If one wishes to take a position in the debate, let him not rely on flimsy "urban legends" for premises.
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.