A new research study found that well-managed fisheries can support the recovery of large marine predators such as seals and porpoises, showing that conservation and sustainable seafood production can go hand in hand.
While the impacts of protected species are often debated, the study led by researchers at University of Miami Rosenstiel School of Marine, Atmospheric and Earth Science's Cooperative Institute for Marine and Atmospheric Studies (CIMAS), showed that fishing effort—not predator recovery—is the main driver of fishery yields in the North Sea.
"Our findings offer an important takeaway: fisheries management goals can be achieved without sacrificing conservation goals," said the study's lead author Matthew Woodstock, an assistant scientist at CIMAS. "This new evidence can help reframe the conversation around how conservation and economic activity can coexist."
To conduct the study, the researchers developed a comprehensive ecosystem model of the southern North Sea and eastern English Channel to capture the full marine food web—from microscopic plankton to top predators such as gray seals, harbor porpoises, and seabirds—alongside 12 commercial fishing fleets. The model was grounded in real-world data, drawing on diet studies, fish stock assessments, and fisheries catch records to reflect conditions as accurately as possible.
The analysis found that the recovery of large marine predators does not automatically lead to declines in fishery yields. Although seals and porpoises consumed more fish as their populations increased, these impacts were outweighed by the effects of fisheries management decisions. In these regions, the data suggest that sustainable fisheries and recovering predator populations can coexist when fishing effort is managed effectively.
This study adds new, data-driven insights from one of the world's most heavily fished regions, showing that increasing seal populations in the southern North Sea have not curtailed fisheries operations.
The findings support ecosystem-based fisheries management—an approach that looks at the entire food web and environment—by demonstrating that predator consumption is often less impactful than human fishing pressure, helping managers balance conservation goals with sustainable seafood production and fishing livelihoods.
The study, titled "Marine mammal and seabird population changes have contrasting but limited impacts on fisheries catches in the North Sea," was published December 17, 2025 in the Canadian Journal of Fisheries and Aquatic Sciences.
The authors include Matthew S. Woodstock a,b, Jeremy J. Kiszka a, Peter G.H. Evans c,d, James J. Waggitt d, and Yuying Zhanga
a)Institute of Environment, Department of Biological Sciences, Florida International University, North Miami, FL, USA; b) Cooperative Institute for Marine and Atmospheric Studies, Rosenstiel School of Marine, Atmospheric, and Earth Science, Miami Florida c) Sea Watch Foundation, Ewyn y Don, Bull Bay, Amlwch, Isle of Anglesey LL68 9SD, UK; d) School of Ocean Sciences, Bangor University, Menai Bridge, Isle of Anglesey LL59 5AB, UK
