Two hundred and fifty two introduced and cryptogenic
marine and estuarine species have been identified
in Australia [5],more than 150 alien species in Port
Phillip Bay alone [6]. New Zealand scientists identified
159 alien marine species [7] while 212 alien marine,
estuarine and freshwater species have been reported in
the San Francisco Bay and Delta,California [8]. In
Hawaii,91 of the nearly 400 marine species present in
Pearl Harbor are alien [9]. Based on historical data,a
new marine or estuarine species establishes itself every
32–85 weeks in each of six ports studied in the US,New
Zealand and Australia,a rate that appears to be
increasing [5].