How do merfolk develop agriculture

Question

Let's say that a race of aquatic merfolk have managed to achieve sapience, they are basic hunter gatherers, living in relatively shallow waters of up to 100 meters deep. As I have begun designing their culture I have ran into a road block, how does such a species develop agriculture? After all, very few plants exist so deep and those that do grow do not produce fruit or vegetables. I had originally planned on them domesticating schools of tuna or salmon or even prawns or krill, but the amount of such an animal they would need to keep in order to provide for even just a town would be way too massive.

How does a culture living underwater develop agriculture? If they cannot develop agriculture, what else can exist for them in lue of it? Let's assume that these merfolk are omnivorous mammals.

Answer 1

Agriculture

Do these guys eat some sort of seaweed? Have them plant seaweed in designated locations, just like we do in fields. Due to certain conditions (maybe a warmer current in the area?) I'm sure that some areas of the sea floor would work better than others, thus giving rise to, essentially, agriculture.

Furthermore, merfolk could build clam gardens gardens close to the shore, and reap the fruits of their labor (check it out, the north american natives did it in British Columbia).

Taming Fish

Fish are not smart enough to tame - especially not entire schools of it. However, why not corral the fish, and eat them at your leisure? Build large nets, and set them up as domed structures, then simply use your superior intellect, and agility to shepherd schools of fish into them.

Better yet, convert the hulls of sunken ships into solid holding pens for all sorts of "snacks".

Food Storage

Your biggest long term problem is actually food storage. Our ancestors would smoke, or salt meat, which will then keep for very long periods of time.

Your merfolk will only be able to corral so many fish, and grow so much seaweed. Eventually, they will run out of food, as fish migrate with the seasons. At that point they themselves may need to move to a different location, which is essentially reverting back to a hunter/gatherer stage.

What you need to establish is either a way for them to keep food from spoiling, or a constant flow of food in their area. Depending on migrations, as opposed to stored food will, however, render them incredibly vulnerable to any sort of environmental upsets (if a migration doesn't take place, or a species is decimated, your merfolk will themselves starve)

Answer 2

Farming is not just about planting seeds or herding animals. A large portion of farming is actually in taking care of the land (tilling, fertilizing, etc.) and also providing care to the things which are growing (pruning, weeding, dealing with insects and other pests, etc.)

Even if the merfolk aren't deliberately planting seaweeds, or actively corralling fish, they can certainly change their environment to maximize the production of useful food.

For example, perhaps a prized food source likes piles of rocks with lots of nooks and crannies. Or is frequently found in conjunction with certain corals or anemones. The merfolk could then deliberately create the appropriate rock piles, or could attempt to provide the right environment for the corals or anemones. In this way, they "cultivate their fields" in order to maximize their fish production.

Additionally, there are likely predators and parasites which will harm their desired foodsources. The merfolk could actively hunt the predatory fish, keeping them away from their "fields" of desirable fish. Or they could "weed" their fish beds by digging out harmful pests (e.g. the Bobbitt worm). Or they could "apply pesticides" by capturing cleaner shrimp from other areas of the ocean, and relocating them to their "fields".

Additionally, there are many things in the ocean which are sessile, or at the very least not very mobile. These are mostly invertebrates, and include corals, sponges, clams/oysters, and some crabs/shrimp. These either stay put on the surface, or will not move very far from their home burrow. All of these could be "farmed" by providing a good environment for them.

One complication here is that a fair number of sessile species in the ocean undergo a planktonic stage, where they young animals are free-floating in the water column. This complicates farming, as the young animals don't stay close to their parents. However, you can still farm these animals, either by providing the ideal environment for the planktonic larvae to settle, or by having the merfolk search for desired young animals "in the wild", and then bring them back to the village fields where they're protected and given a better chance of survival and growth.

Answer 3

Here is a list of sea things edible to humans and human efforts at cultivating them: https://en.wikipedia.org/wiki/List_of_types_of_seafood https://en.wikipedia.org/wiki/Seafood https://en.wikipedia.org/wiki/Seaweed_farming https://en.wikipedia.org/wiki/Aquaculture_of_giant_kelp

If mermaids can digest other foods in addition to these, they will have a larger range of diet. In addition to Andrei's fine points, we do have some basis for agriculture. The sea cucumbers, the kelp, the seaweed, and even edible microphytes. Some of these are a good source of nutrients, thankfully, which in addition to fish and other things should make for a stable diet.

For cultivating fish, crabs, etc., you will need a few things:

1) Environment, they can't freeze or the like. This can vary a bit with season, depending on the depth on the ocean.

2) Food source, you can't have your food starve or you'll starve. The farm's limit is its food's limit. If you can cultivate your farm's food somehow (I am no expert on how), you will cultivate your food. Note that with migratory fish you rely on seasonally, they have the advantage that they get their food source elsewhere.

3) Control, you need to be able to control this farm to an extent, or else it just becomes hunting. If you could enclose your food into a small environment they're easy to catch from, that works--but you have to keep in mind the possibility of them running out of food in this small environment, or spreading disease if they're too enclosed. Clam and kelp gardens are simple, along with other vegetables. Fish are trickier, most will need quite a bit of space, and good places to lay their eggs, and their full diet.

There are various ways you can control this. If you know when the salmon come in and how they get to their grounds, you could set up traps that allow you to capture a percentage of the salmon, and let the rest through to breed. If your mermaids can stand fresh water for a while, they could also wait till most of the salmon have spawned, then swim in to harvest the adults before they die naturally (and some caviar, if they're wasteful). I'm not sure what hunting of post-parent salmon is like.

You might even be able to breed the fish to the point where they'll start to have instincts that makes farming them easier. Other than that, dolphins and whales would be good tamable animals for work, defence, and possibly food. Seals might be, as well.

Sadly, I don't know enough about the needs of fish, to know how to set up these farms, how much space they need, what places for eggs, how much food and how well you can cultivate it. Real examples of fish farming will probably give a good idea of this.

Answer 4

I not a marine expert but im sure they could grow sea weed or some other sea plant the way we started to grow wheat.

If not then perhaps they could become herdsmen instead of farmers. They could grow algae and feed it to fish who they would then eat like we would feed grass to cattle.