Bigelow Lab Scientist and Team Devise New way to Track Right Whales' Favorite Food

A team of researchers led by satellite oceanographer Rebekah Shunmugapandi from the Bigelow Laboratory for Ocean Sciences has devised a way to use satellite imagery to detect the presence of a tiny copepod vital to the survival of North Atlantic right whales.

NASA’s Aqua satellite detected massive clouds of the tiny red plankton called Calanus finmarchicus in the Gulf of Maine. It is the first time these microscopic crustaceans, packed with energy-rich fat, have been tracked from space. Until now, scientists relied on ships to tow fine-mesh nets through the ocean and manually count the plankton, an expensive, time-consuming process.

North Atlantic right whales depend on dense patches of this specific zooplankton to build the energy reserves needed for long migrations. Detecting the presence and concentration of Calanus finmarchicus through remote sensing could help predict whale movements and reduce encounters with ships and fishing gear.

The research team studied the color signatures in the Gulf of Maine using MODIS (Moderate Resolution Imaging Spectroradiometer) aboard NASA’s Aqua satellite. MODIS measures how various wavelengths of sunlight bounce back from the ocean’s surface. When Calanus finmarchicus gather in thick patches near the top layers of water, their bodies, which are rich in a red pigment, absorb light in a way that shifts the ocean’s surface color toward red.

To strengthen the reliability of their satellite readings, the researchers paired MODIS imagery with measurements from a Continuous Plankton Recorder, a towed instrument that collects surface samples of plankton. The comparison helped confirm that the unusual red patterns detected from orbit did, in fact, correspond to dense clusters of Calanus finmarchicus.

Remote sensing through satellites has typically focused on phytoplankton, microscopic plant organisms in the sea. Larger zooplankton like Calanus have remained mostly invisible to satellites. According to the researchers, no one had previously known to look for Calanus finmarchicus using this optical method.

The researchers believe satellite data could soon be integrated with real-time whale sighting reports, helping inform decisions about when and where to put in place right whale protection measures.

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