Today we headed to a different naval buoy to try our luck with the silky sharks again. Silky sharks are a deep-water species that, like the oceanic whitetip, have been severely overfished for their fins and suffered huge population declines from the long-line fisheries. There are not many studies on silkies and we don’t know their migration patterns. The research team hopes to fit silkies with satellite tags to learn more about this elusive shark, including how far they dive down to hunt and where they move. According to Mark, the diving profiles are especially interesting. For sharks, the real data is in how it moves, not where it moves. If sharks are hunting at the same depth as fishing lines, they will likely be caught. Understanding where sharks spend their time is crucial for successful management.
We spent the good part of the morning at the buoy, but didn’t get any bites. It was empty – no sign of marine life other than sea birds. After heading to some fishing sites, we tried another pass at the buoy later in the day. The silkies were still eluding us. Buoys are usually good spots for sharks, but not this time. Later, we found out that this buoy had been removed from the ocean for repairs and just got put back last week. The fish had not re-colonized it yet.
Sometimes science isn’t easy. You can have solid methods, background research, the best-laid plans, and do everything right, but when you are dealing with living things (especially sharks), you can’t always count on them to cooperate…or in our case, bite. It can be really frustrating, but also extremely rewarding. You have to be persistent and take what you can from the situation. Even in failed science is discovery.
What did cooperate today was the weather. It was perfect. The ocean was aqua-green, calm and glass like – completely different from the choppy seas of the past few days. The weather was also perfect – cool breeze, blue skies, and little puffy white clouds.
I also got to try my hand at fishing today, which was a lot of fun. Collecting fish samples is another part of the research expedition. The team wants to study what oceanic whitetips are eating and their place in the food web. By taking samples from a bunch of different fish found in the area, they can use stable isotope analysis for carbon and nitrogen and see where the fish fit in the food web.
Fishing takes lots of patience. Sitting there quietly, waiting, dropping the bait down to the bottom, reeling it up a bit, waiting, feeling a nibble, ready to pull the tip of my rod up…then nothing. More waiting. But always cautiously alert. Then a tug, and this time a bite. I quickly began to reel the fish in at the other end. It was a yellow-eyed rockfish, affectionately called for their big yellow eyes and pinky orange skin.
We mostly trolled, but also tried deep dropping at the ledge of the reef. For deep dropping, we put a bunch of hooks on a line with a weight and dropped it down to the bottom, which was about 400-500 feet down. This method is called a “chicken rig,” no one knew why.
At the end of the day we caught 6 yellow-eyed rockfish, a small Spanish mackerel and a rockhind, which was brown with strawberry pink spots. We also caught a Nassau grouper – a brown and olive striped fish. As Joey was reeling it in, a huge cubera snapper grabbed it and took a big chunk out of its back! We watched the whole attack from above.
When we got back to the dock, we took some measurements and muscle samples. The rest got cooked up for dinner.