Up until the end of the 1950s, the most commonly caught commercial fish (more than 50% of the commercial catch) was a subspecies of the walleye known as the blue walleye ("Sander vitreus glaucus") sometimes erroneously called "blue pike". In the 1970s and 1980s, as pollution in the lake declined, counts of walleyes which were caught grew from 112,000 in 1975 to 4.1 million in 1985, with estimates of the numbers of walleyes in the lake at around 33 million in the basin, with many of or more. Not all walleyes thrived. The combination of overfishing and the eutrophication of the lake by pollution caused the population to collapse, and in the mid-1980s, the blue walleye was declared extinct. But the Lake Erie walleye was reportedly having record numbers, even in 1989, according to one report.