March 7, 2008 — -- Ship captains setting sail will soon have an extra kind of forecast to check – the likelihood of whales.
Satellite predictions of where whales are likely to be will help ships avoid the area, and so reduce the chance of striking a whale or snagging one in fishing nets.
The forecast will be particularly important for finding – and avoiding – critically endangered right whales, which were hunted nearly to extinction in the North Atlantic and have failed to recover.
So many animals have been struck by ships or entangled in fishing gear that wildlife managers are desperate to keep whales and humans apart. Fewer than 400 right whales remain.
Nick Record of the Gulf of Maine Research Institute, Portland, US, has helped develop the satellite detection method, and described it at the 2008 Ocean Sciences meeting in Orlando, Florida, which ended March 7.
The technique uses satellite measurements of sea temperature, and images of chlorophyll, which indicate the concentrations of phytoplankton in different parts of the ocean.
Together the measurements can predict when and where a particular type of zooplankton, called a copepod, will hatch and grow to edible size. Across the Gulf of Maine right whales gather at dense patches of copepods to feed.
Record says that if you can find the copepods, you can find the whales. Right now, managers use airplanes to spot them, but these flights can only sample a small fraction of the gulf. Satellites take in the entire basin.
Using a computer model that combines the satellite information with that of typical patterns of currents in the gulf allows conservation managers to predict where dense patches of copepods will form, says physical oceanographer Bruce Monger of Cornell University, New York, who helped to develop the model.
Ships towing nets have confirmed that the whale forecast works, and sightings of whales also match up with the predicted locations of their prey, Monger and Record both report.
As a start, the team has posted their prediction of when the whales will first arrive in the south channel of the gulf this spring, based on when the first batch of copepods will mature, says Andrew Pershing, who is leading the project.
Eventually they plan to link in data from the satellite soon after it flies over and plug the information into a model that includes detailed forecasts of the currents and eddies in the gulf. That will allow them to say with greater precision where the whales are likely to be found.