The North Atlantic Right Whale (NARW), one of the most critically endangered mammals on Earth, continues to be threatened with several dangers despite the prohibition of commercial whaling. Entanglement in fishing nets and collisions with ships are now the greatest dangers to their existence. To help protect these whales from these dangers, scientists have come up with creative ways of monitoring their habits and reducing these dangers.Another core part of this study is determining the whale’s feeding habit, or how they depend on a specific species of plankton, Calanus finmarchicus, a reddish-colored copepod. Researchers are charting the density of these copepods from NASA satellite imagery and more precisely forecasting the whales’ migratory routes.
NASA tracks plankton populations from space to support right whale protection
The NARW’s food intake is the deciding factor on where they migrate across the ocean. The whales feed mainly on Calanus finmarchicus, a copepod that inhabits huge herds in the ocean. These herds are in certain places, and monitoring where they are is the key to being able to predict the migration of whales. The Gulf of Maine, one of the primary feeding grounds for NARWs, is a place where these copepods occur in large numbers.Researchers have also been looking to map the populations of these copepods so they can estimate where NARWs will be apt to feed, cutting down on ship collision hazards and net entanglements. Satellite technology has a key role to play in this research.
Source: NASA
To track the copepod blooms, scientists used the Moderate Resolution Imaging Spectroradiometer (MODIS), a sensor on NASA’s Aqua satellite. MODIS monitors the manner in which sunlight reflecting off the sea surface varies as it travels through different materials in the water. In this case, it looks for astaxanthin, the red color in Calanus copepods. The occurrence of this pigment affects light scattering and absorption by the sea, which is a parameter that MODIS can observe. When the copepods form swarms in high density, the pigment changes the spectrum of reflected light, and scientists can remotely map their distribution. This is a non-destructive, large-scale technique for finding planktonic swarms without looking at them in situ in the ocean.
Source: NASA
How satellites use astaxanthin to track copepods
Astaxanthin, the reddish pigment in copepods, is of pivotal importance when it comes to MODIS observing zooplankton in the ocean. As massive populations of copepods migrate towards the sea surface, the areal density of the pigment accumulates and thereby affects the scattering and absorption of photons by the ocean. All of these can be observed from orbit, and scientists now have means to quantify copepod population density.Researchers first tested the satellite-based copepod detection method in Norwegian waters but have now expanded the technique to the Gulf of Maine, an important feeding ground for North Atlantic Right Whales. Through the use of satellite measurements, field observations, and sophisticated modeling methods, scientists have improved their capacity to estimate the density of copepods in an area.By integrating data from several sources, scientists are able to paint more precise pictures and forecasts of Calanus swarms on the ocean surface. Through the combined method, it is possible to have better monitoring of whale feeding habits, which can be employed to inform conservation efforts and mitigate the associated risks.
Challenges in satellite-based copepod detection
Although promising, this satellite method has some drawbacks. The MODIS sensor is able to sense the red hue of the copepods but cannot actually sense the organisms themselves. This leaves open the potential for false positives—where the satellite can sense other reddish small animals that are not necessarily copepods. Moreover, satellite remote sensing can be disrupted by clouds and extremely rough seas to the extent that precise readings are not possible under some weather. In addition, if the copepod swarms are deeper in the water column, they cannot be reached from the surface.In its quest to bypass some of those limitations, NASA is introducing the PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) satellite in 2024. The PACE mission has a great deal to bypass zooplankton and phytoplankton detecting ability, greatly lightening the job of monitoring for whales’ target prey. Its satellite replacement will offer more accurate high-resolution observations and improved detection of plankton in different forms of the water, and handling cloud occlusions and the sort of churned ocean water which tends to plague cruise ships. By putting together more modern technology with current research methods, PACE is to provide much more accurate and reliable means of tracking and preserving the North Atlantic Right Whale population.
Advancements in satellite tracking help protect right whales
Observation of the North Atlantic Right Whale through their main source of food, the Calanus copepod, has become an essential component of whale conservation. Through a combination of satellite technology and new approaches, scientists are learning more about whale migration patterns, which may potentially translate to fewer cases of fatal encounters with fishing nets and boats. While the reliability of data and climatic conditions provide hurdles to cross, the future for ocean observation is bright with NASA’s PACE satellite being launched, with still more accurate data to aid in the preservation of these terribly beleaguered animals.Also Read | NASA’s Hubble detects a massive black hole wandering outside its galaxy
