| Invasive species is the term used
to describe plants and animals introduced to new areas where these same species
do not belong. The introduction of invasive species has been a problem for as long
as ships have been traveling the seas. Both plants and animals from land
and sea are moved in, on and under ships from their existing habitat to new
areas where they can become an invasive species. When these foreign species are
introduced into a new habitat and environmental conditions are favorable, these
non-indigenous species become established. They, in turn, can compete with or prey
upon native species of plants, fish, and wildlife. They may also carry diseases or
parasites that affect native species because they have no resistance. This can disrupt the aquatic environment and economy of affected near-shore areas.
Most of the invasive species are introduced from shipping ballast tanks which provides balance and weight to ships when they are not carrying full cargo loads. It can contain a wide variety of microscopic marine life including eggs, cysts, larvae, and bacteria. Global shipping now moves about 80 percent of the worlds' commodities, making this phenomenon a grave threat to all marine environments. "Every assessment indicates that the rate of marine introductions in U.S. waters has increased exponentially over the past 200 years and there are no signs that these introductions are leveling off. New introductions are occurring regularly on all coasts, producing immediate and damaging impacts, and leading to millions of dollars in expenditures for research, control, and management efforts. In the San Francisco Bay alone, for example, an average of one new introduction was established every 14 weeks between 1961 and 1995" (Carlton, J. T., 2001, abstract).
It is estimated that there are hundreds of invasive species within U.S. coastal waters and that they may cost the U.S. hundreds of millions of dollars each year. On average, some two million gallons of ballast are released into U.S. waters alone each hour, resulting in the introduction of potential invasive species. "It has been estimated that exotic species that become invasive cost the United States $137 billion annually… more than earthquakes, floods and fires combined." (Goldsborough, William J., 2003).
Shipping is not the only way in which invasive species are introduced. Marine debris can also allow non-native species to travel great distances where they can eventually be introduced into a new area. The slow rate of travel associated with slower environmental changes can allow the transplanted plants and animals to have a high survival rate. In a survey of some 30 remote islands, David Barnes of the British Antarctic Survey in Cambridge, UK, found that human debris and litter had more than doubled as a vehicle for marine organisms to transport themselves to remote lands. Barnes is further quoted as saying "I estimate that rubbish of human origin in the sea has roughly doubled the propagation of fauna in the subtropics and more than tripled it at high (> 50°) latitudes, increasing the potential for alien invasion and adding to the problems already created by sea-borne plastic materials in the form of injuries and mortality among marine mammals and birds." (Barnes, D. K. A., 2002)
A more recent cause of invasive species problem has been practices within the Aquaculture industry.
|During the last generation as the
human population increased, our demand for fish has grown tremendously. The commercial
fishing industry has been able to meet this demand by creating better fishing techniques.
We have now reached a point when the demand is so high and the technique so
effective that many ocean areas have been over-fished and are now depleted of the
fish quantities that are sufficient to meet the growing demand (more
One potential solution to this problem is aquaculture (see picture below courtesy NOAA). Aquaculture is quite simply the production of fish and other aquatic species by using farming techniques. This method of supplying fish has, in recent years, been growing at a tremendous pace. "Aquaculture is now one of the fastest growing sources of protein, expanding at 10 percent per year. Output more than tripled between 1984 (the first year global aquaculture statistics were compiled by FAO) and 1996, from 7 million tons worth $10 billion, to 23 million tons valued at $36 billion. Today, one out of every five fish consumed comes from the farm." (The Worldwatch Institute, 1998).
While this could be a sustainable method of meeting the seafood demands of the exploding human population, it to date has shown to have some serious problems;
What can you do about it?
Continue to Read about Overfishing