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.

In any history class you’ve ever taken, the first thing you probably talked about was the Fertile Crescent. The half-moon shaped chunk of land in the Middle East, watered by the Nile, Euphrates and Tigris rivers, was the birthplace of human civilization. Today, we associate the area with endless deserts, oil and improvised explosive devices.

But that’s about to change. The endless desert part, anyway. Last Friday, the United Nations announced a plan to restore Iraq’s wetlands (according to some scholars, the site of the Garden of Eden) and list them as a World Heritage Site.

The Iraqi wetlands (saying it over and over doesn’t make the idea seem any less weird, does it?) once covered a tens of thousands of square miles and were home to snakes, lizards, frogs, fish, water buffalo, gazelles, jerboa, birds and tribes of people known as the Marsh Arabs or Ma ˤdān (’dweller in the plains,” a disparaging name given to them by desert tribes).

Today, the wetlands are mostly decimated. First, fighting during the Iran-Iraq War spilled into the area. Then, in the 1990s, Saddam Hussein began draining the area and diverting water flow in order to expand military access to the land, gain more political control over the Marsh Arabs and flush out rebels after a failed Shia uprising.

When U.S. forces invaded in 2003, only some 400 square miles of marsh remained. Once Hussein’s regime was brought down, locals began destroying the dams that held water back and allowed the wetlands to flood again. Today, more than half the original wetlands have been restored, and thousands of birds and fish, as well as the Marsh Arabs, have returned to the land.

The U.N.’s project, which is being partially funded by Italy, will concentrate providing safe drinking water and renewable energy for the Marsh Arabs, planting reed banks and beds and managing the re-flooded areas to ensure the return of plant life. If all goes well, Iraq could be able to approach the World Heritage Committee for listing in two years.

Image: “Marsh Arabs poling a traditional mashoof in the marshes of southern Iraq.” Wikimedia Commons/U.S. Army Corps of Engineers Digital Visual Library