NOAA Teacher at Sea
Aboard NOAA Ship Oscar Dyson
August 13-26, 2019
Mission: Fisheries-Oceanography Coordinated Investigations
Geographic Area of Cruise: Gulf of Alaska
Weather Data from the Bridge
Latitude: 58° 27.67 N
Longitude: 152 ° 53.00 W
Wind Speed: 5.96 knots
Wind Direction: 152°
Air Temperature: 12.4°C
Sea Temperature: 15°C
Barometric Pressure: 1008 mbar
Science and Technology Log
I feel the need to start off by stating that the shark did in fact swim away. During our mid-afternoon trawl haul back, Chief Boatswain Ryan Harris called over the radio that we had caught a shark in the trawl net. We quickly put on our boots, hard hats, and life preservers and headed to the back deck. Unfortunately, a 3.2m female Pacific Sleeper Shark had gotten caught in our trawl as bycatch. Thanks to the quick response of our NOAA deck crew, we were able to release the shark back into the water alive.
Unlike most sharks, the Pacific Sleeper Shark is predominantly a scavenger and rarely hunts. They are slow swimmers, but move through the water quite gracefully without much effort of body movement. This lack of movement allows them to catch prey easy since they don’t make much noise/ vibrations in the water. They feed by cutting and suction. The sleeper shark’s large mouth allows it to suck its prey in. Its spear-like teeth help cut prey down into smaller pieces. It then swallows its prey by rolling its head. For more info about this cool shark, visit: https://www.sharksider.com/pacific-sleeper-shark/ .
Bycatch is defined as the unwanted fish and other marine creatures caught (e.g. hooked, entangled or trapped) during commercial fishing for a different species. Bycatch is both an issue ecologically and economically. Bycatch can slow the rebuilding of overfished stocks. Organisms that are discarded sometimes die and cannot reproduce. These mortalities put protected species such as whales and sea turtles even further at risk. Bycatch can change the availability of prey and cause cascading effects at all trophic levels. Bycatch can also occur when fishing gear has been lost, discarded, or is otherwise no longer being used to harvest fish (aka marine debris).
NOAA Fisheries works hand in hand with fishing industries to better understand fishing gear, and to develop, test, and implement alternative fishing gear. For example, NOAA Fisheries and their partners developed turtle excluder devices to reduce sea turtle mortality in the southeastern shrimp trawl fishery. NOAA Fisheries funds the Bycatch Reduction Engineering Program that supports the development of technological solutions and changes in fishing practices designed to minimize bycatch. Laws like the Marine Mammal Protection Act and the Endangered Species Act also uphold the reduction of current and future bycatch of species.
It’s hard to believe that today is already day eight at sea. To be honest, I don’t even notice that I am on a ship anymore. We have been very lucky weather wise and the seas are still very calm. I have been spending more time on the bridge assisting with the ‘marine mammal watch’. As I said in blog two, we must keep an eye out for any marine mammals in the area before conducting any water surveys. The bridge is amazing because not only do you get the best view, but you also get to observe how the ship operates in terms of headings, maneuverability, and navigation.
The Shelikof Strait is breathtaking. Chief Electronics Technician Rodney Terry pointed out the white ‘cloud’ above one of the snow-capped mountains was actually an active volcano with a smoke plume rising above it. It was incredible to be able to look out and see a glacier and an active volcano in the same panorama.
During one of my marine mammal watches on the bridge, I noticed an oddly flat area of land in the middle of the mountain range that ran along the shoreline. NOAA Corps Officer LT Carl Noblitt explained to me this was actually where a glacier had once weathered down part of the mountain range over time. The glacier has since melted so now all that remains today is its glacial trough.
Animals Seen Today
Besides our unexpected visitor today in the trawl, I was thrilled to hear Chief Boatswain Ryan Harris call out from the scientific deck for Orcas on the horizon. Orcas (aka Killer Whales) have always been a dream of mine to see in the wild. They were pretty far away from the boat, but I was able to see the trademark black dorsal fin rising and sinking at the surface for a few minutes. Hoping to get a photo of one of these pods before our expedition ends.
Another fun organism I got to see in person today was a Lanternfish that was caught in one of our deeper bongo net surveys. Lanternfish are a deep-water fish that gets its name from its ability to produce light. The light is given off by tiny organs known as photophores. A chemical reaction inside the photophore gives off light in a chemical process known as bioluminescence.