Embed Size (px)
Citation preview
Simon Allen
Vanessa Jaiteh, Julian Tyne, Halina Kobryn, Lars Bejder and Neil Loneragan
Murdoch University Cetacean Research Unit Centre for Fish, Fisheries and AquaGc Ecosystems Research
School of Biological Sciences and Biotechnology School of Environmental Sciences Murdoch University, WA 6150
Incidental dolphin capture in a Western Australian trawl fishery: Bycatch reduc8on devices no silver bullet
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
PresentaGon outline: Background -‐ the fishery
-‐ the research Results -‐ spaGal and temporal extent of dolphin-‐fishery interacGons
-‐ underwater video records from within trawl nets Conclusions & RecommendaGons
The Pilbara Fish Trawl (Interim) Managed Fishery (‘PTF’) -‐ single, demersal o`er trawl; 3-‐4 full Gme vessels; 11 licenses -‐ 5-‐6000 trawls p.a.; trawls .5 to 3.5 hours; over ~13,000 km2
-‐ yields 2-‐3000 tons p.a. or ~75% of WA finfish
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Research background -‐ Bycatch in fisheries a global problem (Halpern et al. 2007; Read 2008) -‐ Protected species bycatch in PTF first quanGfied in 2002 (Stephenson & Chidlow 2003) -‐ Summary report for WA Dept. of Fisheries (Allen et al. 2007)
Research objecGves -‐ Examine spaGal, seasonal and daily data on fishing effort and dolphin interacGons from skipper logbooks and observer records (2003-‐2009); -‐ Evaluate net designs, bycatch reducGon devices and dolphin behaviour (Allen & Loneragan 2010)
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Research background -‐ Bycatch in fisheries a global problem (Halpern et al. 2007; Read 2008) -‐ Protected species bycatch in PTF first quanGfied in 2002 (Stephenson & Chidlow 2003) -‐ Summary report for WA Dept. of Fisheries (Allen et al. 2007)
Research objecGves -‐ Examine spaGal, seasonal and daily data on fishing effort and dolphin interacGons from skipper logbooks and observer records (2003-‐2009); -‐ Evaluate net designs, bycatch reducGon devices and dolphin behaviour (Allen & Loneragan 2010)
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
SpaGal and temporal extent of fishing effort and dolphin captures
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
SpaGal and temporal extent of fishing effort and dolphin captures
Skipper logbooks: n = ~30 000 trawls Observer records: n = ~5 000 trawls
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
SpaGal and temporal extent of fishing effort and dolphin captures
Management area Water depth Season (wet-‐dry)
No significant difference in dolphin capture rates:
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Dolphin capture rates varied significantly between trawlers: one vessel caught the highest proporGon of dolphins.
Dolphin capture rates varied significantly by Gme of day: lowest during the early morning period (00:00-‐05:59).
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Different net designs and bycatch reducGon devices
Dolphin capture rates varied significantly by net design: ~50% less dolphins being landed on deck aler the introducGon of BRDs.
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Dolphin capture rates varied significantly by net design: ~50% less dolphins being landed on deck aler the introducGon of BRDs.
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Dolphin deaths Nov 2003 -‐ Sep 2009 Skipper logbooks = 167 Observer records = 370
No Grid: Nov03-‐Feb06 10 933 1 064 Grid: Mar06-‐May08 10 785 2 141 Grid f’ward: Jun08-‐Sep09 5 097 521
Sample sizes:
BUT: -‐ Dolphins are interacGng with acGvely fishing nets almost all the Gme (<99%) -‐ Dolphins are highly moGvated to interact: foraging, play and socialising
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
BUT: -‐ Dolphins are interacGng with acGvely fishing nets almost all the Gme (<99%) -‐ Dolphins are highly moGvated to interact: foraging, play and socialising AND: -‐ U/W video of 44 trawls revealed the incidental capture 86 individuals from
19 species (dolphins, sharks, rays, turtles, sea snakes and pipefish) -‐ 3 dolphins interacted with BRDs; all 3 died; only 1 was landed on deck -‐ 34% of all bycatch either escaped or fell out the bo`om-‐opening escape hatch.
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
BUT: -‐ Dolphins are interacGng with acGvely fishing nets almost all the Gme (<99%) -‐ Dolphins are highly moGvated to interact: foraging, play and socialising AND: -‐ U/W video of 44 trawls revealed the incidental capture 86 individuals from
19 species (dolphins, sharks, rays, turtles, sea snakes and pipefish) -‐ 3 dolphins interacted with BRDs; all 3 died; only 1 was landed on deck -‐ 34% of all bycatch either escaped or fell out the bo`om-‐opening escape hatch.
Bycatch is under-‐reported.
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
Swan River 2009 Pilbara trawl fishery 2009
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
-‐ Difference in bycatch rates between vessels and T.O.D. perhaps a`ributable to skipper and dolphin behaviour, respecGvely?
-‐ Time/area closures (other than an overall reducGon in fishing effort) are unlikely to reduce dolphin bycatch
-‐ Dolphin bycatch might be reduced by deploying improved BRDs
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
a. Top-‐opening escape hatch trials
b. Intensive period of observer coverage and video deployment c. Dolphin populaGon study d. Detailed bycatch study e. Dolphin carcass retrieval
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
a. Top-‐opening escape hatch trials
b. Intensive period of observer coverage and video deployment c. Dolphin populaGon study d. Detailed bycatch study e. Dolphin carcass retrieval
…recommended in AMM 2008 and 2009 …published in FRDC report 2010 …agreement at AMM and SoFAR 2009-‐10
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
a. Top-‐opening escape hatch trials “Dolphins are captured by the Pilbara trawl fishery, but dolphin excluder devices have reduced this incidence to acceptable levels.” (SoFAR 2009-‐10)
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
a. Top-‐opening escape hatch trials “Dolphins are captured by the Pilbara trawl fishery, but dolphin excluder devices have reduced this incidence to acceptable levels.” (SoFAR 2009-‐10)
b. Intensive period of observer coverage and video deployment
0 5 10 15 20 25 30
2005-‐2006
2006-‐2007
2007-‐2008
2008-‐2009
2009-‐2010
2010-‐2011
% observer 22% lower limit
Observer reported dolphin bycatch = 1.6 to 3.7 Gmes higher than skipper logbooks. DoFWA set observer coverage @ ≥ 22% of fishing effort 2006-‐2007 onward. This level was never a`ained and fell each financial year. Low coverage + relaGvely infrequent dolphin capture = low power to detect change
(Allen & Loneragan 2010)
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
a. Top-‐opening escape hatch trials “Dolphins are captured by the Pilbara trawl fishery, but dolphin excluder devices have reduced this incidence to acceptable levels.” (SoFAR 2009-‐10)
b. Intensive period of observer coverage and video deployment
0 5 10 15 20 25 30
2005-‐2006
2006-‐2007
2007-‐2008
2008-‐2009
2009-‐2010
2010-‐2011
% observer 22% lower limit
Observer reported dolphin bycatch = 1.6 to 3.7 Gmes higher than skipper logbooks. DoFWA set observer coverage @ ≥ 22% of fishing effort 2006-‐2007 onward. This level was never a`ained and fell each financial year. Low coverage + relaGvely infrequent dolphin capture = low power to detect change
(Allen & Loneragan 2010)
48% lower limit (Pollock ‘10)
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
c. Dolphin populaGon study “Given the area of distribuGon and expected populaGon size of these protected species [dolphins and turtles], the impact of the fish trawl fishery on the stocks of these protected species is likely to be minimal.” (SoFAR 2009-‐10) d. Detailed bycatch study “Signathid, sawfish [criGcally endangered], and seasnake catches were all below their maximum levels and therefore their catch level is considered acceptable.” (SoFAR 2009-‐10)
Some of our definiGons of ‘minimal’ and ‘acceptable’ seem to vary between stakeholders.
-‐ Nickol Bay Professional Fishers AssociaGon Inc. -‐ Skippers and crew of the Pilbara trawl fishery
-‐ Observer program: Geoff Diver and Gavin Kewan
…Thank you.
Background 1 2 – Results 1 2 3 4 5 6 -‐ Conclusions -‐ RecommendaGons -‐ Acknowledgements
![[Incidental thyroid carcinoma: a multicentric experience]](https://img.pdfslide.net/doc/110x75/633bbd1a0d778cea7b08563a/incidental-thyroid-carcinoma-a-multicentric-experience.jpg)
