Unfortunately, human beings are putting so much pressure on sharks from so many different angles that many species are already endangered. It is thought that more than a third of shark species could become extinct in the near future.

What kind of human threats do sharks face? Let us count the ways.

First there are habitat problems. Human activities impact every part of the ocean. Carbon dioxide in the atmosphere is increasing the acidity of the ocean. Urban runoff, farm runoff, silt runoff and sewage all change ocean chemistry and water quality. There is growing evidence that the Great Barrier Reef will be gone in 20 years because of ocean warming. According to one scientist there is nothing we can do to stop it at this point. With reefs dying off, sharks take a huge hit.

There is also the problem with plastic. The oceans have filled with pieces of plastic both large and tiny, because plastic does not biodegrade. Any species that feeds of plankton, like the whale shark, is now ingesting plastic with its food. This problem will only grow worse going forward, as there is nothing being done right now to solve the problem.

Then there is the loss of fish. Because of everything from overfishing to water quality to loss of habitat, it is thought that the oceans will run out of fish over the next several decades. With nothing to eat, many sharks will perish.

Then there is direct fishing pressure on sharks. One article I read this week mentioned that 100 million sharks are killed each year for their fins alone. That is, the shark is caught, the fins removed, and then the still-living but helpless animal is thrown back in the ocean to die. If you think back to the buffalo that once roamed the American plains by the millions, you see a direct correlation. The buffalo were hunted to near extinction in just a few decades. Sharks are likely to follow the same path unless something is done to stop the carnage.

Finally there is unintended capture. While fishing for other species, fishermen often catch sharks in their nets. The sharks die in the process.

When you put all of these pressures together, it does not look good for sharks. Scientists think that we could lose a third of shark species in the near future.

It seems like an impossible problem. And some parts of it are impossible for us to solve as individuals. But if you have any desire to help sharks and other marine animals, there are two things you, as a single person, can do.

First, you can stop eating seafood - all seafood - and encourage your friends and neighbors to do the same. Get evangelistic about it if you like. If enough people around the world stopped eating things like tuna, flounder, salmon and swordfish, there would be more fish in the ocean. Plus, it will cut back on the sharks killed by fishermen looking for other species. This would give sharks some breathing room and time to recover.

The second thing you can do is to put persistent pressure on local and national governments to stop ocean pollution and to end carbon emissions. The fact that we could lose the Great Barrier Reef should be a wakeup call for all of us. That would be an immense tragedy, and something that should shake us to our core. Help your government see that this situation must be reversed.