6 North West Slope Trawl Fishery

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					         chapTer 6

6 North West Slope Trawl Fishery
         a sampaklis, M rodgers, r Wood and e ansell

F i g u r e 6 .1 	 Relative	fishing	intensity	in	the	North	West	Slope	Trawl	Fishery	(NWSTF),	2005–2007

Ta b l e 6 .1 	     Status	of	the	fishery

 Fishery status                                2007                       2008            Comments
 Biological status                 Overfishing Overfished Overfishing Overfished
 Scampi	                                                                                  Preliminary	assessment	of	catch	per	unit	
 (Metanephrops australiensis,                                                             effort	trends	inconclusive.	No	estimates	
 M. boschmai, M. velutinus)                                                               of	biomass.
 Deepwater	prawns	(6	spp.)                                                                No	current	assessment	with	which	to	
                                                                                          compare	catch;	minimal	take	of	
                                                                                          deepwater	prawns	in	2007	and	2008.
 Economic status                     Net	economic	returns	not	available                   Gross	value	of	production	of	fishery	is	low.	
 Fishery	level

     Not ov erfished / Not sub jec t to ov erfishiNg         ov erfished / ov erfishiNg        u N c e r ta i N      Not assessed

88         Fishery status reports         2008
Ta b l e 6 . 2 	    Main	features	and	statistics	of	the	NWSTF

 Feature                           Description

 Target	species                    Australian	scampi	(Metanephrops australiensis)
                                   Boschma’s	scampi	(Metanephrops boschmai)
                                   Velvet	scampi	(Metanephrops velutinus)
                                   Red	prawn	(Aristaemorpha foliacea)
                                   Royal	red	prawn	(Haliporoides sibogae)
                                   Scarlet	prawn	(Plesiopenaeus edwardsianus)
                                   Striped	prawn	(Aristeus virillis)
                                   Red	carid	prawn	(Heterocarpus woodmasoni)
                                   White	carid	prawn	(Heterocarpus sibogae)
 Byproduct	species                 Goldband	snapper	(Pristipomoides multidens)
                                   Redspot	emperor	(Lethrinus lentjan)
                                   Saddletail	snapper	(Lutjanus malabaricus)
 Fishing	methods                   Demersal	trawl
 Primary	landing	ports             Darwin,	Port	Headland,	Broome
 Management	methods                Input	controls:	limited	entry	(7	permits),	gear	restrictions	(codend	mesh	size	≤50	mm)
 Management	plan                   AFMA statement of management arrangements 2004	(AFMA	2004)
 Harvest	strategy                  Western Trawl Fisheries Harvest Strategy—North West Slope Trawl Fishery (NWSTF) and
                                   Western Deepwater Trawl Fishery (WDTF)	(AFMA	2007)
                                   Species-specific,	multilevel	catch	thresholds	that	initiate	data	collection,	alternative	
                                   management	arrangements	and	catch	limits;	no	formal	reference	points	or	prescribed	control	
 Consultative	forums               Western	Trawl	Fisheries	Management	Advisory	Committee	(WestMAC)
 Main	markets                      Domestic:	Perth,	Sydney	and	Brisbane—fresh	and	frozen
                                   International:	United	States,	Spain,	China	and	Japan—frozen
 EPBC	Act	assessments:
 listed	species	(Part	13)          Current	accreditation	dated	28	September	2005
 international	movement	of	        Current	accreditation	(Wildlife	Trade	Operation)	dated	15	November	2007	and	varied	on	
 wildlife	specimens	(Part	13A)     30	March	2009;	expires	15	November	2010
 Ecological	risk	assessment        Level	1:	Scale	intensity	consequence	analysis	(SICA)	completed	on	157	species—
                                   Level	2:	Productivity	susceptibility	analysis	(PSA)	completed	on	7	species—unpublished
 Bycatch	workplans                 North West Slope Trawl Fishery Bycatch and Discarding Workplan (31 October 2008 –
                                   1 November 2010)	(AFMA	2008)

 Fishery statistics                2006–07                                       2007–08

 Fishing	season                    1	July	2006	–	30	June	2007                    1	July	2007	–	30	June	2008
 TAC	and	catch	by	species:         TAC         Catch                             TAC          Catch
 scampi                            None        Confidential	(<5	vessels)         None         Confidential	(<5	vessels)
 prawn                             None        Confidential	(<5	vessels)         None         Confidential	(<5	vessels)
 Effort                            3912	hours	of	trawling                        2022	hours	of	trawling
 Fishing	permits                   7                                             7
 Active	vessels                    4                                             3
 Observer	coverage                 Zero                                          53	trawl	hours	(2.6%)
 Real	gross	value	of	production	   Confidential	(<5	vessels)                     Confidential	(<5	vessels)
 (2007–08	dollars)
 Allocated	management	costs        $0.08	million                                 $0.11	million

AFMA	=	Australian	Fisheries	Management	Authority;	EPBC	Act	=	Environment	Protection	and	Biodiversity	Conservation	Act	1999;	
TAC	=	total	allowable	catch

                                                                  chapTer 6          North West Slope Trawl Fishery            89
6.1     background                                 Ta b l e 6 . 3 	   History	of	the	NWSTF	

The	North	West	Slope	Trawl	Fishery	                 Year              Description
(NWSTF)	operates	off	north-western	                 1987              Management	of	the	Western	Trawl	Fisheries	
Australia	from	114°E	to	about	125°E,	between	                         commenced	on	1	July	with	the	first	of	a	
                                                                      series	of	annual	development	plans.
the	200	m	isobath	and	the	outer	boundary	of	
                                                    1987	to	1999      Fishing	effort	peaked	at	18	600	trawl	hours.
the	Australian	Fishing	Zone,	taking	into	
account	Australian–Indonesian	maritime	             1990s             In	the	early	1990s,	catch	was	comprised	
                                                                      largely	of	deepwater	prawns	(mainly	royal	
boundaries	(MOU	box,	Fig.	6.1).	The	NWSTF	                            red	prawns),	with	squid	(mostly	Hawaiian	
has	traditionally	targeted	scampi	and	                                flying	squid,	Nototodarus hawaiiensis)	an	
                                                                      important	byproduct.
deepwater	prawns.	More	recently,	there	has	
been	a	shift	towards	targeting	of	scampi	           1985	to	1992      Substantial	decline	in	scampi	and	prawn	
                                                                      catch	rates.
because	of	less	profitable	markets	for	
                                                    1996              Limited	entry	enforced	through	the	issue	
deepwater	prawns;	more	than	97%	of	the	                               of	seven	fishing	permits.
tonnage	caught	in	the	fishery	in	2005–06	
                                                    1998              Recovery	of	scampi	stocks	confirmed	
was	scampi.	However,	targeted	fishing	for	                            through	stock	assessment.
finfish	in	2006–07	and	2007–08	saw	a	               2004              AFMA	Statement	of	Management	
reduction	in	the	proportion	of	scampi	taken	                          Arrangements	commenced	in	lieu	of	a	
to	33%	and	19%,	respectively,	of	the	total	                           management	plan.

catch.	The	advent	of	the	area	closure	in	the	       2005              Preliminary	stock	assessment	(small	sample	
                                                                      size)	indicated	declines	in	scampi	stocks.
north	of	the	fishery	is	likely	to	reduce	
targeted	finfish	catch	and	see	a	return	to	a	       2007              Harvest	strategy	for	the	fishery	adopted	by	
                                                                      AFMA.	AFMA	issued	a	direction	that	
scampi-dominated	fishery	in	2009.	The	                                precluded	fishing	from	areas	in	the	north-
NWSTF	is	the	source	of	approximately	69%	                             east	of	the	fishery	for	2	years	while	OCS	
                                                                      boundaries	were	amended.
of	Australia’s	scampi	production.
    Offshore	Constitutional	Settlement	(OCS)	      AFMA	=	Australian	Fisheries	Management	Authority;	
                                                   OCS	=	Offshore	Constitutional	Settlement
arrangements	between	the	Commonwealth	and	
Western	Australian	governments	determine	
management	jurisdictions.	Under	the	terms	of	
the	OCS,	the	Commonwealth	via	the	                 6.2        h a r v e s T s T r aT e g y
Australian	Fisheries	Management	Authority	
                                                   A	combined	Western	Trawl	Fisheries	harvest	
(AFMA)	has	management	responsibility	for	all	
                                                   strategy	(HS),	which	applies	to	the	NWSTF	
marine	species	taken	by	trawl	in	waters	deeper	
                                                   and	the	Western	Deepwater	Trawl	Fishery,	
than	200	m,	while	the	Western	Australian	
                                                   reflects	the	mixed-species	composition	and	
Government	via	the	Department	of	Fisheries	
                                                   opportunistic	nature	of	the	two	fisheries.	The	
has	responsibility	for	species	taken	with	non-
                                                   HS	acknowledges	that	there	is	no	target	
trawl	methods	in	these	waters	(except	tunas)	
                                                   reference	points	in	terms	of	maximum	
and	for	all	trawling	in	inshore	waters.	The	OCS	
                                                   economic	yield	(MEY).	It	aims	to	strike	a	
arrangements	are	currently	under	review.
                                                   balance	between	precautionary	management	
    The	Western	Trawl	Fisheries	Statement	of	
                                                   arrangements	and	allowing	industry	to	
Management	Arrangements	2004	(AFMA	
                                                   capitalise	on	fishing	opportunities,	while	
2004)	aligns	fishing	seasons	with	financial	
                                                   emphasising	the	need	to	collect	biological	
years,	and	specifies	a	maximum	of	seven	
fishing	permits,	each	valid	for	five	years.	
                                                       There	are	three	catch	trigger	rules	that	
Different	vessels	may	fish	on	the	same	permit,	
                                                   initiate	management	actions	that	progressively	
provided	that	only	one	vessel	is	fishing	at	any	
                                                   increase	data	and	analysis	requirements	on	the	
time.	Fishery	data	and	research	activities	are	
                                                   fisheries	(Levels	1	and	2)	and	establish	a	limit	
currently	insufficient	to	provide	accurate	
                                                   reference	point	(Level	3).	Separate	triggers	and	
estimates	of	sustainable	yields	for	the	fishery.
                                                   control	rules	apply	to	vulnerable	species	

90      Fishery status reports   2008
identified	through	the	ecological	risk	               6.3      The 2008 Fishery
assessment	(ERA)	process;	the	ERA	results	
                                                      Three	vessels	were	active	in	the	fishery	in	
have	not	yet	been	published	by	AFMA.
                                                      2007–08.	As	a	result,	catch	and	effort	data	
    The	HS	prescribes	species-specific	
                                                      cannot	be	reported	for	confidentiality	reasons.	
multilevel	catch	thresholds	that	initiate	
                                                      Fishing	effort	in	2007–08	was	approximately	
alternative	management	arrangements—for	
                                                      2000	hours,	which	is	about	half	of	the	
example,	catch	limits	or	spatial	closures.	
                                                      2006–07	effort	and	much	less	than	the	peak	of	
No	reference	points	are	set	owing	to	the	
                                                      18	600	hours	in	1987–88.	Vessels	operate	
opportunistic	nature	and	variable	catch	
                                                      sporadically	in	the	NWSTF	because	they	also	
composition	of	the	Western	Trawl	Fisheries.	
                                                      work	in	the	adjacent	Northern	Prawn	Fishery	
In	the	absence	of	other	information	or	
assessments,	the	triggers	for	target	species	are	
                                                          The	exit	of	vessels	from	the	NPF	through	
based	on	the	highest	historical	catch.	Level	1	
                                                      the	2006	structural	adjustment	package	(see	
is	half	the	high	historical	catch,	Level	2	is	the	
                                                      Chapter	5),	lower	fuel	prices	at	the	start	of	the	
highest	historical	catch	and	Level	3	is	double	
                                                      2006–07	financial	year	and	high	market	prices	
the	highest	historical	catch.	In	the	case	of	the	
                                                      for	scampi	were	expected	to	make	fishing	a	
NWSTF,	the	zone-specific	trigger	levels	(based	
                                                      more	attractive	proposition	in	the	NWSTF.	
on	relative	historical	catch)	may	in	future	be	
                                                      This	has	not	been	reflected	in	effort	in	recent	
applied	across	three	longitudinal	areas.
                                                      years.	During	2006–07	and	2007–08	there	was	
    The	Level	1	trigger	initiates	an	
                                                      targeting	of	finfish;	however,	catches	of	finfish	
investigation	to	reveal	why	the	trigger	has	been	
                                                      are	expected	to	decrease	with	the	closure	of	an	
reached.	This	is	undertaken	through	analysis	of	
                                                      area	in	the	north-east	of	the	fishery	in	late	2007	
logbooks	and	examination	of	standardised	
                                                      (Fig.	6.1).
catch	per	unit	effort	(CPUE)	data.	It	may	also	
result	in	expert	consultation	and	a	possible	
revision	of	limit	reference	points.	The	Level	2	      scampi
trigger	results	in	stock	assessments	using	           The	scampi	catch	was	down	in	2007–08	
biological	parameters,	such	as	size-specific	         relative	to	recent	catches	due	to	increased	
fishing	mortality,	natural	mortality,	growth	and	     targeting	of	other	species	such	as	goldband	
reproduction.	A	revision	of	trigger	values	is	        snapper	and	redspot	emperor.	Effort	in	the	
also	undertaken.	Exceeding	the	Level	3	trigger	       NWSTF	remained	low.
results	in	a	cessation	of	fishing	effort,	pending	
a	stock	assessment	and	expert	consultation.
                                                      deepwater prawn
The	trigger	values	for	target	species	in	the	
NWSTF	are:                                            Annual	prawn	catches	for	2003–04	to	
                                                      2006–07	have	been	less	than	1	t	and	appear	to	
•	 Level	1:	scampi	50	t,	prawns	9	t
                                                      be	a	byproduct	of	targeting	scampi.	The	
•	 Level	2:	scampi	100	t,	prawns	18	t
                                                      2007–08	prawn	catch,	while	low,	was	
•	 Level	3:	scampi	200	t,	prawns	36	t.
                                                      substantially	higher	than	in	the	previous	
The	HS	also	specifies	control	rules	for	species	      four	years,	indicating	some	level	of	targeted	
identified	as	high	risk	under	the	ERA	                effort	(the	catch	remained	below	the	HS	Level	
framework.	The	measures	include	50	animal	            1	trigger).
move-on	provisions	for	high-risk	
chondrichthyans.	High-risk	teleosts	and	
crustaceans	have	two	trigger	levels:	an	
intermediate	2	t	trigger	(in	effect	initiating	the	
same	management	responses	as	the	Level	1	
trigger	for	target	species)	and	a	4	t	catch	limit	
(Level	2).

                                                      chapTer 6     North West Slope Trawl Fishery    91
                                                                                                                   Catch: scampi, NWS

6.4        b i o l o g i c a l s TaT u s
                                                                                                 *   Confidential data

scaMPi                                                                                    0.20

                                                                Catch (thousand tonnes)



                                                                                                                * * * * *                              * *
                                                                                                 1987−88    1991−92      1995−96   1999−00   2003−04   2007−08

                                                               F i g u r e 6 . 2 	 Scampi	catch	history,	1985–86	to	
                                                               SO U RCE :	Rainer	(1992).
Ta b l e 6 . 4 	   Biology	of	scampi	

 Parameter            Description                              previous assessment
 General              Scampi	aggregate	along	muddy	
                      bottoms	of	continental	slopes	and	
                                                               The	2005	assessment	(Lynch	&	Garvey	2005)	
                      build	extensive	burrows.	They	are	       was	based	on	changes	in	length–frequency	in	
                      relatively	slow	growing	and	long	        the	commercial	catch	and	compared	data	
                      lived,	with	moderately	low	fecundity
                                                               collected	from	1986	to	1988	with	data	
 Range                Distributed	along	continental	slopes.	
                      In	Australia,	scampi	occur	on	the	
                                                               collected	in	2004.	No	substantial	change	in	
                      north-west	slope	in	Western	Australia	   size	range	of	scampi	was	observed.	This	
                      up	into	the	Timor	Sea                    contrasts	with	commercial	logbook	data	
 Depth                250–500	m                                collected	in	1992,	which	showed	that	the	
 Longevity            10–12	years                              average	size	of	Australian	scampi	had	declined	
 Age	at	maturity      3–5	years                                since	the	fishery	began,	and	anecdotal	
 Spawning	season      Timing	of	spawning	unknown,	though	
                                                               evidence	from	industry	suggesting	a	reduction	
                      likely	to	spawn	annually                 in	size.	The	2005	assessment	also	showed	an	
 Size                 Maximum:	~75	mm	CL.                      overall	decline	in	CPUE	from	1985	to	2003.
                      Recruitment	into	fishery	at	~50	mm	CL
                                                               2008 update
                                                               No	assessment	was	conducted	in	2008.	Fishing	
                                                               effort	in	2007–08	was	approximately	one-third	
                                                               of	that	in	2006–07,	with	correspondingly	
                                                               lower	catches	(Fig.	6.2).	Catch	rates	were	
                                                               slightly	lower	than	in	2006–07;	consequently,	
                                                               the	overfishing	status	for	scampi	remains	
                                                               uncertain.	There	are	no	biomass	estimates	for	
                                                               the	stock,	and	it	is	uncertain	if	scampi	is	

92         Fishery status reports   2008
                                                                                                                Catch: deepwater prawns, NWS

reliability of the assessment
                                                                                                    *   Confidential data
The	2005	assessment	used	a	small	amount	of	
commercial	data	for	length–frequency	                                                         1.0
analyses.	It	provided	a	preliminary	assessment	

                                                                    Catch (thousand tonnes)
of	CPUE	trends	for	the	fishery	but	was	not	                                                   0.8

robust	enough	to	provide	a	reliable	assessment	
of	stock	status.                                                                              0.6

Future assessment needs
Future	assessments	would	benefit	from	               0.2

improved	data	on	biological	parameters,	                               * * * * *                     * *
fishery-independent	data,	standardisation	of	               1987−88 1991−92 1995−96 1999−00 2003−04 2007−08
CPUE	trends	and	investigation	of	the	spatial	
characteristics	of	scampi	catch	and	effort.	A	  F i g u r e 6 . 3 	 Deepwater	prawn	catch	history,	1985–86	
stock	assessment	of	scampi	has	been	identified	 to	2007–08
as	a	priority	for	the	NWSTF	by	the	Western	
Trawl	Fisheries	Management	Advisory	
Committee	(WestMAC).                            previous stock assessments
                                                Deepwater	prawn	stocks	in	the	NWSTF	have	
                                                not	previously	been	assessed.
deePWater PraWNs
Ta b l e 6 . 5 	    Biology	of	deepwater	prawns                     2008 update

 Parameter                Description
                                                                    No	assessment	was	conducted	in	2008.	It	is	
                                                                    uncertain	if	deepwater	prawn	stocks	are	
 General                  Deepwater	prawn	species	vary	in	          overfished,	despite	low	catch	levels	(Fig.	6.3).	
                          their	life	history	traits,	but	all	are	
                          found	on	sandy	and/or	muddy	              However,	as	the	level	of	targeted	effort	has	
                          bottoms,	making	them	susceptible	         remained	low,	they	are	considered	not	to	be	
                          to	trawl.	They	are	relatively	short	      subject	to	overfishing.
                          lived,	with	low	productivity	
                          compared	with	their	inshore	
                          relatives.	Very	little	is	known	          Future assessment needs
                          about	their	biology
                                                                    Should	targeted	fishing	recommence,	
 Range                    Coastal	waters	worldwide.	In	
                          Australia,	they	are	distributed	          biological	information	for	different	species	
                          along	the	north-west,	west	and	           will	need	to	be	collected	before	the	stocks	can	
                          east coasts                               be	assessed.
 Depth                    250–800	m
 Longevity                ~5	years
                                                                    bYProduct sPecies
 Age	at	maturity          ~1	year
                                                                    Stocks	of	finfish	(goldband	snapper,	redspot	
 Spawning	season          Royal	red	prawn	is	known	to	
                          spawn	biannually	off	New	South	           emperor	and	saddletail	snapper)	in	the	
                          Wales	in	February–April	and	              NWSTF	have	not	been	assessed.	An	
                          July–August                               assessment	of	goldband	snapper	and	redspot	
 Size                     Maximum:	38–62	mm	CL.                     emperor	in	2002	using	an	age-structured	stock	
                          Recruitment	into	fishery:	1–4	            assessment	model	in	the	Western	Australian	
                          years	of	age
                                                                    Northern	Demersal	Scalefish	Managed	
S OU R C E S :	Rainer	(1992),	Baelde	(1994).
                                                                    Fishery,	adjacent	to	the	NWSTF,	indicated	that	
                                                                    breeding	stock	levels	of	tropical	snappers	were	
                                                                    adequate;	effort	levels	in	2006	were	considered	
                                                                    to	be	not	acceptable	(Newman	&	Skepper	

                                                                    chapTer 6                               North West Slope Trawl Fishery     93
2007).	In	order	to	reduce	fishing	pressure	on	     future considerations
tropical	snapper	stocks,	AFMA	implemented	a	
partial	closure	in	the	north-east	of	the	NWSTF	    The	relationship	between	the	NPF	and	the	
in	depths	less	than	200	m.	An	assessment	of	       NWSTF	is	an	important	consideration	for	
the	extent	and	variety	of	byproduct	(notably	      management.	Given	the	reduction	in	the	
finfish)	is	among	the	most	pressing	research	      number	of	vessels	operating	in	the	NPF,	there	
needs	for	the	NWSTF,	together	with	the	            is	a	chance	that	operators	will	increase	effort	
collection	of	biological	data	for	assessment	      in	the	NWSTF,	but	this	will	be	influenced	by	
purposes.                                          available	labour	and	operating	costs.
                                                       The	fishery	is	currently	managed	using	
                                                   input	controls,	primarily	in	the	form	of	limited	
                                                   entry.	After	reviewing	the	potential	to	
6.5     e c o n o m i c s TaT u s                  implement	individual	transferable	quotas	
                                                   (ITQs)	in	the	fishery	in	2006,	WestMAC	
                                                   concluded	that	these	quotas	do	not	appear	to	be	
economic performance
                                                   a	viable	option	for	the	fishery	at	this	time	and	
No	economic	surveys	of	the	fishery	have	been	      that	the	fishery	should	continue	to	be	managed	
conducted.	Catch	is	confidential	for	2006–07	      using	input	controls	(WestMAC	2006).	The	
and	2007–08,	and	the	only	readily	available	       fishery	is	likely	to	be	operating	with	latent	
indicator	of	economic	performance	is	the	level	    effort,	indicating	low	NER	from	fishing.	
of	latent	effort.

Latency                                            6.6     e n v i r o n m e n Ta l i s s u e s
Effort	is	restricted	in	the	NWSTF	by	a	limit	on	 The	NWSTF	is	traditionally	a	crustacean	
the	number	of	vessel	permits.	In	2006–07	and	    trawl	fishery;	however,	recent	landings	of	
2007–08,	seven	permits	existed	in	the	fishery.	  goldband	snapper,	saddletail	snapper	and	
Given	that	only	three	vessels	fished	in	         redspot	emperor	indicate	that	finfish	species	
2007–08,	and	four	the	previous	year,	some	       are	being	targeted	in	shallow	waters	in	the	
latent	effort	is	present.                        northern	area	of	the	fishery.	In	2007,	AFMA	
                                                 imposed	100	kg	trip	limits	for	goldband	
overall economic status                          snapper	and	red	emperor	as	an	immediate	
The	vessels	operating	in	the	NWSTF	tend	to	      measure	to	reduce	the	risk	of	overfishing	
be	NPF	trawlers	that	fish	opportunistically	     while	an	area	closure	in	the	north	of	the	
while	the	NPF	is	closed.	Consequently,	the	      fishery	was	enacted.	During	the	period	that	
majority	of	capital	in	these	operations	is	      trip	limits	were	in	place,	discarding	of	finfish	
attributable	to	the	NPF,	and	the	capital	costs	  was	reported.	There	are	also	three	marine	
associated	with	operating	in	the	NWSTF	are	      protected	areas	in	the	NWSTF	where	
likely	to	be	quite	low.	The	potential	net	       commercial	fishing	is	excluded;	these	include	
economic	returns	(NER)	from	the	fishery	may	 the	Cartier	Island	Marine	Reserve,	Ashmore	
be	a	significant	proportion	of	gross	value	of	   Reef	National	Nature	Reserve	and	Mermaid	
production	(GVP).	Even	so,	given	that	the	       Reef	Marine	National	Nature	Reserve	(part	of	
GVP	in	the	fishery	is	not	generally	higher	than	 the	Rowley	Shoals).
$1	million	per	year,	and	management	costs	are	       There	have	been	no	reports	of	illegal	
likely	to	remain	low,	further	economic	          fishing	in	the	NWSTF.	No	interactions	with	
research	on	this	fishery	is	unlikely	to	be	      threatened,	endangered	or	protected	species	
justified	on	cost-benefit	grounds.               were	reported	in	the	NWSTF	during	2008.	
                                                 Historically,	interactions	with	two	sea	snakes,	
                                                 which	were	entangled	in	trawl	gear,	were	
                                                 recorded	during	2007.

94      Fishery status reports   2008
6.7     h a r v e s T s T r aT e g y                 Baelde,	P	1994,	‘Royal	red	prawn,	
        perFormance                                     Haliporoides sibogae’,	in	RJ	Tilzey	(ed),	
                                                        The South East Fishery: a scientific review
The	NWSTF	is	traditionally	a	crustacean	                with reference to quota management,	
fishery;	however,	recent	effort	has	targeted	           Bureau	of	Resource	Sciences,	Canberra,	
tropical	snappers	and	emperors	in	shallower	            pp.	257–264.
waters	in	the	north	of	the	fishery.	Finfish	
catches	have	recently	exceeded	crustacean	           Lynch,	AW	&	Garvey,	JR	2005,	North West
catches,	but	finfish	are	not	considered	in	the	         Slope Trawl Fishery scampi stock
NWSTF	component	of	the	HS.                              assessment 2004,	Australian	Fisheries	
    Although	the	HS	has	been	implemented,	              Management	Authority,	Canberra.
catch	levels	of	scampi	and	deepwater	prawns	         Newman,	SJ	&	Skepper,	C	2007,	‘Northern	
have	not	exceeded	the	first	threshold	level	and	       Demersal	Scalefish	Managed	Fishery	status	
so	the	control	rules	have	not	been	enacted.	           report’,	in	WJ Fletcher	&	K	Santoro	(eds),	
There	is	no	evidence	that	stocks	are	below	the	        State of the fisheries report 2006/07,	
default	biomass	proxy,	although	there	is	also	         Department	of	Fisheries,	Western	Australia,	
no	evidence	that	the	HS	will	ensure	stocks	stay	       pp.	161–168.
above	the	limit	biomass	level	at	least	90%	of	
                                                     Rainer,	SF	1992,	The fisheries biology of
the	time.
                                                        deepwater crustaceans and finfish on the
    The	fisheries	are	data	poor;	where	data	
                                                        continental slope of Western Australia,	final	
exist,	the	time	series	is	fragmented	because	of	
                                                        report	to	the	Fisheries	Research	and	
sporadic	targeting.	It	is	too	early	to	know	
                                                        Development	Corporation,	FRDC	project	
whether	the	HS	will	be	effective	in	maintaining	
a	sustainable	fishery,	as	this	will	depend	on	the	
level	of	future	fishing	effort.                      WestMAC	(Western	Trawl	Fisheries	
    The	Western	Trawl	Fisheries	HS	may	not	            Management	Advisory	Committee)	2006,	
adequately	protect	stocks	that	are	subject	to	         MAC Chair’s summary, 7–8 March 2006,	
sustained	fishing	at	low	levels,	particularly	if	      Australian	Fisheries	Management	
stocks	were	substantially	depleted	to	below	the	       Authority,	Canberra.
proxy	biomass	limit	reference	point	in	the	
early	days	of	the	fishery.

6.8     l i T e r aT u r e c i T e d
AFMA	(Australian	Fisheries	Management	
  Authority)	2004,	Western Trawl Fisheries
  statement of management arrangements,	
  November	2004,	AFMA,	Canberra.
AFMA	(Australian	Fisheries	Management	
  Authority)	2007,	Western Trawl Fisheries
  Harvest Strategy—North West Slope Trawl
  Fishery (NWSTF) and Western Deepwater
  Trawl Fishery (WDTF),	December	2007,	
  AFMA,	Canberra.
AFMA	(Australian	Fisheries	Management	
  Authority)	2008,	North West Slope Trawl
  Fishery Bycatch and Discarding Workplan
  (31 October 2008 – 1 November 2010),	
  AFMA,	Canberra.

                                                     chapTer 6     North West Slope Trawl Fishery   95

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