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Ontogenetic depth partitioning by juvenile freshwater sawfish (Pristis microdon: Pristidae) in a riverine environment

Whitty, J.M. and Morgan, D.L. and Peverell, S.C. and Thorburn, D.C. and Beatty, S.J. (2009) Ontogenetic depth partitioning by juvenile freshwater sawfish (Pristis microdon: Pristidae) in a riverine environment. Marine and Freshwater Research, 60 (4). pp. 306-316.

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Article Link(s): http://dx.doi.org/10.1071/MF08169

Publisher URL: http://www.publish.csiro.au/

Abstract

The freshwater sawfish (Pristis microdon) is a critically endangered elasmobranch. Ontogenetic changes in the habitat use of juvenile P. microdon were studied using acoustic tracking in the Fitzroy River, Western Australia. Habitat partitioning was significant between 0+ (2007 year class) and larger 1+ (2006 year class) P. microdon. Smaller 0+ fish generally occupied shallower water (<0.6 m) compared with 1+ individuals, which mainly occurred in depths >0.6 m. Significant differences in hourly depth use were also revealed. The depth that 1+ P. microdon occupied was significantly influenced by lunar phase with these animals utilising a shallower and narrower depth range during the full moon compared with the new moon. This was not observed in 0+ individuals. Habitat partitioning was likely to be related to predator avoidance, foraging behaviours, and temperature and/or light regimes. The occurrence of 1+ P. microdon in deeper water may also result from a need for greater depths in which to manoeuvre. The present study demonstrates the utility of acoustic telemetry in monitoring P. microdon in a riverine environment. These results demonstrate the need to consider the habitat requirements of different P. microdon cohorts in the strategic planning of natural resources and will aid in the development of management strategies for this species.

Item Type:Article
Additional Information:© CSIRO Publishing.
Keywords:External tagging; ontogeny; telemetry; behavioral thermoregulation; acoustic tracking; fishes.
Subjects:Aquaculture and Fisheries > Fisheries > Fishery for individual species
Aquaculture and Fisheries > Fisheries > By region or country
Deposited On:14 Jul 2009 05:50
Last Modified:07 Sep 2010 00:21

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