Metals in Crawfish - Aquaculture and the Environment: A Shared Destiny - page 195

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Metals in Crawfish
Joseph Sneddon* and Joel C. Richert
Department of Chemistry, McNeese State University,
Lake Charles, Louisiana
USA
1. Introduction
1.1 Overview
Much of the information in the first nine sections of this chapter was derived and condensed
from the Louisiana Crawfish Production Manual (McClain et al, 2007). The harvesting of
crawfish (or crayfish) for human consumption has become an important industry in several
areas throughout the world. In the United States, crawfish are common in Louisiana (located
in the southern United States on the Gulf of Mexico) and throughout the southeastern states.
Crawfish (McClain, 2005) are well suited for habitats that have seasonal flooding and
drying, especially when the dry periods occur in the summer and fall. Periods of flooding
allow the crawfish to feed, grow and mature. Dry periods help aeration of sediments, reduce
the abundance of predators and allow for establishment of vegetation, which serves as cover
and food resources when flooded. Crawfish are common in parts of northeastern Mexico,
can be found extensively in southeastern Asia and are grown commercially in China. In the
1970s, crawfish were introduced into Portugal and Spain and thrived in the rivers and
estuaries to the extent that commercial harvesting now contributes significantly to the food
supply in these regions (Alcorlo et al, 2006) (Maranhao et al, 1999). In Louisiana there are
numerous varieties of crawfish but the two dominant species are the red swamp crawfish
( Procamburas clarkii ) and the white river crawfish ( Procamburas zonangulas ). Both species
dominate harvests in natural habitats and on crawfish farms, therefore, unless otherwise
noted these two species are the species of crawfish to which the authors refer.
1.2 History
In Louisiana, crawfish has been a part of the human diet for centuries but the commercial
sales of crawfish began only in the late 1800s. As the demand for crawfish outgrew the
harvest from the wild, the crawfish aquaculture industry was born. Early crawfish
aquaculture consisted only of re-flooding rice fields after the harvest to produce food for the
farm family. Excess production from these fields was sold to nearby consumers. Over time
the demand and supply of crawfish continued to grow and by the 1960s commercial
processing of crawfish began. The peeling and packaging of crawfish tail meat allowed for
the establishment of regional markets. Commercial processing required a steady supply of
crawfish to meet demand. This increased demand was greater than could be supplied by
harvests in natural habitats and lead to a great increase crawfish aquaculture in Louisiana.
In the United States there are few commercial producers of crawfish outside of Louisiana.