Study finds fisheries management—not predator recovery—drives catch levels in the North Sea
Analysis supports fisheries policies that balance economic and conservation goals
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Harbour seals (Phoca vitulina) basking on a rocky shore. Recent data shows these charismatic marine mammals have surged in the past few decades. However, new research suggests this increased population size remains compatible with sustainable fisheries.
view moreCredit: Jeremy Kiszka, Ph.D.,Florida International University.
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-based 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, Ph.D., 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 in the Canadian Journal of Fisheries and Aquatic Sciences.
About the University of Miami and Rosenstiel School of Marine, Atmospheric and Earth Science
The University of Miami is a private research university and academic health system with a distinct geographic capacity to connect institutions, individuals, and ideas across the hemisphere and around the world. The University’s vibrant academic community comprises 12 schools and colleges serving more than 19,000 undergraduate and graduate students in more than 180 majors and programs. Located within one of the most dynamic and multicultural cities in the world, the University is building new bridges across geographic, cultural, and intellectual borders, bringing a passion for scholarly excellence, a spirit of innovation, and a commitment to tackling the challenges facing our world. The University of Miami is a member of the prestigious Association of American Universities (AAU).
Founded in 1943, the Rosenstiel School of Marine, Atmospheric, and Earth Science is one of the world’s premier research institutions in the continental United States. The School’s basic and applied research programs seek to improve understanding and prediction of Earth’s geological, oceanic, and atmospheric systems by focusing on four key pillars:
*Saving lives through better forecasting of extreme weather and seismic events.
*Feeding the world by developing sustainable wild fisheries and aquaculture programs.
*Unlocking ocean secrets through research on climate, weather, energy and medicine.
*Preserving marine species, including endangered sharks and other fish, as well as protecting and restoring threatened coral reefs. www.earth.miami.edu.
Journal
Canadian Journal of Fisheries and Aquatic Sciences
Method of Research
Survey
Subject of Research
Animals
Article Title
Marine mammal and seabird population changes have contrasting but limited impacts on fisheries catches in the North Sea
Sharktober: Study links October shark bite spike to tiger shark reproduction
University of Hawaii at Manoa
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Female tiger shark.
view moreCredit: Cory Fults
New University of Hawaiʻi research confirms that “Sharktober” is real, revealing a statistically significant spike in shark bite incidents in Hawaiian waters every October. The study, which analyzed 30 years of data (1995–2024), found that about 20% of all recorded bites occurred in that single month, a frequency far exceeding any other time of the year. Researchers at UH Mānoa’s Hawai‘i Institute of Marine Biology (HIMB) Shark Lab published their findings in Frontiers in Marine Science.
The research, led by HIMB Professor Carl G. Meyer, determined that this pronounced pattern, informally known as “Sharktober,” is primarily driven by the seasonal movements and biological needs of tiger sharks (Galeocerdo cuvier), which account for at least 63% of the incidents during this month.
“The October spike is real and statistically significant, but the overall risk remains very low,” said Meyer. “This pattern appears to be driven by tiger shark biology, not by more people being in the water.”
The findings suggest a strong link between the October spike and the tiger shark’s reproductive cycle, specifically parturition (giving birth), which occurs during the September–October window. The evidence indicates two primary mechanisms acting together. First, there is a temporary increase in the abundance of large adult females in nearshore habitats, including a partial migration of mature females from the Northwestern Hawaiian Islands to the Main Hawaiian Islands. Second, giving birth to a large litter is energetically taxing, likely leaving postpartum females in a state of poor nutritional condition and increasing their motivation to forage actively to recover energy reserves. This conclusion is supported by multiple independent lines of evidence, including the peak in tiger shark sightings at ecotourism sites that aligns precisely with the pupping season.
Extra caution advised
The study uses Hawai‘i-specific data to address a Hawai‘i-specific concern, providing science-based information that allows residents and visitors to make informed decisions about ocean use during this time of year, supporting awareness and coexistence without sensationalism.
“Understanding when risk is slightly elevated helps people make informed choices, not fearful ones,” notes Meyer.
Ocean users are advised to be aware that large tiger sharks are more likely to be present in the nearshore waters of the Main Hawaiian Islands during October, and extra caution is advisable during this month, particularly for high-risk, solo activities such as surfing or swimming in coastal areas.
Future research will focus on directly studying adult female tiger sharks during the pupping season, including tracking their movements and using non-invasive tools to assess their reproductive status and body condition. The work was conducted as part of the HIMB Shark Lab program at the University of Hawai‘i at Mānoa, utilizing publicly available shark incident data compiled by the Hawai‘i Department of Land and Natural Resources.
Female tiger shark.
Credit
Cory Fults
Journal
Frontiers in Marine Science
Method of Research
Observational study
Subject of Research
Animals
Article Title
‘Sharktober’: tiger shark parturition drives seasonality in shark bite incidents in Hawaiian waters
Article Publication Date
25-Jan-2026
Early-life exposure to a common pollutant harms fish development across generations
Biochar Editorial Office, Shenyang Agricultural University
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Multigenerational developmental and skeletal toxicity from benzo[a]pyrene exposure in F0 and F2 medaka: metabolic trade-offs and survival costs
view moreCredit: Yinhua Chen, Huiju Lin, Jiangang Wang, Feilong Li, Rim EL Amouri, Jack Chi-Ho Ip, Wenhua Liu & Jiezhang Mo
A widely distributed environmental pollutant can leave lasting biological scars that persist long after direct exposure has ended, according to a new study that tracked its effects across multiple generations of fish.
Researchers found that brief exposure to benzo[a]pyrene, a toxic compound produced by fossil fuel combustion and industrial activity, disrupted normal development and skeletal health not only in directly exposed fish but also in their unexposed descendants. The study reveals that these long-term effects are driven by persistent changes in metabolism, shedding new light on how early-life pollution can shape health outcomes across generations.
Benzo[a]pyrene is a type of polycyclic aromatic hydrocarbon commonly detected in air, soil, and aquatic environments worldwide. While its toxic effects are well documented, most studies focus on immediate or single-generation impacts. This new research goes further by examining how early embryonic exposure influences offspring two generations later.
Using medaka fish, a well-established model for environmental and developmental research, scientists exposed embryos to environmentally relevant concentrations of benzo[a]pyrene for just the first eight days of development. The fish were then raised in clean water, and their offspring and grand-offspring were never directly exposed to the chemical.
Despite this, the effects persisted.
The researchers observed reduced survival and delayed hatching in the directly exposed generation. More strikingly, offspring across two generations showed altered body size, abnormal organ development, and a high frequency of skeletal deformities, including craniofacial abnormalities and spinal curvature.
“Our results show that a short window of exposure early in life can have consequences that echo across generations,” said Jiezhang Mo, the corresponding author of the study. “Even when later generations grow up in clean environments, they still carry hidden biological costs from their ancestors’ exposure.”
To understand why these effects persist, the team conducted untargeted metabolomic analyses, a technique that measures hundreds of small molecules involved in metabolism. This approach allowed them to link physical abnormalities with disruptions in core biological processes.
They identified widespread changes in pathways related to energy production, oxidative stress, cell signaling, and developmental programming. Key metabolic signals suggested that exposed fish embryos entered an energy crisis, forcing them to reallocate limited resources to support survival-critical organs at the expense of skeletal development.
“In the second generation, some physical traits appeared to recover, but our metabolic data tell a different story,” Mo explained. “This apparent recovery may reflect a survival trade-off, where energy is diverted away from bone formation to keep essential systems functioning.”
The study also identified specific metabolic signatures that could serve as early warning indicators of long-term toxicity. These biomarkers provide a mechanistic bridge between early chemical exposure and delayed health effects, helping explain why damage can remain hidden until later stages of development or even future generations.
The findings have important implications beyond fish. Benzo[a]pyrene is a ubiquitous contaminant, and early-life exposure occurs in many species, including humans. While direct extrapolation requires caution, the study highlights the potential for early environmental insults to influence health across generations through metabolic reprogramming.
“This work emphasizes that pollution is not just an immediate problem,” Mo said. “Its legacy can extend far into the future, affecting organisms that were never directly exposed.”
The researchers say their results underscore the need to consider multigenerational effects when assessing environmental risks and regulating persistent pollutants. By revealing the metabolic mechanisms underlying inherited toxicity, the study provides a deeper understanding of how environmental contamination can shape ecosystem health over the long term.
The study was published in New Contaminants.
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Journal reference: Chen Y, Lin H, Wang J, Li F, Amouri REL, et al. 2026. Multigenerational developmental and skeletal toxicity from benzo[a]pyrene exposure in F0 and F2 medaka: metabolic trade-offs and survival costs. New Contaminants 2: e002 doi: 10.48130/newcontam-0025-0022
https://www.maxapress.com/article/doi/10.48130/newcontam-0025-0022
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About the Journal:
New Contaminants (e-ISSN 3069-7603) is an open-access journal focusing on research related to emerging pollutants and their remediation.
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Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Multigenerational developmental and skeletal toxicity from benzo[a]pyrene exposure in F0 and F2 medaka: metabolic trade-offs and survival costs
Article Publication Date
19-Jan-2026
