One can now include vulnerability to being caught by anglers among all the heritable traits in fish.
David Philipp and coauthors demonstrated this in a study published in a recent issue of the Transactions of the American Fisheries Society.
The study began in 1977 on largemouth bass (Micropterus salmoides) in Ridge Lake, an experimental study lake in Illinois.
Catch-and-release fishing in the lake was strictly regulated, with the fishes that were caught being measured and tagged.
After four years, the pond was drained, and 1,785 fish were collected. It was found that about 15% of the bass had never been caught, while many others had been caught multiple times.
Males and females that had never been caught were designated Low Vulnerability (LV) parents and were separated to produce a line of LV offspring in brood ponds.
Similarly, males and females caught four or more times in the study were designated High Vulnerability (HV) parents that were spawned in different ponds to produce a line of HV offspring.
The F1 offspring of both lines were marked and put together in a common pond, where they were subjected to one summer of angling pressure. Records were kept of the number of times each fish was caught.
After the summer, HV fish caught three or more times were used as HV parents, and LV fish caught once or not at all were used as LV parents to produce F2 offspring, which were then subjected to the same experimentation and treatment as above to generate F3 offspring. The F3 offspring were also subjected to angling pressure and records kept.
These series of controlled fishing experiments over 20 years showed that the vulnerability to angling of the HV line was greater than that of the LV line, and that the differences observed between the two lines increased across later generations.
This provides the first direct experimental evidence that vulnerability to angling is a heritable trait and, as a result, that recreational hook-and-line fisheries can cause evolutionary change in fish populations.
For more information, see the paper: Philipp, DP, SJ Cooke, JE Claussen, JB Koppelman, CD Suski and DP Burkett (2009) Selection for vulnerability to angling in Largemouth Bass. Transactions of the American Fisheries Society 138, pp. 189"199.