Embed Size (px)
Citation preview
At sea testing of The Popeye Fishbox bycatch reduction device onboard the FV Adelaide Pearl
for approval in Australia’s Northern Prawn Fishery
Erik Raudzens
Australian Fisheries Management Authority
i
Erik Raudzens At sea testing of The Popeye Fishbox bycatch reduction device onboard the FV Adelaide Pearl for approval in Australia’s Northern Prawn Fishery January 2007 AFMA 173 Northbourne Ave Civic ACT 2600 © Commonwealth of Australia 2007 This report should be cited as: Raudzens, E.E. (2007) At sea testing of The Popeye Fishbox bycatch reduction device onboard the FV Adelaide Pearl for approval in Australia’s Northern Prawn Fishery Australian Fisheries Management Authority, Canberra. This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth available from AusInfo. Requests and inquiries concerning reproduction and rights should be addressed to the Manager, Legislative Service, AusInfo, GPO Box 1920, Canberra ACT 2601. Published by the Australian Fisheries Management Authority STREET ADDRESS POSTAL ADDRESS ENQUIRIES 6th Floor Box 7051 Telephone:(02)6225 5555 173 Northbourne Ave Canberra BC Facsimlie: (02)62255500 Civic ACT 2600 ACT 2610
Acknowledgements The author and AFMA are appreciative of the many individuals and groups that provided advice and support for the following trial. Particular mention goes to:
• A. Raptis PTY LTD for their cooperation with the trial. • Mark Robson skipper of the FV Adelaide Pearl • The crew of the Adelaide Pearl (Jackie, Nick, Watto, and Suey) for their
patience in separating prawn catch during the trial • Robert ‘Popeye’ Bennett for his council
This project was funded by the National Heritage Trust through the Department of Agriculture Fisheries and Forestry (as part of Project No. 44144-National strategies to address marine wildlife bycatch issues in Australian fisheries).
ii
Executive Summary The Popeye Fishbox Bycatch Reduction Device (Popeye Fishbox BRD, hereafter) was assessed for approval in Australia’s Northern Prawn Fishery (NPF) against the NPF Bycatch Subcommittee’s performance requirements during October and November 2006. The assessment was undertaken over three weeks for a total of 82 trawls, with 54 trawls trialed with the BRD positioned at a distance of 70 meshes from the codend draw strings and a further 28 trawls trialed at 100 meshes. During the assessment twin trawl nets each containing the same standard Turtle Excluder Device (TEDs) were compared. One net contained the Popeye Fishbox BRD while the other net did not contain a BRD. All small bycatch (including sharks and rays) from both nets were separated and weighed in lug baskets. All prawn catch was also weighed separately to assess the effect on prawn catches. Tests with the BRD located at 70 meshes from the codend draw strings produced a 48% reduction in the weight of small bycatch, an 87% reduction in the number of seasnakes captured and a 35% reduction in the number of sharks and rays captured. Tests with the BRD located at 100 meshes from the codend draw strings produced a 28% reduction in the weight of small bycatch and 27% reduction in the number of sharks and rays captured. Differences in the catch of prawns between nets with and without the BRD were not statistically different. The Popeye Fishbox BRD has achieved the best results to date for BRDs trialed in the NPF making the implementation of the BRD in the NPF highly desirable. Testing of the BRD at different distances from the codend drawstrings during the trial (70 and 100 meshes) suggests that the location of the Popeye Fishbox BRD (and other BRDs) is an important factor in achieving improved bycatch reduction. Further testing of the BRD would be highly beneficial in defining bycatch reduction performance.
iii
Table of Contents
Acknowledgements .................................................................................................................i
Executive Summary ............................................................................................................... ii
Table of Contents .................................................................................................................. iii
List of Figures........................................................................................................................ iv
List of Tables ..........................................................................................................................v
Introduction.............................................................................................................................. 1
Background ........................................................................................................................... 1
Methods .................................................................................................................................... 2
Results...................................................................................................................................... 4
BRD located 70 meshes from codend drawstrings............................................................... 4
Shark and rays during the 70 meshes trial............................................................................ 9
Seasnakes........................................................................................................................... 12
BRD located 100 meshes from codend drawstrings........................................................... 13
Sharks and rays during 100 meshes trial............................................................................ 16
Banana prawn catches........................................................................................................ 19
Catch composition............................................................................................................... 20
Discussion.............................................................................................................................. 23
Conclusions/Recommendations.......................................................................................... 24
References ............................................................................................................................. 25
iv
List of Figures
Figure 1: Sketch of Popeye’s Fishbox BRD. Source QDPI. ........................................................... 2 Figure 2 a,b: Position of Popeyes’s Fishbox BRD during the trial. Source QDPI. ......................... 4 Figure 3: Total small bycatch (kg) by each trawl for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.................................... 5 Figure 4: Total prawn catch (kg) by each trawl for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.................................... 6 Figure 5: Mean total bycatch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF................................................................... 6 Figure 6: Mean total prawn catch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. ...................................................... 7 Figure 7: Mean total bycatch (kg + 95% C.I.) for dusk, early night, late night and dawn hauls for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF............................................................................................................................................ 8 Figure 8: Mean total prawn catch (kg + 95% C.I.) for dusk, early night, late night and dawn hauls for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. ..................................................................................................................... 8 Figure 9: Total count of all shark species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. .................................................... 10 Figure 10: Total count of all ray species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. .................................................... 10 Figure 11: Total count of all seasnake species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. ......................................... 12 Figure 12: Total small bycatch (kg) by each trawl for nets containing Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF. ................................. 14 Figure 13: Total prawn catch (kg) by each trawl for nets containing Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF. ...................................... 14 Figure 14: Mean total bycatch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF. ................................................................ 15 Figure 15: Mean total prawn catch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF. .......................................................... 15 Figure 16: Total count of all shark species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. .................................................... 17 Figure 17: Total count of all ray species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. .................................................... 17 Figure 18: Mean total bycatch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD whilst targeting banana prawns (9-16 Nov 2006).................................................................................... 19 Figure 19: Mean total prawn catch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD whilst targeting banana prawns (9-16 Nov 2006).................................................................................... 19
v
Figure 20: Proportion of demersal, pelagic and other fish species from nets containing in Popeye’s Fishbox and no BRD obtained from subsamples during the BRD trial (24 Oct-16 Nov 2006) conducted in the NPF. ................................................................................................. 20
List of Tables Table 1: Comparison of Popeye Fishbox bycatch and prawn catch during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. .................................................................................. 7 Table 2: Three way ANOVA of mean bycatch for Popeye’s Fishbox, No BRD and time of shot (dusk, early night, late night and dawn) during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. ..................................................................................................................... 8 Table 3: Three way ANOVA of mean prawn catch for Popeye’s Fishbox, No BRD and time of shot (dusk, early night, late night and dawn) during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. ..................................................................................................................... 9 Table 4: Comparison of shark catches for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. ......................................... 11 Table 5: Comparison of ray catches for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. .................................................... 12 Table 6: Comparison of seasnake catches for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. ......................................... 13 Table 7: Comparison of Popeye Fishbox bycatch and prawn catch during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF......................................................................................... 16 Table 8: Comparison of shark catches for nets containing Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF. ............................................... 18 Table 9: Comparison of ray catches for nets containing Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF. .......................................................... 18 Table 10: Comparison of Popeye Fishbox bycatch and prawn catch whilst targeting banana prawns during the BRD trial (24 Oct-16 Nov 2006) conducted in the NPF. .................................. 20 Table 11. Counts of small bycatch species/taxa from subsamples of shots 8, 14, 26 and 52 BRD trial (24 Oct-16 Nov 2006) conducted in the NPF. D = Demersal fish taxa; P = Pelagic/semi-pelagic fish taxa, O = Other or unclassifiable fish taxa. .............21
1
Introduction
Background The Northern Prawn Fishery (NPF), as a tropical penaeid trawl fishery, is categorised by its high biodiversity and bycatch volume. Over 400 fish species have been recorded in NPF bycatch, as well as 6 species of sea turtles, more than 12 species of seasnakes, over 50 species of sharks and rays and 234 invertebrate species (Stobutzki et al., 2001a & b). Historically, bycatch to catch ratios of prawn catches in subtropical trawl fisheries have been recorded to be in excess of 9 to 1 (e.g. for every 100 kg catch, 90 kg is discarded as bycatch) (Barratt et al., 2001). Such high bycatch volumes have led to prawn trawling being recognised as one of the least selective forms of commercial fishing (Alverson, 1994). The assessment of bycatch and demonstrating ecologically sustainable practice has been a focus of recent fisheries research and management (e.g. Stobutzki et al., 2001b, 2002, Hall and Mainprize, 2005). In recent years the NPF has become a national leader in addressing bycatch sustainability issues via management arrangements such as its Bycatch Action Plan (BAP) and its strong support for the development and funding of relevant research projects. Recent achievements have included a 99% reduction in turtle catches and the mandatory use of Turtle Excluder Devices (TEDs) and Bycatch Reduction Devices (BRDs) (Brewer et al., 2006). Despite such successes there has been increasing requirements for Australian fisheries to demonstrate ecologically sustainable development to maintain a high level of acceptance of their practices with national stakeholders and in the global marketplace. The NPF, under the management of the Australian Fisheries Management Authority (AFMA), is required to conform to legislative requirements including the Environmental Protection and Biodiversity Conservation (EPBC) Act 1999, and the Fisheries Management Act 1991. Such legislation requires all Commonwealth fisheries to have management practices in place that address long-term sustainability. In addition, the Federal Minister for Fisheries, Forestry and Conservation, has issued a formal direction to AFMA to take decisive action to ensure the sustainability of our fish stocks and to secure the Australian fishing industry’s future. In response to the Direction and in particular to bycatch issues AFMA has committed to halve bycatch in all Commonwealth fisheries by 2008. The introduction, and concurrent use, of TEDs and BRDs to reduce bycatch is a relatively new concept in fishing practice with the devices now compulsorily employed in the NPF for just over five years. Consequently there is an ongoing process of development in order to maximise bycatch exclusion and minimise prawn loss (Day, 2000). Whilst legally binding definitions of TEDs and BRDs have been developed and approved by NORMAC (Northern Prawn Fishery Management Advisory Committee), and NPF vessels must use devices that conform to these specifications, NORMAC provided scientific permits to operators wishing to trial new designs. This encourages NPF operators to develop new, innovative and effective TEDs and BRDs (Day, 2000). In order to gain approval for use, BRDs must meet the NPF Bycatch Subcommittees performance requirements which stipulate that BRDs must achieve a reduction in bycatch of 10% when compared to a net without a BRD over a trial period of two weeks. To date five BRD’s have gained approval in the NPF with reductions in bycatch varying from 10-25%. Previous studies have found the performance of BRDs
2
to be variable with studies suggesting factors such as the location of the BRD and the amount and type of bycatch encountered effecting results. The majority of studies have suggested that locating BRDs closer to the codend drawstrings would improve bycatch reductions. The Popeye Fishbox BRD was developed by Robert ‘Popeye’ Bennett. Mr Bennett has extensive experience in the NPF both as a commercial fisherman and as a net maker. This BRD has been previously field-trialed in the United States of America and Queensland Prawn Fisheries, by NOAA and QDPI, respectively. Results from the QDPI trial achieved a reduction in bycatch of 30% with insignificant loss of prawn catch whilst the BRD was located at 90 meshes from the codend drawstrings. The Popeye Fishbox BRD is a rigid framed BRD that has been designed to create a turbulent back-current of water flow with the net (Fig. 1). The creation of a turbulent back-current of water is thought to attract fish seeking to escape the net as they instinctively seek areas of low water flow. Once fish accumulate near the back-current they are able to escape through a rigid framed opening in the net.
Figure 1: Sketch of the Popeye Fishbox BRD. Source QDPI. The aim of this project was to trial the Popeye Fishbox BRD under the protocols of the NPF Bycatch Subcommittee performance assessment conditions in order to gain approval for usage in the NPF. The BRD was tested opportunistically at two different locations within the BRD to access potential changes in BRD performance. The BRD was also assessed for catch rates for all sharks, rays and Threatened Endangered and Protected (TEP) species.
Methods At sea testing of the Popeye Fishbox BRD was conducted onboard the FV Adelaide Pearl during the last three weeks of the 2006 NPF tiger prawn season (24 October to 15 November 2006). The trial was conducted during normal commercial operations for 21 consecutive nights with an average of 4 shots per night for a total of 82 shots observed during the trial. The majority of sampling was conducted in the north-western area of the Gulf of Carpentaria, generally in the region north of Groote Eylandt.
3
The performance of the the Popeye Fishbox BRD was assessed using the NPF Bycatch Subcommittee’s performance requirements. These requirements quantify the effectiveness of the BRD by comparing a net containing a BRD to a net lacking a BRD. Using the presence or absence of a BRD in the paired nets as the sole controlled variable, we can then assume that differences in bycatch between nets reflect the impact of the BRD. For this purpose paired nets were assessed simultaneously with both nets retaining Turtle Excluder Devices (TEDs) to ensure the study replicated normal commercial conditions. Bycatch and prawns from each net were separated by a dividing panel placed in the hopper allowing each net to be processed independently. The BRD was tested at two different positions during the trial; firstly with the BRD located 70 meshes from the codend drawstring (Fig. 2a) and secondly at 100 meshes from the codend drawstring (Fig. 2b). The first trial was conducted for a two week period while targeting tiger prawns and completing 54 shots as recommended by the protocols of the NPF Bycatch Subcommittee performance assessment. The second trial at 100 meshes was conducted opportunistically over a shorter period of 1 week, also targeting tiger prawns, and completing 30 shots. The BRD was swapped between port and starboard side nets once during each trial. Data for the two positions trialed were analysed separately for the purposes of this study. In addition six shots during the trial targeted banana prawns. As the study was intended to analyse the BRD performance during normal tiger prawn operations, data from these shots were treated separately due to the large volumes of catch experienced during banana prawn fishing biasing BRD performance. Both starboard and port nets used a headrope length of 14.86 metres, footrope length of 16.60 metres, with the headrope pulled up two links per side and the ground chains pulled up three links per side. Both nets had size eight Bison Boards and a drop chain height of 7 links. Trawl netting meshes were 2.5 inches (57 mm). The distance of BRD from the codend drawstrings during the 70 meshes was 3.99 metres and 5.70 metres during the 100 meshes trial. Shots that were suspected of being TEDed1, or had obvious tears were excluded from the assessment. Comparison of tiger prawn catches between nets was used as a measure of the possibility of a TEDing. If one net was substantially down in tiger prawn weight then this could represent a large animals (e.g. rays or sponges) having become stuck in the TED opening, leaving the flap ajar, and hence experiencing prawn and bycatch loss. This is a reliable measure of a TEDing as each trawl involves numerous runs over the same ground during a shot, consequently the randomness of spatial and temporal catch distribution should become relatively even between the nets over the period of the shot. All bycatch was weighed in lug baskets to the nearest kilogram with a 50kg spring scale. All sharks, rays and seasnakes were separated from the bycatch for identification and counting, with all shark species collectively weighed for each shot. Seasnakes were either measured onboard or photographed with a calibration scale for further measurement and identification. Prawn catch for each net was weighed separately by the crew to the nearest kilogram. Species composition of small bycatch was assessed from a random subsample of each net obtained by shovel until 1 A ‘TEDing’ refers to when a large organism, typically a ray, shark or turtle, becomes wedged in either the TED or the escape flap through which the TED directs these organisms. Under these circumstances the large organism can substantially block the flow of catch into the codend and redirect it through the escape flap resulting in significant loses of both catch and bycatch. A TEDing is identified by an unusually large difference in the volume between the two codends that can not be explained by other factors.
4
reaching a weight of 10 kg from bycatch spilt onto the hopper trays before being processed into the hopper. All species from subsamples were counted and photographed for further identification.
Figure 2 a,b: Position of the Popeye Fishbox BRD during the trial. Source QDPI. Comparisons of prawn and bycatch data for the four nightly shots were carried out using three-way factorial ANOVA contained in the STATISTICA™ package. Each shot was classified as dusk, early night, late night and dawn. Dusk shots were generally performed between 6.30pm and 9.30pm; early evening shots between 9.30pm and 1.30am; late evening between 1.30am and 5.30am and dawn shots between 5.30am and 8.30am. Catch data were log10(n+1) transformed, following the results of the Cochran’s Test for the homogeneity of variance. The Tukey-Kramer procedure was used to ascertain which variables were significantly different from each other. A two-way t-test was utilised to ascertain whether prawn catch between nets with or without the BRD were significantly different.
Results
BRD located 70 meshes from codend drawstrings A total of 54 shots were trialed with the BRD located at 70 meshes from the codend drawstrings with the data from an additional eight shots excluded from the assessment due to TEDing or operational errors. The amount of bycatch obtained per trawl during the trial ranged between 1,426 to 64 kg with a total of 30,654kg measured. The net containing no BRD accounted for 15,768 kg of bycatch with an average of 350.4 kg per shot whilst the net containing the Popeye Fishbox BRD
5
accounted of 7,563 kg of bycatch with an average of 168.1 kg per shot (Fig. 5, Table 1). This represented a reduction in the mean bycatch obtained in the Popeye Fishbox BRD of 48% (Table 1). Prawn catch during the 70 meshes trial ranged between 138.2 kg and 3kg (Fig. 4). Average prawn catch for the net with no BRD was 36 kg whilst average prawn catch per shot for the Popeye Fishbox BRD was 35.3 kg representing a reduction of 1.9% (Fig. 6, Table 1). The difference in prawn catch between the net with no BRD and the net containing the Popeye Fishbox BRD was not found to be significantly different (P = >0.05).
0
200
400
600
800
1000
1200
1400
1600
1 6 10 14 24 28 32 36 40 46 50 54
Shot Number
Tota
l byc
atch
(kg)
Popeye Fishbox
No BRD
Figure 3: Total small bycatch (kg) by each trawl for nets containing the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.
6
0
20
40
60
80
100
120
140
160
180
200
1 6 10 14 24 28 32 36 40 46 50 54
Shot Number
Tota
l pra
wn
catc
h (k
g)Popeye's f ishbox
No BRD
Figure 4: Total prawn catch (kg) by each trawl for nets containing the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.
350.4168.1
0
100
200
300
400
500
Popeye's fishbox No BRD
Mea
n by
catc
h (k
g)
Figure 5: Mean total bycatch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.
7
36.035.3
0
10
20
30
40
50
Popeye's fishbox No BRD
Mea
n pr
awn
catc
h (k
g)
Figure 6: Mean total prawn catch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. Table 1: Comparison of the Popeye Fishbox BRD bycatch and prawn catch during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. Total
(kg) Mean (kg)
Samples (n)
Standard distribution.
Standard error
95% C.I.
Mean reduction %
Fishbox bycatch 7563 168.1 45 112.2 16.7 33.7 -48.0
No BRD bycatch 15768 350.4 45 300.8 44.8 90.4
Fishbox prawn catch
1587 35.3 45 23.2 3.5 7.0 -1.9%
No BRD prawn catch
1618 36.0 45 28.0 4.2 8.4
Comparison of the four nightly shots was conducted during the 70 meshes trial. Each shot was classified as dusk, early night, late night and dawn. Dusk shots were generally performed between 6.30pm and 9.30pm; early evening shots between 9.30pm and 1.30am; late evening between 1.30am and 5.30am and dawn shots between 5.30am and 8.30am. Dawn shots had the highest average amount of bycatch for the net containing no BRD (593.2 kg, S.E. 142.2) and the greatest reduction in bycatch between the net with no BRD and the Popeye Fishbox BRD (65.8 %) (Fig. 7). Late night shots had the lowest average amount of bycatch for the net containing no BRD (218.8 kg, S.E. 43.7) and the lowest reduction in bycatch between the net with no BRD and the Popeye Fishbox BRD (32.1 %) (Fig. 7). Average bycatch weights were found to be significantly lower for the Popeye Fishbox BRD during all shots (Table 2). For nets containing no BRD average bycatch weights were found to be significantly higher during dawn shots (Table 2). The highest average prawn catches for nets with and without a BRD were obtained during early night shot (43.8 and 46.2 kg respectively) whilst the lowest average catch was obtained during dawn shots (17.3 and 15.5 kg) (Fig. 8). Differences in average prawn catch for nets with and without a BRD were not significantly different, irrespective of time although average prawn catch during dawn shots were significantly lower for nets with and without a BRD (Table. 3).
8
0100200300400500600700
Dusk Early night Late night Daw n
Mea
n by
catc
h (k
g)
Popeye'sfishbox
No BRD
Figure 7: Mean total bycatch catches (kg + 95% C.I.) for dusk, early night, late night and dawn hauls for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.
0
10
20
30
40
50
60
Dusk Early night Late night Daw n
Mea
n pr
awn
catc
h (k
g)
Popeye'sfishboxNo BRD
Figure 8: Mean total prawn catch (kg + 95% C.I.) for dusk, early night, late night and dawn hauls for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. Table 2: Three way ANOVA of mean bycatch for the Popeye Fishbox BRD, No BRD and time of shot (dusk, early night, late night and dawn) during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. Factors which were found to be dissimilar from each other for the Tukey-Kramer procedure are underlined. 1 represents dusk; 2 early evening; 3 late evening and 4 early morning. Factor SS Degrees
of freedom
MS F p Tukey
Popeye Fishbox BRD /No BRD
10.772 1 10.772 22.214 0.000010
Time 5.509 3 1.836 3.787 0.013359 1 2 3 4 Popeye Fishbox BRD /No BRD *Time
0.772 3 0.257 0.531 0.662523
Error 40.734 84 0.485
9
Table 3: Three way ANOVA of mean prawn catch for the Popeye Fishbox BRD, No BRD and time of shot (dusk, early night, late night and dawn) during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. Factors which were found to be dissimilar from each other for the Tukey-Kramer procedure are underlined. 1 represents dusk; 2 early evening; 3 late evening and 4 early morning. Factor SS Degrees
of freedom
MS F p Tukey
Popeye Fishbox BRD /No BRD
0.090 1 0.090 0.0256 0.873325
Time 82.854 3 27.618 7.8129 0.000119 1 2 3 4 Popeye Fishbox BRD /No BRD *Time
0.644 3 0.215 0.0608 0.980254
Error 289.863 82 3.535
Shark and rays during the 70 meshes trial During the 70 meshes trial 737 sharks representing 9 species were captured (Table 4). Nets containing no BRD captured 459 individual sharks for a total of 428.9 kg whilst nets containing the Popeye Fishbox BRD captured 278 sharks for a total 247 kg. This represented a reduction of 39.4 % in the number of individuals and 42.4 % reduction in total weight of shark species captured for the Popeye Fishbox BRD (Table 4). The average weight of individual sharks captured was 1.1 kg (Appn. B). The most common shark species captured were milk sharks, blacktip sharks and whitecheeked sharks with the Popeye Fishbox BRD achieving reductions in the capture of individuals of 25.5, 48.9 and 67.6 % respectively for these species (Fig. 9, Table 4). All individual shark specimens obtained during the trial were found dead once processed through the hopper system with the exception of gray carpet sharks of which 91 % of individuals obtained from nets with no BRD were alive and 100 % of those obtained from the Popeye Fishbox BRD were alive (Table 4). During the 70 meshes trial 764 rays representing 6 species were captured (Table 5). Nets containing no BRD captured 468 individual rays whilst nets containing the Popeye Fishbox BRD captured 298 rays representing a reduction of 36.8 % in the number of individuals captured for the Popeye Fishbox BRD (Table 5). The most common rays captured were blackspotted whiprays and Australian butterfly rays with the Popeye Fishbox BRD achieving reductions in the capture of individuals of 35.6 and 39.2 %, respectively for these species (Fig. 10, Table 5). The proportion of individuals obtained alive between nets containing no BRD and the Popeye Fishbox BRD were similar for most species (11-19%) with the exception of White spotted guitar sharks of which none were captured alive in the net with no BRD whilst 40% were obtained alive in the Popeye Fishbox BRD (Table 5). The only sawfish species captured during the trial were narrow sawfish with 5 individuals captured in the net with no BRD and 3 in the Popeye Fishbox BRD (Table 5).
10
0
50
100
150
200
250
300
Milk sh
ark
Blackti
p shark
Whitech
eeke
d sha
rk
Tawny
shark
Weasel
shark
Spot-ta
il sha
rk
Scallo
ped h
amerh
ead
Tiger s
hark
Leop
ard S
hark
Species
Tota
l cou
ntNo BRD
Popeye's f ishbox
Figure 9: Total count of all 9 shark species captured for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.
0
50
100
150
200
250
300
Blackspottedw hipray
Australianbutterf ly ray
Guitar shark Narrawsaw fish
Eagle ray Shovelnoseray
Species
Tota
l cou
nt
No BRD
Popeye's f ishbox
Figure 10: Total count of all 6 ray species captured for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.
11
Tabl
e 4:
Com
paris
on o
f sha
rk c
atch
es fo
r net
s co
ntai
ning
the
Pop
eye
Fish
box
BR
D a
nd n
o B
RD
dur
ing
the
70 m
esh
trial
(25
Oct
- 9
Nov
200
6) c
ondu
cted
in th
e N
PF.
Com
mon
nam
e
Spec
ies
nam
es
Cou
nt N
o B
RD
C
ount
B
RD
To
tal
wei
ght n
o B
RD
(kg)
Tota
l w
eigh
t B
RD
(kg)
% B
RD
ch
ange
co
unt
% B
RD
ch
ange
w
eigh
t
%
aliv
e no
B
RD
%
aliv
e B
RD
Milk
sha
rk
Rhi
zopr
iono
don
acut
us
247
184
179.
5 97
.8
-25.
5%
-45.
5%
0%
0%
Bla
cktip
sha
rk
Car
char
hinu
s til
ston
i 88
45
11
8.8
90.2
-4
8.9%
-2
4.1%
0%
0%
W
hite
chee
ked
shar
k C
arch
arhi
nus
duss
umie
ri 65
22
63
.6
20.1
-6
6.2%
-6
8.4%
0%
0%
Gre
y ca
rpet
sha
rk
Chi
losc
ylliu
m
punc
tatu
m
37
12
41.8
14
.9
-67.
6%
-64.
4%
91%
10
0%
Wea
sel s
hark
H
emig
aleu
s m
icro
stom
a 13
10
9
7.9
-23.
1%
-12.
2%
0%
0%
Spo
t-tai
l sha
rk
Car
char
hinu
s so
rrah
3
0 2.
3 0
NA
NA
0%
NA
Sca
llope
d ha
mer
head
S
phyr
na le
win
i 3
5 10
.2
16.1
66
.7%
57
.8%
0%
0%
Tige
r sha
rk
Gal
eoce
rdo
curv
ier
2 0
2.6
0 N
A N
A 0%
N
A Le
opar
d Sh
ark
Ste
gost
oma
fasc
iatu
m
1 0
1.1
0 N
A N
A 0%
N
A To
tals
10
(spe
cies
) 45
9 27
8 42
8.9
247
-39.
4%
-42.
4%
12
Table 5: Comparison of ray catches for nets containing the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.
Seasnakes A total of 40 seasnakes representing 6 species were captured during the 70 meshes trial. The net containing no BRD captured 35 seasnakes whilst the net containing the Popeye Fishbox BRD captured 5, representing an 87.5% reduction in the capture of seasnakes for the Popeye Fishbox BRD (Table 6). The elegant seasnake was the most common species captured during the trial with 16 and 4 individuals captured in the net with no BRD and the Popeye Fishbox BRD, respectively (Fig. 11). None of the four elegant seasnakes captured in the net containing the Popeye Fishbox BRD were alive as they were all trapped in the meshes of the codend.
02468
1012141618
Hydrophiselagans
Astrotiastokesii
Disteiramajor
Hydrophispacificus
Lapemishardwickii
Aipysuruseydouxii
Species
Cou
nt
No BRD
Popeye's fishbox
Figure 11: Total count of all 6 seasnake species captured for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.
Common name Species names Count No BRD
Count BRD
% BRD reduction count
% alive no BRD
% alive BRD
Blackspotted whipray
Himantura toshi 281 181 -35.6% 11% 19%
Australian butterfly ray
Gymnura australis 158 96 -39.2% 17% 18%
White spotted guitar shark
Rhynchobatus australiae
21 10 -52.4% 0% 42%
Narrow sawfish Anoxypristis cuspidata
5 3 -40.0% 25% 33%
Eagle ray Aebatus spp. 2 2 0.0% 0% 0% Shovelnose ray Rhinobatos typus 1 4 75.0% 0% 0% Totals 6 (species) 468 296 -36.8%
13
Table 6: Comparison of seasnake catches for nets containing the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. No BRD Common name Species Count Average
length % released alive
Elegant seasnake Hydrophis elagans
16 124.8 43%
Green banded seasnake
Lapemis hardwickii
2 198 50%
Olive headed seasnake
Disteira major 4 176.8 25%
Pacific seasnake Hydrophis pacificus
4 195.8 50%
Spine tailed seasnake Aipysurus eydouxii
1 76 100%
Stokes seasnake Astrotia stokesii 8 121 87.50% Totals 6 (species) 35 Popeye Fishbox BRD
Common name Species Count Average length
% released alive
Elegant seasnake Hydrophis elagans
4 111.8 0
Stokes seasnake Astrotia stokesii 1 128 100% Totals 2 (species) 5
BRD located 100 meshes from codend drawstrings A total of 28 shots were trialed with the BRD located at 100 meshes from the codend drawstrings with the data from 2 shots excluded from the assessment due to being TEDed or operational errors. The amount of bycatch obtained during the trial ranged between 891 and 54 kg with a total of 12,334 kg measured (Fig. 12). The net containing no BRD accounted for 7,202 kg of bycatch with an average of 276.9 kg per shot whilst the net containing the Popeye Fishbox BRD accounted of 5,132 kg of bycatch with an average of 197.4 kg per shot (Fig. 14). This represented a reduction in the mean bycatch obtained in the Popeye Fishbox BRD of 28.7% (Table 7). The average weight of bycatch during the 70 meshes trial was higher for nets with no BRD compared to results during the 100 meshes trial (350.4 kg compared to 276.9 kg) whilst nets containing the Popeye Fishbox BRD had higher levels of bycatch during the 100 meshes trial (168.1kg compared to 197.4 kg) (Figs. 3 and 11). Prawn catch during the 100 meshes trial ranged between 335 kg and 11kg (Fig. 13). Average prawn catch for the net with no BRD was 58.9 kg whilst mean prawn catch per shot for the Popeye Fishbox BRD was 60.3 kg representing an increase of prawn catch of 3.1% (Fig. 15, Table 7). The difference in prawn catch between the net with no BRD
14
and the net containing the Popeye Fishbox BRD was not found to be significant (P = >0.05).
0
200
400
600
800
1000
55 56 57 58 59 60 61 62 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82
Shot Number
Byca
tch
(kg)
No BRD
Fishbox
Figure 12: Total small bycatch (kg) by each trawl for nets containing the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.
0
100
200
300
400
55 56 57 58 59 60 61 62 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82
Shot number
Praw
n ca
tch
(kg)
No BRD
Fishbox
Figure 13: Total prawn catch (kg) by each trawl for nets containing the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.
15
197.4276.9
0
100
200
300
400
No BRD Fishbox
Mea
n by
catc
h (k
g)
Figure 14: Mean total bycatch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.
60.358.9
0
20
40
60
80
No BRD Fishbox
Mea
n pr
awn
catc
h (k
g)
Figure 15: Mean total prawn catch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.
16
Table 7: Comparison of the Popeye Fishbox BRD bycatch and prawn catch during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.
Sharks and rays during 100 meshes trial During the 100 meshes trial 476 sharks representing 7 species were captured (Table 8). Nets containing no BRD captured 264 individual sharks for a total of 220.8 kg whilst nets containing the Popeye Fishbox BRD captured 212 sharks for a total 136 kg. This represented a reduction of 19.7 % in the number of individuals and 38.4% reduction in total weight of shark species captured for the Popeye Fishbox BRD (Table 8). The average weight of individual sharks captured was 1.3 kg (Appn. B). The most common shark species captured were milk sharks, blacktip sharks and whitecheeked sharks with the Popeye Fishbox BRD achieving reductions in the capture of individuals of 16.3, 44.4 and 27.3 % respectively, for these species (Fig. 16, Table 8). All individual shark specimens caught during the trial were found dead once processed through the hopper system with the exception of weasel sharks of which 89% of individuals obtained from nets with no BRD were alive and 88% of those obtained from the Popeye Fishbox BRD were alive (Table 8). 385 rays representing 7 species were captured during the 100 meshes trial (Table 9). Nets containing no BRD captured 234 individual rays whilst nets containing the Popeye Fishbox BRD captured 151 rays representing a reduction of 35.1 % in the number of individuals specimens captured for the Popeye Fishbox BRD (Table 9). The most common rays captured were blackspotted whiprays and Australian butterfly rays with the Popeye Fishbox BRD achieving reductions in the capture of individuals of 33.9 and 35.4% respectively for these species (Fig. 17, Table 8). The proportion of individuals obtained alive between nets containing no BRD and the Popeye Fishbox BRD were similar for most species with the exception of white spotted guitar sharks of which 33% were captured alive in the net with no BRD whilst 88% were obtained alive in the Popeye Fishbox BRD (Table 8). The only sawfish species captured during the trial was narrow sawfish with one individual captured in the net with no BRD (Table 8).
Total (kg)
Mean (kg)
Samples (n)
Standard distribution
Standard error
95% C.I.
Mean change %
Fishbox bycatch 5132 197.4 26 116.5 22.8 46.9 -28.7%No BRD bycatch 7202 276.9 26 190.6 37.4 76.8 Fishbox prawn catch
1567 60.3 26 67.3 13.2 27.1 +3.1%
No BRD prawn catch
1532 58.4 26 66.4 13.0 26.8
17
0
50
100
150
200
M ilk shark Blacktipshark
Whitecheekedshark
Tawny shark Weasel shark Scallopedhamerhead
Spinner Shark
Species
Tota
l cou
nt
No BRD
Popeye's f ishbox
Figure 16: Total count of all 7 shark species captured for the Popeye Fishbox BRD and no BRD during the 100 meshes trial (25 Oct- 9 Nov 2006) conducted in the NPF.
020406080
100120140160180
Blackspotted ray
Australianbutterfly
ray
Guitarshark
Eagle ray BlueSpotted
Ray
Narrowsaw fish
Reticulatew hipray
Tota
l cou
nt
No BRD
Popeye's f ishbox
Figure 17: Total count of all 7 ray species captured for the Popeye Fishbox BRD and no BRD during the 100 meshes trial (25 Oct- 9 Nov 2006) conducted in the NPF.
18
Tabl
e 8:
Com
paris
on o
f sha
rk c
atch
es fo
r net
s co
ntai
ning
the
Pop
eye
Fish
box
BR
D a
nd n
o B
RD
dur
ing
the
100
mes
h tri
al (9
-16
Nov
20
06) c
ondu
cted
in th
e N
PF.
Tabl
e 9:
Com
paris
on o
f ray
cat
ches
for n
ets
cont
aini
ng th
e P
opey
e Fi
shbo
x B
RD
and
no
BR
D d
urin
g th
e 10
0 m
esh
trial
(9-1
6 N
ov
2006
) con
duct
ed in
the
NPF
. C
omm
on n
ame
Sp
ecie
s na
mes
C
ount
No
BR
D
Cou
nt B
RD
%
BR
D
chan
ge c
ount
%
aliv
e no
B
RD
%
aliv
e B
RD
Au
stra
lian
butte
rfly
ray
Gym
nura
aus
tralis
56
37
-3
3.9%
3%
0%
B
lack
spo
tted
ray
Him
antu
ra to
shi
164
106
-35.
4%
0%
0%
Blue
Spo
tted
Ray
D
asya
tis k
uhlii
2
0 -1
00.0
%
50%
N
A Ea
gle
ray
Aet
obat
us n
arin
ari
4 1
-75.
0%
0%
0%
Gui
tar s
hark
R
hync
hoba
tus
aust
ralia
e 6
7 14
.3%
33
%
88%
N
arro
w s
awfis
h An
oxyp
ristis
spp
. 1
0 -1
00.0
%
100%
0%
R
etic
ulat
e w
hipr
ay
Him
antu
ra u
arna
k 1
0 -1
00.0
%
0%
NA
Tota
ls
7 (s
peci
es)
234
151
-35.
5%
Com
mon
na
me
Sp
ecie
s na
mes
C
ount
N
o B
RD
Cou
nt
BR
D
Tota
l w
eigh
t no
BR
D
(kg)
Tota
l w
eigh
t B
RD
(k
g)
% B
RD
cha
nge
coun
t %
BR
D
chan
ge
wei
ght
% A
live
no
BR
D
% A
live
BR
D
Milk
sha
rk
Rhi
zopr
iono
don
acut
us
190
159
109.
1 77
.9
-16.
3%
-28.
6%
0%
NA
Bla
cktip
sha
rk
Car
char
hinu
s til
ston
i 9
5 20
.8
12.5
-4
4.4%
-3
9.9%
0%
N
A W
hite
chee
ked
shar
k C
arch
arhi
nus
duss
umie
ri 44
32
64
.2
30.4
-2
7.3%
-5
2.6%
0%
3%
Gre
y ca
rpet
sh
ark
Chi
losc
ylliu
m
punc
tatu
m
12
14
9.1
13.3
16
.7%
90
.0%
0%
0%
Wea
sel s
hark
H
emig
aleu
s m
icro
stom
a 1
2 0.
9 1.
9 50
.0%
-5
2.6%
89
%
88%
Sca
llope
d ha
mer
head
S
phyr
na le
win
i 7
0 14
.4
0 -1
00.0
%
-100
.0%
0%
0%
Spin
ner S
hark
C
arch
arhi
nus
brev
ipin
na
1 0
2.3
0 N
A N
A 0%
0%
Tota
ls
10 (s
peci
es)
264
212
220.
8 13
6 -1
9.7%
-3
8.4%
19
Banana prawn catches Banana prawn schools were targeted in 6 shots during the trial. Mean bycatch per shot for the net with no BRD was 556.5 kg whilst mean bycatch per shot for the Popeye Fishbox BRD was 263.2 kg representing a reduction of 52.7% (Fig. 18, Table 10). Mean prawn catch for the net with no BRD was 135.3 kg whilst mean prawn catch per shot for the Popeye Fishbox BRD was 112 kg representing a reduction of 17.2% (Fig. 19, Table 10).
0
200
400
600
800
No BRD Popeye's f ishbox
Mea
n by
catc
h (k
g)
Figure 18: Mean total bycatch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD whilst targeting banana prawns (9-16 Nov 2006).
0
50
100
150
200
No BRD Popeye's f ishbox
Mea
n pr
awn
catc
h (k
g)
Figure 19: Mean total prawn catch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD whilst targeting banana prawns (9-16 Nov 2006).
20
Table 10: Comparison of the Popeye Fishbox BRD bycatch and prawn catch whilst targeting banana prawns during the BRD trial (24 Oct-16 Nov 2006) conducted in the NPF. Total (kg) Mean
(kg) Samples (n)
S.D. S.E. 95% C.I.
Mean reduction %
Fishbox bycatch 1579 263.2 6 74.6 30.4 74.5 -52.7%No BRD bycatch 3339 556.5 6 347.2 141.7 346.8 Fishbox prawn catch
672 112.0 6 27.1 11.1 27.1 -17.2%
No BRD prawn catch
812 135.3 6 38.7 15.8 38.7
Catch composition Small bycatch composition was analysed for 4 shots during the trial. Fish species were categorised into three habitant preference groups namely demersal, pelagic and other (Table 11). The proportional composition of these groups for nets containing the Popeye Fishbox BRD was dominated by demersal species (57%) whilst demersal species accounted for 32% of the composition of nets without a BRD (Fig. 20, Table 11). The net without a BRD was dominated by pelagic species (51%) whilst pelagic species in the net containing the Popeye Fishbox BRD accounted for 20% of the composition (Fig.20, Table 11).
Figure 20: Proportion of demersal, pelagic and other fish species for nets containing the Popeye Fishbox BRD and no BRD obtained from subsamples during the BRD trial (24 Oct-16 Nov 2006) conducted in the NPF.
Popeye's fishbox
57%20%
23%
No BRD
32%
51%
17%Demersal
Pelagic
Other
21
Tabl
e 11
. Cou
nts
of s
mal
l byc
atch
spe
cies
/taxa
from
sub
sam
ples
of s
hots
8, 1
4, 2
6 an
d 52
BR
D tr
ial (
24 O
ct-1
6 N
ov 2
006)
co
nduc
ted
in th
e N
PF.
D =
Dem
ersa
l fis
h ta
xa; P
= P
elag
ic/s
emi-p
elag
ic fi
sh ta
xa, O
= O
ther
or u
ncla
ssifi
able
fish
taxa
.
Sh
ot 8
Sh
ot 1
4 Sh
ot 2
6 Sh
ot 5
2 To
tals
Fam
ily
Spec
ies/
taxa
C
omm
on n
ame
BRD
N
o BR
D
BRD
N
o BR
D
BRD
N
o BR
D
BRD
N
o BR
D
BRD
N
o BR
D
Cat
egor
y
Acro
pom
atid
ae
Syna
grop
s ph
illip
pine
nsis
Sh
arpt
ooth
sea
bass
0
1 0
01
00
01
1O
Ap
ogon
idae
Ap
ogon
alb
imac
ulos
us
Cre
amsp
otte
d ca
rdin
alfis
h 0
0 1
00
00
01
0O
Ap
ogon
idae
Ap
ogon
poe
cilo
pter
us
Pea
rlyfin
car
dina
lfish
0
0 0
10
01
01
1O
A
rrid
ae
Ariu
s ne
lla
Shie
ldhe
ad c
atfis
h 0
1 2
12
02
16
3D
Br
egm
acer
otid
aeBr
egm
acer
os m
ccle
lland
i U
nico
rn c
odle
t 2
0 1
22
02
17
3O
C
aran
gida
e Al
ectis
indi
ca
Dia
mon
d tre
vally
0
0 0
00
10
10
2P
Car
ango
ides
mal
abar
icus
M
alab
ar tr
eval
ly
00
23
03
03
29
P
C
aran
x ig
nobi
lis
Gia
nt tr
eval
ly
02
02
04
16
114
P
Meg
alas
pis
cord
yla
Finn
y sc
ad
00
01
01
00
02
O
Pa
rast
rom
ateu
s ni
ger
Bla
ck p
omfre
t 1
0 1
01
00
13
1P
C
entro
loph
idae
Ps
enop
sis
hum
eros
a B
lack
spot
but
terfi
sh
12
00
10
0
22
P
Cyn
oglo
ssid
ae
Cyn
oglo
ssid
sp.
To
ngue
sol
es
21
10
30
51
112
D
Dio
dont
idae
D
iodo
ntid
sp.
Po
rcup
inef
ishe
s 1
0 1
01
01
4
0D
E
ngra
ulid
ae
Engr
aulid
sp.
A
ncho
vy s
peci
es
13
14
12
12
411
P
Setip
inna
tenu
ifilis
H
airfi
n an
chov
y 0
0 0
00
10
00
1P
Ep
hipp
idae
R
hino
pren
es p
enta
nem
us
Thre
adfin
sca
t 0
0 1
01
01
03
0O
Zabi
dius
nov
emac
ulea
tus
Shor
tfin
batfi
sh
01
01
10
02
14
P Fi
stul
ariid
ae
Fist
ular
ia c
omm
erso
nii
Smoo
th fl
utem
outh
2
3 0
10
02
24
6O
H
aem
ulid
ae
Pom
adas
ys m
acul
atus
Bl
otch
ed J
avel
in
00
00
10
00
10
O
Leio
gnat
hida
e Le
iogn
athi
d sp
. D
olla
rfish
es
27
1221
38
215
1951
P Lu
tjani
dae
Lutja
nid
sp.
Uni
dend
entif
ied
Lutja
nids
0
3 1
00
00
01
3O
Lutja
nus
boha
r R
ed b
ass
11
00
00
00
11
O
Lu
tjanu
s ru
ssel
li M
oses
per
ch
00
02
00
01
03
O
Lu
tjanu
s se
bae
Red
em
pero
r 0
0 0
00
10
00
1O
M
onac
anth
idae
M
onac
anth
id s
pp
Leat
herja
cket
s
31
10
20
11
72
D
Mug
ulid
ae
Mug
ulid
sp.
M
ulle
ts
00
00
01
00
01
O
Mul
lidae
U
pene
us s
ulph
ureu
s
Sunr
ise
goat
fish
24
32
12
31
99
O
Nem
ipte
ridae
N
emip
teru
s he
xodo
n O
rnat
e th
read
fin b
ream
0
0 0
00
20
00
2O
O
phid
iidae
Si
rem
bo im
berb
is
Gol
den
cusk
0
2 2
11
12
15
5D
O
pist
ogna
thid
ae
Opi
stog
nath
us in
orna
tus
Jaw
fish
00
10
20
10
40
D
Par
alic
hthy
idae
Pa
ralic
hthy
id s
p.
San
d flo
unde
rs
10
00
30
40
80
D
Pla
tyce
phal
idae
C
ocie
lla h
utch
insi
Br
ownm
argi
n fla
thea
d 1
1 1
02
01
05
1D
Ineg
ocia
har
risii
Har
ris' f
lath
ead
00
10
10
10
30
D
22
Tabl
e 8.
Con
tinue
d
Sh
ot 8
Sh
ot 1
4 Sh
ot 2
6 Sh
ot 5
2 To
tals
Fam
ily
Spec
ies
Com
mon
nam
e BR
D
No
BRD
BR
D
No
BRD
BR
D
No
BRD
BR
D
No
BRD
BR
D
No
BRD
C
ateg
ory
Pleu
rone
ctid
ae
Pse
ttode
s er
umei
Q
ueen
slan
d ha
libut
3
4 1
12
12
08
6D
P
loto
sida
e E
uris
thm
us n
udic
eps
Nak
edhe
ad c
atfis
h 0
2 0
10
03
13
4D
Po
lyne
mid
ae
Poly
nem
id s
p.
Thre
adfin
sal
mon
s 0
1 0
10
11
01
3O
P
ristig
aste
ridae
P
ello
na d
itche
la
Ditc
hele
e 0
0 0
01
00
01
0O
S
ciae
nida
e
Atro
bucc
a br
evis
O
rang
e je
wfis
h 1
0 0
10
01
02
1O
John
ius
born
eens
is
Riv
er je
wfis
h 0
0 0
00
10
00
1O
John
ius
laev
is
Sm
ooth
jew
fish
30
00
10
00
40
O
Scom
brid
ae
Sco
mbe
rom
orus
co
mm
erso
ni
Span
ish
mac
kere
l 0
0 1
20
10
31
6P
S
com
bero
mor
us m
unro
i Sp
otte
d m
acke
rel
01
04
02
01
08
P Se
rran
idae
E
pine
phel
us s
exfa
scia
tus
Six
bar g
roup
er
00
01
00
01
02
O
Se
rran
id s
p.
Uni
dend
entif
ied
grou
per
00
10
00
00
10
O
Sphy
aeni
dae
Sph
yrae
na o
btus
ata
Strip
ed b
arra
cuda
0
0 0
10
00
10
2P
S
phyr
aena
put
nam
ae
Saw
toot
h ba
rrac
uda
00
00
01
00
01
P Sy
nodo
ntid
aer
Syno
dus
sp.
Saur
ies
24
28
26
38
926
D
Tera
pont
idae
Te
rapo
n th
erap
s La
rges
cale
gru
nter
0
0 0
01
00
01
0O
Te
traod
ontid
ae
Tetra
odon
tid s
p.
Toad
fishe
s 1
0 2
01
00
34
3D
Tr
iaca
nthi
dae
Trix
iphi
chth
ys w
eber
i B
lack
tip tr
ipod
fish
21
31
24
14
810
D
Tric
hiur
idae
Tr
ichi
urus
lept
urus
La
rgeh
ead
hairt
ail
10
02
12
00
24
P
Trig
lidae
Le
pido
trigl
a ru
ssel
li Sm
ooth
gun
ard
21
12
10
11
54
D
Portu
nida
e C
hary
bdis
cal
liana
ssa
Cor
nfla
ke c
rab
10
01
21
10
42
Po
rtuni
dae
Cha
rybd
is tr
unca
ta
Blu
nt-to
othe
d cr
ab
2
00
10
02
14
Po
rtuni
dae
Por
tunu
s sa
ngui
nole
ntus
Th
ree-
spot
ted
crab
1
0 2
00
20
13
3
Portu
nida
e Po
rtuni
d sp
. U
nide
ndifi
ed s
wim
min
g cr
abs
01
10
20
00
31
Squ
illida
e S
quilli
d sp
. M
antis
shr
imps
2
3 1
41
21
45
13
Enop
lote
uthi
dae
Enop
lote
uthi
d sp
. Sq
uids
1
3 0
01
21
13
6
Scy
llarid
ae
Scy
llarid
sp.
B
ugs
01
00
10
10
21
185
252
23
Discussion
The Popeye Fishbox BRD, having achieved a reduction in small bycatch of 48% when located at 70 meshes from the codend, has achieved the best results to date for BRDs trialed in the NPF. This result equates to a reduction of 8,205 kg in the amount of small bycatch excluded during the 14 day trial. If the same results were achieved throughout the entire tiger prawn season (106 days) on the same vessel approximately 62,000 kg of bycatch would be excluded. Extending this equation to the entire fleet (82 vessels during 2006) would achieve and approximate reduction in the amount of small bycatch of 5,084,000 kg.
In addition to the excellent small bycatch results the Popeye Fishbox BRD also achieved an 87.5% reduction in the number of seasnakes captured and a 38.1% reduction in the number of small sharks and rays captured. This combined with no significant change in prawn catch makes the implementation of the Popeye Fishbox BRD in the NPF highly desirable. The use of the Popeye Fishbox BRD would greatly enhance the Fishery’s ability to meet the Ministerial Direction on halving bycatch whilst having minimal economic and operational impacts. Opportunistic testing of the BRD at a distance further from the codend drawstrings during this trial (100 meshes) suggests that the location of the Popeye Fishbox BRD may be an important factor in achieving improved bycatch reduction. The reduced bycatch exclusion results during the 100 meshes trial may have been more prone to being affected by changes in environmental conditions or other operational issues due to the smaller sampling number. The bycatch reduction figures during this trial at 100 meshes were similar to those achieved during trials by QDPI conducted in north-eastern Queensland (tested at 90 meshes and achieving a 30% reduction). This would suggest that results achieved during this trial were not adversely affected by the reduced sampling period.
A 17% reduction in prawn catch whilst targeting banana prawns during the trial suggests the Popeye Fishbox BRD may not be suitable for usage during the banana prawn season. The author and crew members observed prawns and bycatch escaping from the BRD whilst nets were being retrieved. This was most likely due to nets filling past the location of the BRD and a backflow of water forcing catch through the BRD. Further research and possible testing for a device to prevent a backflow of prawns through the BRD whilst hauling to reduce escapement is recommended. Analyses of bycatch and prawn catch by time of shot were also undertaken during the trial. These analyses showed that morning shots (generally between 5.30 and 8.30am) had approximately twice the amount of bycatch and half the prawn catch for nets without a BRD. It is assumed that this was due to the migration of fish from mid-water to the seafloor during the early morning making them more susceptible to capture in trawl nets. Restricting prawn trawling to hours before sunrise (5.30-6.00am) may also achieve large reductions in the amount of bycatch. As prawn catch during morning shots was significantly lower, this may be beneficial to industry via savings in fuel and crew effort. In order to compensate industry for the reduced time available for fishing, season dates could be extended. Analyses of catch composition of small bycatch was only conducted on four shots during the trial. Despite the limitations of this data, it was found that the catch composition of small bycatch obtained in the Popeye Fishbox BRD had a higher proportion of demersal categorised fish species. This may be due to the poor swimming ability of demersal fish species preventing their
24
ability to swim at speeds faster than the trawl nets and therefore being unable to escape via the BRD. It may also be due to the behavioral response of these species when encountering trawl gear with some species tending to swim upwards in flight response, while others may swim laterally. Further research on the catch composition of the Popeye Fishbox BRD may benefit future design and positioning of the BRD.
Conclusions/Recommendations
From the performance of the Popeye Fishbox BRD during the observer trials, the author would encourage the NPF Bycatch Subcommittee to recommend that NORMAC include the Popeye Fishbox BRD as an approved BRD design.
Opportunistic testing of the BRD at a distance further from the codend drawstrings during this trial (100 meshes) suggests that the location of the Popeye Fishbox BRD is an important factor in achieving improved bycatch reduction. It is recommended that funding for additional research be sought by AFMA and industry. Further trials of the BRD to improve and analyse performance include:
o Testing at the Australian Maritime College Flume facilities to analyse and possibly improve water flow dynamics that may attract unwanted catch towards the BRD exit.
o Further at sea trials investigating BRD performance at different distances from the codend drawstings.
o Trials of backflow devices to prevent prawn escapement during large catches such as those encountered during the banana prawn season.
25
References
Alverson, D.L., Freeberg, M.H., Murawksi, S. A. and Pope, J.G. (1994) A global assessment of fisheries bycatch and discards. FAO Fisheries Technical Paper. 339, 1-233. Barratt, D., Garvey, J. and Chesson, J. (2001) Marine Disturbance in Parts of the Australian Exclusive Economic Zone. In: Australia: State of the Environment Second Technical Paper Series (Coasts and Oceans), Series 2. Department of the Environment and Heritage, 2001. Brewer, David, Don Heales, David Milton, Quinton Dell, Gary Fry, Bill Venables and Peter Jones. 2006. The impact of Turtle Excluder Devices and Bycatch Reduction Devices on diverse tropical marine communities in Australia’s Northern Prawn Trawl Fishery. Fisheries Research 81, 176-188 Day, G. (2000). At-sea testing and assessment of the John Thomas Bigeye Turtle Excluder Device as an approved TED for Australia’s Northern Prawn Fishery. Fishing Technology Unit, Australian Maritime College, Tasmania. Hall, S.J. and Mainprize, B.M. (2005). Managing by-catch and discards: how much progress are we making and how we can do better. Fish and Fisheries. 6, 134-155.
Stobutzki, I., Balber, S., Brewer, D., Fry, G., Heales, D., Miller, D., Miller, M., Milton, D., Salini, J., Van der Velde, T., Wassenberg, T., Jones, P., Wang, Y., Dredge, M., Courtney, T., Chilcott, K., and Eayrs, S. (2001a). Ecological sustainability of bycatch and biodiversity in prawn trawl fisheries. FRDC Project 96/257.
Stobutzki, I.C., Miller, M.J and Brewer, D.T.(2001b). Sustainability of fishery bycatch: a process for assessing highly diverse and numerous bycatch. Environmental Conservation. 28, 167-181. Stobutzki, I.C., Miller, M.J., Heales, D. S. and Brewer, D.T. (2002) Sustainability of elasmobranches caught as bycatch in a tropical prawn (shrimp) trawl fishery. Fisheries Bulletin. 100, 800-821.
