Pollock and cod were both viewed as inexhaustible populations of fish, and thus were both fished hard. Because they are both schooling species, it’s relatively easy to catch them. As seen with the collapse of the cod fishery, this can lead to issues.
Though it seemed as if the cod population was doing alright because fishermen were still able to catch them, numbers were actually declining at a rate that resulted in the crash of the fishery. Additionally, the cod fishery was hundreds of years old and the collapse was a result in increasing effort and fishing technology that allowed for more to be caught.
The pollock fishery is relatively new, only about thirty years old. Today, the fishery is better monitored through scientific data. Though that’s not to say that all catch is reported, and the stock seems to be in decline though this could be attributed to the boom and bust cycles that both pollock and cod experience.
That’s a good point about the boom and bust cycles, I hadn’t thought about that. This can change the data a lot and should be taken into consideration when reading/interpreting the graphs produced for the pollock stocks.