Research into old cod bones has revealed the effects of sea temperature and centuries of fishing on the cod stock. RÚV reports.
Guðbjörg Ásta Ólafsdóttir, a biologist researching the bones, claims there are clear signs of change in the cod stock following increased fishing during the late 1800‘s.
By examining the combination of carbon and nitrogen in the bones, a lot can be learned about the cod’s position on the food chain, as well as its nourishment. A large amount of nitrogen, for example, reveals a high position on the food chain. “This had been steady for hundreds of years, but we can see a clear decrease in these numbers during the latter part of the 1800’s as well as the earlier parts of the 20th century.”
According to Guðbjörg, the likeliest explanation has to be fishing. “The industry removes the largest fish out of the ocean, and trawlers had begun to emerge during this time, which can affect the ocean floor biosphere and available food for the fish.” Guðbjörg’s earlier research had indicated that 16th and 17th-century fishing had also affected the cod stock and its genetic variation.
Although fishing methods used to be different, they weren’t nearly as controlled as they are now. Fish were regularly caught at spawning areas and there were no rules set in place regarding discards.