Personal Interpretation: When first viewing Turner's painting above I am immediately captivated by the sunset in the background. The sun pierces through the canvas with a bright yellow then mellows out to more depressing surrounding colors. The "depressing colors" that are the rest of the painting, are selectively chosen in order to convey the morbid action that is taking place. Apparently the ship was en route and the captain ordered for the dead and dying to be tossed overboard in order to make tax cuts. The turning sea emphasizes the violent act and the bodies floating about with the ship in the distance portrays the betrayal of humankind. I believe Turner painted the ship in one of the more dark colors and also a mere silhouette in order to disgrace the morbid decision to toss the bodies.
Interestingly, I found that Turner showed the painting at an event in which Prince Albert was scheduled to speak, possibly in hopes of further influencing the antislavery movement. It is said that recently after the event, public policy on slavery was indeed changed. As to if the painting had an effect we are unsure but it is peculiar. He also wrote a poem that goes with the painting:
The last line "Where is thy market now?" I believe is the strongest and most important line. Here he is bluntly calling people out stating that slavery is a dying trade and is trying to catalyze is definite end.