Determination of spawning areas and larval advection pathways for King George whiting in southeastern Australia using otolith microstructure and hydrodynamic modelling. II. South Australia

Abstract

Two hypotheses regarding the origin of post-larval Sillaginodes punctata that recruit to nursery areas in South Australia were assessed. These were that post-larvae originate either hundreds of kilometres to the west and are delivered by weather-determined ocean currents or they originate from numerous spawning grounds located only <l50 km from numerous nursery areas. The hypotheses were tested in 2 ways. We compared recruitment rates and early life-history characteristics amongst post-larvae sampled at 4 sites located up to 500 km apart. Recruitment rates, size structures of recruits and age, size and growth rates of recently-settled fish did not reflect systematic variation amongst sites, suggesting that recruitment was determined at a local, rather than regonal scale. We also used numerical hydrodynamic modehng to identify larval advection pathways and possible spawning locations, using larval duration and capture site as input to the model. This modelling suggested that recruits originated at spawning locations that were only a short distance from each nursery area. Results from both studies suggested that the South Australian population is divisible into numerous, discrete, selfrecruiting populations, which contrasts with the situation in Victoria where the population constitutes a single large stock. This difference is a Likely consequence of regional differences in current regimes, and the influence on larval advection. KEY WORDS: Stock structure. Larval advection. Hydrodynamic numerical modelling. Otolith microstructure. South Australia. Sillaginodespunctata

Visual Census of the Reef Fishes in the Natural Reserve of the Glorieuses Islands (Western Indian Ocean)

“…Recent studies have shown that autorecruitment was frequent in isolated coral zones (Galzin et al, 1998;Jones et al, 1999;Cowen et al, 2000;Fowler et al, 2000). It could account for a significant part in the fish recruitment of the Glorieuses Islands.…”

Growth, behaviour and colour changes of juvenile King George whiting (Sillaginodes punctata) mediated by light intensities

“…Seagrass beds typically provide juvenile whiting with protection from predation as well as being the habitat for numerous prey items. Research on this species has focused on migratory patterns (Fowler et al 2000;Fowler et al 2002), larval recruitment and settlement (Jenkins & May 1994;Hamer & Jenkins 1997;Moran et al 2004), and habitat usage (Connolly 1994;Jenkins & Wheatley 1998). However, very little is known about the response of this species to light level manipulation.…”

Identifying critical estuarine seagrass habitat for settlement of coastally spawned fish

“…Passive transport predictions, based on modelled estuarine hydrodynamics, are driven principally by tidal flux and wind-driven flows , Cox 2001). Circulation models have been successful in predicting larval transport entering from the ocean to an estuary in order to link larval pathways to the temporal (Jenkins & Black 1994, Brown et al 2004 and spatial variation , Fowler et al 2000 in recruitment. The 'passive-transport' approach has been effective on a spatial scale of tens of kilometres within the large open estuary of Port Phillip Bay, Victoria , and the more complex estuaries of Beaufort Inlet in North Carolina and Aransas Bay in Texas (Brown et al 2005).…”