Population structure, habitat connectivity and migration patterns of Atlantic Mackerel (Scomber scombrus) in the North Atlantic using otolith chemical and shape analyses

• Main Author: Moura, Ana Catarina Rebelo Lopes de
• Publication Date: 2019
• Format: Master thesis
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10400.1/13387
• topic: Scombridae; Peixe pelágico; Marcadores naturais; Otólitos; Unidades pesqueiras

Atlantic Mackerel is a widely distributed fish species in the North Atlantic with two stocks, one in the North Eastern Atlantic (NEA) and other in the North Western Atlantic (NWA). Each stock is composed of different spawning components which present seasonal and spatial dynamics influenced by the environment. The knowledge on the structure of these stocks and its migration patterns are a challenge to scientists, since many environmental factors can influence this species dispersion. Information on fish stocks with economic importance, such as Scomber scombrus, is important in order to maintain a sustainable fishery. The use of natural tags, such as the chemical and shape signatures of otoliths have been proven to succeed in providing insights on fish populations and habitat connectivity. Here, six locations were analysed, with a total of 180 individuals, which were caught between January and February of 2018: the two spawning components from the NWA stock, the Canadian Northern Component and the US Southern Component; and the three spawning components from the NEA stock, namely the North Sea, Western and Southern Components, plus, an overlapping area, the Bay of Biscay. Both otolith’s chemical and shape signatures had high reclassification percentages in separating the two stocks and the components within each stock, especially when using both tools combined: 100% reclassification for the stocks and the components from the NWA stock, and 82% for the NEA stock components. The Bay of Biscay had a large overlap with the Southern and North Sea Components. Results revealed that these are good tools for population discrimination revealing grouping separation of the stocks and the components. These findings call for the necessity of further investigation and multidisciplinary approach on the assessment of this species and the necessity of revaluating the stocks management, primarily in the NWA stock.