Crustaceans
	Edible Seaweed

1.4 Other St. Lawrence food sources

The St. Lawrence contains other resources that can be eaten by riverside residents. These include crustaceans and, to a lesser degree, seaweed.

Crustaceans

The main crustaceans harvested from the St. Lawrence are the Northern Lobster, Snow Crab, Northern Shrimp, and crayfish. The Northern Lobster and Snow Crab are classified among the most significant commercial species and the most sought after foods from the Gulf. The Northern Shrimp is found in abundance in the Gulf and in the estuary of the St. Lawrence while crayfish can be caught everywhere in Quebec but mainly in Lake Saint-Pierre.42

What do we know about the presence of contaminants in crustaceans?

Data produced by a contaminant tracking program undertaken in the early 1990s by Fisheries and Oceans Canada indicated low concentrations of metals in crustaceans from the estuary and the Gulf. For the group of species studied, mercury content was low, with the exception of Northern Shrimp and Snow Crab from the Saguenay fjord. In fact, these two species continue to have mercury contents approaching the established limit for commercialized fish products, though there was a decrease in the concentrations observed between 1994 and 1997. This situation is attributable to massive mercury contamination of the fjord’s sediment from the early 1970s, when concentrations measured among shrimp exceeded 10 mg/kg.

In terms of organochlorines, levels observed in the musculature are generally low for the crustacean group.43 The available data concerning contamination of crayfish flesh comes from samples taken from Lake Saint-Pierre in the 1980s. The information reveals that, at that time, crayfish experienced little contamination by chemical substances and mercury, PCBs and Mirex levels were below amounts deemed acceptable for commercialized fish products.39

Finally, contaminants have a tendency to accumulate in the hepatopancreas of crustaceans (commonly referred to as the “green liver”). Exposure can be significantly decreased by not consuming this part of the animal.39, 44

What nutritional value do crustaceans provide?

As with mollusks, crustaceans present very significant nutritional value; they are excellent sources of protein, vitamins, and mineral salts, all while being low in fat.

Marine bird eggs

There are areas of the Gulf of St. Lawrence where the springtime collection of eiderdown and seagull eggs is a tradition in certain riverside communities. Studies have shown PCB levels in Herring Gull eggs to be 14 times as high as those measured in cod liver and 200 times as high as those found in seal flesh.45 Therefore, consumption of seagull eggs raises the body’s load of organochlorines to high levels, as shown in certain studies conducted among people on the Lower North Shore.13