A unique group of castaways have taken residence at the Oregon Coast Aquarium.
In April, 2015, a derelect boat was spotted by fishers southwest of Newport. Within the hull, two fish species, yellowtail jacks and banded knifejaws were found trapped inside. While yellowtail jacks are found in waters across the Pacific, the banded knifejaw is only native to the western side of that ocean. This drops the hint that the fish may have originated from the Tōhoku tsunami that struck Japan in 2011. Later genetic testing on the yellowtail jacks confirmed this.
Jim Burke of the aquarium along with invasive species specialist John Chapman boarded the aquarium vessel Gracie Lynn to assess the hull and its contents. It is important to know what could potentially be introduced to the area if the boat hit the beach. Chapman added his insight on invasive organisms:
“Unlike oil spills or chemical leaks that gradually decline over years, decades or millennia, introduced species increase from a tiny initial numbers to massive populations that never go away. Some of the introductions that arrived in the last few decades are clearly very bad by anyone’s standards. Moreover, introductions of marine species around the world seem to be increasing exponentially.”
It was arranged for the vessel to be towed to Yaquina Bay and the aquarium could care for the fish. Chapman added that this method was far less risky than allowing the boat to crash into shore nearby, likely allowing its fish stowaways to escape into a non-native ecosystem.
With the vessel now on dry land and the threat of invasive species controlled, the aquarium could begin rendering care to the 20 jacks and knifejaw that were underweight and struggling with parasites.
Thanks to a security infrastructure already in place, the parasites would only threaten the already affected fish. The aquarium’s life support system sterilizes all water before it vacates the facility. This is an additional safety net to safeguard the Oregon coast from any pollutants, invasive animals, or medications.
Six jacks succumbed to infection before treatment could fully clear their ailments. However, the remaining jacks and knifejaw received a clean bill of health. The fish were not quite ready for exhibit just yet.
Evonne Mochon-Collura, the aquarium’s assistant Curator of Fishes and Invertebrates was tasked with the challenge of diet preparation for the aquarium’s new additions. It was important that the fish showed strong feeding behavior and body tone to acclimate well to the water temperature on exhibit that would be between 50 and 60 degrees Fahrenheit.
Meager diets for a prolonged period in the cold waters of the North Pacific created another set of hurtles in the care of the fish. “They could not open their jaws wide relative to their size, so I had to prepare tiny, bite-sized food for them,” Mochon-Collura said.
Starting with a diet made up of 1.5 inch pieces of krill, shrimp and a nutrient-packed gelatin, the fish were responding positively once the feeding method was customized. The fish were afraid of the bits being thrown into the water because they saw a person throwing it. Once the staff began pouring food into the pool while staying low, the fish began aggressively feeding.
After an epic journey, you can now observe the fish on exhibit at the aquarium. The yellowtail jacks can be found in the Open Sea exhibit and the banded knifejaw have settled in to the California Kelp Forest exhibit.
The tailored expertise of those involved in this endeavor helped save and care for important species of fish while also gaining an opportunity to educate visitors on invasive animals and organisms, a crucial part of environmental science.