Bimini Day 3: first taste of shark science

I strolled into the Shark lab around 8:30 just as the shark lab volunteers were coming off the boats looking exhausted after a long night of shark fishing in Bimini's North Sound. We took off in one of the lab's skiffs towards the pens where the sharks were held from the night fishing. As we approached the shallow water of the sound, the plastic orange mesh of the pens showed up in the distance. After anchoring our boat near the shark pens, Doc Gruber and a French film crew arrived by boat with their cameras ready for some action.



Kristine, the resident principal investigator, gracefully demonstrated the stomach inversions which included capturing and
anesthetizing the sharks, holding them while carefully pulling out the stomach, catching the contents as they spewed from the stomach, and finally raising the shark vertically so that the stomach falls back into place. After contents were collected, water was forced over its gills until it regained consciousness and was placed back into the holding pen. After the film crew got their shots, Jana, Sara, and I took over the inversions and worked on the last few sharks left with full stomachs. Each lemon shark was identified by its individual PIT (Passive Integrated Transponder) tag, and each gut content sample was labeled accordingly. After working hard with the sun overhead, our trip ended with a cold and refreshing rain shower and a quick boat trip back to shark lab!



These smelly shark vomit samples will come back with us to NY for analysis! Our study will determine if the method of DNA barcoding can be used to identify fish species in the gut contents of the lemon sharks. By using universal primers and then amplifying the gut content DNA, this technique will allow us to compare our genetic material to an established prey database. In effect, we will match our gut DNA sequences to sequences of likely prey in the Bimini area. This project will contribute to a larger question to whether Lemon sharks actually prey on the sick or the weaker fish. This would include studying Mahara and their MHC (major histocompatibility complex) gene which is important in immunity and results in immune diversity in the Mahara population. The study will determine if there is a correlation between the high susceptibility genotype of the MHC gene and the fish that are being consumed by the lemons.