CHESS Cruise Summary

After two long months at sea, we wearily and happily returned to San Diego on October 4th, 2001. Despite hurricane Juliette’s best efforts to cause trouble, the cruise was fully successful in meeting our primary objectives. The numbers and kinds of biological samples and data we were able to collect on these wild, tropical, pelagic dolphins are unprecedented, and we will no doubt have many interesting scientific results during the months and years to come. One of the most interesting discoveries while at sea was the highly dynamic nature of the dolphin groups encountered: it quickly became apparent that very few individuals in the schools we observed stayed together from one day to the next. This made our objective of recapturing entire groups very difficult, but we adapted our sampling strategies as needed to nonetheless allow recaptures of small groups of dolphins associated with the tracked radio-tagged animals.

Working with a dedicated and highly experienced crew aboard the chartered tuna purse seiner, we captured and released about 1500 dolphins in 27 targeted sets (most of the captured animals were spotted dolphins, but some spinners were caught, too). We successfully deployed 8 radio tags with time-depth recorders, 2 radio tags with thermal instruments, 6 satellite tags, 8 small ‘bullet’ radio tags, and 213 roto-tags (see photos below). We obtained 70 blood samples for comprehensive laboratory analyses (including 17 samples from repeatedly captured dolphins), 283 skin samples for genetic analyses and skin stress studies, 449 analyzable thermal images of dolphins swimming in the net, 52 body core temperatures, and 95 hours of heat flux data from the two thermal-tag dolphins.

The analysis of all data and samples from the cruise was initiated within days after returning to port, and results are now being compiled for scientific peer-review. The individual projects were designed to integrate with one another, and after the ‘puzzle assembly’ has been completed, the overall results will be included in a Final Report to Congress by the end of 2002. This report will also include the results of the other IDCPA studies conducted since 1998.