Fisheries WA is currently reviewing the relatively uncontrolled wetline sector of the WA commercial fishery with a view to improving the management of stocks exploited by this sector. In reviewing the existing catch data it has become clear that the major tropical stock exploited by the wetline boats and other finfish sectors are the spanish mackerel.

Due to limited information on the biology and population dynamics of spanish mackerel in WA waters, an urgent management requirement to begin research on this species has been identified. Research information will be collected in parallel with the development of management arrangements and will be used to implement and adjust management controls as data becomes available.

For these management arrangements to be effective, however, there is an urgent need to understand the degree of residency of Spanish mackerel in WA waters relative to NT and QLD. Evidence from the pilot study on stock structure suggests that spanish mackerel in northern Australia exhibit a certain degree of residency, rather than ranging over large distances along the coast. Genetic information is not yet available but the residency shown by groups is sufficient to dictate that a system of sampling along the northern WA and NT coasts would provide samples from the most likely stocks. Furthermore, spreading sample collection widely across each region also increases the chance of having biological data for each stock if finer levels of stock delineation are subsequently identified in the stock structure project.