Reproduction vs. growth: indications for altered energy fl uxes in Lake Constance whitefish through size-selective fishery

Fisheries-induced evolution (FIE) has been reported for several intensively exploited fish stocks worldwide. Most studies focused on marine populations of high commercial interest , but FlE may also occur in intensively harvested fTesh water fish stocks. An example is the whitefish (Coregonus lavaretus) stock of Lake Constance. Previous evidence for FlE in this stock, tllrough tile analysis of long-term data sets, showed a long-term effect on growth and reproductive t.raits in addition to the effects of envirollluental factors. In tlus study, we tested whetller growth rates of Lake. Constance whitefish were partially hereditary, and whetiler tlle results of this experiment support the fisheries·· induce.d evolu.tion scenario for Lake Constance whitefish. hI a laboratory experiment using whitefish larvae, we hypotllesized that slow-growing females would produce slow-growing offspring. Our experillle.ntal setup allowe.d rearing of 24 different batches of larvae over 40 clays. GroWtll of larvae was inverse.ly correlated t.o their weight-at-hatch, and larvae wiililarger yolk sac volUlJle grew slower. We a1.tribllte iliis result to tlle intensive size··select.ive harvest. t.hat. has occurred in Lake C011st.ance during tJle. past several decades becanse fish t1l~H allocate more energy to reprocluction at the expense of groWtJl have an advantage under the present harvest regime over fish t.hat follow the opposit.e allocation strategy. Our results are in line with FIE tJleol"), and suggest a genetic component to life-hist.ory t.raits of Lake Constarlce whitefish, whereby slow-growing females tend to produce larvae of a lower growth performance.