Evolutionary effects of fishing

Kyle Shertzer and Jun Yoshizaki

Fishing targets the larger, older fish of a population disproportionately.  
According to life-history theory, increased mortality of adults selects 
for decreased growth and earlier maturity. Therefore, in theory at least, 
fishing can cause the evolution of life-history traits in exploited fish 
populations. Furthermore, such evolution may be rapid, occurring over the 
time scale of generations, and would likely result in a less productive 
fishery.

In this talk, we consider two questions regarding the evolutionary effects 
of fishing.  Question one: How widespread and severe are the evolutionary 
effects of fishing?  We attempt to answer this question in general with a 
simulation model representing many types of life-history and fishery 
characteristics.  Question two: can we detect evolutionary changes in a 
particular species (red porgy) using actual fishery data?  Red porgy, a 
protogynous hermaphrodite, have been heavily exploited in recent decades 
off the southeastern United States.