The FRDC recently commissioned a review of the importance of seagrass habitats to fisheries sustainability in which Connolly et al. (in press) identified the "gaps in our understanding and future research needs" and made "recommendations for future research" (In Press: Report No. 98/223).

Connolly et al. (in press; point seven, section 6.4. Gaps in our understanding and future research needs) suggest that the nature of the links between fish and processes such as "feeding, protection from predators and amelioration of physical disturbance" within seagrass habitats are "poorly known". "Hard data on links between seagrass and fishery species are needed urgently" (Connolly et al., in press; section 6.5. Summary of recommendations for future research). Connolly et al. (in press) identify a need for "small scale manipulative experiments", "conducted over a large enough spatial scale" so that we can increase our capacity "to predict the effects of changes in seagrass extent on commercial fish". It is important to understand the importance of "processes linking seagrass with fish" in order to be "able to predict the effects of seagrass changes on fisheries" (Connolly et al., in press; section 6.5. Summary of recommendations for future research).

Connolly et al. (in press) also suggest that "dietary and isotope studies of piscivorous fish are required " because the role of small, non-commercial species in food chains for commercial species is only known in localized areas" (section 6.4. Gaps in our understanding and future research needs, point 12, section 6.5. Summary of recommendations for future research). Isotope studies will also address the need for research which compares the ecology (e.g. extent of assimilation of food from seagrass beds) of fishery species that spend all or only part of their life associated with seagrass" (point 3, section 6.5. Summary of recommendations for future research).

Cappo et al. (1998) reiterate Connolly et al. (in press) in suggesting that information is needed about the role of predation in structuring fish assemblages within seagrass beds. "There is a surprising lack of basic life-history information for most of the major fishery species in Australia", and "consequently a paucity of information on "critical" habitat requirements and processes such as post-recruitment mortality" (section 1.3.4 Lack of knowledge of links between life-histories and habitats).

There are two basic needs for the ling fishery that are addressed by this proposal:

1) It is important to determine whether pink ling from WA, the GAB, the SEF Eastern sector, and the SEF Western sector represent separate stocks, with the implied need for a separate management plan for each, or are simply components of a single large stock best managed as a single entity. Industry has noted the potential for development of the fishery in the west. It is particularly important to establish whether or not the developing western fishery is distinct from the more fully exploited eastern fishery. Stock delineation work needs to be carried out before reliable biomass and yield estimates of stocks can be derived, and before new management plans are put into operation.

2) It is necessary to know for certain whether the orange form is the juvenile pink ling or whether it is a distinct species. This is necessary to integrate non-trawl components of the fishery with the trawl component. If the orange form is the juvenile of the pink form, then it will be important to manage gear types, such as set-netting, that most affect the smaller orange ling. The lack of such protection may otherwise impact on recruitment to the deepwater part of the fishery, which represents almost all of the economic value of ling. Whilst preliminary allozyme analysis indicates that the two colour forms of ling are the same species, there is a need to confirm this using more powerful genetic techniques.