Growth and Reproduction in the Protogynous Hermaphrodite Pseudolabrus celidotus (Pisces: Labridae) in New Zealand

Abstract

The wrasse Pseudolabrus celidotus was sampled regularly at two areas, Leigh and Wellington, over 18 months. It is found to be protogynous and monandric, but a small proportion at both areas change sex within the initial phase (IP) immediately prior to maturity. IP males have high testes weights relative to terminal phase (TP) males and appear to be functionally analogous to primary males. They grow at the same rate as normal protogynous hermaphrodites (which change sex and color almost synchronously) but tend to change color at a smaller size and may have a better survival rate. The spawning season lasts from late July until the end of November, and sex change occurs between November and May. Color change is often slightly delayed with respect to sex change over this period. Some IP males appear to change color during the spawning season. Growth is slower at Wellington during the first year only and is associated with a much larger recruitment. As a consequence maturity, which is reached during the 0+ year at Leigh, is largely delayed until the 2+ year at Wellington. In both areas, maturity is at a critical size of 100-110 mm SL, although slightly smaller for IP males. Although actual densities are higher at Wellington, the effective densities are = 13 per 500 m2 at both areas. Normal sex/color change occurs at a significantly larger size at Leigh. However, because of the growth difference, changes occur at a younger age. The average mature female phase is a year shorter at Wellington. There are only 3.7 mature females to each TP male at Leigh, as opposed to 8.7 at Wellington. However, because females are smaller at Wellington, the mean weight of ripe ovary available to each TP male is similar. Sex change and color change are always more closely related to size than age, as are maturity and fecundity. The results are discussed in relation to preliminary observations of social behavior, and Warner's (1975a) model predicting the optimal sex change schedule.