The three of them sat there on the shore for a while, too shocked and horrified to do much. They had just been robbed of their manhood and their humanity by some punk with magic powers, and he had left with no mention of ever changing them back. None of them wanted to face the possibility that they were stuck this way for life, but there didn't seem to be any way around it.
The hours wore on, and the kid showed no signs of returning. The longer they spent in open air, the more the three mermaids' tails began to feel dry and itchy. They were appalled at the idea of going into the lake, as if merely taking to the water was a way of giving in, but it looked so cool and inviting...
One by one, they resigned themselves and dragged themselves over to the water's edge, each of them horrified as they rolled into the water, but seeing no other alternative. First was Jason, the former leader of the group, whose rosy tan, golden hair, and emerald scales so fitted the stereotypical mermaid image. After her was Aaron, with her iridescent blue tail, pale skin, and brown hair. Finally, Sam, with her dark, almost olive complexion, salmon-pink fish half, and jet black tresses, gave into the water's call.
The next few weeks were a learning experience for the three of them. Luckily, breathing underwater was an automatic reflex for them, with their throats closing when they inhaled to force water through the gill slits that had formed behind their ears. Talking wasn't too difficult either, although without the diaphragm involved it was harder to achieve any real volume; fortunately, the ease with which sound carried in the lake water meant that wasn't much of a problem.
The was another thing, the underwater acoustics. Sounds attenuated far less underwater, which meant that they were able to pick up the fine details like variations in intensity and arrival time that helped their brains position sounds with far greater clarity than was possible above water. And it wasn't long before they discovered that by emitting sounds themselves, even something as simple as a click of the tongue, they could use that information to find and position things just like a submarine's sonar; things like fish or rocks...
Or the other mermaid. They didn't see much of her; she seemed to be understandably afraid of them, and kept away, though she couldn't stay out of sonar range. Not that they were eager to make friends with the person who'd led them into this trap.
Anyway, while the physical changes that came with being a mermaid took some adjusting, the physical changes that came with being female were simply ignored to the best of their ability; the bigger problem for them was the lifestyle changes. Diet took a lot of getting used to. None of them liked the idea of eating raw fish, but it was either that or lake-weed. And, as they soon discovered, when you're hungry enough, you will eat anything. Catching the fish was a bit more difficult, but as they developed their sonar abilities, it ceased to be a problem.
The other thing fo do in the lake was explore it, so that was what they did in their hours upon hours of free time. With all three profoundly bored and scouring the lake for points of interest, it wasn't surprising when Sam unearthed an underwater tunnel that lead to a nearby lake that was much larger and far more popular. They had to be a lot more cautious here, for fear of being discovered, but they pretty much spent their time eating, sleeping, or exploring one of the two lakes - and trying to ignore the fact that they were female.
But they weren't going to be able to keep that up for long. What neither Jon nor the ex-mermaid hunters had any idea of was the fact that there was a reason behind the tales of mermaids waiting on the rocks to seduce passing sailors. While mermaids existed, there were no such things as mermen - mermaid mothers bore only
daughters - and mermaids old enough to reproduce went through what would colloquially be known as a "heat cycle;" every so often, they would experience an overwhelming and nearly-irresistible desire to mate, a temporary but profound need to bear children. The three former hunters could ignore their new sex for now, but they would have quite a shock in store for them before long.