High levels of spatial and temporal recruitment variability in the temperate sparid Pagrus auratus

Abstract

Knowledge of spatial and temporal variation in the abundance of early life stages is important to developing an understanding of juvenile recruitment processes and, ultimately, the dynamics and demographics of fish populations. In Victoria, south-eastern Australia, snapper, Pagrus auratus, supports an important fishery characterised by high variability in year-class strength. We investigated spatial and temporal variation in the recruitment of small juvenile (0+) snapper by monitoring their abundance in four bay and inlet nursery areas during four consecutive summer/autumn recruitment periods (2000–2003). We found considerable spatial variability in the abundance of recruits, both within and among inlets. Interannual recruitment variation, however, differed among inlets. Recruitment into the largest nursery area and most important fishery, Port Phillip Bay, varied by ~10-fold across years, whereas variation for the other inlets was low or not significant. There were also clear differences in size distributions of recruits among both inlets and years. Strong recruitment in Port Phillip Bay during 2001 was related to a longer period of spawning and successful larval settlement and was associated with above average water temperatures. Future monitoring of 0+ recruitment in Victoria and studies of the recruitment processes should be specific to individual nursery areas.