Otolith microchemistry reveals the migration patterns of the flathead grey mullet Mugil cephalus (Pisces: Mugilidae) in Korean waters

Abstract

Background The flathead grey mullet Mugil cephalus has the widest distribution among mugilid species. Recent studies based on mitochondrial DNA sequences showed that the species comprises at least 14 different groups, three of which occur in the northwest Pacific. We analyzed the otolith microchemistry of M. cephalus at several locations in Korea to improve understanding of migration pattern and population origin. Results We collected 123 sagittal otoliths from seven locations and determined their concentrations of eight elements (7Li, 24Mg, 55Mn, 57Fe, 60Ni, 63Cu, 88Sr, and 138Ba) using laser ablation inductively coupled plasma mass spectrometry. Mean otolith elemental ratios differed significantly among the locations. The Sr:Ca, Fe:Ca, and Ba:Ca ratios were significantly higher than others, and useful chemical signatures for investigating the habitat use of M. cephalus populations. We identified five diverse and complicated migration patterns using the otolith data that we collected: estuarine resident (type I), freshwater migrant (type II), estuarine migrant (type III), seawater resident (type IV), and seawater migrant (type V). A canonical discriminant analysis plot revealed separation of two groups (type II in the Yellow Sea vs. other types in remaining locations). Two locations on Jeju Island, despite their close proximity, had fish with quite different migration patterns, corroborating previous molecular studies that distinguished two groups of fishes. Conclusion We successfully showed that the migration patterns of the Korean mullet varied by location. Only fish from the western sector of Jeju had a unique migration pattern, which is likely confined population in this area. Among the eight otolith elements measured, the Sr:Ca ratio was found to be the best indicator of migration pattern and population origin.

Spatiotemporal structure of narrow-barred Spanish mackerel (Scomberomorus commerson) from the Red Sea and western Indian Ocean based on otolith micro-chemistry

“…Otolith microchemistry has the power to discriminate among populations of fish with distinct spatial distributions over part or all of their life-history (Campana, 1999;Clarke et al, 2015;Elsdon et al, 2008;Panfili et al, 2018;Thresher, 1999). It has been widely used to assess migration strategies and the structure of fish populations (Bae and Kim, 2020;Sturrock et al, 2015;Tanner et al, 2016). In particular, studies have used otolith microchemistry to understand the stock structure of highly migratory tropical tuna populations in the Indian and Pacific Oceans (Artetxe-Arrate et al, 2019Rooker et al, 2016), suggesting that much can potentially be gained from applying this approach to other pelagic species, such as narrow-barred Spanish mackerel.…”

Otolith Microchemistry and Demographic History Provide New Insight into the Migratory Behavior and Heterogeneous Genetic Divergence of Coilia grayii in the Pearl River

“…Improved understanding of anadromous fish population dynamics requires identifying the ecologically different populations, the genetic structure, and a better knowledge of the life histories of individuals in coastal habitats [1,2]. It is difficult to predict the migratory patterns and population diversity of anadromous and estuarine fishes that are not well-resolved, because of variability in movement and great adaptability to the heterogeneous environments [3].…”