Life history, reproductive biology, habitat use and fishery status of eastern sea garfish (Hyporhamphus australis) and river garfish (H. regularis ardelio) in NSW waters
University of Wollongong (UOW)
Ron J. West
There are major concerns over the status of the garfish species in NSW waters, particularly eastern garfish and river garfish. These commercial fishery for these species is considered to be threatened. For example, landings of river garfish from NSW estuaries peaked at over 100t in 1974/75 but have steadily declined since that period. In the past decade, on average less than 30t per year of this species are caught. In addition, there has been a sudden and dramatic drop in the catches of eastern sea garfish in the last decade, from 280t in 1992/1993 to only 29t in 1999/2000. While increasing fishing pressure is one possible cause for these declines in catches, another major concern is the impact of coastal development on the habitats of these species, which appear to have a strong reliance on key estuary and inshore habitats, such as seagrasses (see Background). The continued deterioration of these key inshore habitats in NSW is considered to be another significant impact on the commercial catches. Unfortunately, despite over a century of exploitation, little is known about the biology, life history, or habitat requirements of these two NSW garfish species and no research has been conducted on the fishery itself. With the dramatic drop in catches and the concern about the degradation of key estuarine habitats, there now exists an urgent need to carry out research on the garfishes in NSW waters, particularly on the two exploited species, eastern sea garfish and river garfish. In this joint project carried out by the University of Wollongong and NSW Fisheries, we propose to address this research gap, by providing information on the biology and life history of these two NSW species of garfish, and make recommendations that will help to achieve sustainability of this medium sized, but lucrative fishery.
1. To provide new information on the biology and life history of garfish species in NSW waters, particularly the two dominant species eastern sea garfish and river garfish, including: a. – reproductive biology, b. – time of spawning, c. – age at maturity, d. – initial estimates of growth rate, and, e. – key habitat requirements, particularly the role of seagrasses and other vegetated areas as juvenile nursery areas and as feeding and spawning sites for adults.
2. To provide the research basis for a future stock assessment of eastern sea and river garfish in NSW waters, including: a. – a validated aging technique, b. – estimates of size, age structure and reproductive state of landed catches for both species, and, c. – initial assessment of environmental impacts of the fishery and possible impacts on the fishery.
3. To provide advice to the fishing industry, fishers and NSW Fisheries on the management of the garfish fishery, including recommendations for research and monitoring, to assist in achieving a sustainable fishery in NSW waters.