© Baker, J.L. (2009) Marine Species of Conservation Concern in South Australia Full citation Baker, J.L. (2009) Marine Species of Conservation Concern in South Australia: Volume 1 - Bony and Cartilaginous Fishes. Report for the South Australian Working Group for Marine Species of Conservation Concern. J. Baker (consultant); Science and Conservation Division, and Coast and Marine Conservation branches of S.A. Department for Environment and Heritage (DEH); Marine and Coastal Community Network of S.A. (MCCN), and Threatened Species Network (TSN). Web version published by Reef Watch, South Australia.

---

Blue-throated Wrasse / Bluethroat Wrasse

Family Name:	Labridae
Scientific Name:	Notolabrus tetricus (Richardson, 1840)
Recommended Status in S.A:	possibly Near Threatened
Rationale:  Although the Blue-throated Wrasse is common and widely distributed in S.A., it is included here because (i) the species is highly susceptible to over-exploitation, imbalances in population structure, reduced reproductive success, and population decline, collectively due to its accessibility and ease of capture on nearshore reefs, sedentary nature, highly territorial nature, and life history characteristics (including long life span of more than 15 years, large size, late age at sexual maturity; existence in haremic groups, and protogynous hermaphroditism); (ii) the species is taken commercially and recreationally using a variety of methods, with few controls; it is subject to moderate to intense fishing pressure over much of the range (including most parts of S.A.), with some evidence of localised declines in abundance (particularly the large males), and also, impacts on average size and size structure of the populations. It is noted that the potential vulnerability of Blue-throated Wrasse to over-exploitation is now recognised by marine management in S.A., where the Marine Scalefish Fishery Management Committee (2003) classed wrasses (of which N. tetricus is the main targeted species) as being at high risk of localised depletion; and (iii) in some areas, nearshore habitat degradation may also be a potential threat to this species, with recent studies indicating that loss of macroalgae-dominated habitat can result in emigration of N. tetricus away from its habitat, which may thus affect survival of this territorial species in the long term.

Page Contents

Current Conservation Status

No listings known

Distribution

Southern Australia

Notolabrus tetricus is found in south-eastern Australia, from the Sydney area in New South Wales, through to Victoria, South Australia, and around Tasmania (Hutchins and Swainston, 1986, 2001; Gomon and Russell, in Gomon et al., 1994).
In Victoria, N. tetricus is one of the dominant components of the fish fauna in the Central Victorian and Flinders Bioregions, including areas such as Phillip Island, and reefs around Wilsons Promontory (Environment Conservation Council, 2000; Edmunds et al., 2003).
In Tasmania, N. tetricus is one of the two commonest wrasse species along the north, north-east and east coast (e.g. Barrett and Wilcox, 2001; Edgar et al., 2004). The species is also found around islands in Bass Strait (e.g. Edgar 1984, cited by RPDC, 2002).

South Australia

Records from recreational diving, scientific survey, and commercial and recreational fishing, show that Blue-throated Wrasse is found in most parts of South Australia, and is often a dominant component of the reef fish fauna (e.g. Shepherd and Brook, 2003; Edgar et al., 2006; Shepherd and Brook, in prep.; Shepherd and Baker, in prep.). Examples of locations in S.A. where the species has been recorded include all sides of Kangaroo Island; Encounter Bay area; metropolitan coast of Gulf St Vincent (including artificial reefs and wrecks in the Glenelg area, and reefs at Seacliff, Noarlunga and other locations); central and lower eastern Gulf St Vincent and Fleurieu Peninsula (e.g. Aldinga, Myponga, Carrickalinga, Rapid Head, Rapid Bay, Second Valley, through to Cape Jervis); the upper South-East (e.g. Lacepede Bay – Guichen Bay area, and associated headlands); south-eastern and south-western Yorke Peninsula; mid-eastern Spencer Gulf (Wardang Island); lower Spencer Gulf (including the islands in Thorny Passage); offshore islands at the bottom of the gulfs; Southern Eyre Peninsula (such as Fishery Bay, Cape Wiles, Groper Bay, Cape Carnot, D’Anville Bay, Liguanea Island, Avoid Bay, Greenly Island, and other islands nearshore and offshore, and the southern coastal waters off Lincoln National Park); Western Eyre Peninsula coast and islands, and the coastal reefs and offshore islands of the Eastern Great Australian Bight.
Blue-throated Wrasse is one of the most abundant reef fish in various parts of South Australia. For example, in 2002, a survey of the St Francis Isles in the Nuyts Archipelago (eastern Great Australian Bight) showed that N. tetricus was the most abundant reef fish species, with 1102 individuals recorded in 53 transects (Shepherd and Brook, 2003). Similarly in 2003, during a survey of the marine fauna of the Althorpe group of islands, N. tetricus was recorded as the reef fish species of highest density at those islands (data by G. Edgar and N. Barrett, 2004; Shepherd et al., 2005). During surveys at 53 sites across south-eastern, south-western and southern Gulf St Vincent and Investigator Strait, N. tetricus was recorded at almost all sites; it was the most abundant reef fish recorded at approximately half of those sites; and collectively, more individuals of this species were recorded than any other species during those surveys (Shepherd and Baker, in prep.). At a broader scale, during surveys of more than 150 nearshore reef sites across central and western South Australia (data by S. Shepherd and Reef Watch volunteers, 2002-2006), the species was reported at almost all sites.
During recent surveys in South Australia, examples of locations at which large numbers of juveniles and sub-adults have been recorded include Rapid Head on the Fleurieu Peninsula; Newland Head area near Encounter Bay; Snug Cove and Stokes Bay on northern Kangaroo Island; sites on the northern and north-eastern sides of the Dudley Peninsula (north-eastern Kangaroo Island); parts of Althorpe Island; Memory Cove in south-western Spencer Gulf, and Point Avoid in the eastern Great Australian Bight (S. Shepherd, J. Brook, D. Ashcroft and J. Mather, unpublished data, 2002; S. Shepherd, unpublished data, 2004; S. Shepherd, K. Smith and J. Scott, unpublished data, 2004; S. Shepherd, J. Brook and B. Parkhurst, unpublished data, 2004; Edgar et al., 2006; Shepherd and Baker, in prep.).
Spencer Gulf has been reported, incorrectly, as the western limit for Blue-throated Wrasse in S.A. (see Gomon and Russell, in Gomon et al., 1994); however the species is also recorded as abundant in some areas of the west coast of South Australia. For example, a recent survey at the Nuyts Archipelago in the eastern Great Australian Bight (Shepherd and Brook, 2003), Blue-Throated Wrasse was one of the most abundant fish species recorded, being present in more than 50% of quadrats sampled between 5m and 20m (Shepherd and Brook, 2003). Also, Kuiter (1983) and Branden et al. (1986) recorded the species as common at the islands in the Investigator Group, on the west coast of S.A.

Habitat

Blue-throated Wrasses inhabit reefs (particularly macroalgae-dominated reefs) in both sheltered and exposed coastal waters, between 1m and around 160m (Edgar, 2000).
Adults prefer to live near the bottom close to rocky reefs, and are generally found in deeper waters than juveniles. Immature fish are often found in shallower waters, around kelps and other macroalgae, and near seagrasses, such as Amphibolis and Posidonia (Gomon and Russell, in Gomon et al., 1994; Jordan et al., 1998; Edgar, 2000; Plummer et al., 2003; Shepherd and Brook, 2003; SIV, 2003).
In northern Tasmania, the species has been recorded on reefs with macroalgae cover such as Ecklonia radiata, and Phyllospora comosa, interspersed with barren areas caused by grazing of the urchin Centrostephanus rodgersii (Barrett and Wilcox, 2001). The species also occurs in Giant Kelp (Macrocystis) “forests” (uncited reference, in Edyvane, 2003). Also in Tasmania, juveniles have been recorded in low numbers in Posidonia seagrass beds (e.g. in the Tamar River – Jordan et al., 1998), and adults are reported to occur in seagrass habitat (D. Mills, unpublished data, cited by Jordan et al., 1998) as well as over reefs. On King Island in Bass Strait, and at some sites in northern and eastern Tasmania, N. tetricus has been found in estuaries (e.g. Edgar et al., 1999).
Macroalgae may be an important part of the habitat requirements of this species. An experiment on eastern Tasmanian reefs showed that N. tetricus individuals emigrated from areas artificially cleared of macroalgae (Edgar et al., 2004).
In a survey of the Nuyts Archipelago (GAB) in 2002, Shepherd and Brook (2003) reported that Blue-throated Wrasse juveniles were most abundant at 5m, and declined in abundance with both depth and wave exposure. Densities of post-juveniles (> 10cm) also declined significantly with increasing depth.

Notes on the Biology and Behaviour

Age and Growth

The species grows to around 50cm (Hutchins and Swainston, 1986, 2001; DPIWE Tasmania, 2003b). Males are, on average, between 30cm and 45cm long, and females generally range from 20 to 35cm (Smith et al., 2003). In surveys during the early 2000s in protected areas in Victoria, low numbers of large males in the 40cm – 50cm size category have been observed at Bunurong, Wilsons Promontory, Phillip Island, and in parts of the Port Phillip Heads Marine National Park (Edmunds et al., 2003).
The species can reach up to 4kg in weight (DPIWE Tasmania, 2003b). One of the maximum sizes recorded is 3.3kg, being a specimen taken by spear fishing (Hutchins and Swainston, 1986, 2001). Another large size, recorded by the Australian Anglers Association Records Authority is 2.525kg, being a specimen caught at Coles Point, in 1990 (Australian Anglers Association, 2003). Large specimens have been recorded in some parts of S.A. (e.g. 2.25kg fish from Wardang Island, recorded by ANSA, 1999) and Victoria (e.g. 2.34kg, a specimen caught at Williamstown in 1999, and recorded by Australian Anglers Association – Victorian Division, 2003).
A study in Victoria by Department of Primary Industry’s Marine and Freshwater Systems Platform, formerly MAFRI (see Smith et al., 2003), found that Blue-throated Wrasse is a relatively long-lived fish. Males were found to live to 23 years of age, and the oldest female caught in the study was 19 years old.
Up to the age of 3 or 4 years, growth of Blue-throated Wrasse is very rapid. Growth slows after this age, particularly for females (Smith et al., 2003).

Diet and Feeding Behaviour

Blue-throated Wrasse is a generalist carnivore that feeds diurnally, with a preference for molluscs and small crustaceans (Shepherd and Clarkson, 2001). A study by S. Shepherd of Blue-throated Wrasse over a 15 year period at West Island in S.A., showed that small wrasse eat amphipods and small gastropods living in algae, and larger wrasse eat larger molluscs (including small abalone), crabs, shrimps and sea urchins. Chitons and abalone are the preferred molluscan food, and crabs and shrimps are the preferred crustacean food (Shepherd and Clarkson, 2001). A comparison of prey consumed, with the relative abundance of prey groups, showed that Blue-throated Wrasse takes prey more or less in proportion to its abundance, with variation in this pattern attributed to prey defences and predator choice (Shepherd and Clarkson, 2001).
The 15-year study at West Island in S.A., found that the consumption of young abalone by Blue-throated Wrasse at the study site was 30-70 abalone per year, depending on density. The wrasses controlled abalone abundance, and also controlled crabs, another major predator of small abalone. By controlling crabs, the wrasses ensured that crabs did not reduce abalone abundance substantially. When New Zealand Fur Seals arrived at the island in 1991, they reduced the number of wrasses by 70%, and the survival of young abalone improved substantially, thus demonstrating a “cascade effect” i.e. the abundance of higher order carnivores having a trickle down effect on species lower in the food web (Shepherd, 2003).
Wrasse found around reef areas will aggressively compete with other fish species for territory and food items (DPIWE Tasmania, 2003b).
The species is considered to have a significant ecological role, and may be a “keystone” species, by influencing the abundance of invertebrates, particularly the recruitment of abalone (Shepherd and Clarkson, 2001). A study of abalone over a 15 year period in South Australia (Shepherd, 1998) showed that the mortality rate of small abalone, particularly the greenlip Haliotis laevigata, may be controlled by the density of their major predator, the Blue-throated Wrasse. The long-term study showed that per capita consumption of cryptic abalone increased with increasing abalone density, suggesting a functional response of wrasse to the density of a preferred prey (Shepherd, 1998; Shepherd and Clarkson, 2001).

Migration / Aggregation

Blue-throated Wrasses have a defined home range that increases with increasing size of wrasse (Shepherd and Clarkson, 2001; Edgar et al., 2004). During a study in Tasmania, the home range was estimated to be about 225–725m2 (Barrett, 1995a, cited by Ward et al., 2001). In as more recent study in Tasmania (Edgar et al., 2004). It was shown that some N. tetricus individuals possess small ranges that are maintained for long periods, while other individuals consistently range more widely.
Tag and recapture experiments in Victoria showed that most Blue-throated Wrasse (87%) were relatively sedentary; however 8 fish undertook journeys of 10km or more. One Blue-throated Wrasse was recaptured after undertaking a journey of 40 km. This was considered a surprising result and suggests (in Victorian waters, at least) that Blue-throated Wrasse can move further than previously thought (Smith, 2003).

Reproduction

The species is a sequential protogynous hermaphrodite (Barrett, 1995b; Shepherd and Clarkson, 2001, cited by Shepherd and Brook, 2003; Edmunds et al., 2003). All Blue-throated Wrasse are born female. A study by MAFRI in Victoria found that all young fish smaller than 23cm were female. At about age 4, a few of the larger, dominant females undergo a sex change procedure and turn into completely functional males. The time of the sex change is linked to a complex social structure, as well as the size and age of individuals (Barrett, 1995b; SIV, 2003; Smith, 2003). The sex change is accompanied by a thickening of the body, enlargement of the head, increased body length and change in colour (from mottled browns to blues and yellows) (Edmunds et al., 2003). The male is the dominant individual in a small social harem of females, and he guards the harem against intrusion by other males (Edmunds et al., 2003). Within the harem, there may be up to 10 or 15 females and 1 or 2 males (Shepherd, 2003). The haremic group has a home range of about 2000-3000m² (data by S. Shepherd) If the male fish is removed, then the dominant (usually the largest) female will start to change into a male. Within a one to two month period, a complete sex change will have occurred (Knight and Johnson, 1999; Shepherd, 2003; SIV, 2003). All of the other females will have moved along one position in the line and a vacant position is left at the bottom for a new member (SIV, 2003). Those that subsequently become males grow more rapidly than those that stay as females, hence male Blue-throated Wrasse are generally larger than females.
Females have the capacity to change sex after the age of 4. Sex change can occur when the fish is between 20cm and 25 cm long. In the MAFRI study, researchers estimated that approximately 12% of females per year change sex after age 4. The youngest male caught was 5 years old (Smith, 2003).
The research in Victoria showed that Blue-throated Wrasse females peak reproductively when they are 5 years old and about 25 cm in length, which is below the legal minimum size of capture (28cm) (Smith, 2003).
In Tasmania, spawning occurs between August and January (DPIWE Tasmania, 2003b).
Juveniles are green or brown but as they mature, females gain a black stripe followed by a white stripe across the body. When large females transform into males, they develop a rounded bluish head and yellow pectoral fins and pelvic fins.

Behaviour

According to Barrett (1995a) N. tetricus is a site-associated species, with females having overlapping home ranges and males being territorial.
Individuals have a strong site fidelity to reef areas, and a study in Tasmania showed that N. tetricus generally moved only a small distance (<100 m) from the home reef, during the period of the study (1 year) (Edgar et al., 2004). During that study, movement away from the home reef increased with increasing size of N. tetricus individuals (Edgar et al., 2004). Although N. tetricus are thought to be generally permanent reef residents living in defined home ranges, movement of 40km has been recorded (Smith, 2003).

Fisheries Information

South-Eastern Australia – Commercial

In general, the fish is considered to be very commonly caught on lines and in gill-nets, in southern Australia (Edgar, 2000).
Blue-throated Wrasse is one of the wrasse species taken by commercial fishers in Victoria / Bass Strait (west to Portland) and Tasmania, who also target Purple Wrasse, for the live food fish trade (SIV, 2003; DPIWE, 2003a; Department of Primary Industries, Victoria, 2004).
In Victoria, Blue-throated Wrasse was traditionally used as bait for catching rock lobsters; however, largely due to the growing Asian culture in Australia, this species has increased its value as an eating fish (SIV, 2003). Blue-throated Wrasse became a sought-after commodity for local and interstate restaurants during the 1990s, and a live fishery developed in Victoria at that time. It is now an important target in Victoria for the live fish trade, which supplies specimens to restaurants (e.g. in Sydney), and live fish attract higher prices than gutted fish (Smith et al., 2003, cited by Fairclough, 2004). By the late 1990s, the fishery was harvesting more than 80 tonnes of wrasse per year (Blue-throated and other species) from Victorian coastal waters (Smith, 2003). Wrasse are taken along the entire Victorian coast but catches have been the highest off the central coast (Port Phillip Heads, Western Port, and Wilson’s Promontory), and the west coast of Victoria (Portland, Port Fairy) in recent years (DPI Victoria, 2004). In November 1996 a workshop was held, at the request of fishers, who were concerned about the rapid expansion of the fishery and the level of effort. Following this meeting restrictions were put in place, in 1997. Limitations on the number of operators in the fishery were set. Fishers who could show evidence of a substantial involvement in catching live wrasse were granted an access licence to continue their activity, and a bycatch limit for all other fishers was set, at a maximum level of 8 fish per day (SIV, 2003). During the early 2000s there were 59 Wrasse (Ocean) Access licence holders in Victoria, which reduced to 51 licences by mid-2004 (DPI Victoria, 2004). Baited hand lines with modified hooks (to enable quick release of the fish) are used to catch the wrasse. When caught, the wrasses are placed into a live holding tank on the boat. A small amount (10%) of wrasse is taken as bycatch on long lines, mesh nets and fish traps (SIV, 2003). The wrasse are caught and sold live, and the major market is in Sydney, where wrasses are sold to Asian restaurants. The preferred size for markets is about 30cm total length (SIV, 2003). In Victoria, the commercial fishery harvests Blue-throated Wrasse from reefs in water depths from 20m to 40m. The catch is characterised by 8 - 12 year old males and 5 - 9 year old females (Smith, 2003). Fishers in this fishery release small wrasse under the legal minimum size of 28cm. The proportion of the catch released varies across Victoria, with a recent study showing 25% being released in the east, and 36% in the west; the survival rate of released fish is expected to be high due to the caching method used by operators in this fishery (Smith, 2003).
Total commercial production figures (Anonymous, MAFRI report, 2002a; DNRE Victoria, 2002, 2003, 2004, 2005) for wrasse catches in Victoria are provided (Table 11). During the early and mid 1990s, prior to the development of the specific fishery for wrasse, commercial caches of N. tetricus were lower (e.g. ranging between 1t and 7t per annum, between 1989/90 and 1996/97 (DNRE Victoria, 2002).

Table 11 Commercial catch of wrasse in Victorian Waters 1996 – 2005
Year	Blue-Throated Wrasse Catch (t)	Unspecified Wrasse Catch (t)
1996/97	~ 7	~ 50
1997/98	17	62
1998/99	18	64
1999/00	14	40
2000/01	13	33
2001/02	15	36
2002/03	15	30
2003/04	10	16
2004/05	13	25
(not including Saddled Wrasse)

In Victoria, there is a by-product trip limit of 8 wrasse for fisheries other than the target one, such as the Rock Lobster, Giant Crab, Gippsland Lakes, Port Philip Bay /Western Port Bays and Ocean Fishery Access Licences (DPI Victoria, 2004). Wrasse taken as incidental bycatch and not returned live to the water or sold, are generally used for bait in rock lobster pots (DPI Victoria, 2004).
Temperate wrasses are targeted by commercial fishers in Tasmanian waters for the live food fish trade (Cappo et al., 1998; Murphy and Lyle, 1999). In Tasmania, developments in Australian and international markets and fish handling have recently seen significant increases in effort targeted at wrasses such as Blue-throated Wrasse and Purple Wrasse, which are sold on the premium ‘live fish’ market (DPIWE Tasmania, 2003a, 2004b). Blue-throated Wrasse is listed among the top 5 fish species / groups that suffer catch and release mortality by line fishing in Tasmania (Macleay et al., 2002). In addition to the target fishery, the species is also a bycatch of the fishery for Banded Morwong, but Blue-throated Wrasse are more vulnerable to capture using gillnets of smaller mesh sizes (e.g. 89mm) than are common in this fishery (Murphy and Lyle, 1999). There are minimum (28cm) and maximum (43cm) size limits for the Tasmanian wrasse fishery, and a limited number of licences (Murphy and Lyle, 1999). Landings of both wrasse species have increased during the past decade. The commercial wrasse fishery, which uses hand lines, fish traps and other gear, is now considered to be one of the most important scalefish fisheries in Tasmania (TAFI, 2003). In Tasmania, catches of Blue-throated Wrasse are combined with those of Purple Wrasse, and landings during the past decade are shown below (Table 12).

Table 12 Commercial catches of Blue-Throated and Purple Wrasse in Tasmania, 1990-2003
Financial Year		Catch (t)
1990/91		<80
1991/92		<80
1992/93		100
1993/94		-
1994/95		175
1995/96		80
1996/97		-
1997/98		99 (or 110)
1998/99		98
1999/00		137
2000/01		86 (or 88)
2001/02		90
2002/03		87
(DPIWE statistics, 2002; DPIWE web site, 2003; ABARE and FRDC, 2004).

In Tasmania, Labrids such as Blue-throated Wrasse are commonly used for bait in lobster pots due to their ease of capture and “good numbers” (DPIWE Tasmania, 2003b) (but see below, on Threatening Processes). In a study of bycatch in the Tasmanian Rock Lobster fishery, 18,302 rock lobster pots (without escape gaps) were examined between 1992 and 1997. During that period, 1,452 Blue-throated Wrasse were caught (i.e. an estimate of 13 pot-lifts required for the capture of 1 animal) (Frusher and Gibson, 1998, cited by Ford, 2001). The study also showed that lobster pots with escape gaps can significantly reduce the number of wrasses caught (Frusher and Gibson, 1998, cited by Ford, 2001).
Blue-throated Wrasse are also taken as bycatch in the Commonwealth-managed Southern and Eastern Scalefish and Shark Fisheries (i.e. the SESSF) (AFMA, 2002a), but purportedly have a possession limit of 0 kg when taken from Tasmania, South Australian or Victoria waters, because Blue-Throated Wrasse is a State-managed species. Walker et al. (2003) showed that N. tetricus is vulnerable to capture using gillnets of various mesh sizes and shark hooks of various sizes (including sizes of gillnets and hooks currently used in the Southern Shark Fishery). Although relatively low numbers are recorded in the Southern Shark Fishery, both live and dead specimens are retained, but a proportion is also discarded. Walker et al. (2003) reported that 56 specimens of N. tetricus were retained and 44 were discarded, during a bycatch sampling program in Bass Strait, between 1998 and 2001.
Results of an Integrated Scientific Monitoring Program (Wayte et al., 2004), showed that the bycatch of Blue-throated Wrasse in the South East Trawl Fishery is insignificantly small.
In the Gillnet, Hook and Trap Fishery, Bromhead and Bolton (2005), listed N. tetricus as a retained by-product species, (but see note above, on prohibition of retention in Commonwealth Fisheries, when specimens are taken in State waters).

South-Eastern Australia – Recreational

Blue-throated Wrasse is caught recreationally in southern Australian States. The aggressive (and competitive) behaviour of wrasses makes them prone to easy capture by fishing from rocks, wharves and boats (DPIWE Tasmania, 2003b).
Recreational fishing groups and associations record maximum sizes of Blue-throated Wrasse caught in each State (e.g. Australian Anglers Association – Victorian Division, 2003; Australian Anglers Association, 2005).
In Tasmania, the species is caught by recreational gill-netters; mainly over reefs (see Lyle et al., 2000). In Tasmania, the recreational fishing size limit is 30cm. Previously, there was a daily bag limit of 30 fish, and a possession limit of 45 (DPIWE Tasmania, 2003b); however since November 30^th 2004, the bag limit has been replaced by a personal possession limit of 10 wrasse (DPIWE web site, January, 2005). Because the appearance of male and female Blue-throat Wrasse differs, many anglers assume that they are different species (DPIWE Tasmania, 2003b).
The species is often taken by rock fishers in Victoria, where there is a recreational daily bag limit of 5, and a minimum legal size of 28cm (Fish Victoria, 2003; Department of Primary Industries, Victoria, 2004). The annual retained recreational catch of mixed species of wrasse in Victoria is estimated to be similar to the commercial catch, based on data obtained from the 2000/01 National Recreational and Indigenous Fishing Survey (Henry and Lyle, 2003); however the number discarded is likely to be higher than that recorded, because recreational fishers often discard wrasses (Department of Primary Industries, Victoria, 2004). Anecdotal evidence suggests there is a problem with some anglers who confuse female or juvenile Blue-throated Wrasse with other species of wrasse, and therefore mistakenly believe that no size limit would apply (DPI Victoria, 2004). General notes on recreational fishing of wrasses in Victoria are provided above, in the section on Labridae.
The species is caught be spear fishers across the range. One of the record-sized specimens (3.3kg) was taken by spearfishing (Hutchins and Swainston, 1986, 2001; Australian Underwater Federation, 2003).

South Australia – Commercial and Recreational

In South Australia, the species is caught by commercial and recreational line fishers, spear fishers, and charter boat fishers. Examples of locations where wrasse species are taken (with the majority being Blue-throated Wrasse) include lower Gulf St Vincent through to the Encounter Bay area; Pondalowie and Daly Head area on lower Yorke Peninsula (particularly for recreational and charter boat fishing); south-western Spencer Gulf / Thorny Passage area (a major commercial fishing area for wrasse species); eastern Spencer Gulf (e.g. Wardang Island area); south-eastern Spencer Gulf / Hardwicke Bay area (commercial and recreational); mid-west coast waters, such as the area seaward of Elliston (a major area for commercial and recreational fishing of wrasses); areas seaward of the bays along the far west coast, including the inner islands of the Nuyts Archipelago (commercial and recreational); Avoid Bay and other coastal and island locations off the southern tip of Eyre Peninsula, (mainly commercial fishing, but sports fishing reports also from the area); Wedge Island region and surrounding waters south of Spencer Gulf and north-west of Kangaroo Island (commercial and charter boat fishing); Investigator Strait (commercial and recreational); the mid to lower South-East (e.g. from Beachport to Port MacDonnell and further east to the Victorian border, which is one of the major commercial fishing areas for wrasse in S.A., and recreational fishing also occurs, closer to shore); deeper waters off southern and south-eastern Kangaroo Island, and deeper waters west of Coffin Bay on the west coast, and west of the Robe to Beachport area, in the south-east (the latter three locations are used for commercial fishing) (compiled from recreational fishing reports and surveys, 2000-2003, and SARDI Aquatic Sciences data, 1995-1997).
In S.A., commercial wrasse catches increased rapidly during the mid and late 1990s, and doubled in 5 years, to a maximum of 47 tonnes in 1998 (Knight and Johnson, 1999). Catches decreased from that peak, during the early 2000s. The yield in 2000/2001 was 20t, from 270 boat-days effort (Knight et al., 2002). The market for wrasse species has increased since the 1980s, when catches were lower (i.e. less than 15t per annum in all years of the 1980s for which catch is recorded). The commercial wrasse catch comprises 3 wrasse species (N. tetricus, N. parilus, and Pictilabrus laticlavius), but the majority of the catch is Blue-Throated Wrasse. The commercial wrasse statistics presented below do not include the catch by Commonwealth-licensed trawl and shark fishers (Figure 4).

Figure 4 Wrasses: Commercial catch and effort in South Australia, 1984/85 to 2004/05

(comprises mostly N. tetricus)

The species is also a component of the bycatch in South Australian Rock Lobster Fishery (Sloan, 2003a). In that fishery, Blue-throated Wrasse that are caught in rock lobster pots are permitted to be retained for sale (Sloan, 2003a). Wrasses are also one of the two main groups of scalefish species (along with leatherjackets) taken in rock lobster pots, that are retained for use as bait (Sloan, 2003a). Prescott and Xiao (2001, Table 5), reported that, in terms of numbers caught, wrasses (Labridae) were the second largest group of bycatch species (after leatherjackets) in the Northern Zone Rock Lobster fishery in South Australia, according to a sampling of 32,000 pots in 1991 – 1992. During that period, 1127 Labrids were caught in pots during the bycatch sampling program, of which 177 fish were Blue-throated Wrasse, 10 were Blue Groper, 2 were "parrotfish", and 938 were unspecified species "in the Labridae family". For the Southern Zone (21,000 pots sampled), 205 Labrids were reportedly caught during the 1991-92 season (Prescott and Xiao, 2001 – Table 5). A more recent bycatch survey also showed that Blue-throated Wrasse was one of the most commonly caught scalefish species in both the Northern and Southern Zone of the S.A. Rock Lobster Fishery (Brock et al., 2004). Examples of catches of wrasse species are shown (Table 13). Catches of N. tetricus in the rock lobster fishery are reported to be highest at shallower depths (less than 45m) (Brock et al., 2004).

Table 13 Proportional catch of wrasses (mainly N. tetricus) in the S.A. Rock Lobster Fishery
Northern Zone	No. pot lifts (and percentage of total)	No. Wrasse specimens caught
2001/02	320,003 (51%)	11,113
2002/03	265,843 (47%)	9,156
Southern Zone	No. pot lifts (and percentage of total)	No. Wrasse specimens caught
2001/02	545,886 (60%)	14,844
2002/03	486,155 (57%)	14,658
from Log Book Monitoring 2001-2003 (Brock et al., 2004)

It is noted that during 2002/03, 417 specimens of N. tetricus were recorded in 1% of the total number of pot lifts in the Southern Zone, and 181 were recorded in the Northern Zone. Based on bycatch sampling and logbook monitoring programs, the annual catches of Blue-throated Wrasse in the Northern Zone and Southern Zone were estimated to be about 25,000 and 36,062 individuals respectively (Brock et al., 2004). The accuracy of the total catch estimates cannot be determined here; however, unless the species aggregates in the specific locations sampled, the sample figures indicate that the total annual catches may indeed be in the vicinity of those estimated.
In monitored spear-fishing competition during the early 1980s, Blue-Throated Wrasse formed a significant part of the recorded spear-fishing catch. For example, the species comprised 18% of the total number of fish speared at Gleeson’s Landing (and 30% of the weight of all fish landed from that area); 11% of the number of fish speared at Cape Jervis, and 10% of the total weight of fish landed from Victor Harbor. In some competitions, Blue-throated Wrasse was one of the top 5 species landed, in terms of numbers speared, and the species was listed in the top 5 to 10 species speared in various other events. The species was also caught in spearfishing competitions in which it was ineligible for inclusion (see Johnson, 1985a and 1985b, and tables in Ottaway, 1980). More recently, the species was listed as one of the targets in the 54^th Australian Spearfishing Titles 2006, held on northern Kangaroo Island (Australian Underwater Federation, 2006).
Recreational fishing groups record maximum sizes of Blue-throated Wrasse caught (e.g. ANSA State Record chart for South Australia: http://www.wicked.com.au/ansa-sa/recsa.txt).
During the National Recreational and Indigenous Fishing Survey, recreational catches of Blue-throated wrasse in S.A. were not recorded at species level; however during the survey period, a total of 64,199 wrasses were taken in S.A. (SARDI data, September, 2005), and a large proportion of this catch is likely to have comprised N. tetricus. During the survey period, the recreational catch of wrasses (of which N. tetricus is likely to have been a significant component) was 52.6% of the total (commercial plus recreational) catch (MSFMC, 2003).

Vulnerable Characteristics of the Species, and Threatening Processes

Blue-throated Wrasses have a number of characteristics that make them vulnerable to over-exploitation, and population decline. Blue-throated Wrasses are sedentary, territorial and strongly site-associated with nearshore reefs; long-lived (>15 years); attain a large size; have a late age at sexual maturity; and exist in haremic groups (in which there is only 1 male to a number of females), with size-based hierarchies. The protogynous hermaphroditism - i.e. sex change - in this species may also increase population vulnerability, and heavily fished populations may suffer imbalances in population structure. Intense fishing, by removing the large males and large females, can affect reproductive success and reduce the number of small Blue-throated Wrasse entering the population (Shepherd, 2003). For example, Shepherd (2003, also Shepherd and Brook, in prep.), who monitored the abundance of the Blue-throated Wrasse at Cape Jervis in South Australia over a 22 year period to 2003, reported that, due to intense coastal fishing in the area, wrasse abundance declined over the survey period, and mean size also declined steeply. After an access road was made in 1989, male Blue-throated Wrasses were not seen at all in the area. Shepherd (2003) considered that shore fishers can severely affect populations of these wrasses by fishing the males (which preferentially take the bait), ultimately causing a decline in wrasse numbers. Similarly, in Victoria, male Blue-throated Wrasses are considered particularly vulnerable to fishing due to their large size.
Studies by S. Shepherd (Shepherd and Brook, in press) have shown that mean size of N. tetricus, and the female to male sex ratio at a site, together provides a reliable index of intensity of nearshore rock fishing, and can be used to measure long-term and spatial changes in wrasse populations due to fishing. Large females and males are more vulnerable to line fishing gear than small ones. Due to fishing, mean size of females can decrease, and female to male sex ratio can increase. Studies of size ranges at various areas across S.A. have shown that mean sizes of N. tetricus is larger in areas of low or no fishing pressure (including protected areas), and mean size is low in areas of moderate to high fishing pressure, such as nearshore reefs close to large population centres, or those which are visited by many tourists (Shepherd, 2006; Shepherd and Brook, in press). According to Shepherd, moderate fishing pressure alone is enough to virtually eliminate males from populations and prevent reproductive success.
The reduction in Blue-throated Wrasse may have ecological ramifications, including effects upon the abundance of crabs, abalone and probably many other species in a community (Shepherd, 2003).
Fishing (hook and line, spear, and other methods) is the major threat to this species, and fishing regulations are required in areas where the species is taken, particularly in commercial quantities, and in nearshore areas where recreational fishing is intense, and unmonitored. In Victoria, prior to the development of fishing regulations during the late 1990s, catch rates had declined in the fishery, and the size of the fish in the catch had decreased since the early 1990s (see SIV, 2003 and Smith, 2003). In Victoria, this species is subject to considerable fishing pressure for the live fish market, and because of their larger size, male Blue-throated Wrasse are particularly vulnerable (Edmunds et al., 2003). In Tasmania, fishers noticed a decrease in catch rates of wrasse less than 5 years after the development of the “live fish” fishery (Murphy and Lyle, 1999). The potential vulnerability of this species to over-exploitation is now recognised by marine management in S.A., where the Marine Scalefish Fishery Management Committee (2003) classed wrasses (of which N. tetricus is the main targeted species) as being at high risk of localised depletion.
Wrasses are commonly found around reef areas where they will aggressively compete with other fish species for territory and food items. This aggressive behaviour makes wrasse prone to easy capture by fishing from rocks, wharves and boats. A characteristic of wrasse when hooked is that they will dive in between rock crevices or weed in an effort to evade capture (DPIWE Tasmania, 2003b).Wrasse are active feeders during the day, and therefore easily take baits. In Tasmania (where Blue-throated Wrasse are commonly used for bait in lobster pots), localised stock depletion has been reported on some reefs, due to heavy fishing pressures, particularly by line fishing, and to a lesser extent, netting (DPIWE website, 2002; DPIWE Tasmania, 2003b). The larger individual Blue-throated Wrasses (often males) are attracted to divers (e.g. Barrett and Buxton, 2002) and such behaviour can increases their vulnerability to being speared.
In Victoria, period surveys on a metropolitan reef over a long period have shown that the average number of N. tetricus recorded in the area decreased from an average of 60 sighted per 6 transects in 1959, to 6 sighted in 1964, and 0 in both 1982 and 2006 (Nevill, 2006). The ease with which this species can be taken by spearfishers in the area was considered to contribute to the decline in Blue-throated Wrasse numbers over time (Nevill, 2006).
In some areas, habitat degradation within the nearshore part of the range may also be a potential threat to this species. For example, the species is strongly site-associated with macroalgae-covered reefs, including kelp habitat (Barrett, 1995a, 1995b). Recent study of movements of N. tetricus on Tasmanian reefs (Edgar et al., 2004), indicate that loss of kelp can result in ecosystem changes, in the form of emigration of the abundant wrasse species N. tetricus, and, because of territoriality (Barrett 1995a), such changes perhaps affect survival of this species.

Notes on Current Research and Management

In both Victoria and Tasmania, information is being collected on the species composition, size/age composition and structure of the wrasse fishery. Additionally, trends in catch and catch- per-unit-effort are also being examined, and suitable fishery and biological reference points for the fisheries are being determined. The research in Victoria and Tasmania is being conducted through both sampling from commercial vessels around the State, and fishery independent sampling at sites along the east and south coasts, and the information is being used to further improve the management arrangements for this fishery (Smith, 2003; TAFI, 2003). Details of research programs on Blue-throated Wrasse are outlined in the points below.
In Victoria, the Marine and Freshwater Resources Institute (MAFRI), in conjunction with Seafood Industry Victoria (SIV) and commercial fishers, conducted a comprehensive biological study of N. tetricus in response to the increasing demand, and in order to assist with the development of appropriate management plans (Fairclough, 2004). The study in Victoria of the Blue-throated Wrasse fishery, and the population dynamics of the fish (see summaries by Smith in 2003, SIV in 2003 and Victorian DPI, in 2004), reportedly showed that the current catch levels and fishery regulations (including a legal minimum length, and a cap on the number of operators in the fishery) are adequate to protect the reproductive potential and sustainability of the Blue-throated Wrasse fishery, including the proportion of males in the population (Smith, 2003). The legal minimum length (LML) in the fishery is 28cm, and there is a requirement to return fish under this size to the water. It is noted that the threshold size and age for sex change occurs below the LML, as well as age at maturity, with a peak in reproduction at around age 5 (25cm) (Smith, 2003).
In Victoria, studies have been undertaken into (i) the mechanism of sex change in N. tetricus, and (ii) age estimation using dorsal spine sections, and a comparison with age estimates using otoliths (studies by R. Francis and S. Metcalfe respectively, cited by Anonymous, 2002d and Plummer et al., 2003). The latter study showed no significant difference between the ages estimated using dorsal spines and otoliths, and suggested that dorsal spines may be a preferable method, because the fish do not have to be killed to be aged (study by S. Metcalfe, University of Melbourne, cited in Anonymous, 2002d). Other recent studies include the effects of fishing mortality on demography of Blue-throated Wrasse in Victoria (cited in Plummer et al., 2003).
University-based research into aspects of the ecology of N. tetricus is being undertaken on the east coast of Tasmania, with an emphasis on larval taxonomy, settlement ecology and growth modelling (University of Tasmania, School of Zoology website, 2003).

Research and Management Requirements

There appears to be insufficient monitoring effort and data collection and analysis to assess the long-term sustainability of Blue-throated Wrasse populations in S.A., given that the species is fished by a variety of sources. Stock assessments, similar to those being undertaken in Victoria and Tasmania, are desirable for Blue-throated Wrasse in South Australia. Although there is no specific live fish fishery for Blue-throated Wrasse in S.A., the species is caught in large numbers as a by-product in the rock lobster fishery, also in increasing numbers (during the past decade) in the Marine Scalefish Fishery, and is also caught in significant numbers by recreational fishers.
Commercial catches of wrasses in State waters should be separated by species, and catch statistics should be monitored over space and time. Commercial, by-product, discarded by-catch and recreational catch statistics should all be collated over space and time, as part of an overall assessment of Blue-throated wrasse populations in S.A. waters. Prescott and Xiao (2001) and Brock et al. (2004) demonstrated that fishers in the rock lobster fishery can effectively collate by-product and bycatch data for their own fishery, over space and time. Similar efforts could perhaps be made in the Marine Scalefish Fishery. Assessments of wrasse population status, and of the sustainability of wrasse fisheries in S.A., should be undertaken at suitable spatial scales. For example, research in Tasmania has shown that although wrasse attain maturity well before they are recruited to the fishery, they demonstrate strong site attachment and, therefore, assessment should be based on an appropriate spatial scale. Collection and analysis of catch and effort data at a broad scale (e.g. fishing block) may mask more localised changes in abundance (Lyle and Jordan, 1999), and therefore local population declines may be harder to detect.
Measures to reduce the seemingly large catches of this species in rock lobster fisheries should be implemented. For example, escape gaps, and any other effective fish exclusion devices, should be a requirement for rock lobster pots in all southern Australian fisheries. The practice of catching and killing this species for use as rock lobster bait should be prohibited and alternative bait sources should be investigated.  In Victoria, the practice of retaining wrasses for use as bait is of some concern to fisheries management, because it constitutes a component of the overall mortality of Blue-throated Wrasse that is not accounted for (in stock assessments) (Department of Primary Industries, Victoria, 2004).
In Tasmania and Victoria, where the species is taken commercially, assessment is required of the population impacts of the size selectivity in the fishery, according to the gear used (mainly lines and traps) and the legal minimum and maximum sizes (i.e. mid-size fish are preferentially targeted).
The species occurs in a number of the Aquatic Reserves in South Australia (e.g. West Island, Troubridge Hill, Aldinga and others). However, the size of these reserves is small relative to the geographical range of the species, and the large area over which the species is fished. An increased number and size of marine protected areas in S.A. may be a useful conservation measure for this species, given its strong reef association. There is some evidence that protected areas benefit this species, particularly in areas where recreational fishing may be intense. For example, Shepherd (2003) monitored a reserve area at West Island in S.A. over a 15 year period, and male Blue-throated Wrasses were regularly sited within the protected area. At Cape Jervis, a fished area of the coast to the west of West Island, no male Blue-throated Wrasses have been observed in recent years, and numbers declined over the 15-year period of monitoring. Similarly in Victoria, the Popes Eye area of Port Phillip Bay has long been protected from fishing, as a marine reserve, and is now part of a larger Marine National Park. Recent studies have shown that individuals of N. tetricus are abundant in the Popes Eye area, and that there is a relatively high proportion of males, compared with fished areas. Areas less accessible to fishing (e.g. outside the Heads) also had a reasonably high proportion of male N. tetricus; however in other parts of Port Phillip Bay, where fishing occurs, there were low abundances of N. tetricus; individuals were a small size, the proportion of males in the populations were low (0% - 6%), and few large fish were observed (Edmunds et al., 2003). In the Point Franklin area, where spearfishing pressure is reported to be the highest of all areas in Victoria, surveys over a 5 year period showed that abundances of N. tetricus were very low (Edmunds et al., 2003).  Surveys in the Bunurong Marine National Park showed that the abundance of Blue-throated Wrasse, including large individuals (males), was greater in the centre of the reserve than around the “edges” (i.e. eastern and western sides) (Edmunds et al., 2003). In Tasmania, Edgar and Barrett (1999) showed that after 6 years of protection from fishing, the mean size of N. tetricus increased significantly inside the Maria Island Marine Reserve, compared with fished reference sites outside. A more recent study of movements of reef fish in eastern Tasmania, concluded that the sedentary nature of Labrids such as N. tetricus indicates that relatively small (1km diameter) marine protected areas should generally provide conservation benefits for these fishes, but with few `spill over' benefits in surrounding areas (Edgar et al., 2004).
As well as demonstrating the value of protected areas for reef-associated species such as Blue-throated Wrasse, the 15-year study at West Island in South Australia, demonstrated another value of protected areas, because it showed the strong interaction of different species in the food web, including the key ecological role of Blue-throated Wrasse (Shepherd and Clarkson, 2001; Shepherd, 2003). This ecological study would not have been possible in a fished area. Marine Protected Areas, by conserving the ecosystem in small areas, can help conserve biodiversity, but can also show some of the subtle, long-term effects of fishing in coastal waters (Shepherd, 2003).

Other Information

The species is present in most of the Marine National Parks (MNPs) and Sanctuaries in Victoria. Examples include Corner Inlet, Wilsons Promontory (where N. tetricus is abundant), Merri, Marengo Reefs, Barwon Bluff, Bunurong (abundant), Cape Howe, Gabo Island, Eagle Rock, Mushroom Reef, Point Danger, Port Phillip Heads, Popes Eye (where the species is more abundant inside The Annulus than in surrounding waters), Phillip I. (abundant), Point Lonsdale, Point Nepean (N.B. the previous Popes Eye and Point Lonsdale Marine Reserves are now part of Port Phillip Heads MNP, as is Point Nepean), Point Danger, The Arches, and the Twelve Apostles (Parry et al., 1990; Porter, 1999; Turner and Norman, 1998; Stone, 1999; Ferns and Hough, 2002; Edmunds et al., 2000; 2003; Plummer et al., 2003).
Blue-throated Wrasse occurs in a number of marine reserves in Tasmania, including Maria Island and Port Davey / Bathurst Harbour (Parks and Wildlife Service, 1998; DPIWE, 2005e), Governor Island (Murphy and Lyle, 1999) and Tinderbox, Ninepin Point and Crayfish Point (Barrett and Buxton, 2002; Barrett et al., 2002). It also occurs in the area of the proposed reserve at Three Sisters – Goat Island (Barrett and Wilcox, 2001).
A study of the Maria Island (7 km coastline length) marine reserve in Tasmania over a 6-year period (Edgar and Barrett, 1999), showed that the number and mean size of Blue-throated Wrasse increased significantly within the reserve relative to external reference sites, and this was attributed to the protection from fishing provided by the Maria Island reserve (Edgar and Barrett, 1999).

Support for S.A. Listing:

Barry Hutchins (Western Australian Museum); Scoresby Shepherd (SARDI Aquatic Sciences, South Australia)