fishery. This effect has been termed “Darwinian debt,” and has been suggested to have general applicability (Loder, 2005). That is, timescales of evolutionary recovery are likely to be much longer than those on which undesirable evolutionary changes occur. Conover et al. (2009) provided the first experimental test of this expectation with laboratory populations of Menidia menidia. They found that the selective effects of fishing were reversible, but recovery took more than twice as many generations as the original period of fishery selection. Bromaghin et al. (2008) and Hard et al. (in press), in their simulation studies of Chinook salmon, found that complete recovery of size and age structures generally required 15–20 generations or more of substantial reductions in exploitation rate or no harvest at all. However, gene flow has the potential to accelerate the rate of recovery by restoring alleles or multiple-locus genotypes associated with the trait. For example, trophy hunting might reduce or eliminate alleles for large horn size, but gene flow from areas with no hunting might quickly restore alleles associated with large horn size (Coltman, 2008).
No-take protected areas have considerable potential for reducing the effects both of loss of genetic variation and harmful exploitative selection. Models of reserves in both terrestrial (Tenhumberg et al., 2004) and marine (Baskett et al., 2005) systems support this approach for a wide variety of conditions. However, the actual effectiveness of such reserves on exploited populations outside of the protected area depends on the amount of interchange between protected and nonprotected areas and on understanding the pattern and drivers of dispersal, migration, and genetic subdivision (Palumbi, 2003; Kritzer and Sale, 2004). Some have suggested that as exploitation pressure intensifies outside protected areas, local protection could select for decreased dispersal distance and thereby increase isolation and fragmentation and potentially reduce the genetic capacity of organisms to respond to future environmental changes (Dawson et al., 2006).
We dedicate this chapter to Hampton Carson who failed through no fault of his own to convince F.W.A. of the importance of sexual selection in the conservation of salmon. We thank Joel Berger, Steve Chambers, Dave Coltman, Roger Cowley, Doug Emlen, Marco Festa-Bianchet, Mike Ford, Roger Hanlon, Rich Harris, Wayne Hsu, Dan Jergens, Gordon Luikart, and Robin Waples for providing references and helpful comments. This article is based partially on work supported by the U.S. National Science Foundation Grant DEB 074218 (to F.W.A.) and by the Arctic-Yukon-Kuskokwim Sustainable Salmon Initiative Project 607 (to J.J.H.).