Abstract:
Phenotypic divergence in the reproductive traits of marbled parrotfish (Leptoscarus vaigiensis) was studied during May 2011-April 2012 at six reef sites exposed to varying levels of fishing pressure in coastal Kenya. Baited fish traps were used to capture fish within two no-take marine parks (Malindi and Watamu) and adjacent reserves in which regulated fishing is allowed. Fish samples were also obtained from fishers operating at two unprotected sites (Kanamai and Vipingo). Reproductive attributes (fecundity, oocyte size and length at first maturity) were determined and revealed significant differences in fecundity between sites (F=3.742, P=0.004), fish in the parks and reserves having a higher mean fecundity (110 128±75 492 and 145 570±88 873 respectively) than those on unprotected reefs (76 250±55 337). Fish at unprotected sites had higher fecundities at smaller sizes relative to larger fish at protected sites. In terms of length at first maturity (L50), females at unprotected sites matured at lower lengths (11.2 cm, 11.1-11.4 cm, 95% CI) than those in marine parks (16.7 cm, 15.7-17.3 cm, 95% CI) and reserves (16.8 cm, 16.6-17.1 cm, 95% CI). Overall, the results indicated some level of phenotypic divergence of the fish between sites, which is possibly an adaptive strategy to enhance their resilience to fishing pressure, thereby serving to sustain local populations. The real causes of this divergence cannot be partitioned between fishing mortality, genetic variability or habitat-induced variation. The data provide the basis for future research on causes for differences in the life history traits of marbled parrotfish on variably protected reefs.
