2.6 TRANSIT - SURVIVAL DURING THE VOYAGE

The survival rates of different species in transit differ markedly in response to their tolerance to variables such as temperature, light intensity, salinity and food availability.

The Committee notes, for example, that ballast tank temperatures are highly variable between vessel types and within tanks on a single ship. Depending on tank size and position, a range in temperature distribution may exist within tanks¹⁵ Indeed, temperatures ranging from 5.6^°C to 35^°C were recorded for ballast water sampled from vessels in Canada during August - October¹⁶

The length of time that ballast is stored is another key factor in determining the survival rate of marine organisms. Different organisms have varied tolerances and many are capable of surviving for extended periods. It has been shown that some taxa are capable of surviving for up to 95 days¹⁷ Survival rates are therefore difficult to predict.