184 



Fishery Bulletin 103(1) 



Of the 17 Australian percichthyids, larvae of only 

 Maccullochella macquariensis, M. peelii peelii, and 

 Macquaria ambigua have been described (Dakin and 

 Kesteven, 1938; Lake, 1967; Brown and Neira, 1998). 

 Larval and early juvenile development of the estuary 

 perch (Macquaria colonorum) and the Australian bass 

 (Macquaria novemaculeata) is described from specimens 

 collected from the central and southern coast of NSW, 

 and from reared larvae of the latter species obtained 

 from brood stock from central NSW. This is the first 

 description of the morphological development of the 

 early life history of these two species. 



Materials and methods 



Morphological definitions, measurements, and abbrevia- 

 tions follow Neira et al. (1998) and Leis and Carson- 

 Ewart (2000). Larvae and juveniles were examined and 

 measured under a dissecting microscope at magnifica- 

 tions from 6 to 50x. Precision of the measurements 

 varied with magnification but ranged from 0.02 to 0.16 

 mm. Where morphometric values are given as a percent- 

 age, they are as a proportion of body length (BL) unless 

 otherwise indicated. All pigment described is external 

 unless otherwise specified. The juveniles collected are 

 in transition from larvae to juveniles because they 

 retain some of their larval characters and squamation 

 is incomplete; these are called "transitional juveniles" 

 ( Vigliola and Harmelin-Vivien, 2001). Illustrations were 

 prepared with a Zeiss SR with an adjustable drawing 

 tube. 



Field-caught larvae were collected in a fixed 2-m 2 

 channel net with about 1-mm mesh in Swansea Chan- 

 nel, Lake Macquarie, central NSW. The net filtered 

 surface waters to 1 m depth during night flood tides 

 (Trnski, 2002). Small juveniles were collected in a 30-m 

 beach seine dragged over sand, mud, and Zostera sea- 

 grass in the Clyde River, southern NSW. Reared larvae 

 of M. novemaculeata were obtained from rearing tanks 

 at the Port Stephens Fisheries Centre, an aquaculture 

 research facility of NSW Fisheries. Brood stock came 

 from the Williams River, central NSW. All specimens 

 were initially fixed in 10% formalin and subsequently 

 transferred to 70% ethanol. 



Field-caught larvae were restricted to a narrow size 

 range: 4.8-7.1 mm body length (BL) for M. colono- 

 rum (n=12), and 4.6-7.6 mm BL for M. novemaculeata 

 (n=15). Juveniles of both species ranged from 10.3 to 

 13.5 (n = 5) and from 10.1 to 14.1 mm BL (n = 5), respec- 

 tively. Reared larvae of AT. novemaculeata were available 

 to confirm the identification of the larvae and to extend 

 the developmental series for this species to 3.3-10.2 

 mm BL (ra=18). 



All material examined is registered in the fish collec- 

 tion at the Australian Museum. Registration numbers 

 of M. colonorum larvae are AMS 1.20052-010, 1.41690- 

 005 to -008, 1.41691-002, 1.41692-001, 1.41693-001; 

 M. novemaculeata are AMS 1.20052-012, 1.27051-013, 

 1.41561-001 to -008, 1.41590-001, 1.41641-001, 1.41661- 



001 and -002, 1.41662-001, 1.41668-001, 1.41690-001 to 

 -0004, 1.41691-001, 1.41694-001. 



Identification 



Field-caught larvae and juveniles were identified as per- 

 cichthyids by using the characters in Brown and Neira 

 (1998), particularly the combination of a relatively large 

 gut, the small to moderate gap between the anus and 

 origin of the anal fin prior to complete formation of the 

 anal-fin, continuous dorsal fin, fin-ray, and vertebral 

 counts, and head spination including small preopercular 

 spines, a small interopercular spine, and a smooth supra- 

 ocular ridge. The larvae and juveniles described here 

 were confirmed as being Macquaria colonorum and M. 

 novemaculeata because of their coastal distribution and 

 meristics; all other species in the family are restricted 

 to freshwater. The overlap in meristics between M. colo- 

 norum and M. novemaculeata made separation of the 

 species difficult. The availability of reared M. novemacu- 

 leata from positively identified adults determined the 

 species allocations. 



Results 



Development of Macquaria colonorum 



Adult meristic data Dorsal (D) IX-X,8-11; Anal (A) 

 111,7-9; Pectoral (Pj) 12-16; Pelvic (P 2 ) 1,5; Vertebrae 25 

 17 specimens: 4.8-7.1 and 10.3-13.5 mm BL 



General morphology (Tables 1 and 2, Fig. 1) Larvae 

 and transitional juveniles are moderately deep bodied 

 (body depth, BD 30-35%). The body and head are lat- 

 erally compressed. There are 24-25 myomeres (12-14 

 preanal and 11-13 postanal). The large, triangular gut 

 is fully coiled in the smallest larva examined. The pre- 

 anal length ranges from 60% to 67%. The conspicuous 

 gas bladder located over the midgut is small to moder- 

 ate in size but difficult to distinguish in transitional 

 juveniles. The round to slightly elongate head is large 

 (head length, HL 32-41%). The snout is slightly concave 

 to straight. The snout is approximately the same length 

 as the eye diameter but becomes shorter from 7 mm. 

 The eye is round and moderate in size (27-32% of HL) 

 in larvae but becomes moderate to large in transitional 

 juveniles (32-36% of HL). The large mouth reaches to 

 the middle of the pupil. Small canine teeth are present 

 in both jaws in all larvae examined. The nasal pit closes 

 shortly after settlement, by 12.5 mm. 



Head spination is weak. Three short spines are pres- 

 ent on the posterior preopercular border in the small- 

 est larva examined; a fourth spine is present in some 

 postflexion larvae from 6.3 mm and in all transitional 

 juveniles. The spine at the angle of the preopercle is 

 longest but remains shorter than the pupil diameter. 

 A minute interopercular spine is present from 6.0 mm 

 and persists in all transitional juveniles. A low, smooth 



