I believe with the implementation of fishing, there should be a lot of emphasis on how it would work. Here are a few things I have in mind that I'd hope to be implemented for fishing.

FISHING HOT ZONES:
Throughout the map, there are certain biomes or areas that have a much more abundant source of fish. For example, a biome like marsh can have a much more abundance of fish than savannah.

Despite this though, in order to ensure travel with assets to make sure an asset doesnt stay in just one area relying on fish, these fishing zones periodically move over time. For example, areas not in a fish zone still DO have fish, but a very little amount. While areas in a fishing hot zone have an abundant amount of fish giving more gameplay opportunity for semi-aquatics and assets that rely on a diet of fish, and incorporate spearing.

DRY SEASON AND WET SEASON:
With the implementation of seasons, fish should be heavily affected by these seasons in order to add more engaging gameplay and realisim to profiles such as suchomimus which are much more terrestial in dry season due to the lack of fish.

WET SEASON:
During wet season, fish hot zones are much more abundant and always changing areas, but no matter what, there is always fish in most locations in general.

Hot zones have abundant fish that assets can use to satiate their hunger and have a realistic piscovore diet.

DRY SEASON:
During dry season, fish are no longer generally everywhere throughout the reserve, rather fish only appear in hot zones which may allow competition against assets competing for food, or encourage semi-aquatic assets to hunt other assets.

example: during dry season, fish no longer spawn in general areas, instead restricted to very small hot zones that assets can compete in, but due to competition, most semi-aquatic assets are encouraged to hunt other assets to ensure gameplay doesnt rely on just eating fish.

SPEARING:
Akin to the isle and many other games, spearing is a form of fishing that allows an asset to dip its beak / mouth in the water and just wait to capture fish. I believe that this should be a feature for most semi-aquatics like austroraptor, or suchomimus.

In order to ensure that assets dont rely on spearing to have a safe abundance of fish, spearing can only be done in active fish hot zones. This is to ensure that assets that utilize spearing aren't taking advantage of it as a way to avoid actively hunting other assets or avoid manually having to hunt for fish.

OTHER OPTION FOR SPEARING:
Spearing can be done in any body of water with a general amount of fish, but if done for a long period of time in one area, spearing no longer works and they must move to a different or new area. With hot zones, there is no limit untill the hot zone moves into a different area.

Furthermore, in the dry season, spearing does NOT work in any areas except fish hot zones.

SIMPLIFIED EXPLANATION FOR J:
fish are normally abundant throughout the island like normal ( spawn in most bodies of water )
but hot zones are areas which have more fish and allow assets like austroraptor and suchomimus to be able to spear for fish which makes it easier for them to get fish

Dry and wet seasons will heavily influence how fish are caught

Dry season: fish abundant mostly everywhere, hot zones frequent

wet season: fish only reside in small hot zones forcing assets to compete / hunt other assets