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Day 12, August 12, 2005 TER daily cruise log
More fine weather finds us cleaning up some loose ends around the banks. In the afternoon we steam south to Tortugas South a smaller rectangular refuge established to protect populations of grouper and snapper that aggregate to spawn on a deep bank called Riley's Hump.
Our National Marine Fisheries Service colleges are monitoring these populations closely and the fine weather and efficient operation of the ship has allowed us the opportunity to add to these observations. The very top of the bank rises to about 90 feet and our Grouper Ledge dive has a profile of 110 ft for 30 minutes. The sea here is clearer than in Tortugas North, 60 foot visibility easy and the ledges appear early in the descent in birds eye view. Separated by a narrow sand strip, two gently tilted rectangular outcrops rise from the surrounding sand. The tops are a jumble of rock, honey combed with narrow passages shallow caves. We descend at the deeper end where a school of black and yellow pork fish swirl around and within this jumble like a disturbed nest of giant bumble bees. The deeper edge is ledge, undercut one imagines by centuries of sheltering fishes. There are lots of big fish here and a high diversity of grouper; big blacks, yellow mouth, yellow fin, coney, rock hind, grasby, a pair of the Federally protected Nassau grouper and turning tail in the distance two tiger grouper.
The big snappers are here also, a pair of cubera, giant muttons and dog snapper and the jacks; a greater amber, bar and almaco. It is exhilarating to see this diversity of large predators and to know that here they have a sanctuary. After another dive on Riley's Hump we turn east towards port. Time to break down and pack, sensors for light, navigation, still and video cameras, gear for diving, trawling, coring, repairing, sample preservation and office work. It has been a remarkably successful research cruise. Blessed with perfect weather, without major mechanical or technical failures we were able to complete all the sampling required for our time series analysis of the impact of the Tortugas Ecological Reserve. In addition we were able to collect a series of replicate samples in each of the management zones of the bank top and bank slope communities above our permanent monitoring stations. These samples will provide a link between the deeper communities that we are monitoring and those of the better known bank top. We were also able to collaborate with the National Marine Fisheries Service in their monitoring project of exploited fishes of the Tortugas and assisted the Florida Fish and Wildlife Conservation Commission in recovering 35 of 36 sonic tag receivers that have been collecting data on the movement of tagged groupers. Our job of course, is just beginning.
The data we have collected; still and video images, light measurements, sediment samples, fish counts, trawl samples, fish and invertebrate tissue and macroalgae samples require identification, enumeration, analysis and interpretation. We approach this job with light hearts as the news looks good. The establishment of the reserve appears to be bearing fruit and we feel fortunate to be watching that fruit grow.