Map_thumbnail_large_font

Galaxias gracilis 

Scope:Global
Status_ne_offStatus_dd_offStatus_lc_offStatus_nt_offStatus_vu_onStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Osmeriformes Galaxiidae

Scientific Name: Galaxias gracilis
Species Authority: McDowall, 1967
Common Name(s):
English Dwarf Inanga
Taxonomic Notes:  The taxonomic status for this species is currently under review and has been for some time. It is genetically indistinguishable from Galaxias maculatus. G. gracilis was described on the basis of distinct morphologically. Kai Iwi Lake populations are excluded from this assessment as they are independently derived from G.maculatus (Ling et al., 2001)

Assessment Information [top]

Red List Category & Criteria: Vulnerable D2 ver 3.1
Year Published: 2014
Date Assessed: 2014-07-30
Assessor(s): West, D, Franklin, P., Ling, N., Allibone, R, Crow, S. & Closs, G.
Reviewer(s): David, B., Hitchmough, R. & Gibson, C.
Facilitator/Compiler(s): Gibson, C. & Buley, K.
Justification:
The Dwarf Inanga (Galaxias gracilis) is endemic to North Island, New Zealand, where it is restricted to two groups of lakes in eight distinct locations on North Kaipara Head, Northland. It is a non-migratory species that lives throughout the pelagic and littoral areas of multiple landlocked coastal dune lakes. The estimated area of occupancy (AOO) and extent of occurrence (EOO) are both 2.9 km2. Populations in most of the lakes in which this species occurs have undergone significant declines in over the past 30 years and the species has disappeared from some lakes where it was formerly known. Currently, the population fluctuates naturally due to variable recruitment success, however there is still an overall decline in population trend, although specific data are not available. Population declines have been primarily attributed to the introduction of exotic fish species, a decline in water quality and a reduction in water levels due to plantation and forestry land use. Mosquito Fish (Gambusia affinis) pose a significant threat to this species through competition for food and space in the summer and diet studies indicate that predation by Rainbow Trout (Oncorhynchus mykiss) is common and is likely to have contributed to the extirpation of G. gracilis in proximal areas. This species is assessed as Vulnerable based on a restricted area of occupancy of less than 20 km2 and the plausible threat posed particularly by the potential for illegal introductions of other introduced fish, particularly European Perch (Perca fluviatillis).
Previously published Red List assessments:
1996 Vulnerable (VU)
1994 Vulnerable (V)

Geographic Range [top]

Range Description: The Dwarf Inanga (Galaxias gracilis) is endemic to North Island, New Zealand, where it is restricted to two groups of lakes in eight distinct locations on North Kaipara Head, Northland. In the 1980s this species was translocated to Lake Ototoa on South Kaipara Head; an area outside of this species' natural range (McDowall 2000, Department of Conservation 2004, NIWA 2013). The estimated area of occupancy (AOO) and extent of occurrence (EOO) are both 2.9 km2  and have been calculated using Freshwater Ecosystem of New Zealand spatial representation (polygon) data (FENZ 2010). Both calculations exclude the translocated population at Lake Ototoa.
Countries occurrence:
Native:
New Zealand (North Is.)
Estimated area of occupancy (AOO) - km2: 2.9
Number of Locations: 8
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Populations in most of the lakes in which this species occurs have undergone significant declines in over the past 30 years and the species has disappeared from some lakes where it was formerly known (Department of Conservation 2004, NIWA 2013, McDowall 2000). Currently, the population fluctuates naturally due to variable recruitment success, however there is still an overall decline in population trend (Goodman et al. 2014). This species is listed as 'At Risk - Declining' in the New Zealand Department of Conservation's threat classification system, based on a moderate to large population, but with extreme fluctuations and a restricted range where the area of occupancy is less than 10 km2, with a predicted decline of 10-30% (Goodman et al. 2014).
Current Population Trend: Decreasing
Additional data:

Habitat and Ecology [top]

Habitat and Ecology: This is a non-migratory species that lives throughout the pelagic and littoral areas of multiple landlocked coastal dune lakes. When the species is very small, it occurs in the open waters. Juveniles moves inshore at larger sizes and school around lake edges amongst aquatic vegetation, moving to open waters to feed on zooplankton at night. Adults occur in deeper waters of lakes during the day and return to the littoral zone at night to feed on invertebrates (McDowall 2000, NIWA 2013). G. gracilis is the smallest member of the Galaxidae family in New Zealand. The maximum total length recorded for this species is 80 mm, but mature adults are more typically 40-60 mm, with some adults maturing at only 30 mm in length in some populations (NIWA 2013, McDowall 2000). This species has a mostly annual life-cycle but some individuals may live for 2 possibly up to 3 years. Spawning may occur twice a year in late spring and late autumn and may be tied to the moon phase. Spawning is thought to occur in littoral areas on emergent vegetation, with females producing several hundred tiny eggs (McDowall 2000).
Systems: Freshwater
Generation Length (years): 1
Movement patterns: Not a Migrant

Use and Trade [top]

Use and Trade: This species is not currently utilized, however the reason for the translocation of this species to Lake Ototoa was to provide food for introduced Rainbow Trout (Oncorhynchus mykiss) (a recreational game fish species), although the value of this species as trout forage was considered dubious and the G. gracilis population in this lake seems to be stable and is likely protected by the shelter provided by marginal reed beds (McDowall 2000).

Threats [top]

Major Threat(s): Population declines have been primarily attributed to the introduction of exotic fish species, changes in water quality and reduction in water levels due to plantation and forestry land use. Mosquito Fish (Gambusia affinis) pose a significant threat to this species through competition for food and space in the summer and diet studies indicate that predation by Rainbow Trout (Oncorhynchus mykiss) is common and is likely to have contributed to the extirpation of G. gracilis in proximal areas (McDowall 2000, Department of Conservation 2004, NIWA 2013). The potential for illegal introductions of other introduced fish, particularly European Perch (Perca fluviatilis) is a plausible future threat to G. gracilis (B. David pers. comm. 2014).

Conservation Actions [top]

Conservation Actions: This species was included in the New Zealand Department of Conservation's non-migratory galaxiid recovery plan 2003 - 2013 (Department of Conservation 2004), however the time covered by this plan has now passed. Insufficient resources resulted in limited actions (including monitoring and advocacy) being carried out.

Citation: West, D, Franklin, P., Ling, N., Allibone, R, Crow, S. & Closs, G. 2014. Galaxias gracilis. The IUCN Red List of Threatened Species 2014: e.T8812A3147146. . Downloaded on 25 June 2016.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided