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Using otoliths to estimate age and growth of a large Australian endemic monocanthid, Nelusetta ayraudi (Quoy and Gaimard, 1824)


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Nelusetta ayraudi (the ocean leatherjacket) is an endemic Australian monacanthid species distributed from North West Cape (Western Australia) south to southern Queensland. The commercial and recreational fisheries targeting Nelusetta ayraudi have expanded substantially along the coast of New South Wales (NSW) in recent years but there exists little biological information on which to base effective management of this growing fishery. World-wide, only a few studies have aged monacanthids. Of these, researchers have interpreted periodic increments in bony structures such as vertebrae and anterior dorsal spines in preference to those found in otoliths. In this study we estimated age of N. ayraudi by counting growth increments in sectioned otoliths. The periodicity of increment formation was validated using a vital stain, (oxy-tetracycline), injected into young-of-the-year fish. Growth was rapid especially as juveniles with N. ayraudi attaining approximately 220 mm after 1 year and 340 mm after 2 years. No differences in growth rates were detected between sexes or between fish captured at different latitudes (zones). The largest male (605 mm, Total Length—TL) and female (656 mm, TL) were both recorded from northern NSW, with both sexes attaining the maximum age of 6+ years from northern and southern NSW. The von Bertalanffy parameters describing growth for N. ayraudi were \( {L_\infty } \) = 591 mm (TL), k = 0.377 year−1 and t o = −0.247 years.
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Using otoliths to estimate age and growth of a large
Australian endemic monocanthid, Nelusetta ayraudi
(Quoy and Gaimard, 1824)
Marcus E. Miller & John Stewart & Ron J. West
Received: 17 July 2009 /Accepted: 15 February 2010 /Published online: 20 March 2010
Springer Science+Business Media B.V. 2010
Abstract Nelusetta ayraudi (the ocean leatherjacket)
is an endemic Australian monacanthid species distrib-
uted from North West Cape (Western Australia) south
to southern Queensland. The commercial and recrea-
tional fisheries targeting Nelusetta ayraudi have
expanded substantially along the coast of New South
Wales (NSW) in recent years but there exists little
biological information on which to base effective
management of this growing fish ery. World-wide,
only a few studies have aged monacanthids. Of these,
researchers have interpreted periodic increments in
bony structures such as vertebrae and anterior dorsal
spines in preference to those found in otoliths. In this
study we estimated age of N. ayraudi by counting
growth increments in sectioned otoliths. The periodic-
ity of increment formation was validated using a vital
stain, (oxy-tetracycline), injected into young-of-the-
year fish. Growth was rapid especially as juveniles
with N. ayraudi attaining approximately 220 mm after
1 year and 340 mm after 2 years. No differences in
growth rates were detected between sexes or between
fish captured at different latitudes (zones). The largest
male (605 mm, Total LengthTL) and female
(656 mm, TL) were both recorded from northern
NSW, with both sexes attaining the maximum age of
6+ years from northern and southern NSW. The von
Bertalanffy parameters describing growth for N.
ayraudi were L
=591 mm (TL), k=0.377 year
=0.247 years.
Keywords Ageing
Nelusetta ayraudi
Leatherjackets or filefish of the family Monacanthidae
belong to the highly modified and advanced group of
fish which form the order Tetraodontiformes. Mon-
acanthids are well represented throughout the worlds
oceans with 102 species being recorded (Nelson
2006). The highest monacanthid diversity is found
in Australian waters with a total of 60 species being
recorded, 22 of which are only found in the southern
half of the continent (<30°S), in cooler temperate
waters (Hutchins 2000; Allen et al. 2006). Of the
many monacanthids inhabiting these waters, the
ocean leatherjacket (Nelusetta ayraudi), also known
as the chinaman or sand leatherjacket, is one of
largest monacanthids in the world and the most
Environ Biol Fish (2010) 88:263271
DOI 10.1007/s10641-010-9639-4
M. E. Miller (*)
J. Stewart
NSW Department of Primary Industries,
Cronulla Fisheries Research Centre of Excellence,
PO Box 21, Cronulla, NSW 2230, Australia
R. J. West
ANCORS, University of Wollongong,
Wollongong, NSW 2522, Australia
commonly captured species from Australian waters
(Miller 2007). Thought to be endemic to Australian
waters, N. ayraudi are distributed from North West
Cape in Western Australia around the south of the
continent to Cape Morton in Queensland (Kailola et
al. 1993). In New South Wales (NSW) wat ers, annual
commercial landings of N. ayraudi have increased
rapidly from 134 to 430 tonnes between 20002001
and 20062007 (Miller and Stewart 2009). Despite
the rapidly expanding commercial fishery, there exists
almost no information on the biology of N. ayraudi
on which to base the management of this species.
Ageing monacanthids has proven to be difficult
and the available literat ure indicates a lack of studies
using otoliths to estimat e age. The few studies that
have used otoliths to estimate age have examined
daily incremental development and growth of embry-
onic and pre-larval settling juveniles using whole
sagittal otolit hs (Kingsford and Milicich 1987;
Kawase and Nakazono 1994; Rogers et al. 2001;
Ben-David and Kritizer 2005). The lack of studies
using otoliths to estimate age in post-larval monacan-
thids is curious given that otoliths are recognized as
being the most widely used and reliable structure for
estimating age in bony fish (Campana 2001). One
reason may be that monacanthids have very small and
fragile otoliths which consequently can be difficult to
process and interpret successfully (Grove-Jones and
Burnell 1991; Man cera-Rodriguez and Cas tro-
Hernandez 2004 ). This difficulty, coupled wi th the
fact that few monacanthid fisheries are of sufficient
economic v alue to warrant subs tantial research,
appears to have hampered age estimation in this
group of fish. Studies that have reported estimates of
age and growth in monacanthids have used vertebrae
(Shiqin and Yachu 1980;Park1985; Grove-Jones and
Burnell 1991), anterior dorsal spines (Johnson and
Saloman 1984; Manooch and Drennon 1987;
Mancera-Rodrig uez and Castro-Hernand ez 2004)
and length frequency analyses (Peristiwady and
Geistdoerfer 1991). Validation of the accuracy and
precision of these alternative methods of estimating
age and growth is limited.
In this paper we describe the use of otoliths to
estimate the age of N. ayraudi. Age was esti mated by
counting opaque zones in sectioned sagittal otoliths
from wild caught fish and the method was validated
by using a vital stain (oxy-tetracyclineOTC)
injected into young-of-the-year-fish. Estimates of
size-at-age were used to model rates of growth, which
were compared between sexes and between latitudes
(zones) in eastern Australia.
Materials and methods
N. ayraudi were collected from commercial catches
from two zones along the coast of NSW. The northern
zone was described as the area of co astline stretching
from Forster/Tuncurry (32°11.00 S, 152°31 .00 E) to
the border of NSW and Queensland (28°10
.02 S,
153°33.03 E). The southern zone was described as
the region stretching from Kiama (34°40.20 S, 150
51.54 E) to the Victorian border (37°31.50 S, 149°
58.70 E) (Fig. 1). Twenty fish per month were
collected from each zone between March 2003 and
March 2004. Due to a limited number of large (older)
fish in these monthly samples, a further 19 large fish
were collected from commercial catches at Iluka and
Ballina (northern zone) during September 2005.
Sagittal otoliths were removed from these fish for
age estimation. Juvenile N. ayraudi were also sam-
pled each month from the Port Hacking River (34°
47.50 S, 151°08.00 E) (Fig. 1), between December
2002 and April 2003 and their total lengths (TL, mm)
recorded to estimate monthly growth of the cohort.
Oxy-tetracycline was used to stain the otoliths of
wild-caught young-of-the-year (0+) captive re ared
fish. During December 2002, juvenile N. ayraudi
were collected from the Port Hacking River using
small opera house traps covered with 12 mm mesh set
on a seagrass (Zostera capricorni and Posidonia
australis)/sand bottom. Fish were placed into aerated
5,000 L tanks with flow through ambient seawater
and maintained prior to injection with OTC in March
of 2003. Prior to injection the fish were sedated with
50 mL of benzocaine solution (ethyl-p-amino benzoate
dissolved in 100% ethanol at 100 g·1,000 mL
intraperitoneal injection of tetracycline (Engemycin
100oxytetracycline hydrochloride at 5 mg·mL
body weight (McFarlane and
Beamish 1987). Any leatherjacket louse (Ourozeuktes
owenii) found attached to the fish was removed at this
time. Between 2002 and 2004, fish were sampled
intermittently and their otoliths removed for examina-
tion. Sagittal otoliths were removed by cutting hori-
zontally above the eyes of the fish, exposing the brain
264 Environ Biol Fish (2010) 88:263271
cavity. The otolith sacculus, extending downwards on
either side of the forefront of the brain cavity, were
extracted, otoliths removed and allowed to dry for a
short period of time before being set in resin blocks. A
single bladed low speed diamond saw was used to cut
athin(0.5 mm) cross-section from the dorsal to
ventral margins through each otolith core (primordium).
These otolith sections were mounted on a glass slide and
viewed under reflected light against a black background
with magnification. Counts of opaque zones were
made along a radius from the core to the outer edge of
the ventral lobe of the otolith using a microscope
Forster / Tuncurry
Crowdy Head
Jervis Bay
Coffs Harbour
Cronulla Fisheries Research Centre
Northern Zone
Southern Zone
Port Macquarie
Forster / Tuncurry
Crowdy Head
Jervis Bay
Coffs Harbour
Cronulla Fisheries Research Centre
Northern Zone
Southern Zone
Port Macquarie
Forster / Tuncurry
Crowdy Head
Jervis Bay
100 km
Coffs Harbour
Cronulla Fisheries Research Centre
Northern Zone
Southern Zone
Port Macquarie
Pacific Ocean
Fig. 1 Study locations
along the coast of New
South Wales, Australia,
showing sampling zones
Environ Biol Fish (2010) 88:263271 265
mounted video camera interfaced with a computer,
running Image Pro Plus image analysis software
(Version 4.5.1, media Cybernetics Inc, Bethesda, MD).
The otoliths from fish that were injected with OTC were
observed under reflected light and opaque zones
counted and measured. Observations were then made
using ultraviolet (UV) light to identify the marked area
of OTC on the otolith. Each otolith was measured from
the core to the OTC mark and to the outside edge of
the otolith. All otoliths were re-read to examine the
precision of estimates of counts of opaque zones. The
coefficient of variation (CV) for the two readings for
each otolith was calculated and averaged across all
otoliths (Campana 2001).
A birth date of 1st August was assigned to all fish
based on the peak in the spawning season (Miller
2007). Age was calculated as the number of opaque
zones plus the proportion of the year following this
date that the fish was sampled. N. ayraudi have a
short winter spawning period (Mil ler 20 07)and
therefore errors in under-estimating or over-estimating
the absolute age of fish born slightly earlier or later
than 1st August will be minor. The von Bertalanffy
growth function (VBGF) was fitted to the size-at-age
data for wild caught ocean leatherjackets, using solver
in Microsoft Excel 2003 to minimise the sum of
squares. An analysis of residual sums of squares
(ARSS) (Chen et al. 1992) was used to compare the
VBGFs between: (1) sexes from each latitudinal zone,
and; (2) latitudinal zones.
Otoliths from N. ayraudi are typical of those
described for other monacanthids (Furlani et al.
2007) in being very small, hour-glass shaped, the
dorsal margin flat and slightly irregular and the
ventral margin rounded and irregular (Fig. 2a). They
had a diameter from the posterior to anterior margins
of between 0.5 mm in younger fish to around 3 mm in
older fish and were very fragile. When sectioned, the
internal structure of all otoliths appeared complex.
The core was densely opaque with a larger translucent
zone surrounding it with scattered finer streaks of
opaque markings throughout. This zone represented
the rapid growth fish experience while juveni le. This
structure was followed by a more definite opaque
zone that was scored as the first annulus. The mean
SE) distance (mm) from the core to the outside
edge of the first annulus in the 585 wild fish
examined was 0.345 mm±0.002 mm. Annuli beyond
the first opaque zone were charact erized by reason-
ably well defined alternating opaque and translucent
zones (Fig. 2b).
The young-of-the-year N. ayraudi that were
injected with OTC an d maintained in the aquaria
ranged between 97 and 193 mm TL. The otoliths of
sampled fish all had clearly visible OTC marks when
viewed under UV light (Fig. 2c, d). Thirty were
sampled before they formed thei r first annulus, 21
were sampled when 1+ years and 7 were sampled
when 2+ years (Fig. 3). Otolith growth from the OTC
mark to the edge of the otolith indicated that the
otoliths increased in diameter approximately linearly
during the 26 months of the validation experiment
(Fig. 3). The mean SE) distance from the core to
the outside edge of the first opaque zone in these
otoliths was 0.325 mm±0.006 mm which was similar
to fish from the wild (see above). The OTC mark,
administered during March, was always present
within the translucent zone prior to the first opaque
zone, indicating that the opaque zone was probably
formed sometime during the winter period. The first
opaque zone was scored as completed in 1 of 4 fish
during July and in all fish by August.
Estimates of age were assigned to the 585 otoliths
examined from both the northern and southern zones.
Of the otoliths re-examined, 80.5% were not different
from the original readings, 18.8% differed by ± 1 year
and 0.7% differed by ± 2 years. The coefficient of
variation (CV), averaged across all ages, was 0.066.
Six age classes (1 to 6 years) were recorded from the
585 wild caught fish sampled fr om commercial
landings. Only two fish, one male and one female
were estimated as being 6+ years old. The largest
recorded fish was a female from the northern zone
which measured 656 mm (TL) and was estimated at
5.8 years. The largest male (605 mm TL) was also
from the northern zone and was estimated to be
5.2 years old. The largest fish from the southern zone
was a female (596 mm TL) estimated at 3.8 years old
and the largest mal e from the southern zone (583 mm
TL) was estimated to be 4.2 years old.
Comparisons of rates of growth between sexes
from each zone revealed no significant differences
(ARSS northern zone, f
=0.55, P=0.64 and
southern zone, f
(3, 261)
=1.38, P=0.25). Similarly,
266 Environ Biol Fish (2010) 88:263271
there were no significant differences observed in rates
of growth when the two sexes were combined
between each zone (ARSS f
(3, 579)
=1.34, P=0.26).
As there were no significance differences in the rates
of growth between sexes and zones, growth data for
all fish were pooled to provide a general VBGF for
N. ayraudi. The VBGF parameters (±SE) estimated
were k=0.377 year
(±0.0224) t
= 0.247 ye ar
(±0.032), and L
=591 mm (±15.90) (Fig. 4). The
relationship between TL and body weight for all fish
sampled was described by a power relationship: Body
weight (g) = 0.00003 × TL
Sampling of young-of-the-year N. ayraudi between
December and April indicated rapid growth during
this period (Table 1). The mean length of juvenile N.
ayraudi samp led during April was 176 mm TL and,
based on a birthday of 1st August, these fish were
approximately 9 months old.
This study has demonstrated that the technique of
using sectioned otolith s to estimate the age of fish
Fig. 2 a Whole otolith,
scale: 0.5 mm; b thin-
sectioned otolith viewed
under reflected light against
a black background. The
estimated age and size of
this fish was 4+ years and
551 mm, Scale: 0.5 mm; c a
captive reared 2+ year old
sectioned otolith under
reflected light, Scale:
0.25 mm; and, d the same
captive reared 2+ year old
sectioned otolith under ultra
violet light displaying the
oxy-tetracycline (OTC)
mark, Scale: 0.25 mm
Mar-03 Jun-03 Oct-03 Jan-04 Apr-04 Aug-04 Nov-04 Feb-05 May-05 Sep-05
0+ Year
1+ Year
2+ Year
Mar-03 Jun-03 Oct-03 Jan-04 Apr-04 Aug-04 Nov-04 Feb-05 May-05 Sep-05
Month -Year
Otolith Growth (mm)
0+ Year
1+ Year
2+ Year
Fig. 3 Sagittal otolith
growth after the
oxy-tetracycline (OTC)
mark in February 2003
Environ Biol Fish (2010) 88:263271 267
(Campana 2001) can be successfully applied to a
member of the family Monacanthidae. While the
otoliths of this diverse and abundant family of fish are
very small, fragile and irregular in shape (Furlani et
al. 2007), they display alternating opaque and
translucent zones that can be counted and used to
estimate age. A review of the literature on ageing
monacanthids, and the closely related family of
Balistidae, shows that our results in demonstrating
the utility of using sectioned otolith s to estimate age
could lead to improvements in future studies of age
and growth in these families of fish. In Korea (Park
1985), South Australia (Grove-Jones and Burnell
1991), and China (Shiqin and Yachu 1980), studies
have estimated the age of black filefish (Navodon
modestus), ocean leatherjackets (Nelusetta ayraudi)
and green filefish (Navodon septentrionalis) using
sectioned vertebrae. Anterior dorsal spines have been
used in other ageing studies for the plane-head filefish
(Stephanolepis hispidus) from the Canary Islands
(Mancera-Rodriguez and Castro-Hernandez 2004),
the closely related balistids, the gray triggerfish
(Balistes capriscus) in the north eastern gulf of
Mexico (Johnson and Saloman 1984), and the queen
triggerfish (Balistes vetula) from the U.S Virgin
Islands and Puerto Rico (Manooch and Drennon
1987). None of these studies made use of sectioned
otoliths, with an accompanyin g validation, which is
generally accepted as the best ageing technique for
the majority of fish species (Campana 2001). Rather,
researchers have interpreted the concentric bands in
vertebrae and dorsal spines when estimating annual
ages. These bony structures are not ideal for estimat-
ing age because skeletal growth can be variable and is
influenced by many internal and external factors.
Vertebrae continually resorb tissue which can destroy
periodic growth increments and the spines of older
fish can become hollow and lose record of younger
growth patterns (Panfi li et al. 2002). In addition, the
precision of readings from both vertebrae and spines
tend to be poor compared to those from otoliths and
validation of the ageing interpretations di fficult
(Campana 2001). The negative ramifications of using
incorrect age estimates in fishery management are
well documented (Campana 2001) and our findings
that sectioned otoliths can be used to age monacan-
thids and balistids will be of use to future studies of
these families of fish. Nelusetta ayraudi sagi ttal
otoliths were well stained by OTC at a dosage of
50 mg·kg
body weight. The 58 otoliths examined as
part of the validation experiment had clearly visible
OTC marks when viewed under ultra-violet light.
345 76
= 591
= 0.377
= -0.247
e (Years)
Total Length (mm)
= (±15.9)
= 0.377 (± 0.02)
= -0.247 (± 0.03)
Fig. 4 Estimated length at
age plot for N. ayraudi. The
von Bertalanffy growth
function (VBGF) parameters
for all fish (including
juveniles) combined from
each of the two zones are
shown. Note: open squares =
fish aged from otoliths;
closed diamonds = juvenile
fish aged from the nominated
birth date
Month Number of fish Mean size (mm) (SE) Mean growth (mm)/month
Dec-02 60 108.15 (2.28)
Jan-03 60 124.65 (2.42) 16.50
Feb-03 60 155.70 (1.68) 31.05
Mar-03 30 168.03 (2.70) 12.33
Apr-03 8 176.00 (4.3) 7.97
Table 1 Average juvenile
growth (SE) during the
summer months of
268 Environ Biol Fish (2010) 88:263271
Marking these fish with OTC showed that opaque
zones were formed once per year during the winter.
Many other temperate species in Australian waters
have also been shown to form annual opaque zones
during the winter months (Stewart and Hughes 2007;
Morton et al. 2008). The finding that otolith growth
from the core to the first opaque zone of fish in
aquaria was similar to that of wild fish provided some
confidence that the captivity did not affect the
validation experiment.
The internal structure of otoliths from N. ayraudi
was complex and alternating opaque and translucent
zones were often diffuse. This pattern was interpreted
as being the result of a fast growth rate, particularly
during the early years. Variations in somatic growth
have been shown to effect the internal structural
development of otoliths (Fowler 1995), with fish
having faster growth rates being associated with less
distinct annuli (Esteves and Burnett 1993; Stewart and
Hughes 2007). Nevertheless, the overall precision from
ageing N. ayraudi (mean CVof 6.6%), was comparable
to those reported in other ageing studies (Campana
Growth of juvenile monacanthids has been poorly
documented for other species that are captured in
large commerci al fisheries around the world. Data
exist for the growth of the early stages of develop-
ment of several juvenile species such as Parika
scaber in New Zealand (Kingsford and Milicich
1987), Stephanolepis hispidus in the USA (Rogers et
al. 2001) Navodon modestus (Kakuda 1979)and
Rudarius ercodes and Paramonacanthus japonicus
in Japanese waters (Kawase and Nakazono 1994).
Ishida and Tanaka (1983 ) showed recruitment
and growth of juvenile small filefish (Rudarius
ercodes) in Odawa Bay Japan, while Peristiwady
and Geistdoerfer (1991) reported recruitment of
juvenile Monacanthus tomentosus in sheltered bays
and estuaries of West Seram, Moluccas, Indonesia. In
the present study, juvenile N. ayraudi exhibited rapid
growth during the summer months between Decem-
ber and April. A mean maximum monthly growth of
31 mm occurred during February. Pollard (1994)
noted that seagrass beds ( Zostera capricorni and
Posidonia australis) played an important role in the
early stages of growth for juvenile N. ayraudi and
suggested that the species migrated to deeper waters
as it grew larger. Gro ve-Jones and Burnell (1991) also
had the highest capture rates of juvenile N. ayraudi
from sheltered bays and estuaries, in the months of
February, with a decline in numbers in the months
that foll owed. Again, they assumed that these fish
were recruiting to the fishery offshore. They also
found that the mean growth rates were highest in
February and April (27 mm and 28 mm respectively).
N. ayraudi is a mongst the largest monacanthids in the
world, with a maximum recorded length of 700 mm
(Hutchins and Swainston 1986). The largest fish
sampled during the present study were substantially
smaller than this, suggesting that ocean leatherjackets
may attain ages considerably greater than 6+ years. A
summary of ageing studies done world-wide indicates
Table 2 A review of ageing studies of monacanthid and balistid species, summarising the maximum lengths and ages for sexes
Species Family Maximum length (mm) Maximum age (years) Reference
Nelusetta ayraudi Monacanthidae 656 , 605 6 ,6 1
423 , 393 9 ,7 2
Navodon modestus Monacanthidae 250 , 260 3 , 3
320 , 3 , 4
340 8 5
Thamnaconus septentrionalis Monacanthidae 290 9, 7 6, 7
Balistes capriscus Balistidae 561 , 544 12 ,13 8
Balistes vetula Balistidae 378 , 7 , 9
Monacanthus tomentosus Monacanthidae 117 , 5 , 10
Stephanolepis hispidus Monacanthidae 250 , 3 ,2 11
1) Present Study; 2) Grove-Jones and Burnell (1991); 3) Kakuda (1978); 4) Kakuda (1979); 5) Park (1985); 6) Shiqin and Yachu
(1980); 7) Chen et al. (1998); 8) Johnson and Saloman (1984); 9) Manooch and Drennon (1987
); 10) Peristiwady and Geistdoerfer
(1991); 11) Mancera-Rodriguez and Castro-Hernandez (2004)
Environ Biol Fish (2010) 88:263271 269
that other species of monacanthids are relatively short
lived (<9 years) (Table 2). Nevertheless, our results
indicate very fast growth rates. No differences in growth
rates were found between males and females. The lack
of differences in growth rates with latitude may be a
result of migration between our sampling zones.
Commercial fishers in NSW have provided anec-
dotal evidence that commerci ally-sized fish undergo
large latitudinal movements seasonally, especially
during winter when fish are spawning. Although
these spawning migrations have no t been confirmed
in NSW, Lindholm (1984) reported that N. ayraudi in
South Australian waters were highly mobile and that
larger fish were captured from deeper waters. This
study has demonstrated that monacanthids can be
successfully aged using sectioned otoliths and recom-
mends that future studies on this and other closely
related families adopt our methods. We consider that
the improvements in accuracy and precision by using
sectioned otoliths in preference to the commonly used
vertebrae and dorsal spines outweigh the difficulties
in handling small, fragile otoliths. It would be useful
to use sectioned otoliths to age species that have
previously been studied using vertebrae and dorsal
spines. This new information on age and growth of N.
ayraudi in eastern Australia has provided the first
insight into how the stock may respond to the rapidly
increasing fishery. The relatively few age classes and
rapid growth rates suggest that N. ayraudi maybe
resilient to fishing; however further information on
the re productive biology, life-history, movements,
stock structure and fishery landings are still required
if informed management is to be implemented.
Acknowledgements This study could not have been possible
without the support and enthusiasm of the commercial fishermen
from the NSW ocean trap (fin-fish) and deep water lobster
fisheries. Thank you to Noel Gogerly, Phil Roach, Ray Blake,
and Steve Drake for their expertise in catching ocean leatherjackets.
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... The smaller commercially captured aquarium trade fish, the fantail filefish (Pervagor spilosoma) around the Hawaiian archipelago (Hobson and Chess 1996; Stimson 2005) and the non-commercial slender filefish (Monacanthus tuckeri) around Belize (Ben-David and Kritzer 2005) also display this form of spawning. Ocean leatherjackets, N. ayraudi, are one of the world's largest Monacanthids (Hutchins 2000; Miller et al. 2010). Endemic to Australian waters, they are distributed from the north coast of Western Australia around the south of the continent to southern Queensland , inhabiting inshore coastal bays and estuaries as juveniles and recruiting to deeper offshore waters as they mature. ...
... Endemic to Australian waters, they are distributed from the north coast of Western Australia around the south of the continent to southern Queensland , inhabiting inshore coastal bays and estuaries as juveniles and recruiting to deeper offshore waters as they mature. N. ayraudi have a maximum recorded length of 700 mm (Hutchins and Swainston 1986) and a maximum reported age of 6 years (Miller et al. 2010). N. ayraudi are important targets of commercial and recreational fisheries (Rowling et al. 2010). ...
... 00 S–28°10 0 .02 00 S) and 'southern' (37°31 0 .5 00 S–34°40.2 00 S) areas (after Miller et al. 2010 ...
The ocean leatherjacket (Nelusetta ayraudi) is one of the largest members of the family Monacanthidae. Distributed throughout inshore waters around the southern half of Australia, this schooling species supports substantial commercial and recreational fisheries. N. ayraudi do not conform to either of the general reproductive modes reported within the family, but exhibit characteristics of both strong social reproductive behaviour and of being promiscuous and polygynous. Sexual dimorphism, with males and females exhibiting differing colouration and body shapes, and ripe ovaries being an order of magnitude larger than ripe testes, are characteristic of social reproductive behaviour and pair spawning. In contrast, high batch fecundity (mean of 320 oocytes per gram of body weight), similar sizes and ages at sexual maturity (350 mm and 2.5 years respectively) and the formation of large spawning aggregations in offshore waters are characteristic of being promiscuous and polygynous. Similar to many other coastal marine species off the east and west coasts of Australia, N. ayraudi are partial spawners during the austral winter months with spawning restricted to the part of their distribution that is towards the upper area of the prevailing currents. It is hypothesized that N. ayraudi off eastern Australia have evolved a life-history strategy whereby fish move northwards through time, spawning occurs in these more northern waters and the southerly flowing Eastern Australian Current facilitates dispersal of eggs and larvae southwards. The reproductive characteristics described provide various options to fishery managers who wish to enhance the sustainability of the fishery through increased egg production. These include spatial and temporal fishing closures to protect breeding fish during the spawning period, the protection of juveniles through either inshore area closures, improving the selectivity of fishing gears and/or regulated minimum legal lengths.
... However, growth comparisons between wild and hatchery-origin T. rubripes have been conducted by Ueta et al. (2010) based on vertebrae. Unfortunately, this is not the most exact method because age estimation by vertebrae is inferior to sectioned otoliths in terms of both accuracy and precision (Miller et al., 2010;VanderKooy et al., 2020). Although many age and growth studies have been conducted on T. rubripes because of their importance as a fishery resource (Matsuura, 1997;Yamada et al. 2007), their otoliths have never been used for age estimation. ...
... Wild fish: , observed data; , fitted model. Hatchery-origin fish: , observed data; , fitted model FISH However, a few studies have successfully estimated filefishes age using otolith sections and also emphasized the limitations of age estimation using vertebrae in terms of accuracy and precision (Miller et al., 2010;Visconti et al., 2018). Since errors and biases in age estimation may lead to incorrect stock assessment and disturb stock management (Reeves, 2003;Yule et al., 2008), age estimation should also be based on sectioned otoliths for pufferfishes. ...
Tiger pufferfish Takifugu rubripes (order Tetraodontiformes, family Tetraodontidae) is a highly exploited species, and stocks continue to decline, although hatchery‐reared juveniles have been released since 1965 for stock enhancement. To determine why the stock has not recovered through hatchery‐release practices, this study investigated and compared the population characteristics of wild and hatchery‐origin fish. The length–mass relationship showed that hatchery‐origin fish were skinnier, with males weighing less than 90% of the mass of wild males of the same length. The hepatosomatic index tended to be lower in hatchery‐origin fish. Age was estimated using the otolith‐based method, and the estimates were more accurate and precise than those obtained by the conventional vertebra‐based method. At the age of 2.9 years, an age at which specimens were the most abundant in catches, hatchery‐origin males weighed only 67% of that of wild males. The maximum observed age was 12 years for wild fish and 5 years for hatchery‐origin fish. The instantaneous total mortality rates of hatchery‐origin fish were more than twice as high as those of wild fish. In summary, the hatchery‐origin fish had poor health status, poor growth, and high mortality, and their fitness in natural environments was, therefore, hypothesized to be low throughout life. This article is protected by copyright. All rights reserved.
... Ocean jacket (Nelusetta ayraud) is a large monacanthid species inhabiting coastal waters throughout the southern half of Australia. The species is one of the most common monacanthids caught in Australia (Miller et al., 2010) and prominent in recreational catches from estuaries and nearshore reefs of NSW (Murphy et al., 2020). The steps for linking harvest strategy objectives to empirical performance indicators and their data sources were followed for the ocean jacket stock in NSW (Figure 2). ...
Recreational fishing (RF) is a popular pastime resulting in substantial fish mortality in many regions. Yet inclusion of RF in fishery harvest strategies is limited, because the sector's objectives are poorly understood, as are the data required to track their performance. To address this, we reviewed RF data sources available from a region of globally high participation (New South Wales [NSW], Australia) and evaluated their utility for RF-specific performance indicators within harvest strategies. We then linked these data sources to RF objectives they may be used to monitor. A total of 21 RF data sources were identified in NSW over the past two decades, spanning all major aquatic environments and 146 fished species. Numerous data sources were available to monitor ecological objectives, providing time-series and potential reference points for key indicators such as catch-per-unit-effort. Few data sources were available for social, economic, and institutional objectives, consistent with a global paucity of these data. We found that most social objectives of RF lie outside the scope of traditional harvest strategies, although some are linked to underlying ecological performance. Harvest strategy performance for RF will depend on the relative importance of social objectives and whether these can be achieved by controlling harvest.
... However, due to the fact that ageing fish of the family Monacanthidae is challenging due to the dimension, unusual shape and fragility of the sagittal otoliths (Grove-Jones and Burnell 1991;Mancera-Rodríguez and Castro-Hernández 2004;Kim et al. 2016), there is a lack of information on life history. This appears to have hampered the recognition and understanding of separate stocks not only for M. scaber in New Zealand waters but also that of other monacanthid species around the world (Ministry for Primary Industries 2017; Miller et al. 2010). Recent studies carried out in the Hauraki Gulf (New Zealand) have unlocked various aspects of the species' life-history including its pair spawning behaviour and gonochorism (Visconti et al. 2018a), as well its unexpected longevity (Visconti et al. 2018b). ...
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Demography and life-history characteristics of reef fishes may vary as a consequence of ecological and environmental factors that lead to changes among populations. We evaluated variation in life-history traits in the leatherjacket Meuschenia scaber (Monacanthidae) through age-based analysis of 2112 fish collected from three locations in New Zealand distributed along an 8° latitudinal and 5 °C SST gradients. Meuschenia scaber showed distinct differences in age structure, growth patterns, maximum size and age, sex ratio and mortality across this latitudinal gradient. At warmer lower latitudes (Hauraki Gulf) the population displayed significantly greater mean adult body size (Lmax) and asymptotic length (L∞) in comparison with the other two locations. Fish from Tasman Bay (mid-range latitude) had a longer life span (Tmax) and a maximum age of 19 years, which represents the longest-lived monacanthid documented to date. Fish from Pegasus Bay (cooler higher latitude) showed a slower initial growth than lower latitude counterparts. The difference in maximum age between the sexes declined clinally from 7 years in the Hauraki Gulf to 3 years in Tasman Bay and 1 year in Pegasus Bay. Meuschenia scaber females tended to display heavier and larger body size than males at all three locations. Sex ratios varied among populations and with depth, suggesting females in the Hauraki Gulf and Tasman Bay may move into deeper water with age. Given the increasing global exploitation of monacanthids in multispecies fisheries and their long-living nature, our results provide valuable age-based demographic information essential for future conservation, monitoring and management programs.
... von Bertalanffy Growth Function (VBGF) is a widely used growth model in fisheries, and its parameters are particularly useful in describing general fish growth (Chen et al., 1992;Quinn and Deriso, 1999). Several researchers have successfully used von Bertalanffy growth model for the estimation of growth in different fish species such as Cyprinus carpio (Vilizzi and Walker, 1999), Gerres sp. ( Kanak and Tachihara, 2006), Clarotes laticeps ( Abowei and Davies, 2009), Nelusetta ayraudi ( Miller et al., 2010), Schizopyge curvifrons, Schizopyge niger and Schizothorax esocinus (Sabah and Khan, 2014), etc. The objective of this study was to provide a detailed information on the age and growth of C. punctata in waters of river Ganga, which may prove to be of great utility in its stock evaluations and fisheries management. ...
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The present study was undertaken to estimate age and growth of the spotted snakehead Channa punctata (Bloch, 1793) from the Ganga River, based on 390 fish samples collected during August 2016 to July 2017. Each of the 3 otoliths (lapillus, asteriscus and sagitta) were dissected out, cleaned and observed to identify the annual rings. Based on clarity of annuli and ease of reading, sagittae (whole as well as sectioned) were selected for age estimation. Standard procedures were followed to prepare and study the age structures viz., the otoliths and scales. The alternating opaque and translucent bands present on the ageing structures were interpreted as annuli. Amongst the 3 methods used for age estimation, the sectioned otolith exhibited highest percentage of agreement (92.4) between readers, and least values of average percent of error (2.68) and coefficient of variation (2.36). Age estimates from sectioned otoliths were taken to develop the von Bertalanffy growth equation [Lt = 31.5(1 – e–0.29(t+ 1.06))] for the target fish species. The observed and calculated lengths in the fish did not vary significantly. Thus, the sectioned otoliths may be used for precise age estimation as well as calculation of various age-based population parameters of C. punctata inhabiting the river Ganga.
... The nine annuli found in the vertebrae indicated age classes from 0 to 9. Alternating bands of hyaline and opaque zones have been reported in other studies, based on a variety of methods. Peristiwady and Geistdoerfer (1991) reported five age classes (1-5 years) for Monacanthus tomestosus in Indonesia, based on the length frequency histogram, and Miller et al. (2010) estimated six age classes (ages 1-6) for Nelusetta ayraudi in Australia, based on counts of otolith growth rings. The L ∞ and k values are not an indication of the growth rate. ...
The age and growth of filefish, Thamnaconus modestus (Günther 1877) in the southern waters of Korea were investigated. Samples were collected with commercial trawl catches during the period from May 2009 to December 2011. Of the 2,626 specimens collected, the sex ratio was not significantly different from 1:1 (P > 0.05). The total length ranged from 11.3 to 42.1 cm. The gonadosomatic index for both sexes was the highest in May to June, indicating that May to June is the main spawning period. The length of females at sexual maturity was 25.92 cm. The length-weight relationship of the filefish was TW = 0.0121TL3.0536 (n = 1,692, r2 = 0.9034, P < 0.001). The age of the sampled individuals was estimated by counting growth rings recorded on the 5th vertebrae; ages ranged from 0 to 9 years. The filefish of the same age displayed a high individual variation in total length. Length-at-age data were fitted by using the Von Bertalanffy growth model. The estimated Von Bertalanffy growth parameters were L∞ = 42.04 cm, k = 0.21 year−1 and t0 = −1.56 for females, L∞ = 41.20 cm, k = 0.18 year−1 and t0 = −2.36 for males, and L∞ = 43.16 cm, k = 0.17 year−1 and t0 = −2.18 for the combination of both male and female. These data can be used as useful biological information for the future fishery management of filefish resources in Korean waters.
... Despite their ubiquitous presence on reefs, and their conspicuous nature, there is little knowledge of the biology and demography of monacanthids [48]. Some are known to have very small home ranges on reefs [50], whilst the largest, endemic species Nelusetta ayraudi forms the basis of a significant fishery in sub-tropical and temperate shelf waters [51]. The labrids of temperate reefs are much better known for their hermaphroditism and social organisation [49], territoriality or small home ranges on reefs [52], niche partitioning [53] and plasticity in diet [54]. ...
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Distributions of mobile animals have been shown to be heavily influenced by habitat and climate. We address the historical and contemporary context of fish habitats within a major zootone: the Recherche Archipelago, southern western Australia. Baited remote underwater video systems were set in nine habitat types within three regions to determine the species diversity and relative abundance of bony fishes, sharks and rays. Constrained ordinations and multivariate prediction and regression trees were used to examine the effects of gradients in longitude, depth, distance from islands and coast, and epibenthic habitat on fish assemblage composition. A total of 90 species from 43 families were recorded from a wide range of functional groups. Ordination accounted for 19% of the variation in the assemblage composition when constrained by spatial and epibenthic covariates, and identified redundancy in the use of distance from the nearest emergent island as a predictor. A spatial hierarchy of fourteen fish assemblages was identified using multivariate prediction and regression trees, with the primary split between assemblages on macroalgal reefs, and those on bare or sandy habitats supporting seagrass beds. The characterisation of indicator species for assemblages within the hierarchy revealed important faunal break in fish assemblages at 122.30 East at Cape Le Grand and subtle niche partitioning amongst species within the labrids and monacanthids. For example, some species of monacanthids were habitat specialists and predominantly found on seagrass (Acanthaluteres vittiger, Scobinichthys granulatus), reef (Meuschenia galii, Meuschenia hippocrepis) or sand habitats (Nelusetta ayraudi). Predatory fish that consume molluscs, crustaceans and cephalopods were dominant with evidence of habitat generalisation in reef species to cope with local disturbances by wave action. Niche separation within major genera, and a sub-regional faunal break, indicate future zootone mapping should recognise both cross-shelf and longshore environmental gradients.
Strontium isotopes (87Sr/86Sr) recorded in the otoliths of Pacific Salmon (Oncorhynchus spp.) are commonly used to identify natal origin. For species that migrate at or soon after emergence, the embryonic region of the otolith provides the only record of provenance. However, maternal contribution of Sr from the yolk can confound the isotopic signature of the natal site. We experimentally quantified maternal and exogenous diet contributions to otolith 87Sr/86Sr over embryonic development in Kokanee salmon (O. nerka). Eggs from two populations in isotopically distinct lakes were incubated and reared in a common water source. Timing of developmental events and proportional contribution from yolk to otolith 87Sr/86Sr differed significantly between the two populations. We suggest that the magnitude of difference in 87Sr/86Sr between yolk and water, the relative concentrations of Sr and Ca in these isotopic sources, and population-specific effects on otolith growth and composition contribute to this variation. Understanding how these factors affect otolith 87Sr/86Sr could extend the use of otolith geochemistry for determining provenance to species and populations in which natal site rearing is limited.
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Oxytetracycline (OTC), injected to mark the otoliths of sablefish (Anoplopoma fimbria), causes mortality directly in proportion to the dosage administered. The selection of an appropriate dosage requires minimizing mortality while maximizing the number of fish that have a usable OTC mark. Laboratory studies could not be used to determine appropriate dosages. Dosages that substantially increased mortality in the ocean did not cause any mortality in the laboratory. For sablefish, we recommend a dosage of 25–35 mg OTC/kg fish.
The accurate identification of fish ‘ear-bones’, known as otoliths, is essential to determine the fish prey of marine and terrestrial predators. Fish otoliths are species-specific when combining size, shape and surface features, and can remain undigested for long periods. As a result, they can indicate which fish make up the diet of various predators, including cephalopod, seabird, marine mammal and fish species. Such studies are crucial for understanding marine ecosystems, and trophodynamics in particular. Increasingly, these methods are being used to understand the diet of some terrestrial predators, also extending to that of humans in archaelogical studies. Otoliths of Common Australian Temperate Fish offers users a verified reference collection to assist in the accurate identification of species and size of fish using otoliths. It covers 141 fish species from a broad geographic range of the Australian temperate region and includes commercial and non-commercial fish species. A standardised written description of the otolith structure, size and surface features is provided for each species. Included are brief distribution and ecology notes, and regression for both otolith and fish lengths, together with high-quality SEM photographs of the otolith described. This guide will be an essential reference for marine scientists and marine mammal researchers; ornithologists, fisheries researchers and fish biologists studying age and growth or comparative anatomy; and archaeologists. Winner of the 2008 Whitley Award for Zoological Manual.
Juveniles less than 20mm total length (TL) were collected by hand beam trawl from July through October. Small-sized fish 30 to 50mm TL began to be recruited to the catch by boat seine from August through September. Although they showed annual fluctuation of pattern in the length frequency distribution, small-sized fish grew up to large-sized fish from 50 to 70mm TL in spring through summer of the next year. A negative relationship between population density and growth in weight was observed. The spawning season is estimated to extend from May through September judging from the seasonal change of a gonadsomatic index. Some small-sized fish recruitd in summer also had well developed gonads. The rate of group maturity for females at around the end of August or time of recruitment showed annual variation, and was lower in 1977 when population density was higher than in other years.
The ocean leatherjacket (Nelusetta ayraudi) has a long history of commercial exploitation in New South Wales, Australia. Records of reported landings indicate that substantial peaks of between 600 and 900 tonnes per annum occurred during the 1920s and again during the 1950s. These peaks were followed by large declines, which suggest that this species is vulnerable to over-exploitation. In recent years from 2000/01 to 2006/07, annual commercial landings of ocean leatherjackets using oceanic demersal fish traps and demersal otter trawl have increased from 134 to 430 tonnes. Between 2003 and 2005 ocean leatherjackets in commercial landings ranged approximately between 22 and 65 cm in total length. Ocean leatherjackets were fully recruited to the fishery at two years of age, with the majority of the catch (83%) aged either two or three years. The instantaneous total mortality rate was estimated from an age-based catch curve as 1.1. Natural mortality was estimated as approximately 0.5, based on a maximum age of 6 years. Yield per recruit indicated that under current levels of exploitation the yield per recruit would be maximized at a length at first harvest of 35 cm in total length.
The growth of the planedhead filefish Stephanolepis hispidus was studied on individuals sampled from a small-scale fishery off Gran Canaria (Canary Islands, central-east Atlantic) between March 1998 and August 1999.The age of the sampled individuals, which ranged from 0 to 3 years, was estimated using both the length frequency distribution and the count of growth rings recorded on the anterior dorsal spine. The mean total length of the 0 age class was 10.9 cm, while the ages classes 1, 2 and 3 showed a mean length of 15.8, 19.4 and 21.4 cm, respectively.Differences in the growth rhythms were observed between the sexes. The asymptotic lengths (L∞) were 25.7 and 27.4 cm for females and males, respectively. The curvature parameter (K) of the von Bertalanffy growth equation was 0.40 per year. The amplitude of the seasonal growth oscillation of the von Bertalanffy growth equation (C=0.15) and the Winter Point (WP=0.19) indicate a seasonality in the growth pattern, being slowest at the end of the winter.
Age, growth, and mortality of gray triggerfish, Balistes capriscus, from the northeastern Gulf of Mexico were estimated from sections of the first dorsal spine of 1,746 fish. The oldest female was estimated to be 12 years old and the oldest male was 13 years old. The von Bertalanffy growth equa­ tions, using weighted means, were as follows: males, It = 491.9 (l - e - 0.382(1 - 0.227)) and females, It = 437.5 (1 - e- 0.383(t- 0.150)), where I = fork length in millimeters and t = age in years. The mean annual mortality rate as determined by four methods of analyses (based on number of fish at age) ranged from 0.32 to 0.53. The weight-length relationships of gray triggerfish were males, W = 6.71505 x 10- 6 L3.187, and females, W = 1.3939 x 10- 5 L3.065, where W = weight in grams and L = fork length in millimeters. Exploitation of fish from the northeastern Gulf of Mexico by recreational and commercial fisher­ men has created a demand for underutilized fish resources. One of the abundant fish resources that is being subjected to exploitation is the gray triggerfish, Batistes capriscus. A dramatic in­ crease in demand for this species can be seen in the commercial landings on the west coast of Florida: 7.8 t in 1967 and 26.7 t in 1977 (Anon­ ymous 1967, 1977). This species is known to occur in the western and eastern Atlantic. In the western Atlantic, its range is from Nova Scotia to Argentina, includ­ ing the Gulf of Mexico (Briggs 1958; Moore 1967). In the Gulf of Mexico, the gray triggerfish is a primary reef fish inhabiting the area between 12 and 42 m in depth (Smith 1976), except for its first year of life when it is planktonic and associ­ ated with Sargassum (Dooley 1972). The harvest of the gray triggerfish in the northeastern Gulf of Mexico and its utilization of reef habitats has created a need to know more about the biology of this species, especially age, growth, and mortality. Age and growth of gray triggerfish, using the first dorsal spine, has been reported only for the southwestern coast of Africa (Anonymous 1980; Caveriviere et al. 1981). This paper reports the results of our investigation on age, growth, and mortality, using the first dorsal