NOAA Fisheries scientists pioneer study of environmental influences on fisheries
Following the 2010 Deepwater Horizon oil spill, calls came to shut down longline fishing for Atlantic bluefin tuna across the Gulf of Mexico. Many feared the oil had overrun bluefin spawning habitat and may have reduced recruitment to where the only choice was to stop fishing to protect whatever was left.
But less than a year earlier, as part of a NASA/NOAA–funded research team, Barbara Muhling and John Lamkin of the Southeast Fisheries Science Center and colleagues had combined years of ocean survey data into a model that would tell them, based on temperatures and other oceanographic conditions, where bluefin would have been spawning during the spill.
They compared those data to maps of the oil’s reach, and found limited overlap.
“Our answer was that there was a hit to the fish, but it was a relatively small hit, and no, we do not think you need to shut down fishing,” recalled Lamkin, who leads the SEFSC’s Early Life History Lab. “If we hadn’t just done that work and they had asked that question, we would have had to just shrug our shoulders and say, ‘We don’t know.’”
The insight into effects of the spill illustrates the power of fisheries oceanography, the scientific field that examines how ocean conditions such as temperature and salinity affect fish populations and the fisheries they support. This year the field celebrates its 100th anniversary, marked by a special issue of Oceanography magazine guest edited by NOAA Fisheries scientists, which describes how NOAA research from the Bering Sea to the Gulf of Mexico has revealed telltale interactions between fisheries and the environment.
“We’re on the precipice of another kind of technological revolution. These new tools include satellite sensors, animal tags, and ocean gliders and can be an order of magnitude less expensive than big white ships and give us almost immediate access to much of the information we need.”
Elliott Hazen | Research Ecologist, SWFSC
A Century of Fisheries
Oceanography Tools
Click image to view larger
Fisheries oceanography fosters ecosystem-based management
Fisheries oceanography got its start in 1914 when Norwegian oceanographer Johan Hjort realized that fish populations fluctuated largely based on how the ocean affected early survival of young fish. Today, fisheries oceanography supports NOAA Fisheries’ transition to ecosystem-based management, which incorporates environmental factors and ecosystem processes into fisheries management decisions.
The special issue comes 100 years after Hjort’s influential finding and addresses the question, “where is fisheries oceanography now, and where is it going in the coming century?” said Steven Bograd, lead editor of the special issue and an oceanographer at the Southwest Fisheries Science Center (SWFSC).
“There’s a growing recognition that we can’t manage and maintain the long-term sustainability of fish stocks without an understanding of their environment, including the biological, physical, and chemical components,” said Jon Hare, Chief of the Oceanography Branch at the Northeast Fisheries Science Center. “Climate change and long-term climate variability are also demonstrating the need to understand the interaction between fish populations and the environment.”
More than 15 NOAA Fisheries scientists contributed articles to the special issue. The papers highlight several NOAA Fisheries research programs, including:
- The development of acoustic tools for surveying fish species such as herring, sardine, anchovy, and mackerel, and their promise for the future.
- How jellyfish may divert energy that would otherwise flow more directly up the marine food chain and the potential use of jellyfish as an indicator of ecosystem health.
- Long-running ocean survey programs monitoring ecosystems and ocean conditions off the West Coast, Alaska, Gulf of Mexico, and northeastern United States.
- More than 20 years of multidisciplinary research in the Bering Sea using moorings, ship-based operations, and drifting buoys to understand how climate influences some of the largest fisheries in the world.
“The articles highlight that, while the field has progressed over the last century, many of the issues raised by Hjort are still relevant today,” Bograd said.
“We now know that environmental factors can have a significant influence on many fisheries,” said Nate Mantua, leader of the SWFSC’s Landscape Ecology Team. “But predicting that influence is still very hard because it’s still difficult to disentangle all the various factors affecting many important stocks.”
Technology boosts power of ocean surveys
The key to unraveling these factors is long-running surveys of the ocean environment, which reveal how environmental changes coincide with fish populations. Technological advances are boosting the power of surveys, with automated ocean monitoring and sampling systems that can now inform real-time shifts in fisheries management depending on environmental factors, according to Elliott Hazen, a research ecologist at the SWFSC and coauthor of the introduction to the special issue.
“We’re on the precipice of another kind of technological revolution,” he said. “These new tools include satellite sensors, animal tags, and ocean gliders and can be an order of magnitude less expensive than research ships and give us almost immediate access to much of the information we need. Nonetheless, we still have not figured out a way to automate fishing nets. Thus we still rely on traditional surveys similar to the original days of fisheries oceanography.”
The model that assessed the impacts of the Deepwater Horizon oil spill on Atlantic bluefin tuna drew upon data from the Southeast Area Monitoring and Assessment Program (SEAMAP), which coordinated surveys across the Gulf of Mexico starting in 1982. Basic oceanographic data (such as plankton collected by ship) are now supplemented by satellite data that provide real-time insight into environmental factors such as temperature and chlorophyll that makes models even more powerful, Lamkin said.
“Fisheries oceanography is foundational for our understanding of how so many oceanographic features affect so many facets of the life history of our marine trust fishes,” said Jason Link, Senior Scientist for Ecosystem Management at NOAA Fisheries.
In 2002 NOAA Fisheries launched a dedicated fisheries oceanography program called FATE, for Fisheries and the Environment, which is also described in the special issue. FATE funds 10 to 12 new research projects annually, which have identified key oceanographic indicators around the country that reflect changes in the ocean environment and the living resources it supports. The indicators inform ecosystem status reports and integrated ecosystem assessments, and fuel advanced ecosystem models that help assess and even predict how environmental changes affect fisheries.
Ecosystem indicators at work
For example, sardines off California appear to be more productive when temperatures in the Southern California Bight are near 17.5 ˚C, making temperature a fundamental indicator of their productivity. Model simulations now indicate that the sardine collapse of the 1950s, immortalized in John Steinbeck’s Cannery Row, might have been prevented or lessened if fishing pressure had been reduced during that less-productive, colder period.
Effective ecosystem indicators emerge only through the collection of consistent ocean data that over years or decades reveal how certain environmental factors reflect ecosystem health, said Sam McClatchie, a research oceanographer at the SWFSC and author of a paper in the special issue describing several long-term NOAA Fisheries ocean survey programs. The California Cooperative Oceanic Fisheries Investigations (CalCOFI) is among the longest-running surveys of ocean data in the United States.
CalCOFI took shape in response to the sardine crisis off California, which presented an ecological mystery. Had overfishing driven sardines to the brink, or did changing ocean conditions depress survival? State and federal fisheries agencies (including the forerunner of NOAA Fisheries) launched CalCOFI to examine how ocean conditions affect sardines and hundreds of other marine species.
“CalCOFI was very unusual for its time,” said McClatchie. “It wasn’t just about understanding what happened to sardines, it was about understanding how the California Current system worked. That was a different way of thinking about the ocean.”
Linking ocean conditions to salmon returns
Since 1996 researchers from NOAA Fisheries’ Northwest Fisheries Science Center have similarly sampled zooplankton and ocean conditions along a 25-mile line extending west into the Pacific from Newport, Oregon. The sampling every 2 weeks has revealed that changes in plankton species, as well as other conditions such as temperature and oxygen levels, can reveal important changes in the marine food chain and offshore ecosystem of the northern California Current.
Analysis of the relationships between those indicators and salmon survival has revealed that certain conditions boost survival of juvenile salmon, leading to strong returns to the Columbia and other rivers, while other conditions reduce survival. NWFSC scientists, led by oceanographer Bill Peterson, have used those relationships to develop annual outlooks for salmon returns up to 2 years in advance, with an online “red light-green light” chart that has become popular with commercial and sports fishermen and even fisheries managers who want to be prepared for upcoming fishing seasons.
For example, in the past year waters off the West Coast have been unusually warm and dominated by warm-water copepods, which is not good news for salmon. Warm-water copepods contain lower concentrations of lipids that fuel the growth of young salmon first arriving in the ocean, leading to reduced salmon survival. In turn, the outlook for salmon in 2015 has dimmed.
Peterson is the lead author of a paper in the special issue about the use of ecosystem indicators as barometers of ocean conditions.
Forecasting sea turtle presence
Another successful example of fisheries oceanography at work is TurtleWatch, a real-time indicator of the potential presence of protected loggerhead and leatherback turtles in waters plied by longline fishing boats. Evan Howell at the NOAA Fisheries’ Pacific Islands Fisheries Science Center developed TurtleWatch to support NOAA’s mandate to safeguard the endangered turtles protected by the Endangered Species Act.
The system draws on satellite maps of sea surface temperatures, indicating where and when turtles are most likely to be found. Fishing vessels can check the maps and voluntarily avoid turtle hot spots, protecting themselves and the turtles.
Such tools to adjust fisheries in real time based on environmental changes or trends are essential to “climate-ready” fisheries management that can adjust to both long- and short-term shifts brought about by climate or other environmental changes, said Mantua, who co-authored a paper in the special issue on strategies for managing fisheries in a shifting climate. NOAA Fisheries’ Climate Science Strategy calls for tracking climate and ecosystem trends to provide early warnings of change and anticipate the potential implications for fisheries and the communities that depend on them.
Waters off the northeastern United States are experiencing among the highest rates of warming in the world, Hare said, raising questions about how the trend will affect growth and recruitment of key fish species. Incorporating that trend and projections of its impacts into stock assessments will make the assessments more useful and timely, he said.
“We can’t define exactly what it’s going to look like in 20 years but we have some idea,” Hare said. “The approach of fisheries oceanography and ecosystem-based fishery management brings NOAA Fisheries together in a way that also helps us pull that big picture together.”
