There are bigger forces at work that are only hinted at in the article. The 'foreign imported shrimp' is largely farmed. The domestic shrimp is almost exclusively wild caught. This is the 10,000 year old conflict between hunter gatherers (in this case shrimp boats) and farmers (in this case in ponds rather than fields). It is simply more efficient to deliberately grow things than hunt around looking for them in the wild. Our soybean farmers aren't wandering around meadows looking for wild soybean plants for a reason. But our shrimpers still are. Farmer beats hunter-gatherer hands down, every time.
They wouldn't be "soybean farmers" if they were. They'd be soybean hunters. ba da bing.
A good point, all the same.
And wild game is still preferred by enough people that it commands a premium price either on the menu or in the cost of the supplies and licences required to obtain it. "Wild" shrimp can be marketed to those with discriminating taste and larger budgets.