Biro Peter A, Post John R
Department of Environmental Science, and Institute for Water and Environmental Resource Management, University of Technology Sydney, Box 123, Broadway, NSW 2007, Australia.
Proc Natl Acad Sci U S A. 2008 Feb 26;105(8):2919-22. doi: 10.1073/pnas.0708159105. Epub 2008 Feb 25.
The possibility for fishery-induced evolution of life history traits is an important but unresolved issue for exploited fish populations. Because fisheries tend to select and remove the largest individuals, there is the evolutionary potential for lasting effects on fish production and productivity. Size selection represents an indirect mechanism of selection against rapid growth rate, because individual fish may be large because of rapid growth or because of slow growth but old age. The possibility for direct selection on growth rate, whereby fast-growing genotypes are more vulnerable to fishing irrespective of their size, is unexplored. In this scenario, faster-growing genotypes may be more vulnerable to fishing because of greater appetite and correspondingly greater feeding-related activity rates and boldness that could increase encounter with fishing gear and vulnerability to it. In a realistic whole-lake experiment, we show that fast-growing fish genotypes are harvested at three times the rate of the slow-growing genotypes within two replicate lake populations. Overall, 50% of fast-growing individuals were harvested compared with 30% of slow-growing individuals, independent of body size. Greater harvest of fast-growing genotypes was attributable to their greater behavioral vulnerability, being more active and bold. Given that growth is heritable in fishes, we speculate that evolution of slower growth rates attributable to behavioral vulnerability may be widespread in harvested fish populations. Our results indicate that commonly used minimum size-limits will not prevent overexploitation of fast-growing genotypes and individuals because of size-independent growth-rate selection by fishing.
渔业导致生活史特征进化的可能性，对于被开发利用的鱼类种群来说是一个重要但尚未解决的问题。由于渔业往往会挑选并捕捞最大的个体，因此存在对鱼类产量和生产力产生持久影响的进化潜力。体型选择代表了一种针对快速生长率的间接选择机制，因为个体鱼可能因快速生长而体型大，也可能因生长缓慢但年龄大而体型大。对于直接选择生长率的可能性，即无论体型大小，生长快的基因型更容易被捕捞，这一点尚未有研究。在这种情况下，生长较快的基因型可能更容易被捕捞，因为它们食欲更强，相应地与觅食相关的活动率更高且更大胆，这可能会增加与渔具的接触以及被捕捞的易感性。在一项实际的全湖实验中，我们表明，在两个重复的湖泊种群中，生长快的鱼类基因型被捕捞的速率是生长慢的基因型的三倍。总体而言，50%的生长快的个体被捕捞，而生长慢的个体被捕捞比例为30%，与体型无关。生长快的基因型被捕捞比例更高是由于它们行为上的更大易感性，即更活跃、更大胆。鉴于鱼类的生长具有遗传性，我们推测，由于行为易感性导致的生长速率变慢的进化在被捕捞的鱼类种群中可能很普遍。我们的结果表明，常用的最小尺寸限制不会防止对生长快的基因型和个体的过度捕捞，因为捕捞存在与体型无关的生长率选择。
