As fisherman haul in their lines and nets, inevitably they also haul in fish and marine creatures they didn’t intend to catch. The Food and Agricultural Organization of the United Nations estimates that at least 8 percent of the fish caught around the world is unwanted and discarded. For this "bycatch" this encounter is often fatal, but it doesn’t always have to be so. In fact, commercial and recreational fisherman are trying to save accidentally caught sea critters using innovative tools, reports Millie Kerr for Wired.

One such device, called the SeaQualizer, returns fish safely to the depths from whence they came. Deep-water fish are especially hard to keep alive after they’ve been caught — the change from deep ocean pressure to that at the surface over inflates their swim bladders, which ends up damaging their organs. Without help, they won’t survive.

Typically, fishermen will slash open the fishes swim bladder before tossing them back in order to relieve some of that pressure, a process called "venting." "It’s as barbaric as it sounds and often leads to injury or death, but until around four years ago fishermen had no alternative—in some places, venting was even required by law," Kerr writes.

Crates lowered on a rope offered a low-tech way to return the fish, but fisherman had to approximate the right depth. Now, with the SeaQualizer, two fisherman have hit on a more accurate return method. With the spin of a dial, fisherman can set the desired depth, clip the device to an accidentally caught fish’s jaws and let it go. Once the SeaQualizer detects that it has reached the right depth, it automatically unclips and the fish can swim away. Jeffery Liederman and Patrick Brown built the device in Brown’s parent’s garage. ​

Kerr reports:

The SeaQualizer got its start on red snapper in the Gulf of Mexico, but later expanded to help rockfish off the California coast and lake-dwelling stripers in the South. It now comes in three different models, including a Deep Water version that saves fish living up to 600 feet beneath the ocean’s surface. The product became so popular, the Sportfishing Association of California teamed up with the WWF to put one on every member’s boat.

The SeaQualizer device rings in at $55 each, so the duo’s main customers are probably sports fishermen rather than commercial trawlers. But other solutions are encouraged — by industry experts, grants and by the same competition that brought the SeaQualizer to a wider audience. The World Wildlife Foundation’s International Smart Gear Competition offers up prizes to inspire innovative bycatch solutions.

Some of the other solutions include dissolvable pellets that repel sharks and a laser-sound system that deters sea birds. Other ideas — like lighted exits that help small and undersized fish leave the nets — are also available to help bycatch escape before they get hauled in.