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Earth Science Applications Travelogue: Day 11: Wednesday May 21
May 22, 2014

[image-51][image-78][image-94]As we concluded sampling for this leg of the cruise, I asked Chief Scientist Lamkin to provide his thoughts on the results to date. He indicated that normally the cruise schedule is to sample the eastern Gulf first and then the western Gulf, but decided to reverse the timing of sampling this year by working in the western Gulf first and eastern gulf in the latter half of the cruise. For the last few years, large numbers of Bluefin have been found in the western Gulf and smaller numbers in the eastern Gulf, so the research objective was to determine if timing of the survey more than geographic location could be influencing these results. 

For leg 1 of the cruise that began April 28 in Miami, Florida, and concluded May 9 in Galveston, Texas, Bluefin tuna larvae were not found throughout the west central Gulf transect to Brownsville, Texas, which was unusual given sampling results for the last few years. Water temperatures were below normal, particularly in the western versus the eastern Gulf, which may have contributed to the lack of Bluefin tuna larvae. While in route to port in Galveston and further to the north central region of the western Gulf, two stations produced significant numbers of Bluefin larvae.

After departing Galveston on May 12, the weather was very windy for a couple of days as cold fronts passed through the Gulf. The initial sampling locations had high or favorable sea surface temperatures, but no thermocline (surface layer in water column has similar temperatures that begin to change more rapidly at greater depths) was present in the water column and only very small numbers or no Bluefin larvae were found. Using Roffers’ data, Chief Scientist Lamkin had been evaluating the surface water eddy north off the Loop current for several months. While Bluefin larvae were found at a few stations (65 the largest number at a single station), the gyre was energetic and not as favorable for Bluefin tuna spawning as originally hoped. The most Bluefin larvae were found at the northern edge of the gyre out of an upwelling area in the DeSoto Canyon region of the northeast Gulf of Mexico. 

While the number of Bluefin larvae found has not been as great as some previous cruises, the 2014 cruise has several major successes. Enough Bluefin tuna larvae were found to move forward with planned experiments with isotopes, food web evaluation, and size/age assessments. Climate and related environmental conditions affect larvae growth and predator – prey relationships. Also, the habitat suitability model performance during this spring period predicted below average habitat suitability for Bluefin spawning, which has been confirmed by the lower than average number of samples collected.

This further validation of the habitat suitability model will help the continued integration of knowledge from this project into the fisheries stock assessment process through the updating of indices and the weighting of sample sizes collected under different environmental conditions. For fisheries management, it is important to note that collection of a small number of samples due to unsuitable spawning conditions is not a recruitment failure.

On the final leg back to Miami from Gulfport, Mississippi, sampling may be more productive. The eastern Gulf sea surface temperatures are closer to normal spring values; however, surface temperature cannot provide information on frontal effects or mixing in the water column. 

We arrived at port in Gulfport, Mississippi, about 8 a.m. local time. The last nine days at sea have been a great learning experience and a unique adventure. Much deeper insight has been gained into the usage and benefits of remotely sensed satellite data to support marine field cruises and increase knowledge that will lead to better fisheries management. A much greater understanding of the challenges to live and work for long periods of time at sea was acquired. Observing the spectacular marine sunsets and orange moons, flying fish, schools of spotted dolphin and the microscopic images of recently hatched Bluefin larvae were unique experiences.     

The support of many people made it possible for me to participate in this research cruise. Many thanks to:
 

  • John Lamkin, NOAA Chief Scientist for the 2014 cruise, for inviting me to join, saving a bunk for me and being very generous with his time to discuss satellite remotely sensed data and linkages to Bluefin tuna spawning habitat. 
  • Woody Tuner, Program Manager for Ecological Forecasting and Lawrence Friedl, Applied Sciences Program Manager for supporting my participation in this cruise.
  • John Christy, University of Alabama in Huntsville (UAH), Director of the Earth System Science Center, and Sundar Christopher, UAH,  Professor and Chair of the Atmospheric Sciences Department, for their support and encouragement in research and teaching.
  • My colleagues on board the F. G. Walton Smith for making me feel like a member of the team from the first day and helping me learn so much.
  • Captain Lake and the F. G. Walton Smith crew for sharing their wealth of knowledge with me to enable me to survive at sea for over a week. 
  • Finally, special thanks to my wife Sue and family for supporting my participation and taking on extra duties at home for me.

This is my last blog from my journey aboard the F. G. Walton Smith. Best wishes to everyone for a great summer and many days filled with calm seas and favorable winds.

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The F.G. Walton Smith arrives in Gulfport, Mississippi.
The F.G. Walton Smith arrives in Gulfport, Mississippi.
Image Credit: 
Maury Estes
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The team for the second leg of the science cruise.
The team for the second leg of the science cruise.
Image Credit: 
Maury Estes
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Sunset over the Gulf of Mexico.
Sunset over the Gulf of Mexico.
Image Credit: 
Maury Estes
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Page Last Updated: May 22nd, 2014
Page Editor: Brooke Boen