Why Are Cape Lobsters Dying?: Climate Change A Potential Factor

BARNSTABLE, MA — It's common for fisherman to catch lobsters in Cape Cod Bay, but since last year many of the lobsters brought up in traps already died.

Over the last year, the Massachusetts Lobstermen's Association continued to get calls from fishermen reporting the dead lobsters, causing researchers from the Division of Marine Fisheries and the Center for Coastal Studies to investigate.

An analysis of the water quality at Cape Cod Bay's ocean floor showed dangerously low levels of oxygen, which were killing the lobsters. Researchers nicknamed this low oxygen zone "the Blob," and it could be growing as a result of climate change, Tracy Pugh, a senior biologist with the state Division of Marine Fisheries told the Cape Cod Times.

Pugh said part of the problem stemmed from a hot summer with no storms to mix the water and carry oxygen from the surface to the ocean floor. She said researchers are still unclear exactly why "the Blob" is expanding, but ocean warming due to climate change and nutrient flow from spetic systems may be important factors.

When the lobsters started dying last year, Owen Nichols, the director of marine fisheries research at the Center for Coastal Studies, said warmer than usual water temperatures likely played a role in the lobsters' deaths.

As water temperatures rise, it warms in layers, so the cold water gets trapped at the bottom. As animals breathe in anything at the ocean floor that decomposes, the oxygen gets pulled from the water. The fish can escape by swimming to where there's more oxygen, but any lobsters that ends up in traps suffocate.