As lobsters migrate to colder waters due to climate change, Jonah crabs are becoming one of the most important species for fisheries in Southern New England.

“As the biomass of the American lobster declines due to climate-related changes and shifting ocean conditions, many fishermen have adapted by targeting other valuable species, and the Jonah crab has become a major alternative,” said Emmanuel Oyewole, a first-year Ph.D. student in the University of Rhode Island’s Graduate School of Oceanography. “The Jonah crab used to be considered a bycatch species and thrown back because lobster was so lucrative. As lobsters became less abundant, people started to realise that the Jonah crab is a viable and delicious alternative.”

Oyewole is conducting a study that is partly funded by a grant from The Nature Conservancy into how offshore wind farm structures are impacting the growth and habitats of Jonah crabs.

“Ecologically, Jonah crabs also play an important role in the marine food web,” said Oyewole, who is from Ilé-If?`, Nigeria, a town in the southwestern part of the country. “They are both predators and prey, helping to maintain balance within benthic ecosystems. Because they are closely connected to seafloor habitats, they can help us understand how offshore wind farm structures may influence local biodiversity, habitat use, and the productivity of fisheries.”

When turbine foundations are installed on the seafloor, their hard surfaces become desirable habitats for marine organisms to attach, grow, and live, just as they do on natural rock or reefs. As algae, barnacles, mussels, and other small marine life, settle on these structures, these smaller organisms attract larger species such as crabs and fish that come to feed, hide, or seek shelter.

“The turbines can create a kind of ‘mini ecosystem.’ They provide food and habitat, which can draw marine life into the area and potentially change how species use the surrounding environment,” added Oyewole. “The question is whether they are increasing the overall amount of marine life in the ocean by creating new production or simply concentrating animals that were already living in the surrounding areas.”

The data Oyewole collects and analyses will benefit the Commercial Fisheries Research Foundation, a non-profit organisation founded by local commercial fishermen.

For the last year, Oyewole has conducted field work twice a month, long before sunrise. Boarding lobster vessels at Point Judith, Rhode Island, he has accompanied fishermen as they haul ventless traps from 10 stations near the Revolution Wind and South Fork Wind sites.

“One of the most important things I have learned from commercial fishermen is that the end product of research is just as important as the research process itself,” said Oyewole. “Research should not only answer scientific questions, but it should also be useful to the people and communities most affected by it.”

Oyewole’s conversations with the fishermen have helped inform his research.

“This project has been shaped by listening to their experiences, concerns, and needs. Their knowledge of the water, species behaviour, and changing fishing patterns provides insight that scientific sampling alone can’t capture,” he commented. “Even as data collection continues, their support remains a critical part of the work.”

Rather than completing his fieldwork first and starting lab work later, Oyewole’s project is designed to accomplish both phases concurrently.

“While we are collecting samples, we will begin processing them in the lab for tissue-specific stable isotope analysis,” continued Oyewole. “Field sampling, lab analysis, and data interpretation will build on each other over time.”

With the guidance of Associate Professor Kelton McMahon, Oyewole performs tissue-specific stable isotope analysis on the crabs in the Ocean Ecogeochemistry Laboratory on URI’s Narragansett Bay Campus.

“The isotope analysis helps us understand where these crabs have been living and feeding at different times of their lives,” said Oyewole. “Different parts of the ocean can leave slightly different chemical ‘signatures’ in an animal’s tissues, almost like a natural geographic fingerprint. This will enable us to trace whether the crabs are living and feeding around the wind farm long enough to benefit from the habitat or whether they are simply moving in temporarily from surrounding areas.”

Having grown up in a region where fisheries are both economically important and environmentally vulnerable, Oyewole saw first-hand the challenges communities face in balancing resource use with long-term sustainability.

“My research at URI has shaped my desire to develop practical, science-based management strategies that protect aquatic resources while also supporting local livelihoods,” concluded Oyewole. “My goal is to build a career at the intersection of marine ecosystem science and the sustainability of fisheries, with a particular focus on African waters, especially in my home country of Nigeria.”