A couple of quotes from Terri L. Snyder, "Suicide, Slavery, and Memory in North America," Journal of American History 97 (June, 2010):

"[O]ne study of surgeons' logs for the period 1792-1796 reveals that 7.2 percent of captive Africans killed themselves at some point during capture, embarkation, or along the middle passage." (40)

"We simply cannot know how many enslaved persons--or even free people--chose suicide in early modern America. Because no systematic public accounting of deaths was undertaken when slaves were domestically dispersed, traded, and resold on the North American mainland, suicide figures for disembarkation are difficult to ascertain." (40)

"The fugitive slave Charles Ball related the story of African-born Paul, who argued for the 'propriety of destroying a life which was doomed to continual distress' and eventually hanged himself in the woods. Ball asserted that 'self-destruction was much more frequent among the slaves in the cotton region than is generally supposed' and added that he did not 'marvel that the slaves who are driven to the south often destroy themselves.' His comments suggest that the social and cultural dislocations created by the transatlantic slave trade and the middle passage continued to shape the self-destructive impulses of slaves who were born in the United States and traded domestically." (45-46)