En route to the airport, we had a lively discussion about various parents worried about their offspring being devoured by sharks (among other things) during the course of our expedition. I believe the direct quote was "Y'all are going to be shark bait, for sure". Let me assure all the parents of our fledgeling scientists that nobody be will eaten on this trip. In all my years of diving and snorkeling on these reefs, I have never had cause for concern, with one exception. On a research cruise in 1998, I jumped in the water at Jarvis Island (an uninhabited US possession more remote than Christmas) and instantly drew 50+ curious sharks. I spent less than a minute contemplating whether to continue the dive, and found myself unable to suppress my instinctive fear at their excited collective mass. I have never been so grateful to exit the water. More recent dives across the Line Islands tell of a vastly changed landscape for the Pacific's shark populations - one of massive declines in the face of overfishing fueled by Asia's appetite for shark fin soup, which is prized as an aphrodisiac of sorts. Long-liners from Asia comb the bountiful fisheries across the Line Islands (I have personally observed this on numerous occasions), some of them no doubt compensating the Republic of Kiribati and some operating literally under the radar. Once they catch a shark, they cut off its dorsal fin and often throw the animal back in the sea to die, saving money on transporting a relatively low-value meat back across the Pacific. It is a practice that has been widely condemned, but a robust market for the delicacy, combined with the difficulty of enforcing fishing practices in the most remote areas of the Pacific, ensure that shark finning will continue to wreck havoc on the Pacific's shark populations. Ecologists tout the importance of so-called "keystone predators" (those near the top of the food chain) for the maintenance of healthy marine ecosystems, so it stands to reason that the decline of the sharks across the Line Islands will eventually impact the corals themselves. This stress will add to stressors associated with the local island populations (untreated sewage runoff, illicit trade in aquarium fish, and overfishing of smaller fish who keep algal overgrowths at bay) as well as those associated with climate change (declining pH and rising temperatures). I have only just begun to contemplate how to marry our coral climate reconstruction research with ecological studies of reef health to track coral "health" through time, through natural climate fluctuations such as El Nino events and over the next decades of anthropogenic climate change. A new graduate student named Pamela Grothe will be joining the lab this fall, and will work closely with Scripps Inst. of Oceanography coral reef ecologist Stuart Sandin who has been working on Line Island reef systems since 2005. We are hopeful that we can combine each other's data and approaches to learn more about coral response to environmental stressors, ideally informing coral reef management and climate change mitigation policies.
So unlikely as it is, it would warm my heart to see a healthy shark population at Christmas Island. Definitely check back for our best "shark bait" photos in coming days!