They're also considering ways the fish might be evading the barrier.

WSJ: Study: Asian carp unlikely to stow away in barges

The construction of the Gezhouba dam in 1981 on the Yangtze river also created a barrier to the migrating fish which further affected fish stocks.

BBC: Earth News - Giant fish 'verges on extinction'

Here, fillets are used and parchment paper, rather than just the fish's skin, provides an extra barrier between the meat and the salt.

WSJ: Jenn Louis's Rock-Salt-Roasted Salmon and Turnips | Slow Food Fast

Removing the barrier has connected habitat crucial for these unique fish.

CNN: Migrating fish get help in uphill battle