This is an outcropping of a human actuated overload that presses another one of Earth's natural conditions up against the wall. In this instance... Right Whale potential extinction.
Unfortunately for Earth's millions of natural conditions our human race has already overloaded or is in process of newly overloading hundreds of thousands of natural conditions... some too often reach the point of bust!
Also unfortunately, but this time for humans... civilizations expansion with our resulting natural condition overloads is/are because of life styles and businesses-as-usual that simply can not abruptly be stopped from continuation. Otherwise... the global economic system will collapse.
Therefore, instead of trying to stop human life events in their tracks [such as limiting boat speed to 10 knots] - our human genius capabilities need to concoct solutions that stop human propagated calamities in, to or against Earth's natural conditions.
In this case of "Save the Right Whale" - I propose: Govt subsidized [non intrusive to boat operation] whale-safe propeller cages to be installed on all boats wanting to travel over 10 knots. Just imagine the marine employment positions and boat yard cash flow that would create!
Sure I know that will be a hassle to some boat owners. And, yes... we can all wish items such as speed limits and prop cages were not necessary to be enforced. However, I say: Either our human race learns to live alongside natural conditions without ruining natural conditions or this beautiful planet we live on will have changes in its natural conditions that will eventually kick our rich a$$e$ out!
Think about it. We don't own the world's nature - it owns us; and, can dump us if we don't straighten up our act
!
We gotta straightn up and fly right... or else!!