I think that the way this was handled could definitely be made better. Leashed whales and orcas become detached from the boat due to slight turns and also somewhat randomly it feels like. There is no good way to know if you are tethered as well. Other than moving around to see if the whale/orca comes with you there is no good way of knowing when you are leashed or not.
It would be nice if these things just required a rope and showed a leashed icon like everything else. Also it would be nice if we could pull multiple orcas at once without them clipping each other and detaching. Orcas usually spawn in pods of 2-3 and each one requires its own trip unless you're able to find a nearby and suitable island to pull them onto (which is insanely specific to the point where if 1 pixel is on a water tile they cannot be butchered)
Please just make pulling these things similar/the same as other leashed creatures