Rackham Graduate School - University of Michigan

molecular techniques to my behavioralquestions, it was clear that thiswas the best thing I could do.”In 1997 Sal joined Jeff Jacobsenand Luis Medrano in a project startedover a decade ago. They spentthree months each winter on aMexican Navy base on Isla Soccoro,using crossbows to take biopsies ofwhales, recording their songs andphotographing them. “What we aredoing there is quite unique,” saysCerchio. “Although there exists alarger sample of biopsies from theAtlantic, something like 3,000 overtwo years, our sample in Mexico ismuch more thorough because thepopulation is much smaller. We’venow sampled 400-500 out of a thousandindividuals, and we hope tohave another 150-200 after next season.Plus there is a sighting historyof individuals with behaviors thatgoes back 10 years, plus songs frommany of these animals. In a year ortwo, this sample is going to be a veritablegold mine of information, andwe should be able todo some very interestingstudies with it.There are no otherhumpback whalepopulations that willbe as thoroughlysampled, that’s forsure.”As part of Sal’sdissertation he willbe assessing paternityand male reproductivesuccess.Using the same technology utilizedin human forensic work, he creates aDNA fingerprint of skin samplesobtained from the mother and calf.By comparing a mother’s genotype toPhoto by Danielle Cholewiakher calf’s, he identifies what part ofthe calf’s genotype came from thefather. This is then compared to thegenetic fingerprint of all the malewhales that were sampled. If a matchis found, paternity is determined. Bycomparing many samples he will beable to discern whether humpbacksare polygynous breeders.What’s the point? There are several.First is the growth of humanknowledge: this is the first largestudy of reproductive success incetaceans. Secondly, this researchwill create a model for studyingother species.Finally, there are implications formanagement and conservation of thespecies, which was hunted almost toPhoto by Bill Woodextinction before making a comeback.Successful conservation of thehumpback whale populations musteventually derive from the work ofscholars like Cerchio, lured by thewhales and their siren songs. ■Photo by Salvatore Cerchio11