Human invasion of habitat is the most serious problem that all wildlife face today.  And even though marine mammals tend to live in the ocean, they are still greatly effected by human population growth.

Perhaps the greatest impact is on seals, sea lions, walruses, sea otters and polar bears which live along shorelines and spend time on land as well as the water.  Because the spreading human population is utilizing  more and more coastal areas, the habitats of these animals are rapidly disappearing.  For example, seals are losing haul-out sites and human-induced soil erosion is spoiling vital habitats in coastal bays utilized by sea otters.  

Humans not only take over the shores of an area when then move in, but they also invade the waters by use of boats.  Even well intended boats such as whale watch cruises can disrupt marine mammal activity, altering feeding and social habits.  Boating activity has become a particularly acute  concern in Florida, where manatee populations are imperiled due to increasingly frequent collisions with water craft.   

With the population of the world increasing, is it important that we set up reserves and take precautions to make sure that our activities have as little effect as possible on the natural lives of these creatures.  Although surely all harm cannot be prevented, simple and reasonable things like moderating our fisheries and keeping safe distances from marine mammals can make a huge difference in their lives.