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Fishery Bulletin 103(1) 



Macquaria novemaculeata has only two melanophores, 

 and these are much larger; a third expanded melano- 

 phore develops on the nape from 7.2 mm. In addition, 

 M. novemaculeata lacks a midlateral series of melano- 

 phores along the tail until settlement, and it is never 

 as well developed as that in M. colonorum. On the other 

 hand, M. colonorum has a prominent midlateral series 

 until after settlement. One other morphological char- 

 acter that distinguishes the larvae is a snout length 

 which is about equal to eye diameter in M. colonorum 

 larvae until 7 mm, but snout length is always smaller 

 than the eye diameter in M. novemaculeata. 



Within the genus Macquaria, larval development of 

 only M. ambigua has been described (Lake, 1967; Brown 

 and Neira, 1998). There are several differences in the 

 life history and development of the larvae of M. ambig- 

 ua compared with M. colonorum and M. novemaculeata. 

 Macquaria ambigua is restricted to freshwater, the eggs 

 are large (3.3-4.2 mm in diameter, compared with 0.9 

 mm in reared M. novemaculeata) and the yolk sac in 

 M. ambigua is large in small larvae and is not resorbed 

 until the flexion stage (Brown and Neira, 1998). Com- 

 pared with the larvae described in the present study, 

 larvae of M. ambigua have more myomeres (24-28, but 

 typically 26-27), and these larvae are relatively large 

 by the time they complete notochord flexion (7.3 mm). 

 They also lack an interopercular spine and supraocular 

 ridge, and lack dorsal and lateral pigment on the tail 

 until the postflexion stage. 



Larvae of several other generalized percoid families 

 are morphologically similar to Macquaria, including 

 Latidae (Trnski et al., 2000), Microcanthidae (Walker et 

 al., 2000a), Kyphosidae (Walker et al., 2000b), and some 

 Apogonidae (Leis and Rennis, 2000). The latid genus 

 Lates is morphologically most similar to the Macquaria 

 larvae described in the present study but is tropical 

 and does not have an overlapping distribution with 

 Macquaria. Lates can be distinguished by the small size 

 at notochord flexion (3.0-3.8 mm), dorsal and pectoral 

 fin-ray counts when complete, and heavier melanophore 

 distribution at a given size. Microcanthid and kyphosid 

 larvae can be distinguished from coastal percichthyid 

 larvae by the higher number of fin elements in the 

 dorsal and anal fins, and the presence of supracleithral 

 spines that are absent in larval percichthyids until the 

 juvenile stage. Some deep-bodied apogonids resemble 

 Macquaria larvae but can be distinguished by having 

 separate spinous and soft dorsal fins and a large, con- 

 spicuous gas bladder. 



Larvae of M. colonorum and M. novemaculeata were 

 collected in Swansea Channel from July to August. This 

 collection period coincides with adults of M. novemacu- 

 leata spawning from June to September in central New 

 South Wales (Harris, 1986). Macquaria colonorum prob- 

 ably spawns at a similar time (McCarraher and McK- 

 enzie, 1986), and eggs have been collected from June to 

 November in western Victoria (Newton, 1996). Adults of 

 both species are thought to spawn in the middle reaches 

 of estuaries at salinities above 8-10 g/kg (Harris, 1986; 

 McCarraher, 1986), but M. novemaculeata will spawn in 



waters up to 35 g/kg in culture (Battaglene and Selosse, 

 1996). The optimal conditions for incubation and hatch- 

 ing of M. novemaculeata eggs are 18 [±1]°C and salinity 

 at 25 to 35%r (van der Wal, 1985). Eggs are buoyant 

 within this salinity range and hatch in 42 h at 18 C. 



The presence of field-caught larvae of both species 

 on incoming tides in Swansea Channel indicates that 

 the larvae have spent some time in the ocean and that 

 the eggs were potentially spawned in the ocean rather 

 than in an estuary if they were not carried out to sea 

 by outgoing tides. Macquaria novemaculeata adults 

 move downstream into estuaries to spawn in water of 

 suitable salinity. In low rainfall years, the spawning 

 location is further upstream than in wet years, when 

 spawning can occur in shallow coastal waters adjacent 

 to estuaries (Searle 1 ). Mature M. novemaculeata adults 

 can be found outside of estuaries in wet years (Williams 

 1970). This is verified by the collection of mature adults 

 by trawl in July 1995 in 11-17 m of water off Newcastle, 

 NSW (AMS 1.37358-001). Macquaria colonorum adults 

 have also been collected on the continental shelf (Mc- 

 Carraher and McKenzie, 1986). In addition, larvae can 

 tolerate waters of marine salinity in culture, and late in 

 their larval phase wild larvae can tolerate marine sa- 

 linity as shown from our field collections. The presence 

 of larvae and adults in continental shelf waters may 

 provide two modes of dispersal among estuaries. Thus, 

 these two species of Macquaria may not be confined to 

 freshwater and estuarine conditions as often assumed 

 (Harris and Rowland, 1996; Allen et al., 2002). 



The smallest juveniles of M. colonorum and M. 

 novemaculeata collected in the wild are from the Clyde 

 River estuary, southern NSW. These range in size from 

 10 to 14 mm SL, and were collected among Zostera sea- 

 grass. They are morphologically similar to the largest 

 pelagic larvae collected in the channel net in Swansea 

 Channel. Based on the largest larvae and smallest 

 juveniles, settlement occurs between 7.1 and 10.3 mm 

 SL in M. colonorum and between 9.2 and 10.1 mm in 

 M. novemaculeata. Transition to the juvenile stage is 

 gradual, because scales are not present and juvenile 

 pigmentation is still forming at about 15 mm. Juveniles 

 of both species have been collected in estuarine waters 

 until at least 100 mm SL (AMS fish collection). Juve- 

 niles of M. novemaculeata would be expected to migrate 

 to freshwater because this is the nominal adult habitat 

 (Williams, 1970), but the size at which this migration 

 occurs is unclear. 



The two species described in the present study were 

 the only members of the genus Percolates, until this 

 genus (along with Plectroplites) was synonymized with 

 Macquaria by MacDonald (1978). Analyzing morpho- 

 logical and biochemical similarities of the three genera, 

 MacDonald (1978) listed eight morphological differences 

 that distinguished Percolates from Macquaria and Plec- 

 troplites. Protein electrophoresis similarities were stron- 



1 Searle, G. 2002. Personal commun. Searle Aquaculture, 

 255 School Rd, Palmers Island NSW 2463. 



