Scalefish Southern Garfish Biology


SpeciesHyporhamphus melanochir
Common NameSouthern Garfish
HabitatShallow inshore water in association with seagrass beds
Depth≤ 20 m (Gomon et al., 2008)
DistributionEndemic to Australia, from Eden (New South Wales) to Perth (Western Australia), including Bass Strait and Tasmania (Gomon et al., 2008)
DietPredominantly herbivorous (seagrass, algal filaments) but also consuming planktonic crustaceans, worms, diatoms and stray insects landing on the surface (Edgar, 2008; Klumpp and Nichols, 1983)
Stock StructureFour genetically distinct populations distributed across Western Australia, western South Australia, eastern South Australia/Victoria, and Tasmania; likely at least two subpopulations exist in Tasmania, as indicated by different size and age characteristics on the north vs. east coasts (Grant, 1991; Jones et al., 2002)
MovementSchooling fish, highly mobile, near surface at night and close to bottom during day
M (Natural Mortality)High (55% for adults ≥ 4 years on the east coast) (Jones, 1990)
Maximum Age (years)9 (Jordan et al., 1998)
Unsexed K (von Bertalanffy growth parameter)-0.54 (from 6 months of age)
Unsexed t0 (age (years) when length = 0)0.23 (from 6 months of age)
Unsexed L∞ (asymptotic von Bertalanffy length (fork length; cm))34.3 (from 6 months of age)
(FL; fork length (cm)) – Weight (W; g) RelationshipW=0.0011L^3.4403) (Jordan et al., 1998; Hartmann and Lyle, 2011)
Size at Maturity (length (fork length; cm) at which 50% of population are sexually mature)19.9 (females), 17.1 (males) (Hartmann and Lyle, 2011)
Spawning SeasonOctober – February (peak October – December)
Spawning LocationConcentrated in shallow (<5m) waters over beds of drift algae in eastern Tasmania
Additional Spawning InformationEggs negatively buoyant, sinking to bottom after fertilisation and becoming attached to drift algae (Jordan et al., 1998)
Batch Fecundity (F; number of eggs) to Fork Length (FL; cm)F=188.75L-3585.8 (Hartmann and Lyle, 2011)
Egg Size2.93 mm diameter (Jordan et al., 1998)
Early Life HistoryAfter estimated incubation period of one month, large hatchlings (7.8 – 8.5 mm) are assumed to stay in shallow sheltered waters as indicated by the presence of small juvenile (0+ cohort) in coastal waters of eastern Tasmania (Jordan et al., 1998)