BRACHIONICHTHYIDAE: HANDFISHES

Drawing from Waite, 1921. Reproduced by University of Washington Libraries, Freshwater and Marine Image Bank

The Brachionichthyidae is a small family of Australian endemic fishes (Last and Gledhill, 2003, 2009), and a number of species are found over quite small spatial scales, particularly in Tasmania (Last, in Gomon et al., 1994; Bryant and Jackson, 1999; CSIRO, 2005; Last and Gledhill, 2009). In recent years, a revision of the family has considerably expanded the number of described taxa (to 14 species), and includes a number of handfishes from deeper shelf waters in south-eastern Australia (Last and Gledhill, 2009). South-eastern Australian species include Spotted Handfish (or Spotted-hand Fish) Brachionichthys hirsutus; Red Handfish Thymichthys politus (formerly known as Brachionichthys politus or Sympterichthys politus), and the newly described species Brachiopsilus dianthus, Brachiopsilus dossenus, Brachiopsilus ziebelli, Sympterichthys moultoni, Pezichthys amplispinus, Pezichthys compressus, Pezichthys eltanini and Pezichthys nigrocilium (Last and Gledhill, 2009). Several of the newly named handfish species are known from only a few specimens, collected by trawl or dredge in the Bass Strait and /or northern Tasmanian area (Last and Gledhill, 2009).

One newly described species, Longfin Handfish Pezichthys macropinnis, is known only from the type specimen, collected by trawl in deeper shelf waters of the Great Australian Bight. Another species, Smooth Handfish Sympterichthys unipennis, is known only from the type material obtained by Péron during Nicolas Baudin’s expedition to Australia in the first decade of the 1800s. Seven of the 14 known species appear to be confined to Tasmanian waters (Last and Gledhill, 2009). Two of the species, Australian Handfish Brachionichthys australis and Warty Handfish Thymichthys verrucosus (formerly known as Sympterichthys verrucosus or Brachionichthys verrucosus) have broad south-eastern to southern Australian distributions.

Characteristic features of fish in the family include arm-like pectoral fins, and three dorsal fin spines, the first forming an illicium (luring apparatus) and the last two spines interconnected by a membrane, to form a fin that is separate from the more posterior, elongate dorsal fin (Last, in Gomon et al., 1994; Kuiter, 2000).

Bryant and Jackson (1999), Pogonoski et al. (2002) and Commonwealth of Australia (2004) provided an account of the Handfishes (family Brachionichthyidae), and pertinent notes are summarised here: Many of the recognised species have among the narrowest ranges of any of the 4000+ marine fishes of the Australian region, and are potentially at risk due to their small population sizes (Bruce et al., 1998). Although occasionally observed by divers, or collected in dredging or trawling operations, most species have very restricted distributions and their abundances are normally low (Last et al., 1983). Adult and juvenile handfishes are largely sedentary; these shallow-water species are known to have small, distinct and measurable populations over small ranges; they have low fecundity; they rely upon benthic structures for nesting, and have a high degree of parental care of the eggs, fully formed young at hatching (i.e. no larval phase), and poor dispersal capability. Handfishes are slow to expand their range and colonise new areas. The shallow-water species found in estuaries and associated channels are particularly vulnerable to site-specific impacts.

One species, the Spotted Handfish Brachionichthys hirsutus, found mainly in the Derwent estuary in Tasmania, is listed on the IUCN Red List of Threatened Species (IUCN, 2009) as Critically Endangered, particularly due to the decline in quality of its essential habitat. The Spotted Handfish is listed under the Australian Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) as Endangered. Impacts and threats include the widespread occurrence of the introduced Northern Pacific Seastar Asterias amurensis (which eats the “sea tulips” - i.e. solitary ascidians - around which many of the Spotted Handfish lay their eggs in the wild); smothering of handfish egg masses by oysters; illegal collecting; sedimentation / siltation and other pollution from urban and industrial developments in the Derwent area, and habitat disturbance by dredging and net fishing (the latter prior to the late 1980s – early 1990s) (Bruce and Green, 1998; Green and Bruce, 2000, 2001; Commonwealth of Australia, 2004; DPIWE Tasmania, 2005f; CSIRO, 2006). The species was considered to be relatively common in local areas up till the 1980s. Following the marked decline in Spotted Handfish observed during surveys the early-mid 1990s, recovery programs have been undertaken in Tasmania during the past decade, with the involvement of CSIRO Marine Research, Commonwealth Department of the Environment and Heritage, Department of Primary Industries, Water and the Environment (DPIWE), the Tasmanian Aquaculture and Fisheries Institute (TAFI), the University of Tasmania, the Hobart Ports Corporation, and the Tasmanian Conservation Trust. Recovery efforts included a program to control Northern Pacific Seastar populations; a captive-breeding program for Spotted Handfish; monitoring and restoration of spawning sites, and a program to create artificial nests. Captive-bred individuals have been released back into the Derwent system, but the mortality rate is high (Commonwealth of Australia, 2004). Plastic rods have also been laid out in the estuary, so that Spotted Handfish have an alterative vertical structure around which to lay their eggs, and these plastic rods have been used as nests with some success (CSIRO, 2006). There is, however, concern about oysters settling on the artificial nest structures and smothering the egg masses, and also storms removing these rods from the substrate (Commonwealth of Australia, 2004). In addition to stalked ascidians and plastic rods, the Spotted Handfish also uses seagrasses, sponges, a species of Caulerpa (green macroalga), and polychaete worm tubes as spawning substrates (Spotted Handfish Recovery Team 2002, cited by Commonwealth of Australia, 2004). The recovery team for the Spotted Handfish has transplanted species of Caulerpa into the Derwent, in areas depleted of natural spawning substrate (Green and Coughanowr, 2003; Commonwealth of Australia, 2004).

Another Tasmanian species, the Red Handfish Thymichthys politus (formerly Brachionichthys politus or Sympterichthys politus) is listed under the EPBC Act as Vulnerable. T. politus is a shallow-water species found in south-eastern Tasmania (including the Forestier Peninsula, and Actaeon Islands, D'Entrecasteaux Channel) and in Bass Strait, off northern Tasmania (Last and Gledhill, 2009). It occurs in mixed sand and rocky reef habitats, to a depth about 20m deep, and appears to rely upon the green macroalga Caulerpa sp. as a spawning substrate (Commonwealth of Australia, 2004). Like other handfish species, B. politus has low egg production and low dispersal rates, which limit the capacity of the species to occupy a larger range, and make it vulnerable to localised population extinction (Commonwealth of Australia, 2004; Australian Government Department of DEH, 2005c). One Tasmanian species with separate colour morphs, Ziebell's Handfish Brachiopsilus ziebelli, is also listed under the EPBC Act as Vulnerable (DEWHA, 2010) and, like other shallow-water Tasmanian handfishes, has a geographically restricted range, small population sizes, low fecundity, and relies upon specific habitats for spawning (e.g. in the case of Ziebell’s Handfish: sponges and around the edges of macroalgae such as Macrocystis pyrifera on reef patches, surrounded by sand or other soft bottom). Apart from population impacts due to habitat degradation, all handfish species are believed to be subject to illegal collecting and small-scale illegal trade (Commonwealth of Australia, 2004).

The listings for the aforementioned species at State level, under the Tasmanian Threatened Species Protection Act 1995, are identical to the EPBC Act listings. The two handfish species that occur in South Australia have much larger geographic ranges than the endemic Tasmanian species. These southern Australian handfish also have broad depth ranges across the continental shelf, and are thus of less conservation significance than the geographically- and habitat- restricted Tasmanian species. Both are discussed below, due to their strong site association, localised reproduction, capture in trawl fisheries, and lack of information on population sizes or distribution within the range. A third species in South Australia, recently described from the single known specimen, more closely resembling a 45 million year old fossil handfish than any other living handfish, is also discussed here.

Associated taxa