Kate Madin, Woods Hole Oceanographic Institution
Today we made an unusual dive inside Orona’s lagoon. We took the skiffs in at near-high tide, and it was still so shallow that we had to get out and walk the skiff through the entry channel. But the dive was our reward: At about 40 feet down, giant clams (Tridacna) were everywhere, each about 8”, with their mantles (lips) exposed to the sun and looking like sapphires nested in the coral. Every individual clam had a different light and dark blue pattern on its mantle. Tiny fish flocked around separate coral castles and mountains rising from white sand, going in and out of their entrance, going about their business.
Then came the final dive of the expedition, at noon on Orona’s windward side. Larry took a video camera down, but seas were rough. I stayed on Nai’a this time. Now comes the time to pack up, stow gear, and talk over the memories and meaning of this expedition, as we steam back to Fiji.
The reef fish story
Everywhere we have visited, divers saw abundant large and small fish populating the reefs, making the scientists think there has been little fishing here recently. Stuart Sandin said, “These reefs have the signal of an unfished reef – the fish are all there, doing their jobs.”
The Phoenix Islands corals have definitely taken a serious hit from that 2002 unprecedented temperature spike. “This place has been hammered by heating”, said Stuart. “The temperature recorders David Obura retrieved show the most extreme heating seen anywhere on the planet – elevated temperatures for longer times than measured on any other reef system.”
“The message is one of hope,” Les Kaufman added, “If you don’t fish, the fish are there, and the corals are benefitting from fish eating the fleshy algae that overgrows dead coral. The importance of the fish as a bridge or shield, to carry the ecosystem over and keep algae cleared off until the corals re-grow, cannot be overstated.”
The shark story
But some fish were scarce: divers saw fewer, much smaller sharks than were here in years past.
Sharks are the targets worldwide of a lucrative trade in shark fins for the Asian market, and in many places there are almost no sharks left.
Fish biologist Greg Stone said, “We’re seeing the result of shark fishing that happened before PIPA was protected. We know that commercial long-lining fishing vessels came through in 2001 and 2005, and we saw some of this fishing happening at the time, but the Phoenix Islands were not a protected area until 2006.”
The problem is that sharks reproduce slowly and don’t grow quickly, so there are only young, small sharks on the reef. “The success,” said Greg, “is that there are many young sharks, and the Kiribati government has great surveillance systems in place to protect them and the reefs.”
Tukabu told our group, “Kiiribati has signed an agreement with the U.S. Coast Guard in Hawai’I to allow Kiribati officers on USCG ships, and they are authorized to arrest fishing boats here illegally – they have surveillance on the area, and inform our security system if boats are here illegally. The Kiribati government has recently fined two illegal shark fishing vessels five million dollars.” The scientists hope that this action will send a strong message: stay out of PIPA, and let the reefs be. Like the Phoenix, they will rise.
The photos of the gray reef shark are by Jim Stringer; the photo of clams on the reef is by Randi Rotjan; the photo of schooling silver jacks is by Greg Stone; the red snapper sillhouetted against other fish on the reef is by Larry Madin.