Bivalve mollusc Production, Trade and Codex Guidelines
Iddya Karunasagar Products, Trade and Marketing Service Fisheries and Aquaculture Department Food and Agriculture Organization of The United Nations. Rome, Italy
Global fish production In 2010, global fish production by capture and aquaculture was 148 million tonnes of which 128 million tonnes were used for food. Bivalve molluscs represented almost 10% of the total world fishery production, but 26% in volume and 14% in value of the total world aquaculture production. World bivalve molluscs production (capture + aquaculture) has increased substantially in the last fifty years, going from nearly 1 million tons in 1950 to about 14.6 million tons in 2010.
Global bivalve production 2000 - 2010
While production by capture has marginally declined from about 1.9 million tones to about 1.7 million tons in 2010, production by aquaculture increased from 8.3 million tons in 2000 to 12.9 million tons in 2010
Major bivalve producing countries China is by far the leading producer of bivalve molluscs, with 10.35 million t in 2010, representing 70.8% of the global molluscan shellfish production and 80% of the global bivalve mollusc aquaculture production. All of the Chinese bivalve production is cultured. Other major bivalve producers in 2010 were Japan (819 131 t), the USA (676 755 t), the Republic of Korea (418 608 t), Thailand (285 625 t), France (216 811 t) and Spain (206003t)
Production by aquaculture- Species
By species, the bivalve mollusc production by aquaculture in 2010 consisted of 38.0% clams, cockles and arkshells, 35.0% oysters, 14.0% mussels and 13.0% scallops and pectens
Marine bivalve production by capture-trends 1,000,000 900,000 800,000 700,000
Tonnes
600,000
Abalones, winkles, conchs Clams, cockles, arkshells
500,000
Mussels 400,000
Oysters Scallops, pectens
300,000 200,000 100,000 0 year 2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Scallops and pectens are a major group produced by capture, followed by clams, cockles and arkshells
Bivalves: Trade The increase of bivalve mollusc production was driven by international demand since the early 1990s. Total bivalve trade has expanded continuously during the past three decades to reach US$ 2.1 billion in 2009. In terms of quantity, scallops accounted for 24% of export, while mussels contributed to 48%. In terms of value, scallops are the most important species with 46% of value, followed closely by mussels (26%).
Causes of non-compliance in trade - EU
There have been 52 rapid alerts for bivalve mollusks in the EU Rapid Alert System for Foods and Feeds (RASFF) during 2009, 78 in 2010 and 68 in 2011. The major causes were related to hygiene (Escherichia coli exceeding limits), biotoxins, viruses (norovirus), pathogenic bacteria (Salmonella) and other causes (labeling, organoleptic etc)
Safety record of bivalve molluscs The safety record of bivalve molluscs that are managed by sanitary surveys has been fairly good. According to database of the US Center for Science in Public Interest (CSPI), during the decade of 1999 -2008, there were 792 seafood associated outbreaks involving 6337 cases. Of these, 118 outbreaks involving 1444 cases were due to bivalve molluscs. The causes of illnesses range from bacteria (V. parahaemolyticus) to viruses (norovirus), biotoxins. In the EU, during 2009, out of 977 foodborne outbreaks for which a cause could be verified, 35 (3.6%) were linked to shellfish including crustaceans and molluscs
Bivalve mollucs - hazards Naturally occurring bacterial pathogens- eg Vibrio parahaemolyticus, V. vulnificus; Enteric bacterial pathogens – eg Salmonella Enteric viral pathogens – eg Norovirus, Hepatitis A Biotoxins Chemical contaminants
FAO/WHO Scientific support for Codex work
SPS/TBT and Codex World Trade Organisation
CODEX Guidelines Standards Codes of Practice
National Regulations
Monitoring and classification of harvesting areas Classification of growing areas by sanitary survey, monitoring of E. coli/fecal coliforms at an appropriate frquency based on the risk of contamination; Harvesting areas may be classified as suitable for harvesting for direct human consumption or for purification by depuration/relaying or approved processing to reduce/limit target organisms Closure/reopening of growing areas by monitoring biotoxins in bivalve mollucs alone or in combination with monitoring of phytoplankton in seawater at an appropriate frequency based on probability of contamination
Pathogen monitoring Shellfish sanitation programmes rely on use of indicator organisms for the presence of contamination rather than upon attempts to monitor specific pathogens; However, where there has been a shellfish-borne outbreak caused by an identified pathogen such as Salmonella or viruses, monitoring of bivalves may be appropriate as part of closure/reopening of the affected harvesting area.
Factors to be considered in determining the need for controls in a given harvest area include: • The number of sporadic illnesses and outbreaks of V. parahaemolyticus and V. vulnificus associated with bivalve molluscs harvested from a distinct hydrographic area, and whether these illnesses are indicative of an annual reoccurrence or an unusual increase of Vibrio spp. illnesses is reported; • Water temperatures representative of harvesting conditions. Water temperatures below 15ºC 12 for V. parahaemolyticus and below 20ºC for V. vulnificus have generally not been historically associated with illnesses; • Time period to first refrigeration and post-harvest air temperatures above the minimum growth temperatures for V. parahaemolyticus (10ºC) and V. vulnificus (13ºC), which may increase risk regardless of harvest water temperature;
• Harvest practices that allow radiant solar heating to raise
temperatures of bivalve molluscs to temperatures above ambient air temperatures prior to harvest (i.e. intertidal harvest) and exposure time; • Salinity ranges and optima are different for V. parahaemolyticus and V. vulnificus. Environmental and epidemiological data indicate low V. parahaemolyticus and V. vulnificus levels and few cases of illnesses are associated with bivalve molluscs when salinity exceeds 35 ppt (g/l) and 30 ppt (g/l), respectively.
US FDA V. parahaemolyticus control plan Limit time from harvest to refrigeration to no more than five (5) hours or other times based on modeling and sampling in consultation with FDA. Limit time from harvest to refrigeration such that levels of total Vp after completion of cooling to 60 °F do not increase more than 0.75 log from levels at harvest. Calculations for 0.75 log increase can be based on the table as shown below or based on validation studies. The authority may use the FDA Risk Assessment to determine the initial "at harvest" levels. The term refrigeration is storage in a container that is capable of dropping and maintaining ambient air temperature of 45 °F (7.5 °C).
The level of faecal contamination may indicate the potential for the presence of human enteric viruses. To control the hazards, identification and monitoring of growing areas is very important for bivalve molluscs safety. E. coli/faecal coliforms are used as indicators of faecal contamination. Monitoring data should be interpreted within the context of the sanitary survey, as viruses may be present in the absence of these bacterial indicators.
When there has been a bivalve molluscs-borne outbreak caused by an identified pathogen such as NoV or HAV and the area has been closed, viral testing of the bivalve molluscs or an approach consistent with the requirements of the competent authority should be used as part of the process of reopening the affected area to ensure product safety using either standardized methods or alternative validated methods. Other conditions, including meeting the sanitary survey requirements, should also have been satisfied as a condition of reopening the area. Ideally they should include the identification of sources of pollution/ contamination and prevention of future contamination events.
Heat Treatment: Heat treatments of bivalve molluscs should be validated for their ability to inactivate viruses. An internal temperature of 85 to 90 °C for at least 90 seconds is considered to be a virucidal treatment. However, this degree of cooking would probably render specific bivalve molluscs, such as oysters, unpalatable to consumers. Even though cooking temperatures typically used by consumers may not achieve 90 °C for at least 90 seconds and thus ensure inactivation of viruses, any cooking would reduce viral levels and depending on the initial level of contamination possibly would reduce the risk of causing foodborne infection.
High Hydrostatic Pressure (HHP): HHP may reduce virus titers in bivalve molluscs with relatively small effects on the character of the meat. The HPP conditions for inactivation depend upon pressure as well as time, temperature and the salinity of the water, e.g. a pressure of 600 MPa applied at 6 ºC for five minutes can completely inactivate NoV in oysters. The use of HHP alone or in combination with other inactivation procedures should be validated for the virus of concern in the specific bivalve mollusc species prior to its application
SUMMARY Bivalve safety management is mainly through sanitary surveys and biotoxin monitoring Additional measures may be required in areas associated with outbreaks eg Vibrio parahaemolyticus, V. vulnificus, noroviruses or Hepatitis A.
