Final answer:
The trends of fishing effort and catch in the last 50 years indicate overfishing and the depletion of fish populations, leading to disruptions in the marine ecosystem.
Step-by-step explanation:
The trends of fishing effort and catch in the last 50 years tell us that there has been a significant increase in fishing effort, with larger and more efficient fishing fleets, resulting in overfishing and the depletion of fish populations. The catch has also declined in many areas due to overfishing, causing disruptions in the marine ecosystem. For example, the collapse of the northwest cod can be attributed to the excessive fishing effort in the region.