That might be the problem right there. If the supply of illegal and import labor ended today this business man might have to do what other business owners have had to do in the past, pay better or find another way to process his product. Not sure why some conservatives have a have a hard time understanding that labor is subject to the same market pressures as other commodities. If you can't attract labor because you can not or will not pay what the market will bear, you need to look at your business model.
The availability of cheap, often illegal labor has killed the "dirty job" market for Americans by driving down the acceptable wage rate below livable standards. Not big screen TV, SUV, four bedroom three baths 2200sq ft on a half acre living, but two bedroom, one car, walk up living.
If memory serves me right the problem of catfish packers with employees goes back to the beginnings of the new catfish farming methods that brought more catfish to market than the market could absorb. Packers, facing declining prices have consistently attempted to control labor costs. News stories from thirty years ago describe American workers being forced to work with minimum bathroom breaks, driven to carpal tunnel syndrome. Some things never change. Cat fish packing is a competitively cut throat business and as long as Americans reject the product, for the most part, it will remain a dead end business