Dave Nelson, commanding officer of Oregon II, pilots the ship across a busy shipping channel. The Gulf of Mexico is a highly industrialized environment, with a large number of oil rigs and the support vessels that supply them. Photo: NOAA
by NOAA fisheries staff
As commanding officer of Oregon II, the oldest research vessel in the National Oceanic and Atmospheric Administration’s (NOAA) fleet, Dave Nelson pilots the ship through a busy ship channel in on its way into the Gulf to collect data during a recent groundfish survey.
Built in 1967, Oregon II is the oldest research vessel in the NOAA fleet. Photo: NOAA
During the next six weeks, he will navigate the aging ship though numerous oilrigs and the support vessels that supply them, so NOAA research scientists can collect data at roughly 300 randomly selected points between the shore and the shelf break from Texas to Florida.
The NOAA research ship runs from the Texas-Mexico border and around to the Florida Keys, staying at sea for two weeks at a time.
The survey area is vast, and the task of sampling 300 stations seems both Herculean and inadequate at the same time. A single survey in isolation would provide little insight, however sampling consistently, year after year, gives scientists the statistical power they need to begin to understand what’s happening beneath the waters of the Gulf.
The Science of Seafood
Sustainable seafood starts with sound science.
Fishing sustainably means leaving enough fish in the water so that they can replace through reproduction what we remove through fishing. To do that, knowledge of how many fish are out there to begin with is needed.
The groundfish survey runs 24 hours a day, with one shift working noon to midnight and the other midnight to noon. As in a continuous production factory, the work is non-stop. Photo: NOAA
Fish are constantly in motion, as well as constantly eating each other. Getting an accurate estimate of numbers requires hard work.
One important piece of that work is the fish survey, a monumental task requiring the combined expertise of mariners, scientists, and fishermen. In the Gulf of Mexico, NOAA Fisheries scientists conduct a groundfish survey twice a year
The NOAA fish survey is conducted using a statistically rigorous fishing trip conducted consistently and repeatedly over time. This information gathered during the fish survey allows scientists to monitor trends in fish abundance and changes in the marine ecosystem.
NOAA scientists conduct fish surveys all along each of the nation’s coasts. The data from these surveys are used, along with data collected from fishermen and other sources, to set sustainable catch limits, ensuring that we can enjoy a healthy supply of seafood both today and into the future.
Among the NOAA personnel on board are several with the job title Fisherman. These are the men and women who operate the cranes, winches and other heavy industrial equipment used in fishing. Like many NOAA fishermen, Chris Nichols is a U.S. Navy veteran, and he has spent most of his adult life at sea. In this photo, Nichols keeps an eye on the winch as he reels in the trawl net. Photo: NOAA
Chris Nichols, a U.S. Navy veteran, is among the NOAA personnel on board with the job title of Fisherman. Using a trawl net very similar to those used by commercial shrimpers, he and his fellow co-workers operate the cranes, winches and other equipment to harvest the various species for scientists to study.
To collect data at each station, Nichols and his fellow fishermen trawl for exactly 30 minutes at 2.5 knots to see what species are harvested. Scientists measure environmental variables such as temperature, salinity, and oxygen level at each sampling station.
A 24 Hour-a-Day Operation
In the control room, fisheries scientists Kristin Hannah (left) and Kim Johnson discuss the results they’re seeing. Photo: NOAA
A single haul in the Gulf often brings up over thirty species of fish, molluscs (mainly squid), and crustaceans such as shrimps and crabs).
The haul is sorted by species. NOAA biologists Kim Johnson and Kristin Hannan, and their fellow co-workers, then weigh, measure, and sex a subsample of each species, not just the commercially important ones. This allows for monitoring changes to the Gulf ecosystem over time, another important goal of the survey.
Just a few of the many species of fish, molluscs, and crustaceans that turn up during the Gulf of Mexico groundfish survey. Photo: NOAA
Pink, white and brown shrimp are important commercial species–in 2011 Gulf trawlers landed over $400 million worth of shrimp. One of the main purposes of this survey is to estimate the abundance and growth rates of these shrimp species. Those estimates will be used, along with other data, to set sustainable catch limits for the coming season.
The groundfish survey is a continuous production factory running 24 hours a day, with one shift working noon to midnight and the other midnight to noon.
Use of Latest Scientific Tools
The CTD is an indispensable tool of the oceanographer. The name stands for conductivity, temperature, and depth. Photo: NOAA
The primary tool for determining essential physical properties of seawater is a CTD — an acronym for Conductivity, Temperature, and Depth. It gives scientists a precise and comprehensive charting of the distribution and variation of water temperature, salinity, and density that helps to understand how the oceans affect life.
The oceanographer’s indispensible tool contains sensors that measure dissolved oxygen. By collecting these variables at each sampling station, scientists can assess how environmental conditions impact populations of fish and other species. The oxygen sensors also allow scientists to map the Gulf of Mexico Dead Zone–the area of very low oxygen that appears each summer, forcing fish and shrimp to flee for fresher waters.
The Gulf of Mexico survey is run twice a year, every year, since the early eighties. The continuity is important so scientists can understand changes in the ocean ecosystem by comparing findings against the light of a long-term dataset. When measuring the impact of storms, oil spills, and other events, this type of baseline data is essential.
Fisheries biologist Alonzo Hamilton has worked on various aspects of the Gulf of Mexico groundfish survey since his grad student days. The survey has run twice a year, every year, since the early eighties. This continuity is important because scientists can only understand changes in the ocean ecosystem by holding up today’s findings against the light of a long-term dataset. Photo: NOAA
After the survey is completed, results are combined with other sources of data, such as landings data from the fishing industry. The combined information is fed into statistical models estimating the abundances of important fish and shrimp species, as well as projections on their future growth.
The final product of Captain Nelson’s Oregon II’s Gulf trip is the stock assessment report—a document fishery managers use to set sustainable catch limits so recreational fishermen can enjoy the sport and commercial Gulf fishermen can continue to deliver the freshest, tastiest seafood to consumers around the world.
NOAA Fisherman James Rhue awaits a signal from the control room telling him to lower the CTD into the ocean. Photo: NOAA
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