Short term tech:
Aquaculture

Long term tech:
Lab salmon. Grow & print em' in a dish. We have the early tech now.

Lab steak. YUM!

Keep in mind, that is a whole muscle steak, not some mushy lab meat that looks like burger. A "steak". Printed today. That is mind-blowing in it's own right. In 15 - 25 years, we will be able to literally print & cook food & complete meals on demand (made to order) at grocery stores and restaurants. Common raw base materials or "ingredients" will come in large "print cartridges" much like bulk soda syrup boxes today. The printer reads the request and viola! Printed salmon with capers and béarnaise sauce.

We put a man on the moon. One would think we could figure out fish.