We sample marine animals to "see" into the ocean.
The acoustic data helps us see what's in the water column, but direct sampling helps us validate, or ground truth, the organisms that are creating the acoustic backscatter. Direct sampling is an essential component for the Joint U.S.-Canada Integrated Ecosystem and Pacific Hake Acoustic-Trawl Survey, known as the hake survey. Using fishing nets, or trawling, to ground truth, the scientists from the Fisheries Engineering and Acoustic Technologies team use the information from the organisms caught to describe that backscatter. For Pacific hake (hake, Pacific whiting, Merluccius productus) specifically, the information from the trawl provides scientists with information on how big the fish are, which helps them convert the backscatter to abundance estimates and, ultimately, a biomass estimate of hake.
Scientists and volunteers sort the catch from each trawl by organism, weigh each group, and count if possible. Experience and identification guides help the scientists identify organisms to the lowest taxonomic level possible. While the main species of focus for the hake survey is hake, it is important to document all species captured. That information can then be used within the survey to help identify backscatter that isn't hake and better understand the other organisms in the California Current Large Marine Ecosystem.
In addition to the composition of the species in the trawl, our scientists record several biological measures. These data points help describe the size, age, and health of the population. We also take a variety of biological samples from hake to better understand their life history.
Other species are also sampled, depending on current protocols, for special projects. These projects can be from within our team to better understand the backscatter, or from outside investigators who want more detailed information on their species of interest.
We use the sex and length of a subsample of the catch to characterize the size distribution of fish in the school to scale the acoustic backscatter of the target layer to abundance. We sample some of those fish for their individual weight and age. To determine the fish's age, we take and analyze the otoliths (hard, calcium carbonate structures located near the brain) in our Ageing Lab.
Information on fishes' diet is essential for understanding the relationship between predator and prey in the ecosystem. Stomach contents provide a record of what a fish ate at a specific time and place. While we typically focus on hake, other surveys in our Division examine the diets of several species. For more information, visit our West Coast Groundfish Diet Research page.
Age-at-maturity and spawning stock biomass (SSB) are essential components that feed into stock assessments. We provide gonads of hake and other species of interest for examination by the Groundfish Ecology Histology Lab.
The fins of fish hold crucial genetic information about the fish. Fins are clipped and carefully preserved at-sea. They are brought back to land for analysis in the lab to extract this genetic information, which can then be used for various valuable projects. In hake, for example, there are at least a couple of different stocks. Our survey focuses on the large migrating stock that sustains the fishery. Using genetic information can help determine the boundaries of the stocks. Our Genetics and Evolution Program processes our collected fin clips.
We support several projects by freezing a variety of species from the catch. We also collect tissues for projects. Contact the wet lab lead for more information.
We have a limited number of spots to bring out volunteers to help with the biological sampling. It is a messy, smelly, and satisfying experience. You will learn to identify common organisms, determine the sex of several species, and collect various fish specimens.
Learn more about volunteering for this and other NOAA survey cruises.
Cape Shirreff field camp on Livingston Island, one of the most breathtaking places in Antarctica. Credit: NOAA Fisheries
North Pacific right whale. Credit: Brenda K. Rone
An oceanic whitetip shark swims near the surface of the water. Photo courtesy of John Carlson.
