11.1 Oysters
and Kepone
11.2
Oysters and Paralytic Shellfish Poisoning
11.3 Clams and
Gastroenteritis
11.4 Mussels and
Toxic Algae
11.5 Oysters,
Clams and Red Tide
11.6 Contaminated
Oysters
11.7 Fish and Shellfish
11.8 Sydney Rock Oysters
11.9 United
States Seafood in General
Today is a period of instant information. News reports can be transmitted world-wide in a matter of minutes, and millions of individuals can receive information which may or may not be accurate or based on the best scientific analysis or source. News stories can be used to inform potential consumers of the danger of consuming unsafe seafood or they can be used or misinterpreted with consumers responding through reduced seafood consumption when it was not warranted15. News and educational efforts can also be used to properly inform consumers on the safety attributes of seafood in a way that increases seafood consumption or allows the consumers to make informed decisions regarding the risks they take in making food purchase and consumption decisions. Several attempts have been made to measure the effects of news stories on seafood sales and to gauge consumer response and the use of educational information16.
In December 1975, the James River in Virginia, United States, was closed to the harvest of all seafood due to trace elements of Kepone in several species. Oyster harvest was prohibited for ten months even though no sample of the oysters contained concentrations of Kepone in excess of EPA guidelines. Many news stories emphasized the possibility of seafood contamination and a study was conducted to determine how news stories influenced the demand for oysters from other areas which were completely isolated from James River oysters (Swartz and Strand 1981). The measure used to indicate news story effects on the contamination indicted a decrease in per capita oyster consumption of one-half gallon per thousand Maryland residents. Negative consumer reaction apparently declined after eight weeks and consumption returned to previous levels. Estimated avoidance costs (in a no news situation, or government news of "no problem" if consumers had completely believed the information) of US$13 000 were estimated for one product form of oysters passing though one market.
During 1980, United States West Coast oysters were implicated in paralytic shellfish poisoning (Conte 1984). Sixty-one cases with no deaths were attributed to commercial oysters and 36 cases with one death were attributed to sports-harvested mussels from four bays in California. A four-week quarantine on harvest from the bays was implemented, with an additional two weeks passing after the quarantine to allow time for harvest and reopening of markets. News reports about the closure affected 100 percent of oyster sales in California, and about 25 percent of oyster sales in California by firms in Washington and Oregon that market their oysters in California. The total economic loss reported by oyster growers in California, Washington and Oregon was US$630 456. The most severe impact was the loss of cash flow during the critical reseeding time to insure future production. The method of estimating the economic loss was not reported.
During the summer of 1982, 22 outbreaks of seafood-associated gastroenteritis were recorded in New York State. A total of 443 people were affected, with the outbreaks traced to the ingestion of raw or lightly cooked clams. Using an economic model, it was estimated that the price of littleneck clams dropped nine percent due to the outbreak. Cherrystone and chowder clam prices declined comparable amounts. The total market loss was estimated at US$1.84 million over a five month period and the cost of the investigations, medical care, lost time and materials was US$630 thousand (Brown and Folsom 1983).
An example of the economic impacts associated with algae toxin contamination is also available through measuring the change in demand for mussels in Montreal, Canada, following the 1987 toxic algae contamination of Prince Edward Island mussels (Wessels, Miller and Brooks 1994). A ban was issued about the consumption of all mussels regardless of their origin, including the United States Atlantic coast on 8 December 1987. The ban was lifted by 8 January 1988 on much of Canadian Atlantic and United States shellfish waters. By 2 March 1988 all Canadian waters were open for harvesting. Total losses due to the outbreak of domoic acid have been estimated at approximately CDN$8.4 million. Wessells, Miller and Brooks estimated a set of demand equations to determine the effect of the ban and associated news articles on the sales from a local mussel farm that was incorrectly implicated in mussels which caused deaths of consumers because of the contamination. Results indicated that during the ban period, consumers based their purchase choices primarily on immediate news, rather than past information. Sales losses to the mussel farm both during the ban and following the lifting of the ban due to lingering concerns about the contamination amounted to about 14.5 percent of its annual sales during 1989 and 1990.
A red tide in late October 1989 off North Carolina resulted in closures along the North Carolina coast to shell fishing the first week of November 1989. Shellfish bed closures lasted up to six months and covered approximately 50 percent of the oyster harvesting grounds in North Carolina and 95-98 percent of the clam grounds (Brooks, Miller and Wessels 1995). Economic losses to the area were estimated at US$24.7 million, including loss of employment and loss of revenues by the fishing industry and other businesses such as tourism (Tester, Stumpf and Fowler 1988). The total value of the North Carolina shellfish harvest was estimated to have been reduced by almost 50 percent from the previous season, resulting in a loss of US$2.0 million (Tester and Fowler 1990). Reports by the media and other sources raised concerns about eating any seafood, and the seafood industry and others complained about the early negative and misleading media coverage, and lack of useful information about the safety of finfish. Harvest and price data indicated that the red tide had a significant effect on price (increase due to decreased supply) and harvest (decline) (Brooks, Miller and Wessels 1995).
A United States ABC Television national 20/20 news magazine story was broadcast 9 February 1990 focusing on FDA risk estimates, problems in current shellfish inspection programmes, and giving examples of health problems caused by consuming contaminated shellfish. The news story was broadcast between two waves of interviews of oyster consumers in January 1990 and April-June 1990 which were designed to measure the perceptions of consumers about oyster consumers (Lin, Milon and Babb 1991). This provided a unique opportunity to measure the effect of national media attention on individual consumers' oyster safety perceptions. The average individual, whether an oyster consumer or not, gave a statistically significant lower safety rating to oysters if they had seen the ABC 20/20 story, suggesting that individuals re-evaluate their perceptions of food safety based on factual information about the product.
The 1993 survey of seafood consumers in the United States Northeastern and Mid-Atlantic areas also asked questions about the effect on seafood consumption behavior due to exposure to news related to finfish and shellfish. Fifty-seven percent of the consumers from both the finfish and shellfish consumer surveys had heard stories in the news media about seafood in 1992. Thirteen percent had heard only positive stories, 33 percent only negative stories and 43 percent both positive and negative stories (Wessells et al. 1994). Seventy-three percent said the stories had no effect on their seafood consumption. A higher percentage of the shellfish survey consumers (84 percent) had seen stories than had the finfish respondents (79 percent). Salmon received more negative publicly, with the amount of publicity decreasing in order listed for trout, hybrid striped bass and tilapia. More than 50 percent of the shellfish stories encountered were negative. Twenty-two percent of finfish consumers and 28 percent of shellfish consumers decreased their consumption due to the news stories.
In March 1997 a major hepatitis A outbreak across Australia was attributed to consumption of Sydney rock oysters from the major producing area of Wallis Lake. The outbreak was attributed to fecal pollution of Wallis Lake. This destroyed oyster sales in Australia for several weeks and reportedly had a negative impact on seafood sales for several months. In January 1997 the buyers in the Sydney Fish Market had been surveyed for a research project. The survey was repeated in June 1997 to determine the impact of the Wallis Lake incident on sales. Buyers did not see pollution or oyster safety as a threat to business either before or after the outbreak. Seafood sales soon returned to normal and the downturn in seafood sales attributed to adverse media publicity over Wallis Lake oysters was not as bad as newspaper reports suggested. Sales later in the year were strong and cleared the build-up of stocks due to lack of sales earlier in the year (Ruello 1998).
An analysis of structural changes in United States consumers' preferences for seafood indicate that since the mid-1960s, consumption mostly increased despite an overall trend of increasing relative price (to meats), except during the latter 1970s to early 1980s, and then again during the late 1980s. The positive trend during the 1980s may have resulted from highly publicized advice to "eat seafood twice a week" in order to benefit from omega-3 fatty acids. The end of the positive trend after 1987 coincided with media coverage of seafood safety following the Exxon-Valdez oil spill and numerous incidents of water and beach pollution along all coasts (Edwards 1992).
