Mission: Alaska Walleye Pollock Survey Geographical Area: Gulf of Alaska Date: July 6th, 2013
Location Data from the Bridge: Latitude: 55.29.300 N
Longitude: 156.25.200 W
Ship speed: 10.7 kn
Weather Data from the Bridge: Air temperature: 8.6 degrees Centigrade
Surface water temperature: 8.6 degrees Centigrade
Wind speed: 14 kn
Wind direction: 210 degrees
Barometric pressure: 1008.5 mb
Science and Technology Log:
The Oscar Dyson is equipped with several labs to accommodate the researchers on board. In this blog post I will describe to you what is happening in the wet/fish lab. This is where I have experienced quite a bit of hands-on data collection.
Pollock being separated on the conveyor belt.Basket full of pollock.
After a trawl, the crew dumps the load of fish into a bin. Inside the lab we can raise or lower this bin to control the amount of fish coming onto a conveyor belt. Once the fish are on the belt the scientists decide how they will be separated. We separate the pollock according to age into baskets. They are categorized by size; under 20 cm (age 1), under 30 cm (age 2), and any larger than 30 cm
A lumpsuckerA basket full of small squid
At this time we also pull out any other sea creatures that are not pollock. So far we have pulled up quite a few jelly fish, la lumpsucker, shrimp, squid, eulachon, and capelin. These are also weighed, measured, and in some cases frozen per request of scientists not currently on board.
Larger squid.
After organizing the pollock into appropriate age groups, we then measure and record their weight in bulk. Scientists are using a scale attached to a touch screen computer with a program called CLAMS to record this information. The pollock are then dumped into a stainless steel bin where their sex will be determined. In order to do this the fish must be cut open to look for “boy parts, or girl parts”. After the pollock are separated into female and male bins we begin to measure their length.
This is the tool used for measuring length of the fish.
The tool used to measure length is called the Ichthystick. This tool is connected to the CLAMS computer system. The fish is placed on the Ichthystick and a pointer with a magnet in it is placed at the tail end of the fish. There are three different types of length measurement that can be done: fork length, standard length, and total length. When the magnetic pointer touches the Ichthystick it senses that length and sends the information to the CLAMS computer system.
Northern shrimp
One of these bins of fish is placed aside for individual weighing, length measurements, and removal of otoliths. You may recall that I mentioned otoliths in the last blog post. These ear bones are sent to a lab and analyzed to determine the age of each of these individually measured fish. The Alaska Fisheries Science Center has created a demonstration program where you can try to determine the age of different types of fish by looking at their otoliths. Click here to try it yourself! (I will add hyperlink to: http://www.afsc.noaa.gov/refm/age/interactive.htm)
Personal Log:
Ben and Brian in fire gear with flares.
One afternoon while waiting for the fishermen to bring up the trawl net, I watched a group of porpoises swimming behind the ship. Another day I was able to see whales from up on the bridge. These were pretty far out and required binoculars to see any detail. I observed many spouts, saw one breach, and some flukes as well.
There is quite a bit of downtime for me on the ship while I am waiting in between trawls. I get to read a lot and watch movies in my free time. I have had the opportunity to talk with different members of the crew and learn about their roles a bit. The chief engineer gave me a tour of the engine rooms (more about this with pictures in a future post.)
The 4th of July fireworks show on the Oscar Dyson was like no others I have ever experienced. Two of our crew, Ben & Brian, dressed in official fire gear shot expired flares off the ship into the sea. America themed music was played over the PA system. I have attached a video of our fireworks display. Happy Independence Day everyone!
NOAA Teacher at Sea
Rita Salisbury
Aboard NOAA Ship Oscar Elton Sette
April 14–29, 2013
Mission: Hawaii Bottomfish Survey Geographical Area of Cruise: Hawaiian Islands
Date: Tuesday, April 23, 2013
Science and Technology Log
CDT being lowered over the starboard side
A few days ago we dropped the CDT, an apparatus that collects data on the conductivity, the depth, and the temperature of the sea water in which the acoustic survey is taking place. All of these three things impact how quickly sound travels underwater. The scientists collect the information and then use it to figure out an accurate rate of speed for the sound waves. Once they have that information, they can determine how far a target is from the ship.I was able to ride along in a small boat to Maui to pick up parts for the AUV. While in the Maui harbor, I had the opportunity to visit the Huki Pono, a small boat working on this survey that is using BotCams to survey the fish population. The palu, or bait, that I help make every day is frozen and then transferred to the fishing boats. It is frozen in a shape that fits into a cage on the BotCam located near the camera. As the bait breaks up, fish are attracted to it and come close enough to the BotCam to be visually recorded. There is a lot of video to go through so Dr. Kobayashi says they won’t have the data from the BotCams for a while. But the other three fishing boats assigned to this project turn their survey information in every evening and I get to add it to a spreadsheet to help keep track of what section the boats were in and what they found while they were there.
BotCam on the deck of the Huki Pono
Work continues with the ROV and AUV. The scientists are always working on them, trying to make them run as smoothly as possible. We worked on calibrating the acoustics again this morning for the same reason. The better the information you have when you start a project, the better chance you have of having a successful outcome.
As I mentioned before though, not everything we are doing is high tech. We fish off the side of the ship in the evenings, dropping our lines all the way to the bottom so they are on the sea floor. The scientists running the acoustics tell us if they see fish and then we do our best to catch a representative sample. Here are two of the fish I caught off the bottom: an opakapaka and a taape. The observers that ride in the small boats every day spend the night on the Sette. That way, they can turn their logs in and I can record the data. As a bonus, a few of them are expert fishermen and are a huge help to us as we fish from the ship.
Opakapaka and ta’ape
Personal Log I’m really enjoying my time on the Sette. In addition to learning new things that I can apply in my classroom, I’m making new friends. Everyone is exceptionally friendly and they go out of their way to explain things to me. Most of them call me “Teach” or “Taz” and almost all of them have sailed with a Teacher at Sea before.
Did You Know? You can tell the age of a fish by their otoliths? The picture has the otoliths from an opakapaka, an ehu, and a hogo. Otoliths are a fish’s “ear bones” and they have growth lines in them much like a tree has growth rings.
Location Data
Latitude: 61°12’61” N
Longitude: 178°27’175″ W
Ship speed: 11.6 knots (13.3 mph)
Weather Data from the Bridge
Wind Speed: 11 knots (12.7 mph)
Wind Direction: 193°
Wave Height: 2-4 ft (0.6 – 1.2 m)
Surface Water Temperature: 8.3°C ( 47°F)
Air Temperature: 8.5°C (47.3°F)
Barometric Pressure: 999.98 millibars (0.99 atm)
Science and Technology Log
At the end of last blog, I asked the question, “What do you do with all these fish data?”
The easy answer is… try and determine how many fish are in the sea. That way, you can establish sustainable fishing limits. But there is a little more to the story…
Historically, all fisheries data were based on length. It is a lot easier to measure the length of a fish than to accurately determine its weight on a ship at sea. To accurately measure weight on a ship, you have to have special scales that account for the changes in weight due to the up and down motion of the ship. Similar to riding a roller coaster, at the crest of a wave (or top of a hill on a roller coaster), the fish would appear to weigh less as it experiences less gravitational force. At the trough of a wave (or bottom of a hill on a roller coaster), the fish would experience more gravitational force and appear to weigh more. Motion compensating scales are a more recent invention, so, historically, it was easier to just measure lengths.
One of the motion-compensating scales onboard the Oscar Dyson.
For fisheries management purposes, however, you want to be able to determine the mass of each fish in your sample and inevitably the biomass of the entire fishery in order to decide on quotas to determine a sustainable fishing rate. So, you need to be able to use length data to estimate mass. Here is where science and math come to the rescue! By taking a random sample that is large enough to be statistically significant, and by using the actual length and weight data from that sample, you can create a model to represent the entire population. In doing so, you can use the model for estimating weights even if all you know is the lengths of the fish that you sample. Then you can extrapolate that data (using the analysis of your acoustic data – more on this later) to determine the entire size of the pollock biomass in the Bering Sea.
How do they do that? First, you analyze and plot the actual lengths vs. weights of your random sample and your result is a scatter-plot diagram that appears to be an exponential curve.
Scatterplot showing observed Walleye pollock weights and lengths for a sample of the population.
Then you create a linear model by log-transforming the data. This gives you a straight line.
Linear regression of the Walleye pollock length and weight data.
Next, you back-transform the data into linear space (instead of log space) and you will have created a model for estimating weight of pollock if all you know are the lengths of the fish. This is close to a cubic expansion which makes sense because you are going from a one-dimensional measurement (length) to a 3-dimensional measurement (volume).
Observed weight and length data showing the model for predicting weight if all you know are lengths.
Scientists can now use this line to predict weights from all of their fish samples and then extrapolate to determine the entire biomass of Walleye pollock population in the Bering Sea (when combined with acoustic data… coming up in the next blog!) when the majority of the data collected is only fish lengths.
Another interesting question… How does length change with age? Fish get bigger as they get older, all the way until they die, which is different from mammals and birds. However, some individual fish grow faster than others, so the relationship between age and length gets a little complicated. How do you determine the age distribution of an entire population when all you are collecting are lengths?
Several age classes of Alaskan pollock (Theragra chalcogramma). Can you tell which one is youngest? Are you sure???
Just like weight, you can determine the age from a subset of fish and apply your results to the rest. This works great with young fish that are one year old. The problem is… once you get beyond a one-year-old fish, using lengths alone to determine age becomes a little sketchy. Different fish may have had a better life than others (environmental/ecological effects) and had plenty to eat, great growing conditions, etc and be big for their age relative to the rest of the population. Some may have had less to eat and/or unfavorable conditions such as high parasite loads leading them to be smaller… There are also other things to consider such as genetics that affect length and growth rate of individuals. Here is where the collection of otoliths becomes important. By collecting the otoliths with the lengths, weights, and gender data, the scientists can look at the age distributions within the population. The graph below shows that if a pollock is 15 cm long, it is clearly a 1 year old fish. If a pollock is 30 cm long, it might be a 2 year old, a 3 year old, or a 4 year old fish, but about 90% of fish at this length will be 3 years old. If a fish is 55 cm long, it could be anywhere from 6 to 10+ years old!
Graph showing age proportions of the Walleye pollock population when compared to length data.
Collection of otoliths is the only way to accurately determine the age of the fish in the random sample and be able to extrapolate that data to determine the estimated age of all the pollock in the fishery. Here is a photo comparing otolith size of Walleye pollock with their lengths.
A comparison of otolith sizes. These otoliths were taken from fish that were 12.5cm, 24.5cm, 30.5cm, 39.0cm, 55.5cm, and 70.0cm counter clockwise from top, respectively.
If we wanted to find out exactly how old each of these fish were, we would need to break the otoliths in half to look at a cross section. Below is what a prepared otolith looks like (courtesy of Alaska Fisheries Science Center). You can try counting rings yourself at their interactive otolith activity found here.
Cross section of Walleye pollock otolith after being prepared (courtesy of the Alaska Fisheries Science Center).
All of these data go into a much more complicated model (including the acoustic-trawl survey walleye pollock population estimates) to accurately estimate the total size of the fishery and set the quotas for the pollock fishing industry so that the fishery is maintained in a sustainable manner.
Next blog, we will learn about how the various ways acoustic data fit into this equation to create the pollock fishery model!
Personal Blog
Ok, so here is a long overdue look at the NOAA Ship Oscar Dyson that I am calling home for three weeks. I was pleasantly surprised when I saw my state room. It is bigger than I thought it would be and came with its own bathroom. I was also pleasantly surprised to learn I would be sharing my state room with Kresimir Williams, one of the NOAA scientists and an old college friend of mine! Here is a picture of our room.
My state room on the Oscar Dyson. The curtains around each bunk help block out light.
The room has a set of bunk beds. Thankfully, my bed is on the bottom. I do not know how I would have gotten in and out of bed in the rough seas we had over the last couple of days. If I do fall out of bed, at least I will not have far to fall. Last year, the ship rocked so hard in rough seas that one of the scientists fell head first out of the top bunk! The room also had two lockers that serve as closets, a desk and chair, and our immersion suits (the red gumby suits). The bathroom is small and the shower is tiny! Notice the handles on the wall. These are really handy when trying to shower in rough seas!
The bathroom in my state room. Notice the essential handles.
Next, we have the Galley or Mess Hall. This is where we have all of our meals prepared by Tim and Adam. Notice that all of the chairs have tennis balls on the legs and that each chair has a bungee cord securing it to the floor! There are also bungee cords over the plates and bowls. Everything has to be secured for rough seas.
The Mess Hall, also known as “The Galley.”The chairs in the galley have tennis balls on their feet and have bungee cords holding them down so they will not move during high seas.The coffee bar and snack bar in the galley.
The Mess Hall also has a salad bar, cereal bar, sandwich fixings, soup, snacks like cookies, and ice cream available 24 hours a day. No one on board is going hungry. The food has been excellent! We have had steaks, ribs, hamburgers and fish that Tim has grilled right out on deck. Here is a picture of my “surf and turf” with a double-baked potato.
“Surf and Turf” meal, courtesy of Stewards Tim and Adam. Yummy!
Most of my work here on board (other than processing fish) has been in the acoustics lab, also known as “The Cave” since it has no windows. This is where the NOAA scientists are collecting acoustic data on the schools of fish and comparing the acoustic data with the biological samples we process in the fish lab.
The acoustics lab, also known as “The Cave” since it has no windows.
I also spend some time up on the Bridge. From the Bridge, you can see 10 to 12+ nautical miles on a clear day. This morning, we saw a couple of humpback whales blowing (surfacing to breathe) about 1/4 mile off our starboard side! A couple of days ago (before the weather turned foul), we spotted an American trawler.
An American Trawler spotted in some foggy weather.
Today, we got close enough to see the Russian coastline! Here is a picture of a small tanker ship with the Russian coastline in the background!
Land Ho! A small tanker off the Russian coastline.
Here are some pictures of the helm and some of the technology we have onboard to help navigate the ship.
The “helm” of the Oscar Dyson.Radar showing numerous Russian fishing vessels near the Russia coastline.
I have also spent some time in the lounge. This is where you can go to watch movies, play darts (yea, right! on a ship in rough weather???), or just relax. The couch and chairs are so very comfy!
The Lounge aboard the Oscar Dyson.
When you have 30 people on board and in close quarters, you better have a place to do laundry! Here is a picture of our very own laundromat.
The onboard laundry facilities.
All for now. Next time, I will share more about life at sea!
Location Data
Latitude: N 61°39’29”
Longitude: W 117°55’90”
Ship speed: 11.7 knots (13.5mph)
Weather Data from the Bridge
Wind Speed: 26 knots (30mph)
Wind Direction: 044°
Wave Height: 4 meters (12 ft)
Surface Water Temperature: 8.2°C ( 46.8°F)
Air Temperature: 7.4°C (45°F)
Barometric Pressure: 994 millibar (0.98 atm)
Science and Technology Log:
Last blog, we learned about the different trawl nets and how the NOAA scientists are comparing those nets while conducting the mid-water acoustic pollock survey. We left off with the fish being released from the codend onto the lift table and entering the fish lab. Here is where the biological data is collected.
Walleye pollock on the sorting table. Various age groups are seen here, including one that is 70cm long and may be over 12 years old! Most are 2 to 4 year olds.
The fish lab is where the catch is sorted, weighed, counted, measured, sexed, and biological samples such as the otoliths, or earbones, are taken (more about otoliths later in this post). First, the fish come down a conveyor belt where they are sorted by species (see video above). Typically, the most numerous species (in our case pollock) stay on the conveyor and any other species (jellyfish and/or herring, but sometimes a salmon or two, or maybe even something unique like a lumpsucker!), are put into separate baskets to weigh and include in the inventory count. In the commercial fishing industry, these species would be considered bycatch, but since we are doing an inventory survey, we document all species caught. Here are some pictures of others species caught and included in the midwater survey.
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The goal of each trawl is to randomly select a sample of 300 pollock to measure as a good representation of the population (remember your statistics! Larger sample sizes will give you a better approximation of the real population). If more than 300 pollock are caught, the remainder are weighed in baskets and quickly sent back to sea. All of the catch is weighed so the scientists can use the length and gender data taken from the sample to extrapolate for the entire catch. This data is combined with the acoustics data to estimate the size of the entire fishery (more on acoustic data in a future post). Weights are entered via touch screen into a program (Catch Logger for Acoustic Midwater Surveys – CLAMS) developed by the NOAA scientists onboard.
The CLAMS display showing that I am “today’s scientist.”
The 300 pollock are sexed to determine the male/female ratio of this randomly selected portion of the population. Gender is determined by making an incision along the ventral side from posterior to anterior beginning near the vent. This exposes the internal organs so that either ovaries or testes can be seen. Sometimes determining gender is tricky since the gonads look very different as fish pass through pre-spawning, spawning, or post-spawning stages. When we determine gender, the fish are put into two separate hoppers, the one for females is labeled “Sheilas” and the hopper for males is labeled “Blokes.”
Making incision to determine gender on pollock sample.Hopper for female pollock ready to be measured with the Ichthystick and entered into CLAMS.
We use an Ichthystick to then measure the males and females separately to collect length data for this randomly selected sample. Designed by NOAA Scientists Rick and Kresimir, the Ichthystick very quickly measures lengths by using a magnet placed at the fork of the fish’s tail (when measuring fork-length). This sends a signal to the computer to record the individual fish’s length data immediately into a spreadsheet and the software creates a population length distribution histogram in real-time as you enter data.
The Ichthystick with fingertip magnet used to quickly measure and enter length data into CLAMS.
A randomly selected subset of 40 pollock get individually weighed, length measured, sexed, evaluated for gonadal maturity and have the otoliths removed. Otoliths (oto = ear, lithos = bone) are calciferous bony structures in the fish’s inner ear. These are used to determine age when examined via cross-section under a dissecting scope. The number of rings corresponds to the age of the pollock, similar to rings seen in trees. The otoliths are taken by holding the fish at the operculum and making an incision across the top of the head to expose the brain and utricle of the inner ear. The otolith is found inside the utricle. Forceps are used to extract the otoliths, which are then washed and put in individual bar-coded vials with glycerol-thymol solution to preserve them for analysis back at the Alaska Fisheries Science Center.
Incision across the skull revealing the otoliths on either side of the brain stem.One otolith from a Walleye pollock.
Watch this short video to see what the entire process of data collection looks like.
So… why collect all of this data? How is this data analyzed and used? Stay tuned to my next blog!
Personal Log:
Well, I can officially say… the honeymoon is over. The Bering Sea had been so extremely kind to us with several days of great weather while we had a high pressure system over us. We enjoyed spectacular sunrises and sunsets, cloudless days and calm seas.
Sunny skies and calm seas on the Oscar Dyson.
Now… we have a low pressure system on top of us. Last night, we experienced 35 knot winds and 12 foot seas. I have spent a lot of time in my room in the past 24 hours… Late this morning, the sun came out and the winds calmed down, but the barometric pressure was still very low (around 990 mbars) which basically meant we were in the center of the low pressure system (similar to the eye of a hurricane, but not as strong… thank goodness!). We had a few hours relief, but we are back to pounding through the waves as the wind picks back up. It will be another long and sleepless night for this landlubber…
On a positive note, we did see two Laysan Albatrosses (Phoebastria immutabilis) from the Bridge as the winds began to kick up. They seemed to really enjoy the high winds as they soared effortlessly around the ship. The Officer on Deck (OOD) also said he saw a humpback breaching, but by the time I got up to the Bridge, it had moved on…
Next blog, I will share pictures of my room, the galley, “the cave,” the Bridge, etc. Right now, I am just trying to hold on to my mattress and my stomach…
NOAA Teacher at Sea
Carmen Andrews Aboard R/V Savannah July 7 – 18, 2012
Mission: SEFIS Reef Fish Survey Location: Atlantic Ocean, off the coast of Cape Canaveral, Florida Date: July 15, 2012
Latitude: 28 ° 50.28’ N Longitude: 80 ° 26.26’ W
Weather Data: Air Temperature: 28.6° C (83.48°F)
Wind Speed: 18 knots
Wind Direction: from the Southeast
Surface Water Temperature: 27.6 °C (81.68°F)
Weather conditions: Sunny and Fair
Science and Technology Log
How are fish catches transformed into data? How can scientists use data derived from fish to help conserve threatened fish species?
The goal of the Southeast Fishery-Independent Survey or SEFIS is to monitor and research reef fish in southeast continental shelf waters. Marine and fisheries scientists have developed sophisticated protocols and procedures to ensure the best possible sampling of these important natural resources, and to develop fisheries management recommendations for present and future sustainability.
During the cruise, important commercial fish in the snapper and grouper families are caught over as wide an area as possible; they are also taken in large enough numbers that they can be worked up into statistically reliable metrics. In addition to counts and measurements, biological samples are also taken at sea for future analysis in land-based research labs.
Gag grouper ready for its work-up
Scientists strive to render an informative snapshot of reef fish stocks in a given time interval. Reports that analyze and summarize the data are submitted to policy-makers and legislators to set fisheries rules, restrictions and possible quotas for commercial and sports fishermen.
After fish are caught and put on ice, processing includes several kinds of measurement that occur on deck. This data is referred to as ‘Length Frequency’. Tag information from the trap follows the fish through all processing. Aggregate weight measurements for all the fish of one species caught in a trap are made and recorded in kilograms.
David is weighing the gag grouper, with Adam P. looking on
The length for each fish in the trap is noted, using a metrically scaled fish board. Not all fish are kept for further processing.
David measuring the length of the gag grouper
Species-specific tally sheets randomly assign which fish from the catch are kept and which ones are tossed back into the ocean. These forms, which specify percentages of fish identified as ‘keepers’, are closely consulted by the data recorder and the information is shared with the scientist who is measuring the catch.
Shelly is recording length frequency measurement dataLength frequency data entriesRed Porgy keep/toss percentage sheet
Kept fish are put in a seawater and ice slurry. The others are thrown over the side of the boat.
Age and reproductive sampling are done next in the wet lab.
Small yellow envelopes are prepared before fish work up can begin. Each envelope is labeled with cruise information, catch number, fish number, and the taxonomical name of the fish, using binomial nomenclature of genus and species.
Adam P. and Shelly labeling envelopes and plastic specimen containers
A small color-coded plastic container (the color indicates fish species tissue origin), with the fish’s source information riveted at the top, is also prepared. This container will store fish tissue samples.
The fish trap catch number is documented on another data form, along with boat and science team identification, collection method and other important information about the circumstances surrounding the fish catch. Each species’ data is separately grouped on the data form, as individual fish in a catch are sequentially numbered down the form.
Me, transcribing fish weight & length data
Each fish is weighed, and the weight is noted in grams. The scale is periodically calibrated to be sure the fish is weighed accurately.
Vermilion snappers and scamp, labeled and ready for dissection
Three length measurements that are made: standard length (SL), total length (TL), and if the fish species has a fork tail — fork length (FL). The fish is laid, facing left on a fish board. The board is long wooden plank with a metric measuring scale running down the center.
Standard length does not include the caudal fin or tail. It begins at the tip of the fish’s head; then the fish measurer lifts the tail up slightly to form a crease where the backbone ends. Standard length measurement includes the fish’s head to end of backbone dimension only. Total length is the entire length of the fish, including the caudal fin. In fork-tailed species, the fork length measurement begins at the fish’s snout and ends at the v-notch in the tail.
Fish length measurements
Source: Australian Government – Department of Environment, Water, Population and Communities
Part of the dissection of every fish (except gray triggerfish) is the extraction of otoliths from the fish’s head. An otolith is a bone-like structure made of calcium carbonate and located in the inner ear of fish. All vertebrates have similar structures that function as gravity, balance, movement, and directional indicators. Otoliths help fish sense changes in horizontal motion and acceleration.
To extract the otoliths, the scientist makes a deep cut behind the fish’s head and pulls it away from the body. The left and right otoliths are found in small slits below the brain. They must be removed carefully, one at a time with forceps. They can easily break or slip into the brain cavity.
Red snapper with removed otolith
Otoliths reveal many things about a fish’s life. Its age and growth throughout the first year of its life can be determined. Otoliths have concentric rings that are deposited over time. The information they show is analogous tree ring growth patterns that record winter and summer cycles. Other otolith measurements can determine when the fish hatched, as well as helping to calculate spawning times in the fish’s life.
The oxygen atoms in calcium carbonate (CaCO3) can be used to assay oxygen isotopes. Scientists can use these markers to reconstruct temperatures of the waters the fish has lived in. Scientists also look for other trace elements and isotopes to determine various environmental factors.
Each pair of otoliths is put into the small labeled yellow envelope.
The otoliths on the gray triggerfish are too small to be studied, so the spine from its back is collected for age and growth analysis.
Spine removed from a gray triggerfish
The last step standard data collection is determining the sex and maturity of the fish. The fish is cut open at the belly, similar to preparing the fish as a filet to eat it.
Making a cut into a vermilion snapper
If the fish is big, the air bladder must be deflated. The intestines are moved or cut out of the way. The gonads (ovaries and testes) are found, and the fish can be identified as a male or female. (Groupers can be hermaphroditic.) The fish’s stage of maturity can also be determined this way. Maturational stages can be classified with a series of codes:
U = undetermined
1 = immature virgin (gonads are barely visible)
2 = resting (empty gonads – in between reproductive events)
3 = enlarging/developing (eggs/sperm are beginning to be produced)
4 = running ripe (gonads are full of eggs/sperm and are ready to spawn)
5 = spent (spawning has already occurred)
Dissected gonad specimens are removed from the fish and placed in a plastic containers, snapped shut and stored in a formalin jar to preserve them. These preserved samples will be analyzed later by histology scientists. Histology is the science of organ tissue analysis.
Dissected fish gonads
Red snappers have their fins clipped to provide a DNA sample. They may also have their stomachs removed and the contents studied to better understand their diets.
Video data from the underwater cameras is downloaded in the dry lab. This data will be analyzed once scientists return to their labs on land.
Personal Log
Many different kinds of echinoderms and other invertebrates have been pulled up in the fish traps. Several are species that I’ve never seen before:
I am holding a basket star. It is a type of brittle star in the echinoderm phylum.A red sea starSpikey sea starSmall crab, covered in seaweed, shell and sand
We also catch many unusual large and small fish in the traps and on hooks. Several of these have been tropical species that I’ve only seen in salt water aquariums.
LizardfishSargassumfishHooked blacktip sharkScrawld FilefishSpotted butterflyfishJack knife fish
