In a recently published research paper, scientistis from Ifremer and La Rochelle University studied feeding strategies of fishes, all the way from the surface to the deepest depths in the Bay of Biscay.

Fishes residing within the deep sea (200+ m), limited by food due to the lack of photosynthesis, are generally thought to have one of two feeding strategies. They can either be opportunistic feeders, having a broad and varied diet - or they can be specialists, feeding on much more specific prey.

A: Clusters of fish isotopic niche (diet) overlap. B: Vertical nocturnal distribution of 16 species. Colors represent fish having similar diets. (Figure 3, retrieved from Loutrage et al. 2024)

The authors were able to show that different species who eat similar prey are separated by depth. In this way, they avoid having to compete for the food within the same depths! They also found that competition for food has likely led to a higher level of trophic specialization in the deep sea, meaning that some species have very different diets.

You can access the full article here (open access): https://doi.org/10.1016/j.dsr.2024.104347