Bottomfish Bio-sampling from the Small Boat on the NOAA Ship Oscar Elton Sette Cruise (SE-14-04 Legs I and II) to the Northern Mariana Islands
The expression “well that’s why it’s called fishing and not catching” is something a friend or a spouse might say to support and cheer-up a weary angler from a long day on the water with little or nothing to show for it.
For this sampling team in the Northern Mariana Islands, the challenge was not whether we were going to catch fish today, but rather could we find and target certain high priority species when the grounds were loaded with a few dominate and aggressive species, namely Gindai (Pristipomoides zonatus) and Yellowtail Kalekale (Pristipomoides auricilla). Those two fish were like pigeons in a park when all you are trying to do is feed the timid ducks, KaleKale and Gindai were just everywhere. Although they too are needed for the project, they were so common that very soon they became “non-target”.
Within days it became apparent that collecting species of importance would prove to be difficult. The species on the list were: Opakapaka (“pink” and “yellow eye”) (Pristipomoides filamentosus and Pristipomoides flavipinnes), Onaga (Etelis coruscans) and Ehu (Etelis carbunculus).
The team knew each species inhabited different depths, so to find the “magic depth” for each island the team would have to “prospect around” and see what species bit at what depth. There were three things the team noticed:
- Each island was different, and as such the species would be found in different depths. For example, Onaga were found shallower (750-850 ft) at Pagan but at other islands like Asuncion and Sarigan they were found deeper in about 890-1000 ft.
- The steepness of the slope would determine species. Basically Opakapaka and Silver Mouths (common name Lehi in Hawaii) (Aphareus rutilans) would not be caught on anything that was too steep and they seemed to be in about 540-630 feet of water. There were only a few islands that had the geography that fit a shallow sloped bottom at that depth. Silver Mouths (Lehi) would bite around 600-650 feet of water.
- The currents switched around hourly, however if the target fish were not biting, the Gindai and Yellow Tail Kale Kale would. So it was only on certain currents that the target fish would become dominant and jump on the hook first. One thing seemed consistent. The fish would congregate on the lee side of the feature and hide in the eddy. It was just luck and timing that allow us to bring in the prized samples.
Furthermore, there were large eight-banded Groupers (Hyporthodus octofasciatus) that lurked in the “Onaga range depths”. If you were trying to target Onaga, before you knew it a grouper would jump on and pull your rig into a hole and make you fight to recover your equipment. Grouper are strong powerful predators and when fishing in these remote locations, if they were around, you would find them. Although we would sample groupers for their gonads and otoliths we did not target them. In fact, when we caught enough by day eight, we started to use hooks that would straighten and let the fish swim away. It was unnecessary to collect so many of these giant fish, so the fishermen decided to modify their gear to limit the take of these supreme predators. This was out of respect for the fish that may be older than the fishermen themselves, and because it felt like the right thing to do. Ironically the samples the scientists and fishermen collected on this project will inform the Pacific Islands Fisheries Science Center (PIFSC) of exactly how old they are.
A great example of how difficult it was to target certain species was when Tony Flores was fishing for Onaga and he had just felt a small fish jump on. He guessed it was too small to be an adult Onaga, so he decided to leave the rig down and wait. Within half a minute he got “stuck” the line went tight and it did not budge. The team did boat maneuvers but nothing worked, and they thought they were going to have to bust the rig off. But Tony is a patient guy and slowly he was able to make some ground and within ten minutes line was starting to fill his spool. Fifteen minutes later a huge grouper floated to the surface lifting his five pound lead and his whole rig. It was an amazing fish – the mouth was big enough to fit a basketball. When the monster fish came next to the boat the small fish, a Gindai of course, was inside the grouper’s mouth. Tony needed to use a large meat hook to safely pull this fish into the Steel Toe boat. The team’s guess is the fish hook that caught the Gindai ended up snagging the Grouper in the lip as he went to swallow the tasty one-pound bottomfish.
It is a dog-eat-dog world down there (or should we say, fish-eat-fish), and sampling for certain species meant that catching fish did not always mean it was a productive day for the science the team was here to accomplish. However, for the CNMI fisherman: Jesse Guerrero, Greg Camacho , Tony Flores and Jamie Barlow as coxswain, using their local expertise they overcame these challenges, hunted down the fish needed for the Life History Project and delivered hundreds of valuable samples.