Studies on the yellow-eye mullet: Aldrichetta Forsteri (CUV. & VAL.) (MUGILIDAE)

Abstract

4,700 Yellow-eye mullet, Aldrichetta forsteri (Cuv. & Val), Australasian sp., one of two mugilids in New Zealand, studied from Wellington. Gill-raker and scale data of E. and W. Australian and N.Z. fish suggests a cline and casts doubt on validity of W. Aust. subsp. A.f. nonpilcharda. Head pointed; neurocranium moderately broad; epiotics bristle-like; premaxillae protrusible; pharyngeal apparatus well developed; opercular bones large; ligament links postcleithrum and pelvis; 24 vertebrae (11+13). Musculature typically teleostean; ad. mandibulae and ad. maxillae completely separated, the latter overlying former. Pharyngeal pads large, toothed; pyloric stomach gizzard-like; two large caecae; double-looped intestine; swim-bladder physoclistous. Faunal associates include Mugil cephalus Linnaeus, and ecto-parasites Peniculus fissipes Wilson (Copepoda) and Codonophilus imbricatus Fabricius (Isopoda). Linear body proportions constant; weight-length relationship normal. Well-defined scale annuli from pectoral region used for age and growth rate; straight line relationship between scale and body length; annulus formed in September; one-year fish attains maximum of 180 mm., seven-year from 325-350 mm.; older year classes smaller than Aust. fish. Growth rings on otolith and operculum illustrated. First spawns at end of third year (178-250 mm.), determined from ova measurements and gross observations; ova size (mean: 0.48 mm. diam.) uniform for all lengths; ova development starts in July, reaching maturity late December; summer spawning: late December-late March, (when each fish spawns once) corresponds to that of E. Aust, sp.; 680,000 ova in 350 mm. female to 117,000 in 211 mm.; eggs pelagic. Food: planktonic crustacea, algae, also diatoms and detritus; juveniles eat larval crustacea. Insignificant contribution to N.Z. fisheries; recent (1961) kippering industry has increased demand.