Movements in the harlequin fish (Othos dentex), a large predatory serranid from southern Australia: implications for detection and protection

Figures & data

Figure 1. Map showing: A, The study region within Australia; B, the Ironstone Hill study site on NE Kangaroo Island in relation to Gulf St Vincent and Backstairs Passage; C, the locations of the seven receivers adjacent to Ironstone Hill. The circles around each receiver indicate a 200 m detection radius.

Table 1. Summary of the 10 harlequin fish tagged within the receiver array.

Fish no.	Total length (mm)	Approx. wt (kg)	Release date	Last day detected	Total no. detections	Total no. days detected	Residence time (%)
1	410	1.0	7 June 2010	26 July 2011	5696	257	53.3
2	410	1.0	7 June 2010	10 July 2010*	1422	26	5.4
3	460	1.5	7 June 2010	5 October 2011	54,631	479	99.4
4	570	2.5	7 June 2010	5 October 2011	7422	421	87.3
5	410	1.0	7 June 2010	5 October 2011	75,185	481	99.8
6	580	2.5	10 June 2010	5 October 2011	7071	408	84.6
7	570	2.5	10 June 2010	5 October 2011	37,723	468	97.1
8	620	3.0	10 June 2010	5 October 2011	56,628	472	97.9
9	510	2.0	10 June 2010	5 October 2011	34,205	476	98.8
10	330	0.5	11 June 2010	15 June 2010	713	5	1.0

First and last days of detections were nominally 11 June 2010 and 5 October 2011, respectively.

Total number days detected is the number of days in which ≥1 detection occurred in a 24-h period.

Residence time is the total number days detected divided by the total number days available for detection (482 days).

*A single detection was later recorded on 31 December 2010.

Figure 2. Time series of all daily detections within the receiver array for each of the 10 harlequin fish from June 2010 to October 2011. The control transmitter was detected every day and is not plotted.

Figure 3. Receiver detections against time for the 10-day period between 8 July 2010 and 18 July 2010 for harlequin Fish 1 to 9 and the control transmitter.

Figure 4. Depth detections against time for the 10-day period between 8 July 2010 and 18 July 2010 for harlequin Fish 1 to 9.

Figure 5. Diel activity pattern for all fish combined: mean (±SE) control-corrected standardised detection frequency per hourly bin for harlequin Fish 1 to 9.

Figure 6. Depth utilisation by harlequin Fish 3, 5, 7, 8 and 9 during the day and night. Data are percentages of the total number of depth detections across 1 m depth classes for day (0900–1600 h) and night (2100–0400 h). Depth classes are 0–1 m (=1), 1–2 m (=2), etc. Note that the y axis range varies between fish. The black bar on the day graphs indicates the night modal depth.