Researchers at the University of Illinois recently published the results of an experiment that spanned 20 years and involved several generations of largemouth bass and an untold of amount of bait. Their conclusion: The apple doesn’t fall far from the tree, even, apparently, if you’re a fish.

The study started in 1975 at Ridge Lake, an experimental study lake in Fox Ridge State Park in Charleston, Illinois. Over the course of four years of controlled fishing, the bass from the resident population of the lake were caught, measured and tagged to keep track of how many times each fish had been caught, and then released.

The researchers recorded thousands of catches and found that some fish went for the bait more often than others, a lot more. One fish was caught three times in the first two days of the experiment, and another was caught 16 times in one year. When the lake was drained, the researchers also found some 200 fish that had never been caught during the study.

A total of 1,700 fish were collected from the drained lake. Male and female fish that had been caught four or more times in the study were designated High Vulnerability (HV) parents, and those that had never been caught were designated Low Vulnerability (LV) parents. The HV and LV groups were placed in separate university research ponds, where they spawned and produced lines of HV and LV offspring. These two lines were marked, raised in common ponds until they were big enough to be fished and then the anglers were let loose, starting the process over again.

Through three generations, the fish in each group followed closely in their parents footsteps (finsteps? finswims?) of either getting caught, or not (the difference in vulnerability between the HV and LV lines grew even larger with each generation), confirming that vulnerability to being caught by fishermen is a heritable trait in largemouth bass.

While that fact might make for great trivia, the study gives us more than just gee-whiz science. It suggests that recreational fishing can cause evolutionary changes the same way commercial fishing can.

The researchers found that most of the selective pressure is occurring on the LV fish, making fish that are already unlikely to be caught even less vulnerable. On the other hand, there was only a small increase in vulnerability to being caught in the HV group[1].

The researchers aren’t sure which inherited behavior causes these differences (it may be a wariness of anglers’ hooks and general lack of aggression that are passed on to offspring), but both these changes, they suspect, have implications for the bass’ reproductive success. Female largemouth bass swim away from their eggs after laying them, while the males stay with the eggs and until they hatch and guard the fry for the first month of their lives. The LV males may go after anglers’ hooks less often, or not at all, but their lack of aggression may also mean that they provide less protection from predators for their young. More aggressive HV males likely have higher mating success and are good protecting their fry from predators, but that aggression also makes them more likely to go after lures, get caught and leave their offspring vulnerable to predators.

During spawning season (in Illinois, this is from about April 1-June 15), males are caught the most, which causes concern for the HV males. Most bass anglers practice catch-and-release fishing, and the research team says that perception is that this has no negative impact on the fish, but during spawning season, if a male bass caught and kept away from their nests for more than even a few minutes, that may be enough time for predators to find the nest and eat the eggs or fry (a previous study by other researchers showed that, if a smallmouth bass is away from the nest for 1.4 minutes, as many as 1,100 eggs can be eaten).

The researchers suggest that wildlife management agencies set aside portions of lakes as bass spawning sanctuaries, where all fishing would be prohibited, and makes catch-and-release mandatory in the rest of the lake during the spawning season. They also recommend immediate catch-and-release regulations in fishing tournaments held during the bass’ reproductive period.

Reference: Philipp, David P., Cooke, Steven J., Claussen, Julie E., Koppelman, Jeffrey B., Suski, Cory D., Burkett, Dale P. Selection for Vulnerability to Angling in Largemouth Bass. Transactions of the American Fisheries Society 2009;138:189–199. DOI: 10.1577/T06-243.1

Image:”Largemouth Bass – Micropterus salmoides.” Trisha M Shears.

Only about 10 percent of the world is left-handed, and with good reason. My southpaw brethren and I are at an extreme disadvantage in the evolutionary race. We’ve been shown to have greater risk of schizophrenia, autism, epilepsy and learning disabilities, and are shorter lived, just plain shorter and more likely to be homosexual than righties. All that makes it difficult for lefties to attract mates, reproduce and pass on their genes, so scientists have been wondering for a long time why left-handedness persists.

A team of researchers at the Institute of Evolutionary Sciences at the University of Montpellier, France who surveyed the existing literature on the evolutionary perspectives of left-handedness, including its mechanisms and the costs and benefits acting as selective forces on the left-handed, say they may have found the secret to southpaw survival. We lefties simply had a tactical advantage in one-on-one competition.

The team’s study suggests that because lefties are in the minority, right-handed opponents may not have been used to the way they fight, and the element of surprise gave lefties an advantage. Their very uncommonness, and a good left hook, gave them an edge.

Because the advantage allowed them to survive physical confrontation and win resources and mates, left-handedness ies became more frequent over the generations through natural selection.

We can see sort of the same thing happening in the success of left-handed boxers like “Gentleman Jim” Corbett and Oscar de la Hoya and left-handed tennis players like John McEnroe and Jimmy Connors. Death isn’t on the line at Wimbledon, but everyone loves a winner, so they attract more sex partners and are more likely to reproduce.

The researchers also noted that lefties in many European countries have higher average incomes and are well represented among gifted children with high IQs. Although an advantage in fist fighting explain that, a place at the top of the socio-economic ladder certainly promotes reproductive success, so smarts and cash would result in higher birth rates for lefties and the passing along of left-handedness.

Reference: Llaurens, V., Faurie, C. and Raymond, M. 2009 : Why are some people left-handed? An evolutioanry perspective. Philosophical Transaction of the Royal Society B. doi:10.1098/rstb.2008.0235