An Notice from Maine Department of Marine Resources on Keeping Native Shell Fish Cool in the Summer Heat.

Vibrio – A Good Reason to Keep Shellfish Cool

    By Kohl Kanwit

Vibrios are a naturally occurring bacteria typically found in marine waters. Several species of Vibrio can cause illness in humans through the consumption of raw or undercooked seafood or by wound infections. Bivalve shellfish are filter feeders, meaning they feed by straining the surrounding water in order to collect food particles; these particles (including bacteria) can then become concentrated in their guts. Vibrios are present throughout the marine environment, but pathogenic strains tend to be associated with warmer waters in the summer months. If Vibrios are already present in shellfish, they can multiply within harvested bivalves which are exposed to warm temperatures like the deck of a boat on a sunny day in August or an un-shaded summer picnic table. Research indicates the growth rates of Vibrio parahemolyticus (Vp) within harvested bivalves are determined by temperature; at 90°F the Vibrio population will double every hour, at 80°F it takes about two hours, at 60°F it takes over a day for the bacteria population to double, and below 50 the growth of Vp essentially stops. The best way to keep bivalve shellfish safe from Vibrio contamination is by cooling product as quickly as possible after harvest. This applies to recreational harvesters and retail purchases as well; keep your catch or purchase in a cooler with an icepack until you are ready to enjoy it. The best defense against the threat of Vp in Maine shellfish is education of the industry and consumers, as well as a commitment from harvesters and dealers to adhere to time/temperature controls. Keep Maine shellfish safe by keeping it cool!