Influence of anticyclonic, warm-core eddies on mesopelagic fish assemblages in the Northwest Atlantic Ocean.

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Publisher: Elsevier B.V.
Document Type: Report; Brief article
Length: 372 words

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Keywords Mesopelagic fishes; Fish assemblages; Anticyclonic eddies; Warm-core eddies; Deep-scattering layer; Northwest Atlantic Highlights * Mesopelagic fish assemblages were investigated in relation to anticyclonic eddies. * Species richness and diversity was higher in sets occurring inside eddies. * 5 assemblages were identified and related to proximity to eddies. * Eddies harbored more juveniles and rare species, including more southerly species. Abstract Variability in mesopelagic fish assemblages of the deep-scattering layer were explored in relation to mesoscale anticyclonic (warm-core) eddies in the western North Atlantic Ocean. Exploratory fishing with a mid-water herring trawl was combined with oceanographic sampling aboard the RV Celtic Explorer in the Spring of 2015 and 2016 to characterize mesopelagic fish assemblages along transects through anticyclonic eddies identified using real time satellite-derived sea level anomaly. Sampling yielded a total of 6087 fish specimens, representing at least 109 species across 38 families. The families Myctophidae and Stomiidae were the most speciose taxa sampled and comprised 50% of total catch abundance in each year. Species richness and diversity (H') were significantly higher in sets occurring inside relative to outside the eddy structures. Community analyses indicate significant differences in daytime assemblage structure between both depth groups (shallow 200--400 m versus deep 400--700 m) and eddy groups (inside versus outside), with ordination discrimination of 5 pelagic fish assemblages related to eddy groups. Anticyclonic eddies also harbored more juveniles and rare species, including species with more southerly distributions within the Gulf Stream. Our results indicate anticyclonic eddies may play an important role in structuring fish assemblages and the dispersion of mesopelagic species in the Northwest Atlantic. Author Affiliation: (a) Centre for Fisheries Ecosystems Research, Fisheries and Marine Institute of Memorial University of Newfoundland, 155 Ridge Rd., St. John's, NL, A1C 5R3, Canada (b) Ryan Institute, Earth and Ocean Sciences, National University of Ireland, Galway, University Road, Galway, H91 TK33, Ireland (c) Population Ecology Division, Science Branch, Fisheries and Oceans Canada, PO Box 1006, Dartmouth, NS, B2Y 4A2, Canada * Corresponding author. Department of Integrative Biology, University of Windsor, 401 Sunset Ave, Windsor, ON, N9B 3P4, Canada. Article History: Received 30 June 2020; Revised 22 March 2021; Accepted 27 April 2021 Byline: Brynn Devine [bmdevine@uwindsor.ca] (a,*), Sheena Fennell (b), Daphne Themelis (c), Jonathan A.D. Fisher (a)

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Gale Document Number: GALE|A664259234