Temperature-dependent development rates of plaice (Pleuronectes platessa L.) eggs from the Irish Sea

Experimentally derived temperature-dependent development rates for planktonic fish eggs are required for developing Individual Based Models (IBMs) of early life history stages and for estimating daily egg production in ichthyoplankton surveys. Development rates of Irish Sea plaice eggs were experimentally detemined for temperatures between 4.5 and 12 degreesC. Differences in development rates were apparent when these results were compared with literature data for eggs from North Sea parents. On average, Plaice eggs from the Irish Sea developed more rapidly and hatched up to 2 days earlier compared with North Sea eggs incubated at the same temperature. In terms of parental effects, larger females tended to produce larger eggs but egg size decreased over successive batches from the same female within a year. Temperature-dependent egg development rates were influenced by egg size in a non-linear manner for eggs incubated at 6 degreesC, but egg size had no effect at higher temperatures. Since most plaice eggs sampled from the Irish Sea during ichthyoplankton surveys in 1995 and 2000 were found in waters cooler than 8 degreesC, such effects may modify egg development rates in the wild.