David Knight: Water Hauls and Spaghetti, July 13, 2018

NOAA Teacher at Sea

David Knight

Aboard NOAA Ship Pisces

July 10-23, 2018

 Mission: Southeast Fishery-Independent Survey

Geographic Area: Southeastern U.S. coast

Date: July 13, 2018

Weather Data from the Bridge:

Latitude: 33° 26.6 N
Longitude: 77
° 02.02 W
Sea wave height: 1- 3 ft
Wind speed: 10.4 kts
Wind direction: 39.9

Visibility: 10 nm
Air temperature: 30.2
Barometric pressure: 1018.5 mb
Sky: Scattered Clouds

Science and Technology Log

Numerous physical, chemical, and biological factors determine the distribution of any organism in its environment, and throughout the first few days that traps have been set and retrieved I have witnessed changes in fish distribution firsthand.  Some factors affecting the distribution of fish would include water temperature and currents, available nutrients, the presence of predator or prey species, and the type of habitat substrate (e.g., sand/mud vs hardbottom vs pelagic). We learn in biology or marine science about species richness and species abundance. Species Richness is the number of different species one may find in a particular area; in one trap you may find four or five different species of fish with one particular species represented once and others represented in high numbers.  Large numbers of one particular species of fish would be considered a high Species Abundance.

Stenotomus sp. from one trap.

Members of each team watch each trap as it rises out of the water hoping for both high species richness and abundance. On the second full day at sea a trap was brought up containing 262 total fish and 8 different species that included: 174 Black Sea Bass (Centropristis striata), 1 White Grunt (Haemulon plumierii), 1 Gray Trigger (Balistes capriscus), 1 Spottail Pinfish (Diplodus holbrookii), 1 Pinfish (Lagodon rhomboids), 67 Tomtate (Haemulon aurolineatum), 6 Bank Sea Bass (Centropristis striata), and 7 Stenotomous sp. Compared to other traps, both the richness and abundance present in this trap were high.  The abundance of Black Sea Bass in this trap was fairly high, but other traps during the day had a much greater number of exclusively Tomtate, creating a “Tomtate Tornado”.  Traps occasionally come up with nothing in them, to the disappointment of all—I quickly learned this is called a “water haul”. On July 12th, we caught 1060 fish, and the following day, July 13th, we caught 37 fish, and the distance between trap sets was only 10 miles!  This is why sampling from six different locations at a time and over a wide geographic area is important, one trap only gives you a glimpse into the fish in that particular area which may not represent the area’s true species distribution.  Sampling up to twenty-four different locations per day along the coasts of North and South Carolina, Georgia and Florida will allow members of the SEFIS group (Southeast Fishery-Independent Survey) to better understand the populations of fish in these waters, allowing state and federal agencies to make informed decisions about the management of these fish stocks.

Friday the Thirteenth…today has been both a low species richness and species abundance day, but it has produced some interesting finds, not least of which was an Almaco Jack (Seriola rivoliana). This large, I would say plain looking, fish has a long, extended dorsal and anal fin and look like they are built for speed. After the otoliths were removed, I was collecting scales to take back to my class for use during a lab when one of the scientists said, “If you want to see something really disgusting, we should fillet that fish so you can see some parasitic worms.”  Like any good parasite, Amberjack, or Spaghetti worms, take advantage of the feeding behaviors of multiple hosts. Passed up the food chain from eggs, to larvae and then into prey species of the Almaco Jack, the larvae take up residence in the muscle of the intermediate host Jack waiting for its final host species, a shark.  Once a shark consumes a Jack, the larva then become adult tapeworms within the digestive tract of sharks and from there, the entire life-cycle begins again……now that’s scary.

Image from NCFishes.com

Personal Log

I have quickly learned how many different government agencies participate and contribute in the SEFIS survey. There are state biologists from the North Carolina Division of Marine Fisheries, South Carolina Department of Natural Resources, and from the Southeast Fisheries Science Center which is part of the National Marine Fisheries Service and NOAA. These various groups collaborate in data collection so accurate models can be created to estimate fish stocks. Estimates are obtained through fishery dependent and independent sampling methods.  Fishery dependent sampling involves gathering data from commercial and recreational fisherman through the use of surveys, phone apps, and going to the docks of these fisherman and sampling their catch. Because fisherman want to ensure a good catch, they will go to locations that they know are good fishing spots, or will only try and catch a particular species of fish, introducing statistical bias into the sample. Fishery independent sampling is what SEFIS does, collecting data at predetermined locations, not based on what they may or may not catch, thus decreasing statistical bias in the hope of obtaining a true picture of the fish populations. Together, both fishery dependent and independent sampling are then analyzed to create an assessments of the fish stock.

Not a bad way to end the day. (photo by David Knight)

Did You Know?

You can see an 8.8 m long tapeworm that was pulled out of a human on display at the Meguro Parasitological Museum in Tokyo, Japan. The museum has over 300 different types of parasites on display.


Amberjack Worms

Amberjack Worms

Meguro Parasitological Museum


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