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We present findings of the first mesoscale study linking larval fish assemblages and water masses along shelf waters off south-eastern Australia (southern Queensland-New South Wales), based on vertical, non-depth discriminate data from surveys in October 2002 and 2003 (spring) and July 2004 (winter). Clustering and ordination were employed to discriminate between larval assemblages and, for the first time, to define water masses from water column temperature frequencies. Surveys yielded 18 128 larval fishes comprising 143 taxa from 96 identifiable families, with small pelagics accounting for 53% of the total. Three major recurrent larval assemblages were identified during the study, each of which matched one of three water masses, namely East Australian Current to the north (EAC; 20.5-23.4°C), Tasman Sea to the south (TAS; 14.8-17.5°C), and mixed EAC-TAS water in between (MIX; 18.3-19.9°C). All three assemblages were present in spring, whereas only EAC and MIX occurred in the more northerly constrained winter survey. Furthermore, boundaries between the EAC, MIX and TAS assemblages were found to be dynamic, with locations shifting temporally and spatially depending on EAC extent. Assemblage composition differed significantly between water masses across surveys, with EAC-TAS being most dissimilar. Such contrast was due to the presence of tropical ⁄ temperate taxa in EAC, primarily temperate-associated taxa in TAS, and a combination of EAC-TAS taxa within MIX consistent with the convergence of both waters. Results highlight the strength of employing larval assemblages as indicators of water masses, particularly in view of the potential effect of climate change on spawning habitats of shelf fishes.

In May 1995, numbers of little penguins, Eudyptula minor, coming ashore declined at Phillip Island and St Kilda concurrently with deaths of many penguins in western Victoria and a massive mortality of one of their food species (pilchard) throughout southern Australia. Among 1926 dead penguins reported were 131 banded birdsrecovered from Phillip Island (86% adults and 14% first-year birds), 26 from Rabbit Island and six from St Kilda. The number of banded penguins found dead per number of adult Phillip Island birds at risk was 2.3% in 1995 compared with an annual mean of 0.7% for 1970–93. Of 29 corpses autopsied, at least 26 died of starvation associated with mild–severe gastro-intestinal parasitism. Following the pilchard mortality, egg-laying by penguins in the subsequent breeding season (1995–96) was ~2 weeks later than the long-term mean and 0.3 chicks were fledged per pair compared with the long-term mean of 1.0. Unlike previous years, few penguins were recorded in Port Phillip Bay in September–October 1995, a period when pilchard schools were infrequently seen. It is concluded that the increase in penguin mortality in northern Bass Strait and the significant reduction in breeding success were associated with the widespread pilchard mortality.

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Fish larvae were sampled in the entrance channel and in the two basins of the permanently open Nornalup-Walpole Estuary, on the southern coast of Western Australia, in each month between October 1989 and September 1990. Sampling yielded a total of 39 068 larvae belonging to 36 species and 23 families, with the engraulidid Engraulis australis (56.7%) and the gobies Pseudogobius olorum (24.4%) and Favonigobius lateralis (15.0%) being the most abundant species. Most of the larvae were caught between November and March, with the concentrations of the most abundant species reaching peaks between January and March, when water temperatures had reached 21-24�C. In terms of number of larvae, the larval fish assemblage in the basins was dominated by species that spawn within the estuary, with the larvae of these species contributing ≥98.7% to the totals at the basin sites. Although the larvae of 26 marine species were caught in the entrance channel, these were either rare or absent in the basins, except for those of the terapontid Pelates sexlineatus, which were moderately abundant in the outer basin. The fact that the larvae of most of these marine species were at the preflexion stage, and that all but three of those species had never been previously recorded as either juveniles or adults within the system, indicates that they were passively transported from outside the estuary. The absence of larvae of most of the marine teleosts that are abundant in the basins of the Nornalup-Walpole Estuary parallels the situation in the nearby and seasonally closed Wilson Inlet.

We describe findings of three ichthyoplankton surveys undertaken along south-eastern Australia during spring (October 2002(October , 2003 and winter (July 2004) to examine spawning habitat and dynamics of blue mackerel (Scomber australasicus). Surveys covered 860 nautical miles between southern Queensland (Qld; 24.6°S) and southern New South Wales (NSW; 41.7°S), and were mainly centred on the outer shelf including the shelf break. Egg identifications were verified applying mtDNA barcoding techniques. Eggs (n = 2971) and larvae (n = 727; 94% preflexion) occurred both in spring and winter, and were confined to 25.0-34.6°S. Greatest abundances (numbers per 10 m 2 ) of eggs (1214-7390) and larvae (437-1172) occurred within 10 nm shoreward from the break in northern NSW. Quotient analyses on egg abundances revealed that spawning is closely linked to a combination of bathymetric and hydrographic factors, with the outer shelf as preferred spawning area, in waters 100-125 m deep with mean temperatures of 19-20°C. Eggs and larvae in spring occurred in waters of the East Australian Current (EAC; 20.6-22.3°C) and mixed (MIX; 18.5-19.8°C) waters, with none occurring further south in the Tasman Sea (TAS; 16.0-17.0°C). Results indicate that at least some of the south-eastern Australian blue mackerel stock spawns during winterspring between southern Qld and northern NSW, and that no spawning takes place south of 34.6°S due to low temperatures (<17°C). Spawning is linked to the EAC intrusion, which also facilitates the southward transport of eggs and larvae. Since spring peak egg abundances came from where the EAC deflects offshore, eggs and larvae are possibly being advected eastwards along this deflection front. This proposition is discussed based on recent data on blue mackerel larvae found apparently entrained along the Tasman Front.

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Larvae of all three southern hemisphere anadromous parasitic lampreys were collected from rivers in Australia, New Zealand and South America. Body intervals were measured, trunk myomeres counted and the frequency of pigmentation in different body regions recorded. Morphometric data were subjected to multiple group principal components analysis (MGPCA) which took into account changes during growth. The components (together with myomere counts) and the pigmentation data were both subjected to discriminant analysis. Ordination and rank correlation tests revealed no evidence for either latitudinal clines or a continuum of circumpolar change amongst larval lamprey populations. Clustering of population centroids clearly distinguished between Mordacia lapicida (Gray) from Chile and M. mordax (Richardson) from south‐eastern Australia. Populations of Geotria australis Gray divided into groups representing three geographical regions, namely Argentina, Chile and Australasia (Western Australia, Tasmania and New Zealand). Ammocoetes from Argentina were the most divergent, possessing a more posterior cloaca, taller dorsal fins, a greater gap between dorsal fins, and distinctive pigmentation on the head and caudal fin. Within the Australasian group, Western Australian and New Zealand populations clustered closer than either did with those from Tasmania. The cluster analyses for larval populations of G. australis suggest that, during their marine trophic phase, the adults of this species originating from Argentinian and Chilean rivers follow different migratory routes, whereas those from Western Australia, New Zealand and, to a lesser extent, Tasmania intermix.