San Diego is synonymous with seafood. Even before the arrival of the Spanish in 1769, fish, including tuna, were a dietary staple of native people. As modern San Diego expanded in the early 1900s, tuna fishermen made San Diego Bay their home base and canneries sprang up, ultimately growing into a multi-billion dollar industry.

Though the word “tuna” may conjure up images of cans of Chicken of the Sea or a gorgeous piece of sashimi, many people haven’t seen a tuna up close. Museum volunteers are preparing two specimens that will allow people to see the skeletons of these impressive fish in incredible detail.

Those now in the Museum’s collection were caught in 2018 by a fisherman named Phil, who, like his ancestors, used a pole with a line and hook to fish for food. He caught both a yellowfin tuna and a bluefin tuna, both delicious fish. Phil and his fellow fisherman removed the meat and donated the bones to The Nat. The bones encompass the entire vertebral column, the ribs, some fins and finlets, and all the bones in the enormous head—in fact, the heads alone have about 130 bones each!

Thus began a long and painstaking process to prepare these specimens for display. The tuna skeletons, like most other skeletons in our collection, took months if not years to prepare. First, the residual bits of meat had to be cleaned off, not by people with tiny scrapers, but by dermestid beetles. These insects consume carrion, or the flesh of dead animals (learn more about them here). This took some months.

Because the beetles also ate most of the ligaments, tendons, and cartilage that once held the bones in place, the skeletons had to be completely reassembled. So, from a pile of hundreds of bones, putting them together so they are anatomically correct took more months. Researching the structure and engineering the wires, glue, and supports needed to hold the skeleton together took Zaira Marquez, who led the effort, still more time.

Each of these fish has 39 vertebrae making up the spine. From the vertebrae, there are two sets of rib-like protrusions, one going upward from the spine (neural spines), one going down (mostly pleural ribs). Some of the other bones don’t attach directly to the vertebral column. The bony spines of the fins “float” on the outside of the fish in the same plane as the vertebral column and rib-like structures.

Once fully reassembled, the final step is to design a custom case so the skeletons can be safely displayed, at which point they will be on view in one of the Museum’s galleries or science departments. This is a coup for The Nat, as there are very few tuna skeletons that have been fully articulated and mounted previously. While some museums may have them in their collections, we know of only two on public display—one at Harvard University in Cambridge, Mass., and the other at Oxford University in England.

Not only are these specimens incredibly cool to see, they also provide an important reference point for people working in the field of zooarchaeology. Also known as faunal analysis, this is the study of animal remains—such as bones, shells, hair, scales, and hides—from archaeological sites. Only by reference to skeletons in the Museum’s research collection can zooarchaeologists identify bones found at archeological sites. This helps us understand what people’s life was like in the past—where they lived, how their settlements were organized, what they ate, and how they ate it. Now we can identify tuna bones with confidence too.

Posted by The Nat.