Summary

This report documents the results of the FRDC funded study into “Life history, reproductive biology, habitat use and fishery status of eastern sea garfish (Hyporhamphus australis) and river garfish (H. regularis ardelio) in NSW waters.”

There have been major concerns over the status of garfish stocks in New South Wales waters since the late 1990’s. These concerns stemmed from large declines in commercial landings and the degradation of habitats resulting from coastal development. This study addressed these concerns by investigating, for the first time ever, the biology and fisheries for garfish in New South Wales.

There were found to be 3 distinct fisheries for garfish in New South Wales: those for eastern sea, river and snub-nosed garfish. In-depth analyses of reported commercial catch statistics indicated that the fishery for eastern sea garfish has been in serious decline in terms of catches and catch rates. Landings of river and snub-nosed garfish have declined, but were associated with declines in fishing effort.

The reproductive biology of each species of garfish was also described. All 3 species had protracted spawning seasons (~ 6 months), during which time individual fish spawned several times. Garfish have very large eggs (3mm in diameter) in relation to their body-size, resulting in relatively low numbers of eggs being produced at each spawning event. Sexual maturity occurred at ~ 1 year of age in each species.

New methods were developed to estimate the age of garfish. Maximum ages of 4 years for eastern sea garfish and 7 years for river and snub-nosed garfish were observed. Growth rates were fast in all 3 species and they became vulnerable to fishing at around 1 year of age.

During the study period (2001 to 2003) the commercial fisheries for river and snub-nosed garfish were dominated by fish aged between 2 and 4 years old. Stocks of river and snub-nosed garfish were found to be heavily exploited, with egg per recruit and spawner biomass per recruit modeling indicating present levels at around 40% of the unexploited stocks. The fisheries for river and snub-nosed garfish appear sustainable at present levels of exploitation.

The commercial fishery for eastern sea garfish was dominated (97%) by fish aged less than 2 years old. Estimates of annual mortality rates indicated that approximately 96% of eastern sea garfish died each year, and that much of this was due to fishing. Egg per recruit and spawner biomass per recruit modeling indicated present levels of between 10 and 25% of the unexploited stock. These low levels, combined with high levels of fishing pressure and the life-history of this species (short-lived with recruitment likely to be variable and dependant upon environmental conditions) suggest that the stock of eastern sea garfish has been in danger of recruitment failure. The NSW DPI, in conjunction with commercial fishers, have developed a recovery program for eastern sea garfish that is mainly designed to reduce fishing pressure on the stock. This reduction in fishing pressure, in conjunction with the declaration of sanctuary areas through Marine Parks, and the life-history of sea garfish (having fast growth rates with sexual maturity occurring at around 1 year of age) suggest that the stock should recover if favourable environmental conditions for recruitment occur in the future.