Final answer:
The availability of sunlight is the abiotic factor that most limits the productivity of a fishery in coastal aquatic ecosystems.
Step-by-step explanation:
The abiotic factor that most limits the productivity of a fishery in coastal aquatic ecosystems is the availability of sunlight. Many organisms that serve as food for fish are photosynthetic and rely on sunlight for their survival. If algal blooms occur and obscure the light, these organisms will die, leading to a depletion of food for fish and a decrease in fishery productivity. The temperature of water bodies also has a significant impact on the productivity of a fishery. Temperature can affect metabolic rates of aquatic organisms and also has implications for the levels of dissolved oxygen in the water. Cold water can hold more dissolved oxygen compared to warm water, which can result in higher productivity in colder waters.
While other factors such as nutrients, currents, and tidal changes are also important, the limitations imposed by sunlight and dissolved oxygen concentration are particularly acute for the productivity of fisheries.