Jeff Peterson: The Work in the Western Gulf, July 15, 2018

 NOAA Teacher at Sea

Jeff Peterson

Aboard NOAA Ship Oregon II

July 9 – July 20, 2018

 

Mission: SEAMAP Summer Groundfish Survey

Geographic Area of Cruise: Gulf of Mexico

Date: July 15, 2018

 

Weather Data from the Bridge

Date: 2018/07/18

Time: 16:05:45

Latitude: 30 05.44 N

Longitude: 085 52.76 W

Speed over ground: 05.3 knots

Barometric pressure: 1015.62 mbar

Relative humidity: 81%

Air temp: 27.6 C

 

Science and Technology Log

At the time of writing, we’ve completed the “stations” (i.e., the appointed stops where we trawl to collect specimens) in the western Gulf of Mexico, and are headed to the Florida coast, where we’ll conclude the 3rd leg of the Summer Groundfish Survey. Sometime tonight we’ll arrive and resume work, trawling and identifying fish. What follows is my attempt to furnish a detailed description of where we are and what we’re doing.

Stations: Where We Stop & Why

As I explained in my previous blog post, “Learner at Sea: Day 1,” the survey work being performed on this cruise contributes to a larger collective enterprise called SEAMAP, the Southeast Area Monitoring and Assessment Program. The “sample area” of SEAMAP is considerable, ranging from Texas-Mexico border to the Florida Keys.

image 1 SEAMAP - coverage

Spatial coverage of SEAMAP Summer and Fall Trawl Surveys in the northern Gulf of Mexico

Fisheries biologist Adam Pollack tells me that the total trawlable area–that is, excluding such features as known reefs, oil rigs, and sanctuaries–consists of 228,943.65 square kilometers or 88,943.65 square miles. That’s a piece of ocean of considerable size: nearly as big as Louisiana and Mississippi combined.

SEAMAP divides the sample area into a series of statistically comparable “zones” (there are two zones within each of the numbered areas in the diagram above), taking into account a key variable (or stratum): depth. It then assigns a proportionate number of randomized locations to every zone, arriving at 360-400 stations for the sample area as a whole. Statisticians call this method a “stratified random design.”

While Louisiana, Mississippi,  Alabama, and Florida participate in the SEAMAP, the lion’s share of stations are surveyed by NOAA.

These are the 49 stations we sampled during the first half of the cruise, off the shore of Louisiana:

leg 3 west

Stations covered in the western Gulf during the 3rd leg of the Summer Groundfish Survey

The data from the Summer Survey is analyzed in the fall and available the following spring. NOAA’s assessments are then passed along to the regional Fisheries Management Councils who take them into account in setting guidelines.

The Trawl: How we Get Fish Aboard

NOAA Ship Oregon II brings fish aboard using an otter trawl. As described in “Mississippi Trawl Gear Characterization,” “The basic otter trawl is the most common type of trawl used in Mississippi waters to harvest shrimp. The otter trawl is constructed of twine webbing that when fully deployed makes a cone shape. Floats on the head-rope (top line) and chains on the foot rope (bottom line) of are used to open the mouth of the trawl vertically. To spread the mouth of the trawl open as large as possible, each side (wing) is attached to trawl doors” (http://www.nmfs.noaa.gov/pr/pdfs/strategy/ms_trawl_gear.pdf). Positioned by chains so that their leading edges flare out, those doors are sizable and heavy, 40 inches high and 8 feet long, and help not only to spread the net open (and ‘herd’ fish in) but also to keep it seated on the ocean floor.

An otter trawl deployed

An otter trawl deployed

To mitigate environmental harm–and, in particular, to help save inadvertently caught sea turtles—trawling time is limited to 30 minutes. The trawl is 40 feet wide and is dragged over 1.5 miles of ocean bottom.

Here are the trawl’s technical specifications:

Trawl schematic

Trawl schematic, courtesy of NOAA fishing gear specialist Nicholas Hopkins

It should not go without saying that deploying and retrieving gear like this is mission critical, and requires physical might, agility, and vigilance. Those tasks (and others) are performed expertly by the Deck Department, manned on the day watch by Chief Boatswain Tim Martin and Fisherman James Rhue. Fisherman Chris Rawley joins them on the swing shift, coming on deck in the evening.

The process of bringing the trawl aboard looks like this:

doors up

Trawl doors on their way up toward the starboard outrigger

separating

Seizing the “lazy line” with the hook pole

orange section

The “elephant ear” (orange section) secured

cod end at the rail

Chief Boatswain Tim Martin brings a catch over the rail

The bottom of the trawl is secured with a special knot that permits controlled release of the catch.

knot

Among other names, this piece of handiwork is known as the “double daisy chain” or “zipper knot”

 

The catch emptied into baskets

The catch emptied into baskets

CTD

Before every trawl, the CTD is deployed from the well deck (port side) to collect data on, as its acronym suggests: Conductivity, Temperature, and Depth. According to NOAA’s Ocean Explorer website, “A CTD device’s primary function is to detect how the conductivity and temperature of the water column changes relative to depth. Conductivity is a measure of how well a solution conducts electricity. Conductivity is directly related to salinity, which is the concentration of salt and other inorganic compounds in seawater. Salinity is one of the most basic measurements used by ocean scientists. When combined with temperature data, salinity measurements can be used to determine seawater density which is a primary driving force for major ocean currents” (https://oceanexplorer.noaa.gov/facts/ctd.html).

The CTD secured on deck

The CTD secured on deck

 

CTD in the water

The CTD suspended at the surface, awaiting descent

During daylight hours, a scientist assists with the deployment of the CTD, contributing observations on wave height and water color. For the latter, we use a Forel-Ule scale, which furnishes a gradation of chemically simulated water colors.

 

Forel-Ule scale

Forel-Ule scale

 

The Wet Lab: How We Turn Fish into Information

Once in baskets, the catch is weighed and then taken inside the wet lab.

the wet lab

The wet lab: looking forward. Fish are sorted on the conveyor belt (on the right) and identified, measured, weighed, and sexed using the computers (on the left).

Once inside the wet lab, the catch is emptied onto the conveyor belt

Fish ready for sorting

Fish ready for sorting

Snapper on the belt

A small catch with a big Snapper

Next the catch is sorting into smaller, species-specific baskets:

Emily McMullen sorting fish

Emily McMullen sorting fish

 

batfish face

Say hello to the Bat Fish: Ogecephalus declivirostris

Calico Box Crab, Hepatus epheliticus

Calico Box Crab, Hepatus epheliticus

 

Blue Crab, Callinectes sapidus

Blue Crab, Callinectes sapidus

At this stage, fish are ready to be represented as data in the Fisheries Scientific Computing System (FSCS). This is a two-step process. First, each basket of fish is entered by genus and species name, and its number recorded in the aggregate.

Andre entering data

Andre DeBose entering initial fish data in FSCS

Then, a selection individual specimens from each basket (up to 20, if there are that many) are measured and weighed and sexed.

Andre and Emily measuring

Andre and Emily measuring and sexing fish

Occasionally researchers from particular laboratories have made special requests for species, and so we label them, bag them, and stow them in the bait freezer room.

requests

Special requests for specimens

 

IMG_8214

Red Snapper, Lutjanus campechanus, for Beverly Barnett

Once every animal in the trawl has been accounted for and its data duly recorded, it’s time to wash everything down and get ready to do it all over again.

porthole

Late afternoon view from the wet lab porthole

 

Personal Log

The key to enjoying work in the wet lab is, as I see it, the enduring promise of novelty: the possibility of surprise at finding something you’ve never seen before! For me, that promise offsets the bracing physical rigors of the work and leavens its repetitiveness. (Breathtaking cloudscapes and gorgeous sunsets do, too, just for the record. Out here on the water, there seem to be incidental beauties in every direction.) Think of the movie Groundhog Day or Camus’s “The Myth of Sisyphus” and cross either of them with the joys of beach-combing on an unbelievably bounteous beach, and you’ll have a sense of the absurd excitement of identifying fish at the sorting stage. Life in the wet lab is a lot like Bubba Gump’s box of chocolates: “You never know what you’re gonna get.”

At the next stage, data entry, the challenge for the novice is auditory and linguistic. Between the continual growl the engine makes and the prop noise of the wet lab’s constantly whirring fans, you’ve got the soundscape of an industrial workplace. Amid that cascade of sound, you need to discern unfamiliar (scientific) names for unfamiliar creatures, catching genus and species distinctions as they’re called out by your watch-mates. The good news is that the scientists you’re working with are living and breathing field guides, capable of identifying just about any animal you hold up with a quizzical look. It’s a relative rarity that we have to consult printed guides for IDs, but when we do and that task falls to me, the shell-collector kid in me secretly rejoices.

IMG_7825

I found it! Ethusa microphthalma (female)

I’m enjoying the camaraderie of my watch, led by Andre Bose, and, as my posts suggest, I’ve had some good opportunities to pick Adam Pollack’s brain on fisheries issues. My partner in fish data-entry, Emily McMullen–an aspiring marine scientist who’ll be applying to graduate programs this fall–did this cruise last summer and has been an easy-going co-worker, patient and understanding as I learn the ropes. I’ve also had some wonderful conversations with folks like Skilled Fisherman Mike Conway, First Assistant Engineer Will Osborn, and Fisheries Biologist Alonzo Hamilton.

It’s been a busy week, as you’ll have gathered, but I’ve still managed to do some sketching. Here’s a page from my sketchbook on the CTD:

CTD

Sketch of the CTD. The main upright tanks, I learned, are Niskin Bottles

And here’s a page from my journal that pictures three species we saw quite often in the western Gulf:

Longspined Porgy - Butterfish - Brown Shrimp

Longspine Porgy (Stenotomus caprinus), Butterfish (Peprilus burti), and Brown Shrimp (Farfanepenaeus aztectus)

Had I the time, I’d sketch the rest of my “Top 10” species we’ve seen most commonly in the western Gulf. That list would include (in no particular order): the Paper Scallop, Amusium papyraceum; Lookdown, Selene vomer; Blue Crab, Callinectes sapidus; Squid, Loligo; Lizardfish, Synodus foetens; Croaker, Micropogonias undulatus; and Red Snapper:

Red Snapper

Presented for your inspection: Red Snapper, Lutjanus campechanus

Did You Know?

Four of the species visible on the surface of this basket have been identified in the blog post you’ve just read. Can you ID them? And how many of each would you say there are here on the surface?

Basket of fish

Basket of fish

 

 Look for a key in my next blog post.

 

Michelle Greene: Getting Ready for a Big Adventure, July 18, 2018

NOAA Teacher at Sea

Michelle Greene

Aboard NOAA Ship Gordon Gunter

July 19 – August 3, 2018

 

Mission: Cetacean Survey

Geographic Area: Northeast U.S. Atlantic Coast

Date: July 18, 2018

 

Latitude: 34° 18.967′ N

Longitude: 79° 52.047′ W

Temperature: 89° F (32° C)

Tomorrow is the big day!  I am getting ready to board the plane from Florence, SC to Charlotte, NC to Providence, RI.  I have never been to Rhode Island, so this is going to be a bucket list activity to keep adding states to my history.  Rhode Island will make state number 24…almost half way!

I teach in a very rural high school in Lamar, South Carolina which is approximately 90 miles from Myrtle Beach.  Lamar High School has about 280 students.  This year we had a graduating class of 52 students.  I teach Calculus, Statistics, and Algebra 2 Honors.

Teaching statistics is the main reason I applied to the Teacher at Sea program.  I wanted to give my students some real world experience with statistics.  I try to create my own data for students, but I end up using the same data from the Census, Bureau of Labor Statistics, Major League Baseball, etc.  I had one student a couple of years ago in Algebra 2 Honors who is a weather lover.  His favorite website is NOAA, and he would give me the daily weather or hurricane updates.  Any time we had a baseball game, he would be able to tell me if we were going to be able to play the game.  Being able to provide him and his classmates projects using data from something he loves will help me to reach that one student.  Hopefully, I might even spark interest in other students.

Helping my students to become statisticians is the main reason I applied; however, I also applied to challenge myself.  Throughout my life, I have not been the kind of person who deals well with creepy crawly things.  Being on a ship on the ocean will definitely force me to deal with that.  I want to do my very best to get involved in all kinds of neat activities.  I hope “Cool Beans!” will be my daily saying.

I am really looking forward to working with the scientists on the Gordon Gunter.  Having read as much as I can about the Passive Acoustic Research Group has helped me to understand a little of what we will be doing on our 15-day journey.  I hope that I can help them to further their research to learn the patterns that cetaceans use to communicate with each other!

Meredith Salmon: Xtreme XBTs, July 14, 2018

NOAA Teacher at Sea

Meredith Salmon

Aboard NOAA Ship Okeanos Explorer

 July 12 – August 4, 2018

 

Mission: Seafloor Mapping in support of Galway Bay Initiative

Geographic Area:  Atlantic Ocean, south of Bermuda

Date: July 14, 2018

Weather Data from the Okeanos Explorer Bridge – July 14, 2018

Latitude: 28.58°N

Longitude: 65.48°W

Air Temperature: 27.4°C

Wind Speed:  13.96 knots

Conditions: Rain and clouds

Depth: 5183 meters

 

Science and Technology Log

Temperature and salinity are two main variables when determining the density of water. The density of water or any acoustic medium is a very important factor in determining the speed of sound in water. Therefore, temperature data collected by Expendable Bathythermograph (XBT) probes, as well as historical salinity profiles from the World Ocean Atlas, are used to create sound velocity profiles to use to correct for sound speed changes in the water column.

Expendable Bathythermograph (XBT) probes are devices that are used to measure water temperature as a function of depth. Small copper wires transmit the temperature data back to the ship where it is recorded and analyzed. At first, I was surprised to learn that temperature data is such an important component of multibeam mapping operations; however, I learned that scientists need to know how fast the sound waves emitted from the sonar unit travel through seawater. Since these probes are designed to fall at a determined rate, the depth of the probe can be inferred from the time it was launched. By plotting temperature as a function of depth, the scientists can get a picture of the temperature profile of the water.

On our expedition, we have been deploying XBT’s on a schedule as the ship is making its way to the survey area. The XBT Launcher is connected to a deck box, which translates information to computer systems onboard so the data can be logged when the probes are deployed into the water. On the Okeanos Explorer, up to 8 tubes can be loaded at one time and launched by scientists on board.

XBT closet in the Dry Lab

XBT closet in the Dry Lab

 

 

 

 

 

XBT Data

XBT Data from a launch aboard the Okeanos Explorer. The colors on the graph indicate the XBT number and the data is plotted on a temperature and depth scale.

 

 In addition to launching XBTs and collecting data, we completed a Daily Product so that we can communicate the data we have collected to anyone on shore. The Daily Products are completed not only to ensure that the hydrographic software systems are working correctly but to also inform the public our current location, where we have collected data, and if we are meeting the objectives of the mission. Once onshore, NOAA uses this information to analyze the quality of the data and use it for analysis for dive planning. In order to generate the Daily Field Products, we use hydrographic computer systems such as QPS Qimera for advanced multibeam bathymetry processing, Fledermaus for 4D geo-spatial processing, and Geocap Seafloor for digital terrain modelling. In addition, the Daily Field Products allow us to double check the quality of the data and search for any noise interferences due to the speed of the ship or the type of seafloor bottom (hard vs soft).

 

Personal Log

One of the coolest parts of learning onboard the Okeanos Explorer is the fact that I am a part of scientific exploration and discovery in real time.  Known as “America’s Ship for Ocean Exploration,” the Okeanos Explorer is the only federally funded U.S. ship assigned to systematically explore our largely unknown ocean for the sole purpose of discovery and the advancement of knowledge. This is the first U.S.-led mapping effort in support of the Galway Statement on Atlantic Ocean Cooperation and all of this information is going to be available for public use. Not only do I get the opportunity to be involved with “real-time” research, but I am also responsible for communicating this information to a variety of different parties on shore.

Being immersed in the “hands-on” science, learning from the survey techs and watch leads, and observing all of the work that is being done to collect, process, and analyze the data is a really exciting experience. I am definitely out of my element when it comes to the content since I do not have any prior experience with seafloor mapping, sonars, etc., but I am really enjoying playing the role as the “student” in this situation. There is definitely a lot to learn and I am trying to soak it all in!

 

Did You Know?

XBTs contain approximately 1,500 meters of copper wire that is as thin as a strand of hair!

Meredith Salmon: Setting Sail! July 12, 2018

NOAA Teacher at Sea

Meredith Salmon

Aboard NOAA Ship Okeanos Explorer

July 12 – August 4, 2018

 

Mission: Seafloor Mapping in support of Galway Bay Initiative

Geographic Area:  Atlantic Ocean, south of Bermuda

Date: July 12, 2018

Weather Data from the Okeanos Explorer Bridge – July 12, 2018

Latitude: 32.094°N

Longitude: 69.591°W

Air Temperature: 26.2°C

Wind Speed:  10.7 knots

Conditions: Sunny

Depth: 693 meters

Survey Area

Map showing the planned operations area for the expedition outlined in yellow. Image courtesy of the NOAA Office of Ocean Exploration and Research.

Science and Technology Log

According to the Oceanic Institute, the oceans cover 71% of the Earth’s surface. This is calculated to be 335,258,000 square kilometers! Recently, the Okeanos Explorer mapped over 1,000,000 square kilometers of the seafloor using high- resolution multibeam sonar. Although this may not seem like much, that region is larger than the areas of Arizona and Texas combined!

So why is it so important for the Okeanos Explorer to map the seafloor? The ocean’s terrain plays a very important role in ecosystems since underwater valleys determine currents and weather patterns, sea topography influences fishery management, and seamounts serve as protection against unpredictable storms. Therefore, high-resolution maps allow scientists to categorize marine habitats, provide information vital to protecting and tracking marine life, and enable us to make smart decisions for solid, sustainable conservation measures.

In order to successfully map the ocean floor, multibeam sonar is used. The Okeanos Explorer uses an EM 302 multibeam system that is designed to map a large portion of the ocean floor with exceptional resolution and accuracy. The EM 302 transducers pointing at different angles on both sides of the ship to create a swath of signals. Transducers are underwater speakers that are responsible for sending an acoustic pulse (known as a ping) into the water. If the seafloor or object is in the path of the ping, then sound bounces off the object and returns an echo to the transducer. The EM 302 has the ability to produce up to 864 depth soundings in a single ping. The time interval between the actual signal transmission and arrival of the return echo (two way travel time) are combined with a sound velocity profile to estimate depth over the area of the swath. In addition, the intensity of the return echo can be used to infer bottom characteristics that can be utilized for habitat mapping. Since the EM 302 creates high density, high-resolution data as well as water column features, this sonar system is ideal for exploring the seabed for geographic features.

The image below shows data being collected by the multibeam sonar on the Okeanos Explorer. The colors are used to indicate swath depth (warm colors indicate shallow waters while cool colors indicate deeper waters).

Multibeam sonar data

Multibeam sonar data including backscatter (lower left), depth (upper center) and water column data (lower center) from 7/12/2018 the Okeanos Explorer

 

As this data is being collected, it must be “cleaned” to eliminate any erroneous points.  Data is collected and cleaned in both the Dry Lab and Mission Control Room.

Dry Lab

Dry Lab, equipped with 12 computer monitors, used to process data onboard the Okeanos Explorer

Mission Control

Mission Control Room aboard the Okeanos Explorer

 

Since we have not reached the survey area yet, we have been monitoring the depth of our path thus far. We are collecting transit data which is considered to still be valuable data for unmapped seafloor area, but it may not be as high quality as focused mapping data. We will continue to collect transit data until we reach the survey area near Bermuda.

Personal Log

Life onboard the Okeanos Explorer has been a very interesting and fun learning experience! The ship runs on a 24/7 operation schedule and people are working diligently at all hours of the day. Everyone on the ship has been really welcoming and willing to share their stories and insights about their careers at sea. I am really looking forward to speaking with more people to learn about their experiences!

We set sail out of Norfolk today and began our 3.5 day/4 day transit to the survey area near Bermuda. This morning, we found out that we will need to schedule an emergency dry dock towards the end of our mission to solve an issue with a stern thruster necessary for ROV cruises. As a result, we will not be ending up in port in St. George, but we will still be able to map the area 200 nautical miles off the coast of Bermuda, so that is great!

 

Did You Know?

Sonar is short for Sound Navigation and Ranging.

Check out this video for a visual representation of the process sonar uses to generate data! https://oceanservice.noaa.gov/caribbean-mapping/mapping-video.html

 

Resources:

https://www.oceanicinstitute.org/aboutoceans/aquafacts.html

https://oceanexplorer.noaa.gov/okeanos/one-million/welcome.html

David Knight: Work Out and Work Up: Part II, July 18, 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 18, 2018

Weather Data from the Bridge:

Latitude: 29° 45.3′

Longitude: 80° 22.5′

Sea wave height: 1-3 ft

Wind speed: 5 kts

Wind direction: 241

Visibility: 10 nm

Air temperature: 28 °C

Barometric pressure: 1014.9 mb

Sky: Scattered Clouds


Science and Technology Log

Part II. DNA, Gonads, and Diet

DNA Samples.

Certain fish that we collect have samples of their fins collected for DNA testing. For example, if a Spotfin Butterflyfish (Chaetodon ocellatus) is brought up in a trap, a small pair of scissors are used to clip a portion of its anal fin in order to obtain a sample that is then place in a micro-test tube containing a buffer. Back in the on-shore lab, technicians will obtain the DNA, which is then used to determine the genetic make-up of the population in a particular area.

Fin clip

Fin clip sample from Spotfin Butterfly fish. (photo by David Knight)

One may assume that the genetic make-up of a population is uniform across the east coast, after all, fish can swim, right? However, that is not necessarily the case. Changes in the frequency of particular alleles create spatial differences in some stocks of fish over a broad area. In other words, there may be slight genetic differences in a population of Gray Triggerfish off of the coast of North Carolina compared to those found in the waters of Florida.

Why does this matter? Currently, the management of most fish occurs over a broad area, often including many states. By understanding the slight differences that may be present in a smaller subset of a population, scientists can create better, more accurate management plans instead of a “one size fits all” model.

Gonads.

As written in an earlier blog, many fish in this region are sequential hermaphrodites and change sex during their life-time, starting off as females, then changing to males.  By taking the gonads of certain species, scientist can determine if the fish is male or female, and taken together with size and age, it is possible to estimate when these fish are transitioning from one sex to another.

Ovaries from a Vermilion Snapper

Ovaries from a Vermilion Snapper – I made a small incision so you can the eggs. (photo by David Knight)

By sampling the ovaries of fish, it is possible to estimate the fecundity of the species. Fecundity is the reproductive potential an organism possesses. The number of eggs in an ovary can be estimated and then, taking the age and size data of the specimen, it is possible to predict the potential a population has for growth. Many factors, such as the number of males in a population and the season, can influence the reproductive behaviors of fish, so sampling the gonads provides an additional pieces of data.

Finally, sampling the gonads of fish can help determine the sex ratio in the population. In fish that display sequential hermaphroditism, such as the Black Sea Bass, the number of males in the populations increase with age.

Question: Fisherman will be able to get more money for larger fish, so naturally they will want to “select for” larger fish, potentially decreasing the number of reproductive males in the population. If the number of large, reproductive males in a population decreases, then more females will transition to become male.

What may happen to the average age of sex transition in sequential hermaphrodites?

Diet.

A select few species have their stomach contents sampled. If we know what a particular species is eating, then we are able to understand the trophic interactions within the ecosystem much better. An ecosystem-based management plan will look at the interactions taking place between the many prey and predator species, whom are often competing for the same resources.  Because the diverse species in an ecosystem are inextricably linked, an increase in one species is likely to affect the other. If one species is over-fished or not reproducing at its potential, this may create a ripple effect throughout the ecosystem.

 

 

Personal Log

The food on board the NOAA Ship Pisces has been great. The Stewards, Rey and Dana, have kept us well fed with a variety of great meals. We’ve had everything from hot dogs and hamburgers to bacon wrapped filet mignon and shrimp, and a crew favorite, Taco Tuesday! Meal time is very important because not only is the crew refueling for work, but it affords them a chance to sit down, talk, and to catch up on Chip and Joanna Gaines’ newest “Fixer Upper” on the TV that runs continuously. The first day on board, Operations Officer, Lieutenant Jaime Park, told me that any NOAA ship runs on two very important things: 1) diesel fuel, and 2) COFFEE.  The galley is open 24-7 with snacks and drinks always available since crew members are working in shifts, with some getting off at midnight or 4 a.m.. And…., I recently found the freezer that contains Klondike Bars, popsicles, ice cream, and Hot Pockets.

 

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Did You Know?

The Red Snapper (Lutjanus campechanus) gets its name from its enlarged canine teeth. According to the 2016 stock assessment of South Atlantic red snapper, the stock is overfished and subject to overfishing, but is rebuilding.  Management plans in the South Atlantic and Gulf of Mexico place annual catch limits on both commercial and recreational fisherman to decrease the pressure on the fish, as well as minimum size restrictions to protect young and juvenile snapper. Red Snapper can live over 50 years and are of reproductive age as early as two.

range of red snapper

Range of Red Snapper-South Atlantic (NOAA)

Site Map

Sites where traps were set. 32 nautical miles southeast of Cape Fear, North Carolina. Blue indicates deep water, Red indicates more shallow water. (image by Nate Bacheler)

snapper_red2_locationmap

Range of Red Snapper-Gulf of Mexico (NOAA)

Reference:

NOAA Fisheries. https://www.fisheries.noaa.gov/species/red-snapper

 

 

 

 

 

David Tourtellot: The Speed of Sound, July 15, 2018

NOAA Teacher at Sea

David Tourtellot

Aboard NOAA Ship Thomas Jefferson

July 9-26, 2018

Mission:  Hydrographic Survey – Approaches to Houston

Geographic Area of Cruise: Gulf of Mexico

Date: July 15th, 2018

Weather Data from the Bridge

Latitude: 28° 49.4115’N

Longitude: 93° 37.4893’W

Visibility: 10+ Nautical Miles

Sky Condition: 4/8

Wind: Direction: 240°, Speed: 7 knots

Temperature:

Seawater: 31.7°C

Air: Dry bulb:31.5°C          Wet bulb: 27.5°C

 

Science and Technology Log

 

NOAA Ship Thomas Jefferson is well underway in its mission of surveying the seafloor. The primary tool that the ship (as well as its 2 Hydrographic Survey Launches) is using to accomplish this task is sonar. Sonar was originally an acronym for SOund Navigation And Ranging. If you are familiar with echolocation – the system that some animals (such as bats and dolphins) use to navigate their surroundings – then you already have a basic understanding of how sonar works. The sonar transmits a short sound (called a ping) that will travel down, away from the ship, until it hits the seafloor. At this point, it will reflect off of the sea floor, and echo back up to the ship, where it is detected by the sonar’s receiver. The crew aboard are then able to calculate the depth of the water.

To make the necessary calculations, there are 3 variables at play: the time that it takes for the ping to travel; the distance that the ping travels; and the velocity, or the speed, at which the ping moves through the water. If we know two of those variables, it is easy to calculate the third.

When using sonar to determine the depth of the water, distance is the unknown variable – that’s what we’re ultimately trying to figure out. To do so, we need to know the other two variables. Time is an easy variable for the sonar to measure. The sonar has a transmitter, which generates the ping, and a receiver, which hears it. These two components communicate with one another to give us an accurate measure of time. The third variable, velocity, is a bit trickier.

In saltwater, sound travels approximately 1500 meters per second. However, that rate can vary slightly based on water conditions such as temperature and salinity (how salty the water is). In order for sonar to get as accurate a reading as possible, it needs to calculate the precise speed of sound for the particular water it is in at the moment. The sonar is able to do that by using a component called a sound velocity sensor, known colloquially as a singaround.

Sonar 1 Singaround

The sonar on the hull of one of the Hydrographic Survey Launches. The orange rectangles are the projector (or, the transmitter) and the receiver, and the component in the green circle is the singaround

A singaround looks like a bar with a nub on each end. One nub is a projector, and the other is a reflector. The projector broadcasts a ping that travels parallel to the hull of the ship, bounces off of the reflector, and returns to the projector. We use that information to calculate velocity. The calculation uses the same 3 variables as above (time, distance, and velocity), but this time, distance isn’t the unknown variable anymore – we know exactly how far the ping has traveled, because we know how far the projector and reflector are from one another. The singaround electronically measures how long it takes for the ping to travel, and since we now know two of the variables (distance and time) we can calculate the third (velocity) for our particular water conditions at the face of the sonar.

Sound travels roughly 4 times faster in water than it does in air (this is because water is denser than air). To ensure that the sonar gets an accurate reading, it is important that air bubbles don’t get in the way. The boat’s hull (bottom) has a triangular metal plate directly in front of the sonar, which routes air bubbles around to the side of the sonar.

Sonar 2

The hull of one of the Hydrographic Survey Launches.

 

Personal Log

Each day, the ship’s CO (Commanding Officer) publishes a POD, or Plan Of the Day. This is full of important information – it tells us what the ship will be doing; if/when we will deploy the launch boats, and who will be on them; what time meals will be; and the expected weather conditions. Below is an example from Friday, July 13th.

Plan of the Day

NOAA Ship Thomas Jefferson Plan of the Day for Friday, July 13, 2018

On Friday, I had the opportunity to go out on one of the Hydrographic Survey Launches. Because of their smaller size, the launch boats are great for surveying difficult to maneuver areas. For instance, we spent most of the day surveying an area near an oil rig, and were able to get much closer than the Thomas Jefferson could.

Mike Below Deck

Survey Tech Mike Hewlett collecting and analyzing survey data aboard a launch boat

Oil Rig and Boat

An oil rig and a supply vessel

I’ve been very impressed by how multi-talented everyone on the ship seems to be. In addition to analyzing data, the ship’s survey techs can also be found handling lines as the survey boats are launched and recovered, and do a lot of troubleshooting of the hardware and software they’re using. The coxswains (people who drive small boats) double as engineers, fixing issues on the launch vessels when away from the ship. I’m surrounded by some very gifted people!

Fixing the AC

Coxswain Francine Grains and Survey Tech Brennan Walters fixing the air conditioner on one of the launch boats that had stopped working unexpectedly. They had it up and running in no time

Did you know?: As president, Thomas Jefferson ordered the first survey of the coastline of the United States. Because of this, NOAA Ship Thomas Jefferson is named for him. 

Latest Highlight: While surveying, we spotted a water spout in the distance. A water spout is a tornado that forms over water. Luckily, we were a safe distance away. It was an amazing sight to see!

 

David Knight: Work Out and Work Up: Part I, July 17, 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 17, 2018

Weather Data from the Bridge:

Latitude: 30° 30.2 N
Longitude:
80° 15.6 W
Sea wave height:
1-2 ft
Wind speed:
15 kts
Wind direction:
187°
Visibility:
10 nm
Air temperature:
30.1 °C
Barometric pressure:
1014.7 mB
Sky:
Broken Clouds

Science and Technology Log

Warning!!! Great Science Ahead…


Part I.

Waiting to see

Waiting to see what the traps have brought up this time… (photo by David Knight)

As fish traps begin to be brought up by the deck crew, scientist wait to see what may be in the trap. I’ve actually found that I am looking over the deck in anticipation of new fish that may have been caught, or to see how many fish will need to be “worked up.” Once the fish have been removed from the trap and emptied into a large bin, they are then sorted by species into 17-gallon bins to determine the total weight of all fish.  Moving 17 gallons worth of fish up to the lab bench to the scale can be quite a “work out.” There have been a couple of hauls that have captured so many fish of a particular species that more than one bin has to be used. After the fish have been weighed, the total length of each fish is determined to get a length frequency of the entire catch.  For species like Tomtate (Haemulon aurolineatum), every fish is measured and then returned to the ocean. For some species, a pre-determined percentage are kept for a more detailed work up that may include the extraction of otoliths, removal of gonads, or a collection of stomach contents. The data collected from each fish will then be used by scientists in a number of different agencies and in different states to better understand the growth and reproduction of the particular species. All of this data is then used to create management plans for economically and ecologically important fish as well as to gain a better understanding of its life history.

Work Up

Length.

Measuring fish

Measuring the length of each, individual fish. (photo taken by Nate Bacheler)

One may assume that a very long fish is also very old, but that is not necessarily the case. The length of a fish is not a good way to determine the age of a fish because factors such as temperature and food availability may alter the growth rate. Many fish grow very rapidly early on, but then slow their growth, so it is possible that a fish that is twelve years old is the same size as a fish that is three years old. Because many fish demonstrate logistic growth rates in terms of length, it is important to use additional pieces of data to determine their age.

Otolith.

In the head of ray-finned fish, one can find small, bone-like structures called otoliths. These structures have a variety of sensory functions that include detection of sound vibrations in water, movement, and its orientation in the water. As fish age, calcium carbonate will be added to the otolith, forming ring-like structures that can be used to determine the age of a fish, much like a tree will add new tissue each season forming tree rings.  Otoliths are the best way to determine the actual age of a fish.

IMG_6677

Otoliths. [left to right: Black Sea Bass, Red Snapper, Jackknife fish] (photo by David Knight

For the fish that we were sampling, we remove the sagittal otoliths which are located beside the brain just about level with the eyes. To extract them, a cut is made on the dorsal side of the fish with a sharp knife to gain access to the skull case.  To extract otoliths from some very “hard-headed” fish, a saw is used, while others take little effort. After a few hours of otolith extraction, I feel as though I am getting the hang of it, although I am nowhere near as fast as the biologist on board! I’ve been collecting otoliths from Black Sea Bass (Centropristis striata) and Vermillion Snapper (Rhomboplites aurorubens) to bring home with me to create a lab for my class and to post on the NOAA Teacher-at-Sea website.

Extracting otolith

Looking for a perfect extraction of otolith from Vermilion Snapper. (photo taken by Nate Bacheler)

Be sure to check back for Part II. Gonads, Diet and DNA


Personal Log

The motion of the ship has not been a problem so far and I stopped taking any motion sickness pills after the first day. As I have been removing otoliths from fish, I cannot help but think about the similarities in how both fish and humans perceive their spatial environment and maintain balance. In our vestibular system, we too have otoliths that help to sense acceleration in a vertical and horizontal direction. Of course my thoughts then go to a dark place…what if someone were removing my otoliths to determine my age?

 

Did You Know?

The longest known life span in vertebrates is found in the Greenland Shark (Somniosus microcephalus). It is estimated that the Greenland shark grows less than 1 cm per year. Since sharks do not have otoliths, scientist have to analyze proteins found in the lens of their eye.  In 2016, scientist from the University of Copenhagen collected a 5 m shark that was estimated to be about 392 years old, but may be anywhere from 272 to 512 years old.

Reference: Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus). Science  12 Aug 2016: Vol. 353, Issue 6300, pp. 702-704