Spot prawn (Pandalus platyceros) season started here early in the month so by now, you should be able to get a good deal at any local supermarket. I've found them for around $8 dollars at T&T and other Asian markets. They are also available at the False Creek Fisherman's Wharf, but at a premium. Supposedly you'll get fresher and bigger specimens, but I've never compared.
As food, spot prawns have a prominent sweet note with an interestingly firm texture. When cooking them, I tend to keep it simple. Most of the time, I steam or boil them plain just until the tails turn white. Occasionally, I will cook them with garlic and cooking wine or dip them in a lemon pepper mixture. The key is to not overpower the natural flavours of the shrimp.
My favourite part to eat has always been the "head". Anatomically, that part of the prawn contains the hepatopancreas (digestive gland) which is an organ that contains functions similar to the mammalian liver and pancreas. In lobsters and crabs, the hepatopancreas is commonly known as tomalley, the tasty green gooey paste.
So, why are they a sustainable choice?