)13 (4,110,000)1 (140)1 (7,300)1 (7,300)22 (7,950,000)37 (12,170,000)11

Table 6. Number of organisms and percent of total shipped to each bioregion annually.NorthernCaliforniaCentralCaliforniaSpoon WormRed AbaloneSouthernCalifornia9,500 (100%)27,700 (5%)442,000 (74%)Clam (unidentified)60,000 (36%)108,000 (64%)Northern Quahog32,600 (25%)100,000 (75%)200 (0.03%)716,000 (42%)975,000 (58%)Manila ClamNew Zealand Cockle403,000 (21%)Edible Mussel60,000 (9%)New Zealand Mussel501,000 (64%)Virg

Center for Research on Aquatic Bioinvasions (CRAB) Richmond, CA. Introduction 1 Previous Studies 1 Methods 2 Definitions, Classifications and Scope 2 Data Sources 3 Existing Databases with Species Data 3 Survey of Seafood Wholesalers 4 Site Visits and Examination of Sea