Movements and environmental preferences of the shortfin mako, <Emphasis Type="Italic">Isurus oxyrinchus</Emphasis>, in the southeastern Pacific Ocean |
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Authors: | Francisco J Abascal Manuel Quintans Ana Ramos-Cartelle Jaime Mejuto |
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Institution: | 1.Instituto Espa?ol de Oceanografía,Santa Cruz de Tenerife,Spain;2.Instituto Espa?ol de Oceanografía,A Coru?a,Spain |
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Abstract: | Nine individuals of shortfin mako, Isurus oxyrinchus, were tracked in the southeastern Pacific Ocean, off northern Chile, by means of pop-up satellite archival tags. No common
pattern was observed in their trajectories, apart from a movement onshore of all the fish tracked during June–August. The
average estimated rate of movement was of c. 27 km day−1. Data were collected and processed for a total of 341 days, including 33 days for one recaptured fish specimen, allowing
high-resolution archived data to be downloaded. The fish spent most of their time in the mixed layer but undertook dives down
to 888 m. Ambient temperatures ranged between 4.6 and 24.1°C, and the sea surface temperatures recorded ranged from 13.4 to
24.1°C during the study period. No clear diel pattern in depth behavior was observed, but mean vertical distribution was deeper
during the daytime. Moreover, a foraging pattern, consisting of rapid descents below the thermocline followed by slower ascents,
was generally observed during daylight hours. Dissolved oxygen concentration and water temperature seem to be the main factors
affecting the vertical range of the species in the area. This is the first study on electronic tagging of the shortfin mako
in the southeastern Pacific Ocean and covers the longest total tracking period reported so far for this species. |
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