© 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.

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Weeping Toado / Banded Toadfish / Common Blowfish / Blowy

Family Name:	Tetraodontidae
Scientific Name:	Torquigener pleurogramma (Regan, 1903)
Recommended Status in S.A:	Data Deficient
Rationale:  Weeping Toado is included here because (i) within the Australian part of the range, the species has mainly an eastern and western distribution, and therefore has a limited presence in South Australia, apparently being found in the central coastal area of the State; (ii) T. pleurogramma is known from a narrow depth range, in estuaries and shallow bays, hence may be susceptible to habitat impacts in coastal waters; (iii) estuaries may be significant nursery areas for juveniles, and there are few estuaries in S.A., hence available habitat for one of the life stages is limited; (iv) the species aggregates seasonally for spawning, which can increase its vulnerability to impacts; (v) pufferfishes lay demersal eggs, and this benthic, site-specific mode of reproduction may increase the vulnerability of populations to impacts; (vi) recreational fishers consider the species to be a nuisance, which increases the mortality rate (particularly in W.A.); and (vii) within South Australia, there is inadequate information available on the relative abundance and population dynamics of this species in the gulfs, or the number taken by recreational fishers, or as bycatch in trawl and other net fisheries.

Page Contents

Current Conservation Status

No listings known

Distribution

Australia

In Australia, the Weeping Toado is found mainly from central Queensland through to southern New South Wales on the east coast; and from the Coral Bay / Exmouth area down to about Albany on the west coast (Hardy, in Gomon et al., 1994; Hutchins and Swainston, 1986, 2001; OZCAM database, 2007). There are abundant records from the entire length of the New South Wales coast (OZCAM database, 2007).
The species is also known from Lord Howe Island and surrounds (Francis, 1993; Hardy, in Gomon et al., 1994; Speare, 2004).

South Australia

Weeping Toado is known from the central S.A. coast, but not from south-eastern South Australia or western South Australia / Great Australian Bight. Examples of locations in S.A. where the species has been recorded include shallow waters in the Whyalla area, and other locations in northern Spencer Gulf; mid-eastern Spencer Gulf (e.g. Port Broughton / Tickera, Wallaroo Bay, Tiparra Bay, and Balgowan area); the “heel” of Yorke Peninsula (e.g. Edithburgh / Troubridge Island area); the Port River / Barker Inlet region and the metropolitan coast of Gulf St Vincent (e.g. old records from the early and mid 1900s, ranging from Outer Harbour to Hallett Cove); the Onkaparinga Estuary; and Encounter Bay (Anonymous, 2003b; P. Jennings, SARDI, unpubl. survey data, 2003; Branden et al., 1974, cited by Hammer, 2006a; J. Aldenhoven, pers. comm. to S.A. Museum, 2006; S.A. Museum records, Museum of Victoria records, cited in OZCAM database, 2007).

Habitat

The Weeping Toado is a shallow water demersal species, found in marine and brackish estuaries and coastal waters (May and Maxwell, 1986, cited in Froese and Pauly, 2007).
The species is common in estuaries and coastal bays in south-eastern and south-western Australia, particularly in southern W.A., where it forms large schools (Potter et al., 1988, 2000; Hutchins and Swainston, 1986; Table 11).
 

Table 11 Estimated biomass of T. pleurogramma as a percentage of all fish biomass in various south-western estuaries.
Estuary	Date of Study	% Biomass	Reference
Canning River	1977-81 1995-97	2% 15%	Loneragan, unpubl. data Kanandjembo, unpubl. data
Upper Swan	1995-97	1%	Kanandjembo, unpubl. data
Middle Swan	1977-81	9%	Loneragan, unpubl. data
Lower Swan	1977-81	78%	Loneragan, unpubl. data
Peel-Harvey	1995-97	70%	Young, 2000
Leschenault Estuary	1993-94	17%	Tiivel, unpubl. data
(Adapted from Platell and Hall, 2006)

At the shallow end of the depth range, it occurs in a variety of habitats, such as the bank edges of coastal rivers (Potter et al., 1988); sandy surf zones (Ayvazian and Hyndes, 1995); rock pools (e.g. Griffiths et al., 2004), and in coastal lakes (e.g. Lake Illawara Authority of N.S.W., undated).
In a study of nearshore marine habitats in south-western W.A., Valesini et al. (2004) reported the both adults and juveniles from moderately sheltered and very sheltered areas, with dense or sparse seagrass within 50m of the shoreline, and also further offshore. A study in 2001-2002 showed that Weeping Toado comprised 3% of the fish biomass over sandy substrates in shallow, nearshore marine waters of south-western Australia (Valesini, unpubl. data, cited by Platell and Hall, 2006).
A study by Hyndes et al. (2003) on differences in fish species composition in seagrass beds of differing structure, showed that the number of Weeping Toado was significantly higher in the vicinity of Posidonia coriacea (which provided a landscape of patchy seagrass amongst areas of bare sand), compared with numbers in denser beds of Posidonia sinuosa, or Amphibolis griffithii.
A study in W.A., showed that estuarine and nearshore marine assemblages of Weeping Toado may remain separated for many months, but that some mixing could occur during the reproductive phase, when fish leave the estuary prior to spawning (Potter et al., 1988). In a more recent study, seasonal differences in numbers of Weeping Toado caught in particular habitat types, support the concept of seasonal migration in this species.
At various locations in south-western Australia, the species has been recorded rarely in reef habitats (Valesini et al., 2004; Hutchins, 2005).
The depth range of Weeping Toado is from the shallow subtidal to about 27m (Hardy, in Gomon et al., 1994) or 30m deep (May and Maxwell, 1986, cited in Froese and Pauly, 2007). There are records in S.A. of specimens from very shallow water (e.g. 0m, 2m) (Museum of Victoria records, cited in OZCAM database, 2007).

Notes on the Biology

Age and Growth

The species grows to around 22cm (Hutchins and Swainston, 1986) or 23cm (Potter et al., 1988).
Weeping Toado may reach a weight of 0.290 kg, the maximum size recorded in W.A., being a specimen caught in the Swan River, in 1990 (Australian Anglers Association, W.A. Division, 2002a). Previously, Potter et al. (1998) had recorded a maximum size of about 220g.
A study in W.A. showed that by the end of their first and second years of life, Weeping Toado reach approximately 90mm (= 14g) and 125mm (39g) respectively (Potter et al., 1988).
The species may live for at least 7 years, based on a study that showed up to 7 age classes present in the Swan River estuary (Potter et al., 1988).

Diet

A study in W.A. reported that T. pleurogramma feeds on a wide variety of organisms, and in estuarine conditions, the main components of the diet are polychaetes and amphipods for fish <130 mm, and bivalve molluscs for larger fish (Potter et al., 1988).

Reproduction

In a study of an estuarine population of Weeping Toado in W.A., sexual maturity was generally not reached until the end of the second year of life. The presence of higher gonadosomatic indices and more mature gonads in fish collected just outside than within the estuary, indicated that T. pleurogramma leaves the estuary before spawning (Potter et al., 1988).
There is little information on the reproduction, but in general, pufferfishes are reported to lay demersal eggs in a nest (Nelson, 1994, cited in Froese and Pauly, 2007).
Large numbers of juveniles may recruit periodically to estuaries, which are nursery areas for this species (e.g. see Potter et al., 1988, 2000).

Other Information

There is some indication that the species may be more active at night than during the day (Valesini et al., 2004).  As well as seasonal movements, it is also reported that aggregations of this species move inshore with the tide (Breidahl, 2001).

Fisheries Information

Southern Australia

Weeping Toado is a minor component of the bycatch (less than 1%, according to one bycatch study) in the shelf sector of the Ocean Trawl Fishery in New South Wales (N.S.W. DPI, 2004).
The species is also part of the bycatch in the estuarine fish haul fishery in New South Wales. For example, a bycatch study (Gray and Kennelly, 2001) showed that Weeping Toado specimens are discarded in the fish haul catches in Botany Bay, Clarence River, and Lake Macquarie.
The Weeping Toado, also known as the “Blowfish”, is unpopular with recreational fishers in southern W.A. and other areas where it is plentiful, due to it habit of taking baits. The fish is very commonly caught in estuaries in south-western W.A., and aggregations of caught and discarded blowfish are sometimes left to die on shore. The Department of Fisheries in W.A. (2005f) advised against this practice, pointing out the important ecological role of T. pleurogramma as estuarine scavengers. Although the species is not edible, a survey in 1998 of the recreational fishing catch in the Leschenault Estuary in W.A., showed that the Common Blowfish (Torquigener pleurogramma) was one of the main finfish species caught by shore-based fishers during the survey period, with an estimate of 428 specimens (S.E. 236) kept and 302 released (S.E. 99) during the survey period (Malseed et al., 2000). In the Leschenault, Peel-Harvey and Swan-Canning estuaries, surveys have shown that the species is retained by both shore-based and boat-based anglers (Malseed et al., 2000; Malseed and Sumner, 2001a, 2001b). In the Peel-Harvey Estuary, a survey in 1998-99 reported that boat-based fishers caught and kept 421 (SE 139) T. pleurogramma specimens, and caught and discarded 3,064 (S.E. 471) specimens (Malseed and Sumner, 2001b). The number caught and kept by shore-based fishers was much higher, with an estimated retained catch from the Mandurah entrance channel of 2,025 (S.E. 1,146), with a further 18,410 (S.E. 2,326) caught and discarded (Malseed and Sumner, 2001b). During the same survey period, in the Swan-Canning system, boat-based fishers caught and kept 793 (SE 189) T. pleurogramma specimens, and caught and discarded 14,086 (S.E. 928) specimens (Malseed and Sumner, 2001a). Shore-based fishers in the Swan-Canning caught 3,544 (S.E. 777) Common Blowfish, with a further 24,801 (S.E. 2,972) caught and discarded (Malseed and Sumner, 2001b).
An example of the large number of unspecified toadfish species (some of which may be T. pleurogramma) caught by recreational fishers in W.A., is provided in the section on the Tetraodontidae family.
Some clubs and associations keep records of the maximum sizes caught by anglers (e.g. Australian Anglers Association W.A. Division, 2002a).

South Australia

Weeping Toado has been recorded from the vicinity of the trawl grounds in central Spencer Gulf (S.A. Museum record, cited in OZCAM database, 2004), hence the species may form part of the prawn trawling bycatch in that gulf. It is noted, however, that a prawn trawl bycatch survey during the mid 1990s (Carrick, 1997), did not record this species from tows at 32 trawl stations in Spencer Gulf. During a recent bycatch survey (Dixon et al., 2005), the species may have been grouped with “miscellaneous fishes”, for which species-specific catch statistics were not recorded.
In S.A., the species is reported to be a very minor part of the bycatch in the Blue Crab Fishery. During bycatch sampling in the Blue Crab fishery in 2002-2005, catches in each gulf were as follows: 1, 1, 4 and 3 specimens caught in Spencer Gulf in 2002, 2003, 2004 and 2005 respectively;  and 0, 1, 6 and 15 specimens caught in Gulf St Vincent in those years (Svane and Hooper, 2004; Currie and Hooper, 2006).
The species is not known to be taken recreationally in South Australia. Catch statistics for unspecified toadfish, pufferfish, and blowfish (which might include a proportion of T. pleurogramma) are provided above, in the section on Tetraodontidae.

Vulnerable Characteristics of the Species

Although the Weeping Toado has a broad distribution in south-eastern and south-western Australia, it appears to have a limited spatial distribution within S.A., being found to date mainly in the gulfs region.
The species is relatively abundant in estuarine areas of eastern and western Australia, where it resides for part of the life cycle (e.g. Potter et al., 1988). There are very few estuaries in South Australia, and therefore limited available habitat for this species.
Pufferfishes lay demersal eggs in a nest (Nelson, 1994, cited in Froese and Pauly, 2007), a population characteristic that increases their vulnerability, compared with fish that do not have such strong site association and site-specific, benthic reproduction.

Threatening Processes

Bycatch in trawl and other net fisheries, and non-target catch by recreational fishers, may both be threatening processes; however there are no fisheries statistics available for this species in South Australia, nor any information on population sizes within the gulfs region.
This species has a relatively shallow distribution (0-30m), and in S.A., it is present in Spencer Gulf and Gulf St Vincent, both regions having been subject to numerous nearshore habitat impacts over many decades (see Baker, 2004, for summary). Given that this species reproduces at a local scale, in the benthic environment, ongoing nearshore habitat degradation may adversely affect populations of Weeping Toado; however there are no data.
A study of the susceptibility of trawl-caught fishes to population impacts (Stobutski et al., 2001) ranked fish bycatch species according to two main characteristics (based upon biological and ecological criteria): (i) susceptibility to capture and mortality due to prawn trawling, and (ii) the population's capacity to recover after depletion. The rank of each species on these two characteristics determined its relative capacity to sustain trawling, and therefore its priority for research and management. Species that were the least likely to be sustainable included those in Tetraodontidae. These species are highly susceptible to capture by trawls, they are benthic or demersal, their primary habitat is soft sediments, and their diet may include prawns, or species that are found in prawn grounds. The recovery capacity of species in Tetraodontidae is also considered to be low, with the estimated removal rate by trawling (Stobutski et al., 2001).

Research Requirements

More information is required on the distribution and relative abundance of this species in S.A., both in the gulfs region, and in western and eastern South Australia.
In S.A., more specific information is required on the capture of this species in commercial trawl fisheries, and by recreational fishers.

Management Requirements

The intentional killing and discarding of pufferfishes such as T. pleurogramma should be discouraged through material (like that produced by W.A. Fisheries) and education programs (e.g. through Fishcare volunteers).
Generally, bycatch of pufferfish species in trawl and other net fisheries should be recorded at species level, over space and time, and methods to reduce bycatch should be adopted.

Other Information

The species is poisonous to eat, due to the presence of tetrodotoxin (a neurotoxin).
Weeping Toado is promoted as a species that is suitable for aquariums, and specimens are sold in shops and through the internet.