WALPOLE — Researchers from the University of Maine, in partnership with the Maine Department of Marine Resources (DMR), are analyzing more than 20 years of fishery survey data from the Gulf of Maine to examine how environmental change is reshaping marine ecosystems.

The work aims to understand how changes impact the effectiveness of long-running DMR surveys that inform fishery management. It will also provide a model for evaluating and adapting survey methods to inform effective, science-based assessment and management of culturally and economically important marine resources like lobster, herring and shrimp.

The first of three surveys to be examined was the Maine-New Hampshire Inshore Trawl Survey, which monitors a swath of species in the Gulf of Maine. Researchers analyzed survey data collected between 2000 and 2023.

The analysis, published in the journal PLOS Climate and led by Hsiao-Yun Chang ’21G, a postdoctoral research associate at UMaine, identified that a rise in bottom water and sea surface temperatures occurred between 2010 and 2012. Using that shift as a dividing point, the researchers compared conditions before and after the warming period to examine how seasonal species distribution and biodiversity changed across Maine’s inshore habitats.

Because the survey has been conducted consistently for more than two decades, it provided a strong foundation for analysis. The results show that many species are shifting deeper and farther northeast and that dominant, fishery-relevant species have become less diverse. At the same time, some species are more abundant during the spring.

Despite those changes, the survey has remained 90% consistent at capturing data on key species and providing robust data for stock assessment and fishery management.

“This study is a great example of collaboration between UMaine and DMR and how our shared expertise and insights can support the ability of researchers, regulators and industry to adapt to a changing climate,” said Department of Marine Resources Commissioner Carl Wilson. “This milestone achievement will greatly improve Maine’s ability to monitor, conserve and increase the resilience of our coastal and marine ecosystems.”

Michelle Staudinger, associate professor of fisheries science at UMaine, is leading the collaborative effort between UMaine and the state agency. She is supporting Chang’s in-depth reviews of the three surveys while also completing a broader analysis of various DMR programs.

Staudinger worked with DMR division director Jesica Waller and science program leads to complete a review of eight of the department’s monitoring and assessment programs. The goal was to better understand how the programs operate and where additional research and monitoring could help the state respond to environmental change.

“We know that there’s increased variability and changes in the distribution of species in the Gulf of Maine, and fishermen and other industry members have seen these changes over the last few decades,” Staudinger said. “If they know that the data that they’re helping collect is informing fishery management decisions, we want them to feel confident that the data is accurately representing the state of the stocks.”

With the analysis of the Maine-New Hampshire Inshore Trawl Survey complete, the researchers will next examine the Sea Urchin Dive Survey and the Ventless Trap Survey for lobster. The team selected these surveys because of their cultural and economic importance to Maine’s fisheries and will evaluate them using similar approaches.

Understanding change in biodiversity

The trawl survey primarily tracks groundfish species such as haddock, flounder and cod and invertebrates such as squid that are caught by the net as it drags along the ocean floor.

Chang said one of the most important findings of her analysis was a subtle, but critical shift in biodiversity. In ecology, biodiversity can be viewed in two ways: abundance, which is the total number of individual organisms, and biomass, the total weight of those organisms.

“In fisheries research, we prioritize biomass data because it reveals which species are the functional pillars of the ecosystem,” Chang said. “If biomass is distributed across several dominant species, the ecological risk is spread out. However, our study shows that the weight is becoming concentrated in fewer species, meaning the diversity of the catch is actually shrinking.”

In the spring, while individual abundance increased among species, biomass diversity decreased. This suggests that even as the headcount for species appears more balanced, the bulk of the community is becoming increasingly dominated by a smaller number of species.

Chang said this biodiversity trend mirrors the reality of Maine’s coastal economy. Just as the state’s fishing industry relies heavily on a small number of high-value species like lobster, the underwater ecosystem is becoming more concentrated in fewer species.

Understanding these changes, she said, is critical for sustaining the marine environment and Maine’s blue economy.

“This work will not only support better fisheries management in the Gulf of Maine but will provide a template for researchers and managers around the world to support ocean stewardship,” Waller said. “Combined with the expertise of our staff, quantitative analyses like this one will guide our decision making in future survey design and data interpretation. This comprehensive, collaborative approach will allow us to bring data to industry and research partners to make well-informed decisions about the future of fisheries management.”

The initiative to analyze and update these surveys from the Department of Marine Resources is driven by the work of the Maine State Climate Council and its Coastal and Marine Working Group.

About the University of Maine: As Maine’s only public research university and a Carnegie R1 top-tier research institution, the University of Maine advances learning and discovery through excellence and innovation. Founded in 1865 in Orono, UMaine is the state’s land, sea and space grant university with a regional campus at the University of Maine at Machias. Our students come from all over the world and work with faculty conducting fieldwork around the globe — from the North Atlantic to the Antarctic. Located on Marsh Island in the homeland of the Penobscot Nation with UMaine Machias located in the homeland of the Passamaquoddy Nation, UMaine’s statewide mission is to foster an environment that creates tomorrow’s leaders. As the state’s flagship institution, UMaine offers nearly 200 degree programs through which students can earn bachelor’s, master’s, professional master’s and doctoral degrees as well as graduate certificates. For more information about UMaine and UMaine Machias, visit umaine.edu/about/quick-facts/ and machias.edu/about-umm/umm-facts/.