Gray Seals Seen Hunting Harbor Porpoises

Written by on January 28, 2014 in Marine Life

Daily Summary

Irish fishing vessels.

Irish fishing vessels. Photo credit: infomatique via photopin cc.

Better data to support the sustainable development of fisheries and aquaculture sectors
The newly reformed Common Fisheries Policy, implemented on January 1st, “places data and knowledge at the heart of decision making.” The reforms seek to end wasteful fishing practices and bring stocks back to sustainable levels by banning discards, supporting small scale fisheries, and improving scientific knowledge on the state of stocks. The Fisheries Commission recently held a meeting to discuss ways to improve Data Collection Regulation. Topics included improving the quality of data and making it more accessibly without compromising personal data protection, increasing regional cooperation, and much more.

Gray seals.

Gray seals. Photo credit: NOAA.

Gray seals snack on harbor porpoises
Gray seals (Halichoerus grypus), found across the northern Atlantic, can grow up to 3.3 meters in length and weigh over 300 kilograms. They feed primarily on fish, but researchers are learning that they also like to eat harbor porpoises (Phocoena phocoena). In 2011, researchers studied the bite marks found on two dead porpoises that had washed up on a beach in eastern Belgium, which appeared to match the gray seal’s jaw. Then in early 2013, researchers caught gray seals in the act…three separate times. This behavior hadn’t been seen before 2011, but now it’s pretty clear that the gray seals appear to be hunting harbor porpoises. Researchers don’t yet know the reason for the change in diet, but it may have to do with the high energy content in the fat of the harbor porpoises and a decrease in other high-energy prey.

Relief map of the South China Sea.

Relief map of the South China Sea. Photo credit: Nzeemin, CC BY-SA 3.0.

Sea drilling project launches
The South China Sea typically makes its way into the news for political reasons, but it should also be known for its important geological features. Today (January 28), an international team of scientists is setting sail from Hong Kong to determine the age of the South China Sea and resolve the ongoing controversy over how it was formed. The sea is more than three million square kilometers, but that’s relatively small compared with major ocean basins. It’s also relatively young — between 25 million and 42 million years old — which means that researchers can study its entire history in only a few expeditions. The team will drill up to two kilometers into the seabed to collect rock samples. The ages and characteristics of the rocks will help researchers determine their origins.

Copyright © 2014 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .


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