During Texas Pelagic trips we keep track of the trips course and coordinates of all bird and animal sightings. Over the course of 25 years of Texas Pelagics this has become a wealth of information. I have created Google maps of 44 of these courses where the data was available to me and they are all now posted individually along with the trip report. This Google Map illustrates all 44 trips compiled onto one map. If more data becomes available I’ll work on creating trip courses for more trips.

In addition the POI markers are Points of Interest tagging subsea, bathymetric high features that are likely to act as areas that congregate fish due to upwellings of deep water from Gulf Currents. Some of these are well know fishing areas for offshore deep water fisherman. All of these seamounts are cored by subsurface diapiric salt domes, a geologic feature caused by the buoyancy of salt relative to the sediments deposited above it. Think of High Island, which also sits on top of a hill cored and caused by a salt dome, but with much greater vertical relief and overall size. 

The POI’s are subdivided into Lower, Central and Upper Texas Coast, divided by which port they are closest to. Lower Coast POI’s are reached from South Padre Island, Central Coast POI’s are reached from Port Aransas and Port O’Connor (past trips in the 1990’s) and Upper Coast POI’s are closest to Freeport. I am currently working on arranging longer duration trips from Freeport that could reach this area of Offshore Texas which is rarely birded.

Also the gray lines indicate the distance from each port to the closest shelf edge, or to significant POI’s.

Finally the Ultra-Deep Water POI’s mark three submarine canyons from west to east: The Perdido, Alaminos and Keathly Canyons and the edge of the Sigsbee Escarpment, in addition to some other large salt withdrawal basins on the continental slope of the Gulf of Mexico in offshore Texas.

The Alaminos Canyon is the largest of the 3 major submarine canyons in offshore Texas. It is about 30 miles long and 15 miles wide with a depth ranging from about 4,500 feet deep along the edges to a depth of 8,000 – 9,500 feet deep in its center.  The total relief of 3,500 to 5,000 feet is similar to the depth of the Grand Canyon which is a mile deep at it’s deepest and about 7-8 miles wide. I’ll bet that not many people imagine a canyon like this exists in Texas, even if it is a mile underwater. 

The Sigsbee Escarpment marks the downdip edge of the continental slope and is formed by a allocthonous Jurassic age salt mass that is still being thrust over the younger abyssal plain sediments.  Bathymetrically it is a steep escarpment of about 5,000 feet of relief where the seafloor drops from about 4,500 – 5,000 deep down to 10,500 ft on the abyssal plain. 

I think would be interesting to investigate these gigantic submarine canyons and escarpments in a possible future overnight Texas Pelagic. Stay tuned for more developments on this possibility.

GOOGLE MAP OF COMPILED TRIP COURSES 1994 to 2018:

Click on the box in the upper left of the map to view the map legend. 

This map is best viewed in a larger window. Click on the box in the upper right of the map.

Click on each track and the data label will appear showing the date of the Texas Pelagic trip.

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