Researchers: Stevens, John, Dr (Point of contact, Author)
Brief description From April 2007 to June 2009, six field trips were undertaken to investigate the elasmobranch faunal composition of the Ningaloo Marine Park (NMP), determine the distribution and abundance of species, and examine the habitat utilisation, movement patterns and activity space of selected key species. Dive and longline surveys, passive acoustic telemetry and satellite tracking were used to collect data. Of interest to management, was whether existing sanctuary zones were effective for elasmobranchs as well as the location and timing of aggregation sites reported for some species.
Lineage Statement: SPECIES COMPOSITION *Lagoon and reef edge surveys* Snorkel and SCUBA underwater visual surveys were conducted as part of four field trips to Ningaloo in April and June 2007 and August and December 2008. The June and August surveys were restricted to the reef edge on SCUBA, while the April and December surveys were mainly on snorkel and in the lagoon. While the original intention was to provide coverage through the different seasons, poor weather conditions coincided with most of the planned fieldwork (including Cyclone Nicholas) resulting in re-scheduling of some trips. *Offshore surveys* Longline fishing was used to survey elasmobranchs outside the reef and was carried out from the Western Australia Fishery Department vessel RV ‘Naturaliste’. Longlines comprised 1 km of 12 mm diameter mainline with (usually) 50 hooks. Snoods were 8–10 m apart and each snood was 2 m long and had an 11/0 or 12/0 J hook baited with mullet. About 250 hooks were set per day, as between one and five separate lines. Lines were generally set for periods of between 2.4 h and 5.2 h (mean of 3.6 h) over the dawn period but 10 lines (set over 2 days) were set at dusk and retrieved at dawn the following day (mean soak time of 15.2 h). *Comparison with historic research data* The Western Australian Department of Fisheries has conducted longline research cruises with RV ‘Naturaliste’ throughout NMP and beyond since November 2001. *Data analysis* The number of shark sightings (dive surveys) and catch rates (longline surveys) were compared between sanctuary and non-sanctuary zones with a one-way Analysis of Variance (ANOVA). Further details are in the final report
Lineage Statement: SPATIAL DYNAMICS *Acoustics* Elasmobranchs were tagged with acoustic tags and subsequently monitored with acoustic receivers (Vemco VR2, VR2W and VR3) moored on the seabed that constitute the Ningaloo Reef Ecosystem Tracking Array (NRETA). This array is part of the nationwide network of marine acoustic monitoring, the Australian Acoustic Tagging and Monitoring System (AATAMS). A total of 96 acoustic receivers are deployed at Ningaloo Reef between Coral Bay and Tantabiddi. These are deployed as three curtains (Tantabiddi, Norwegian Bay, Coral Bay), three arrays (Mangrove Bay, Coral Bay, Stanley Pool), and three points of interest (Coral Bay). Arrays were deployed in November and December 2007, whereas curtains were deployed in February 2008. The Tantabiddi curtain comprises 7 receivers (10–96 m), the Norwegian Bay curtain 13 receivers (95–160 m) and the Coral Bay curtain 12 receivers (7–66 m). The array at Mangrove Bay consists of 50 receivers (1–47 m) and the Coral Bay array consists of 14 receivers (2–34 m). *Satellite tagging* Two types of platform transmitter terminals (PTTs) were used, Wildlife Computers (Redmond, USA) smart position or temperature transmitting tag (SPOT4 or SPOT5) and SPLASH tags. SPOT tags provide ARGOS locations together with water temperature reported as time-at- temperature histograms in user defined bins. SPLASH tags provide ARGOS locations together with depth and temperature reported as time-at-depth and temperature histograms in user defined bins. Depth is recorded down to 980 m (resolution = 0.5 m; accuracy +-1 m 0–100 m, 1% 100– 1000 m), temperature is measured from –40 degrees C to +60 degrees C, with a resolution of 0.2 degree C and accuracy +- 1 degree C. Tags were attached by two 5 mm diameter bolts which passed through the first dorsal fin and were secured on the other side by two washers and nuts. Tags were secured so that the antenna extended out of the water when the fin broke the surface. Transmissions were detected and processed by the ARGOS data collection and location system The accuracy of ARGOS position estimates is coded by location class (LC) 3, 2, 1, 0, A or B, with LC3 being the most reliable with a root mean square error of <150 m. The other numeric LC codes decline in reliability and can be within several kilometres of true (ARGOS, 2008). Sharks were caught by longline and, depending on size, either landed on deck for tag attachment or held in a sling at the stern of the vessel while the tag was attached. Further details are in final report
Notes
Credit
JD Stevens, PR Last, WT White (CSIRO Marine & Atmospheric Research, Hobart) RB McAuley (Department of Fisheries, Government of Western Australia, Perth) MG Meekan (Australian Institute of Marine Science, Perth)
Notes
Purpose
The main objectives of this project were to investigate the elasmobranch faunal composition of the Ningaloo Marine Park (NMP), determine the distribution and abundance of species, and examine the habitat utilisation, movement patterns and activity space of selected key species.
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