Abstracts (first author)
Rapid phenotypic and genetic changes in experimentally exploited fish populations
Size-selective fishing has the potential to cause changes in life-history traits, which are often at least moderately heritable. Thus, size-selective fishing has the potential to cause genetic changes in exploited populations. We subjected populations of wild zebrafish (Danio rerio) to size-selective harvest over five generations by establishing three treatment groups: selection for large, random and small body size and focused on three questions that have not been thus far studied experimentally in fisheries context: 1) How do life-history traits, such as maturation, growth and reproductive investment, collectively respond to size-selective harvesting? 2) How the potential changes in life-history traits affect population growth rates? 3) Can size-selective harvesting induce rapid molecular-level responses in the experimentally exploited populations? Five generations of size-selective harvesting caused lower maximum length, earlier maturity and higher energy investment to reproduction among the small-size selected fish. Life-history changes induced differences in population growth rates such that small-size selected fish adapted to size-selective fishing environment and had higher population growth rate compared to other selection treatments. However, they had lower population growth rate in the absence of fishing. Thus, our results suggest that exploited populations might not only be unprofitable for fisheries but also impair the recovery potential of exploited stocks. Finally, we show that size-selective harvesting induced rapid and replicable genetic changes in the experimentally exploited fish populations. Our study contributes to the understanding of the rate of phenotypic and evolutionary changes in size-selective fisheries. Further, our results suggest that fisheries-induced evolution is not necessarily a long-term process but it can be rapid and may become a short-term concern in fisheries management.