Another whale into Rotterdam, DOA
ROTTERDAM _ In early August _ and for the 3rd time in 2 years _ a container ship carried a dead whale, pinned to its bulb bow, into the Port of Rotterdam. The mammal had been scooped up by the 335m Hanjin Hamburg that has a top speed of 25.2 knots. Rotterdam reported dead whale incidents in 2011 and 2012, too.
What scientists call “ship strikes” are a rising problem worldwide. A 2012 study by the US National Oceanic and Atmospheric Administration said increasing cargo traffic “exposes marine mammals to chronic underwater engine and propeller noise (which) can impact the ability of whales to communicate with each other, navigate, forage, and detect danger.”
Reliable data is scare for several reasons. In documented ship strikes off San Francisco in the 1988-2011 period, 20 whales were killed. Another 10 were injured and, in all likelihood, subsequently died, said the report. But the true death rate is higher because most ship strikes go undocumented and whales sink after they have been hit. “The proportion of struck whales that strand … could be at least 10 times higher than the number documented,” says the NOAA study.
Cargo vessels emit a loud, low-frequency underwater noise. Propeller cavitation _ the loud hiss created by the formation and collapse of bubbles in the water _ is a primary source of underwater ship noise.
It “masks’’ the frequency range used by such cetaceans like he blue, fin, humpback and grey whales and interfere with their prey detection and communication.