Reflecting on 15 Years of Science Since Deepwater Horizon: Supporting Restoration

NOAA Fisheries' Office of Habitat Conservation has led post-spill restoration efforts , which involve an intricate network of partners across the Southeast region. NOAA scientists were, and continue to be, involved in many of these efforts.

Mesophotic and Deep Benthic Communities

Deep beneath the surface of the Gulf, deepwater coral communities also felt the impacts of the spill. Scientists and experts from the Department of the Interior, NOAA, academic partners, and non-governmental organizations set out to assess damage. They used technologies such as remotely operated vehicles. The team found more than 770 square miles of deep-seafloor habitats damaged, including coral habitats. Many of these corals grow very slowly and can live for centuries, meaning natural recovery would take a long time.

One restoration project focuses on repopulating injured habitat by helping corals reproduce , and even propagating and planting lab-reared corals. The work involves collecting fragments of mesophotic and deep corals underwater, either with ROVs or technical divers , and bringing coral fragments up to the surface. Scientists then mount them on a substrate and grow them in laboratory aquaria designed especially for this purpose. The team then places the fragments back on the seafloor.

So far, the effort has been a huge success. "We've made significant progress over the past few years both in the field and lab," stated Chris Gardner, a project manager on the project. Three mesophotic coral species are now spawning in the lab, and fragments collected and transplanted offshore are surviving well. The Southeast Fisheries Science Center's Coral Propagation Laboratory in Galveston, for instance, had more than 50,000 eggs spawned in captivity over about 4 months. "This led to more than 30,000 larvae and more than 1,200 new coral colonies for us to grow and outplant in further restoration efforts. Now, our team is working on maximizing survival and optimizing feeding to grow to a size where they're more likely to survive once outplanted."

Learn more about the Coral Propagation Technique Development Project

Bycatch Reduction to Help Species Recover

One way to help species recover from a disaster is to find other ways to reduce mortality. One innovative method for sea turtles has been around since the 1970s-the turtle excluder device, or TED. It allows turtles to escape in the event they are caught in a shrimp net. While TEDs have changed over several decades , NOAA led an effort following Deepwater Horizon to further improve designs to give sea turtles a better chance at recovery.

TEDs with narrow bar spacing were already being used throughout the industry to exclude bycatch. Scientists at the Southeast Fisheries Science Center worked with commercial shrimp fishermen to make and test gear improvements by:

• Identifying the optimum bar spacing that maximized sea turtle exclusion
• Testing different TED sizes and orientations
• Documenting catch retention on both research vessels and commercial fishing boats

The primary focus was on TEDs with smaller bar spacing , which help ensure juvenile turtles can escape as well as adults. Juveniles are especially vulnerable to capture because their small size allows them to slip through the TED bar spaces into the net. They also have difficulty pushing through the TED opening to escape.

The team also developed other bycatch reduction devices to help non-target fish escape shrimp nets as well. "The use of these nets doesn't just help reduce bycatch to help populations recover," said Blake Price, a former research fishery biologist within the center's Fisheries, Assessment, Technology, and Engineering Support Division. "They also reduce the amount of discards the shrimpers have to sort through on the boat. The use of these devices can help cut down their processing time, and hopefully increase their efficiency on the water."

The next phase for the TED project is to incentivize the use of the new devices. NOAA plans to talk with shrimp fishermen along the Gulf about the project and get their input. We have already successfully engaged with industry members on other bycatch reduction devices and received valuable feedback. By working hand-in-hand with the shrimp community, we hope to reduce the number of turtles and fish caught in nets, while maximizing shrimp retained.

Restoring Reef Fish Populations Through Better Fishing Practices

It's challenging to restore individual fish lost from the population due to the spill. But we can try to counteract these population-level effects by alleviating another source of mortality-fishing discards. When fish are brought up from depth, they sometimes experience a phenomenon called barotrauma -when gases in the fish's tissues and organs expand, and sometimes rupture. Fish released in this state have a very low chance of survival.

A restoration project was established to restore reef fish populations by promoting the use of fish descender devices and other best release practices to reduce release mortality. The project involves multiple partners, including NOAA and the Gulf States Marine Fisheries Commission. Florida Sea Grant leads the effort through the Return 'Em Right outreach and education program, which has been a huge success . More than 28,000 anglers have received descending gear. Ninety-eight percent of participants reported a better understanding of barotrauma and its impact on fish, as well as improved knowledge on venting techniques.

The team identified a need to quantify how many fish were being discarded and to calculate updated discard mortality estimates for use in stock assessments. That's where the science center comes in. Rob Cheshire, acting recreational fisheries monitoring branch chief, stated, "Our science is showing that we've underestimated discard mortality in previous years. When we consider the most recent literature, we're seeing large discrepancies. For instance, for gray triggerfish, we originally estimated about 12.5 percent discard mortality for triggerfish in the 2015 stock assessment , and when recent studies were evaluated in 2023we saw a jump to 58.9 percent ."

How do we evaluate the benefits of using best release practices and use that information in stock assessments? Rob has been working with a team to incorporate new questions into the Southeast Region Headboat Survey to track how many fish are descended or vented before release. These data will help us improve certainty in our stock status and give credit to fishermen in terms of reduced discard mortality rates. "Since we added these fields to our headboat reporting forms, we're collecting much better information on these questions and seeing impressive results-with as many as 60 percent of released red snapper being descended rather than just tossed back in the water."

Our next steps are to validate these numbers to ensure their accuracy and incorporate these updates into the stock assessment process moving forward. Ultimately, best release practices such as venting and descending fish will help populations recover more quickly, from the spill and other stressors. They will also leave more fish for us to catch in the future.

Tracking Marine Mammal Restoration

Restoring the injuries from an oil spill for long-lived species like marine mammals is not an easy task. We are developing several restoration projects to reduce human impacts on marine mammals to help their populations recover faster from the oil spill. These include projects to:

We are collecting data to monitor these projects and the marine mammals they aim to benefit.

Many organizations collect information on whales and dolphins, each using their own data formats and management systems. To improve this, a team is developing a cloud-based platform that will provide user-friendly access to data and visualization tools. This will allow us to assess the health of whale and dolphin stocks in the Gulf of America, better understand their stressors, and consistently track the progress of marine mammal restoration. The project focuses on Rice's whales, sperm whales, Risso's dolphins, beaked whales, oceanic bottlenose dolphins, and pantropical spotted dolphins.

Dr. Garrison noted the contributions of the science center to this effort by stating, "We're investing significant time adding data to this system. This is a valuable outlet to ensure that those who use our data to make decisions have the information they need-not just from Deepwater Horizon -related efforts, but all of our historical data."

This project is bringing the data together in a single system, with uniform standards and comprehensive data management capabilities. Ready access to the most up-to-date information on cetacean abundance, spatial distribution, habitats, health, and stressors is expected to make for more timely and effective responses.

Follow Along to Explore Our Role in Monitoring Recovery

The next story in this series will explain the role of the Southeast Fisheries Science Center in monitoring species recovery over the past 15 years.

Explore part one: Response and Assessment