How are Fishermen Changing the Genetics of the Ocean

A little while ago in my ecology of fishe course we discussed an interesting topic that has to do with both gentics and fisheries management. There are a great many fish that have been fished for a long time. Fishermen tend to fish for the biggest catch. The reason that this is such a problem, is that traditionally in certain species, there are a few genes that promote dwarfed sized fish. These dwarfed sized fish if mate with bigger fish will cause the resulting offspring to be much smaller than the big fish. Therfore as fishermen continue to overfish the big fish of different species, it is not only depleting the fish resource, but is caausing a shift in the allele frequencies of the dwarf fish genes in the population and thus the the trend observed in the oceans, are that there are not only far less fish available, but the majority of the fish are small. Just something to think about.