The influence of nursery ground processes in the determination of year-class strength in juvenile plaice Pleuronectes platessa L. in Port Erin Bay, Irish Sea

The interannual variability in settlement and mortality of juvenile plaice Pleuronectes platessa L. was investigated between 1992 and 1998 on Port Erin Bay, west side of the Isle of Man, Irish Sea. The dampening influence of factors operating on the nursery grounds was especially obvious in 1992 and 1996. In these years extremely high numbers of individuals settled, yet the population sizes in July were similar to other years. Thus the nursery ground processes were likely to be density dependent. Shrimp and crab densities were low in Port Erin Bay and probably had little predatory impact on young plaice. Crustacean densities were not significantly related to winter temperatures. In the Irish Sea, year-class strength is determined during the nursery ground phase, in contrast to the North Sea where determination of year-class strength occurs prior to the nursery ground phase.