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Passive acoustic telemetry reveals highly variable home range and movement patterns among unicornfish within a marine reserve

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posted on 2023-05-21, 09:18 authored by Alyssa MarshellAlyssa Marshell, Mills, JS, Rhodes, KL, McIlwain, J

Marine reserves are the primary management tool for Guam’s reef fish fishery. While a build-up of fish biomass has occurred inside reserve boundaries, it is unknown whether reserve size matches the scale of movement of target species. Using passive acoustic telemetry, we quantified movement patterns and home range size of two heavily exploited unicornfish Naso unicornis and Naso lituratus. Fifteen fish (N. unicornis: n = 7; N. lituratus: n = 4 male, n = 4 female) were fitted with internal acoustic tags and tracked continuously over four months within a remote acoustic receiver array located in a decade-old marine reserve. This approach provided robust estimates of unicornfish movement patterns and home range size. The mean home range of 3.2 ha for N. unicornis was almost ten times larger than that previously recorded from a three-week tracking study of the species in Hawaii. While N. lituratus were smaller in body size, their mean home range (6.8 ha) was over twice that of N. unicornis. Both species displayed strong site fidelity, particularly during nocturnal and crepuscular periods. Although there was some overlap, individual movement patterns and home range size were highly variable within species and between sexes. N. unicornis home range increased with body size, and only the three largest fish home ranges extended into the deeper outer reef slope beyond the shallow reef flat. Both Naso species favoured habitat dominated by corals. Some individuals made predictable daily crepuscular migrations between different locations or habitat types. There was no evidence of significant spillover from the marine reserve into adjacent fished areas. Strong site fidelity coupled with negligible spillover suggests that small-scale reserves, with natural habitat boundaries to emigration, are effective in protecting localized unicornfish populations.

History

Publication title

Coral Reefs

Volume

30

Pagination

631-642

ISSN

0722-4028

Department/School

Institute for Marine and Antarctic Studies

Publisher

Springer-Verlag

Place of publication

175 Fifth Ave, New York, USA, Ny, 10010

Rights statement

© 2011 Springer-Verlag.

Repository Status

  • Open

Socio-economic Objectives

Fisheries - recreational marine; Wild caught fin fish (excl. tuna); Assessment and management of benthic marine ecosystems

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