|Impact of juvenile growth on recruitment in flatfish|
van der Veer, H.W.; Berghahn, R.; Rijnsdorp, A.D. (1994). Impact of juvenile growth on recruitment in flatfish. Neth. J. Sea Res. 32(2): 153-173
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579, more
|Authors|| || Top |
- van der Veer, H.W.
- Berghahn, R.
- Rijnsdorp, A.D., more
In this review, the impact of juvenile growth on subsequent recruitment in flatfish is discussed. Recruitment is defined as the number of specimens of a specific year class that survives to attain sexual maturity and joins the reproductive population. Theoretically, variability in growth rate can have an impact on recruitment either by means of size-selective mortality during juvenile life and/or by means of size-dependent onset of maturation. In flatfish up to about 10 cm, growth depends on size in such a way that variability in size within a population increases during the first year of life, and decreases again in the subsequent part of juvenile life. Temporal variability in size within local populations appears to be lower than spatial variability. Due to the prolonged spawning period, and hence period of settlement, variability in size of juvenile flatfish increases with decreasing latitude. As a consequence of these patterns, size-selective mortality appears to be mainly restricted to the 0-group and to gain importance with decreasing latitude. A literature search for field data yielded only a few references suggesting size-selective mortality. In none of the studies was any relationship with ultimate recruitment studied or even suggested. Size-dependent onset of maturation has been found in some flatfish species, with slow-growing individuals or cohorts showing delayed maturation. Size-dependent onset of maturation has a clear effect on the level of recruitment. However, in the species studied, the main traits in year-class strength still existed at the moment of recruitment to the reproducing stock. Size-dependent onset of maturation also appeared to affect the year-to-year variability in recruitment, but different effects were observed among species. It is argued that both size-selective mortality and size-dependent onset of maturation are more likely to dampen than to generate variability in recruitment. The study of the impact of juvenile growth on recruitment in flatfish is hampered by the absence of long-term data sets on recruitment. Especially comparable series of (sub)tropical species and of populations covering the total range of distribution of a species are lacking.