Among all shapes with the same area, a circle has the shortest perimeter.If the given marine reserve is a circle then area of circle is given as 58,000 square miles.
Area of any circle can be found using the formula
where r is the radius of the circle.
Or 58,000 =


r= 135.9miles.
Perimeter is the length all around the circle= 2πr =2(3.24)(135.9)=853.51 miles.
The least length of rope one would need to rope off the perimeter is 135.9miles.