Using Satellites to Monitor Fisheries and Improve Sustainability

This high-quality image captured by PACE reveals eddies, the Loop Current, river plumes and coastal circulation in the Gulf of Mexico. (Credit: The Optical Oceanography Lab, University of South Florida)

While there are many methods used to monitor the world’s oceans and lakes, remote sensing technologies like satellites have become more popular for large-scale viewing of water quality, seabed topography, coral reef health, sea surface characteristics and other environmental conditions.

For example, Maury Estes, a principal research scientist with the University of Alabama in Huntsville and Associate Program Manager for the Ecological Conservation Program, National Aeronautics and Space Administration (NASA) Earth Action Program, shares an example of how water quality is derived from satellite imagery that calculates total suspended matter and can be used to determine the effect of nearshore runoff on the health of coral reefs health.

Such monitoring programs are important components of fisheries management and research, as environmental conditions can impact fish recruitment, distribution, abundance and availability in a particular location.

For example, temperature fluctuations may trigger migratory movements, reproductive processes, growth rates and other behaviors, as well as influence habitat suitability.

Rabbitfish (Siganus lineatus) fingerlings, known locally as ‘klesebuul,’ are produced at the Palau Community College hatchery for stocking at aquaculture fish farm sites. (Credit: The Nature Conservancy)

Satellites Currently Monitoring the World’s Waters

Estes explains, “Many satellites are actively monitoring the ocean, including those from NASA, National Oceanographic and Atmospheric Administration (NOAA), and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT).”

Ocean height, temperature, color, and other physical and biological ocean features are all being actively monitored by scientists who use the data to develop a better understanding of the dynamic nature of the ocean and environmental responses to climate change and other stressors.

According to Estes, the Jason series of satellites and the Sentinel 6 mission measure ocean height, which helps researchers understand sea level rise, ocean currents and storm prediction, all of which can influence fish behavior and habitat suitability.

The Moderate Resolution Imaging Spectroradiometer (MODIS) – Aqua satellite is critical for a variety of ocean color and temperature products, including KD 490, remote sensing reflectance, Photosynthetically Active Radiation, Chlorophyll-a, sea surface temperature, particle organic carbon among others.

While MODIS is still operating past its design life, the Visible Infrared Imaging Radiometer Suite mission will continue to provide similar ocean color products for years to come.

Several of the NASA satellite networks also monitor climate conditions as these influence water quality and aquatic ecosystems. The recently launched NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission is one example of this.

“The capability of PACE to provide information on the distribution of phytoplankton communities and ocean color products is of particular interest to identify high plankton concentrations as a signal for potential fish spawning areas and to monitor fish stock changes,” states Estes. (PACE ocean color image)

The NOAA Geostationary Operational Environmental Satellites collect ocean and climate data in specific regions, and Europe’s EUMETSAT satellites provide data on ocean color, sea surface height, sea ice extent and sea surface temperature

Another type of PACE image that shows coastal phytoplankton blooms. The greenish patch on the center of the West Florida shelf is the Karenia brevis red tide. The greenish color off the Mississippi Delta and Texas represents a bloom. (Credit: The Optical Oceanography Lab, University of South Florida)

Using Satellites to Inform Fisheries Management 

The data collected by these satellites measure physical aquatic conditions that are important to marine ecosystems and species.

“Measurements and data products are being provided at various spatial scales for global oceans including ocean fronts, surface optical or bio-optical products (ocean color, total suspended matter, and water clarity), upwelling areas, sea surface temperature, chlorophyll, salinity, vertical and horizontal circulation, phytoplankton distributions and biomass” explains Estes.

Many of these measurements are used in the fisheries industry as a means of monitoring the marine environment and making decisions about issues such as overfishing, illegal fishing activities, and ecosystems health. These data also provide input to stock assessment models to inform fisheries management as well as help monitor bycatch and changes in biodiversity.

For example, satellite imagery and data can help fisheries managers determine sites that should be designated as Marine Protected Areas, areas suitable for aquaculture, as well as help inform fishing regulations and restrictions based on observed fish migration and population size. (image of aquaculture operations for Rabbitfish in waters around the Republic of Palau)

Estes also highlights the use of satellite data in developing habitat suitability models, evaluating the effects of climate change on fisheries habitat and migration patterns, and identifying fishing habitat suitability zones to encourage fishing success for desired commercial species while decreasing the chance of bycatch. (Image climate effects on habitat zones for selected species)

The impacts of climate change are already substantial for some species. Bluefin tuna and shortfin mako sharks are predicted to experience similar northward shifts in their habitats by the end of the century (A). However, bluefin habitat has, in the last 30 years, already re-distributed about one-third of the expected total change (B). The species habitat shifts northward over time. The bluefin tuna (greenish colored line) are already re-distributing northward in the last couple decades. During that same time, shortfin mako shark (gold/brown) does not follow that same pattern of change. However, they both are predicted to have moved northward 2-4º latitude by the end of the century. The difference is that bluefin are already moving northward overall, and we don’t see evidence of the mako starting that move northward yet. (Credit: This figure was modified from Braun et al., 2023).

How Satellites Innovate the Fisheries Space

Perhaps one of the greatest benefits is the ability to view habitat and ecosystems at a much larger scale from space, particularly for large regional and global scale assessments—this helps reduce the field time and resources needed for habitat evaluation as the environment can be observed from afar.

“The high temporal resolution of satellite data provides rich data sources over days to months and years that allows for in depth evaluation of ecosystems, habitats, food sources, and migration patterns,” explains Estes.

He continues, “[Satellites] provide a global perspective of the physical conditions and overall health of the Earth’s oceans that was not possible before NASA and other domestic and international satellites begin providing global marine datasets.”

In addition to the visual components, satellites open the door for large-scale, near real-time data on physical ocean conditions, which allow scientists to determine optimal fish habitats, monitor distributions of important species, combat illegal fishing, and promote more data-based sustainable fishing practices.

“Data on whale movements and predictions using satellite data on the ocean environment are being combined with shipping navigation routes to provide alerts to the shipping industry to avoid whale strikes,” states Estes

Conclusion

The satellites also make collaboration between agencies easier as they all work off shared imagery and data. Such partnerships between the public and private sectors allow for a more comprehensive and united response to climate change and other stressors that threaten fisheries.

A pilot-scale floating fish farm for rabbitfish production, capable of yielding up to 1,600 lbs. of fish every 6 to 8 months. (Credit: The Nature Conservancy.)