Why is the harbor seal endangered or threatened?

The Harbor Porpoise is NOT endangered.

Though many people think it is, the harbor porpoise is threatened in some places. However, it is not endangered.

The harbor porpoise is threatened mainly by all catch. This means that when fishermen go out and catch herring, for example, sometimes the net will ally envelop a porpoise. The porpoise then dies of suffocation, for it cannot go back up to the water to breath air through it's air hole.

Another reason, as almost always, as hunting on purpose. There have been regulations made on the of porpoises, but only in some places. Fortunately, in 1998, catching porpoises was made illegal in Peru, which at that time was the Porpoise catching place.

The last one is water pollution. Pollution from plastic bottle companies and oil factories continues to kill porpoises worldwide.