Slavery in South Texas?

Several reasons we don't hear much about slavery in our south Texas history is that labor here has always been cheap and slaves were expensive and an escaped slave could easily cross the border into Mexico to become free.  That's what makes this interesting I guess.  I couldn't make out the year on this document but transcribed the gist of it.

Manifest of Slaves, on board the [Schooner?] Fanny of ___ ... whereof Forte [Captain?] is at present Master, bound from the Port of NEW ORLEANS for the Port of Point Isabel

Name:  Rebecca   Sex:  female  Age: 11  Stature:  4 ft 4 in  Class:  Gulf [?]  Shippers or owners:  Samuel A. Belden  Residence:  Texas

District of New Orleans - Port of New Orleans, the 9th day of July 18__
Samuel A Belden ___ Owner of the Slaves named and particularly described in the above Manifest , and Forte   Master of the Steamship Fanny [?] do solemnly, sincerely and truly Swear [?] according to the best of our [?] knowledge and belief, that the persons above described were not imported into the United States since the first day of January, 1808 and that under the laws of the State, they are held to service and labor.

So Help us [?] God
Samuel Belden    Daniel Forte Master Steamer Ship Fanny