Abstract
Myctophid fishes constitute a major component of the world’s ocean biomass and are seen as a potential resource for commercial exploitation. Within this family, the glacier lanternfish Benthosema glaciale (Reinhardt, 1837) is the dominant North Atlantic species and plays a key role in pelagic food webs in open waters, deep coastal regions and fjords. Previous studies employed genetic markers to evaluate population structuring across the species’ broad distribution range, detecting heterogeneity in shallow-silled fjords. However, genetic methods cannot reconstruct ontogenetically determined movements, and research on alternative methods is lacking. Here, we examine whether otolith features can resolve coastal connectivity in B. glaciale. We collected individuals from a coastal site and a range of fjord types along the complex Norwegian west coast to capture topographic and environmental characteristics that could give rise to population structuring. We show that otolith shape coefficients and temporally-resolved microchemical signatures reveal consistent and significant patterns of variation supporting the presence of subpopulations within small geographic distances. Contrary to earlier hypotheses, we propose that oceanographic dynamics affecting early life stages have a greater influence on shaping coastal mesopelagic populations than topographic barriers. This study presents the first evidence of the effectiveness of otolith morphometrics and microchemical analysis in addressing ecological questions in this abundant myctophid, and highlights their potential to provide valuable information for future management and conservation strategies.
Data availability
The raw data used in this study are available upon request to the corresponding author.
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Acknowledgements
The authors are grateful to Frank Midtøy, Heikki Savolainen and Julie Skadal (University of Bergen, UiB), and to the crew members aboard the research vessels G.O. Sars, Dr. Fridtjof Nansen and Kristine Bonnevie (Institute of Marine Research, IMR) for their fundamental contribution to collecting the material used in this study. Thanks also to: Øyvind Andersen, Carl Bukowski, Mari Munkeby, and Catharina Olsen (UiB) for extracting and photographing parts of the otolith material; Debra Driscoll (State University of New York) for her hospitality and guidance in the LA-ICP MS lab; Richard Telford (UiB) for providing statistical support; Kélig Mahé (IFREMER) for sharing part of their R code; Bence Paul and Joe Petrus (Elemental Scientific Lasers) for providing a free Iolite student license and technical support.
Funding
Open access funding provided by University of Bergen. Funding for this work was provided by the Research Council of Norway under the project number 301077 (HypOnFjordFish, UiB). Some of the samples were collected by the CoastRisk project (IMR) funded by the Research Council of Norway under project number 299554.
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FS and NDG designed the experiment, collected the samples, prepared and analysed the otoliths using the LA-ICP MS instrumentation in KL’s lab, and collected image data. FS performed data cleaning and processing, conducted the formal analysis and wrote the main text. KL helped with conceptualisation, provided the instrumentation and guidance for collecting trace element concentrations, and assisted with the interpretation of the results. AF and AGVS supervised the project and assisted with the interpretation of results. AGVS was responsible for project administration and funding acquisition. All authors reviewed the manuscript.
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Saltalamacchia, F., Gallo, N.D., Limburg, K. et al. Otolith shape and microchemistry reveal fine-scale population connectivity in the myctophid Benthosema glaciale (Reinhardt, 1837) along a complex seascape.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-46216-3
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DOI: https://doi.org/10.1038/s41598-026-46216-3
Keywords
- Coastal populations
- Fjord
- Lanternfish
- Mesopelagic
- Oceanographic connectivity
- Population structure
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