NOAA Teacher at Sea
Christopher Tait
Aboard NOAA Ship Reuben Lasker
March 21 – April 7, 2017
Mission: Spring Coastal Pelagic Species Survey
Geographic Area of Cruise: Pacific Ocean from San Diego, CA to San Francisco, CA
Date: April 1, 2017
Weather Data from the Bridge
Time 8:51 PDT,
Current Location: South West of Santa Rosa Island, Latitude 33.37N Longitude -120.7 W
Air Temperature 13.4 oC (56.1 oF)
Water Temperature 13.1 oC (55.5 oF)
Wind Speed 12 kts
Barometric pressure 1013.98 hPa
Science and Technology Log
Oceans cover 71% of the surface of Earth and 99% of the livable space (Figure 1). The Coastal Pelagic Survey is taking several approaches to map the distribution of anchovy, sardine, and other target species within the epipelagic zone. This zone is the thin surface layer extending to the depths light penetrates the ocean, which is approximately 200 meters near California. The epipelagic zone in some coastal areas is very productive due to the upwelling of nutrient rich water causing an abundance of primary production by phytoplankton. Besides the net trawling and acoustic transects, the researchers are using samples of fish eggs and ichthyoplankton (ichthyo = fish, plankton = drifting) to determine locations of spawning. This voyage is mostly surveying over the continental shelf and I am amazed at the diversity of organisms we have found thus far. In this modern era of exploration of the vastly unknown deeper regions, I can only imagine the species still to be discovered!
Figure 1: Ocean Layers
(c) Knight, J.D., 1998, Sea and Sky, http://www.seasky.org/deep-sea/ocean-layers.html
CUFES:
A CUFES (Continuous Underway Fish Egg Sampler) system is used to determine the location of fish eggs as we travel transects on a continuous daily basis (Figure 2). Water from 3 meters below the surface is pulled into the boat at 640 L/min. and poured through a filter to collect fish eggs and other plankton. The collected samples are analyzed every 30 minutes to determine a density of eggs and which species are spawning. The collected samples are further analyzed at NOAA’s SWFSC (Southwest Fisheries Science Center) in La Jolla, CA.
Figure 2: CUFES Schematic
Figure 3: Preliminary Results of CUFES Survey
The CUFES data is overlaid on sea surface temperatures measured by satellite.
PairoVET Tow & Bongo Tow
A PairoVET (paired vertical egg tow) sample is collected using a pair of small, fine mesh nets dropped to 70 meters deep and vertically towed to the surface to collect fish eggs and zooplankton in the water column at predetermined locations along our transects every 20 nautical miles. This is generally the depths that sardine release their eggs. The Bongo net gets its name because the nets are the size of bongo drums (Figure 4 & 5). This is a plankton tow that is pulled alongside the ship and occurs every 40 nautical miles. The net is dropped to a depth of 210 meters and pulled up at a 45 degree angle to get a more complete sample of the ichthyoplankton and zooplankton throughout the water column at location.
Figure 4: Bongo net in center of image and PairoVET on the right.
Figure 5: Bongo going overboard.
Figure 6: Preserving the Bongo Sample for later analysis.
CTD: Conductivity, Temperature and Depth Probe
The scientists use a CTD (conductivity-temperature-depth) probe to measure the physical properties of the seawater throughout the water column that biologic samples are being taken (Figure 7). Conductivity is used to calculate the salinity of the water. These physical properties are very important in determining the types of organisms that are present at varying locations.
Figure 7: CTD (Conductivity Temperature Depth) Analysis
Personal Log
One of the great mysteries of waking up is answering the question of “where am I?” After a long evening of trawling for fish and keeping an eye on where you are, you go to bed. Exhausted, the boat rocks you to sleep. When I wake up the first thing I do is, jump out of bed and run out onto the front deck. Some days, there is ocean for as far as the eye can see, some days a mysterious island (Figure 8) in the distance and sometimes there is the mainland (Figure 9)! I run to grab my phone when mainland is in sight to get a couple of phone calls out to family.
Figure 8: The mysterious island turns out to be Anacapa Island, which is part of the Channel Islands National Park. The waters surrounding the park are part of a national marine sanctuary.
Figure 9: Sunrise over Santa Barbara. Time for me to make a call home!
In the Dry Lab there is a computer with a map showing where we are currently located, a red track line showing where we have been and transect lines displaying where we will soon be (Figure 10). On our acoustic transects, we follow the parallel lines to mow the lawn and find the location of the CPS (coastal pelagic species) from their echoes. When we trawl, we break transect and go to places that showed promise in the acoustic backscatter.
Figure 10: Without tracking our location on the computer I would feel totally lost! The blue lines are where we plan to go, and the red lines show where we’ve actually gone.
Catch of the Day
As I get ready for my night shift, I feel this anticipation to discover what species we are going to find! Every day brings a new catch of the day!
Grey Smoothhound Shark (Mustelus californicus): This small coastal shark feeds on small invertebrates and fish.
Needle Fish (Family Belonidae): This large needle fish is coastal piscivorous fish, meaning they specialize at eating other fish. They have a mouth full of tiny needle like teeth to prevent a slippery fish from getting away.
Northern Anchovy (Engraulis mordax): This is one of our target species on this survey. Anchovy have the potential to form massive schools and have a tremendous impact of the ecology of the California Current Ecosystem. They feed on zooplankton, provide food for other fish, sea birds, and marine mammals. They are also an important fishery which have the potential to be over fished if not properly managed.
Pacific Sardine (Sardinops sagax, top specimen) and Pacific Mackerel (Scomber japonicas, bottom two specimens): These two species are also part of the Coastal Pelagic Species community, which this survey are targeting. The sardine is another very important fish due to their ability to form tremendous schools, impacting plankton through feeding, providing food for larger predators, and they are a valuable fishery. Sardine populations have the ability to boom and crash, and the cause is still not fully understood. The Pacific mackerel is a species that has been populous at times of lower sardine and anchovy abundance.
Pacific Sardine (Sardinops sagax) and Pacific Mackeral (Scomber japonicus)
Pacific Mackeral (Scomber japonicus)
Jack Mackerel (Trachurus symmetricus) and Larval Rockfish (Sebastes sp.): Jack Mackerel is another target species of the Coastal Pelagic Survey.
