After a long two day cruise to the southern tip of Texas, we finally started fishing. I learned quickly that everyone has a job, and when you are done with your job, you help members of your team complete their tasks. The coordinates of all of the survey locations are charted using a program called Novel Tec, and once the captain has determined that we have reached our designated location, the fun begins. To deploy the longline there are many important responsibilities that are delegated by the Chief NOAA Scientist.
#1- All scientists work together to bait 100 hooks with mackerel (Scomber scombrus).
#2- High-Flyer Release – Once the long line has been attached to the high-flyer, it is released from the stern of the boat. The high-flyer consists of a buoy to keep it above water, and a flashing light, so we know the exact location of the beginning of the longline.
#3 Weight Attachment – A NOAA fisherman is responsible for attaching the weight at the appropriate distance, based on the depth of that station to ensure the gear is on the sea floor. This also keeps the high-flyer from drifting. Alongside the weight, a TDR is attached to the line, which records temperature and depth.
#4 Numbering of baited hooks – After the first weight goes out, one by one the gangions are numbered and set over the edge of the ship, but not let go. A gangion consists of a 12ft line, a baited hook, and hook number.
# 5 Hook Attachment – A NOAA fisherman will receive one gangion at a time, and attach it to the line. Another weight is attached to the line after 50 hooks have been deployed, and once all 100 hooks are deployed the final weight is attached. Then the line is cut, and the second high-flyer is attached and set free to mark the end of the survey area. This process goes fairly quickly, as the longline is continuously being fed into the water.
#6 Data Collection – Each piece of equipment that enters the water is recorded in a database on the computer. There should always be 2 high-flyers, 3 weights, and 100 gangions entered into the database.
#7 Bucket Clean-up – The buckets that were holding the baited hooks need to be scrubbed and prepared for when we haul the line back in.
Once all of the gear is in the water we wait for approximately one hour until we start to haul back each hook one by one. The anticipation is exciting to see if a shark or other fish has hooked itself.
I would say that my body has fully adjusted to living at sea. I took off my sea sickness patch and I feel great! Currently, Tropical Storm Gordon is nearing to hit Mississippi this evening. We are far enough out of the storm’s path that it will not affect our fishing track. I am having the time of my life and learning so much about the Oregon II, sharks, and many other organisms that we’ve seen or caught.
Did you know?:
NOAA Ship Oregon II creates freshwater via reverse osmosis. Sea water is pumped in and passed through a high pressure pump at 1,000psi. The pump contains a membrane (filter), which salt is too big to pass through, so it is disposed overboard. The clean freshwater is collected and can be used for showering, cooking, and drinking. In addition to creating freshwater, the engineers are also responsible for the two engines and the generators.
Mission: Long Line Shark/ Red Snapper survey Leg 1
Geographic Area: Southeastern U.S. coast
Date: August 29, 2018
“Shark On!” was the shout from the first person that sees a shark hooked to the long line that was being hauled up from the floor of the ocean. I heard this phrase often during the first leg of the long line Red Snapper/ shark survey on the NOAA ship Oregon II. We began fishing in the Northwest Atlantic Ocean, off the coast of West Palm Beach, Florida. We traveled north to Cape Hatteras, North Carolina, and back south to Port Canaveral over 12 days this summer.
During our long line deployments each day, we were able to catch, measure, tag and photograph many sharks, before returning them to the ocean quickly and safely. During these surveys, we caught the species of sharks listed below, in addition to other interesting fish from the ocean. This blog has scientific information about each shark, and photographs taken by myself and other scientists on board the Oregon II. The following information on sharks, in addition to scientific data about hundreds of other marine wildlife can be found online at the NOAA Fisheries site: http://fisheries.noaa.gov.
Great Hammerhead Shark-Sphyrna mokarran Hammerhead sharks are recognized by their long, strange hammer-like heads which are called cephalofoils. Great hammerheads are the largest species of hammerheads, and can grow to a length of 20 feet. The great hammerhead can be distinguished from other hammerheads as they have a much taller dorsal fin than other hammerheads.
When moving through the ocean, they swing their broad heads from side to side and this motion provides them a much wider field of vision than other sharks. It provides them an all around view of their environment as their eyes are far apart at either end of the long hammers. They have only two small blind spots, in front of the snout, and behind the cephalofoil. Their wide heads also have many tiny pores, called ampullae of Lorenzini. They can sense tiny electric currents generated by fish or other prey in distress from far distances.
Male Great Hammerhead 10. 5 ft.
Great Hammerhead cephalofoil
The great hammerhead are found in tropical and temperate waters worldwide, and inhabiting coastal areas in and around the continental shelf. They usually are solitary swimmers, and they eat prey ranging from crustaceans and squid, to a variety of bony fish, smaller sharks and stingrays. The great hammerhead can bear litters of up to 55 pups every two years.
Nurse Shark-Ginglymostoma cirratum Nurse sharks are bottom dwellers. They spend their life in shallow water, near the sandy bottom, and their orangish- pinkish color and rough skin helps them camouflage them. At night they come out to hunt. Nurse sharks have short, serrated teeth that can eat through crustaceans such as crabs, urchins, shrimp, and lobsters. They also eat fish, squid, and stingrays. They have two feelers, or barbels, which hang from either side of their mouth. They use their barbels to search for prey in the sand. Their average adult size is 7.5- 9 feet in length and they weigh between 160-230 lbs. Adult females reach a larger size than the males at 7- 8.5 feet long and can weigh from 200-267 lbs.
Nurse sharks are common in the coastal tropical waters of the Atlantic and also in the eastern Pacific Ocean. This species is locally very common in shallow waters throughout the Caribbean, south Florida to the Florida Keys. Large juveniles and adults are usually found around deeper reefs and rocky areas at depths of 10-250 feet during the daytime and migrate into shallower waters of less than 70 feet deep after dark.
Nurse shark in cradle
Nurse shark in cradle
Juveniles up to 6 feet are generally found around shallow coral reefs, grass flats or mangrove islands in shallow water. They often lie in groups of forty on the ocean floor or under rock ledges. Nurse sharks show a preference for a certain resting site, and will repeatedly go back to to the same caves for shelter or rest after leaving the area to feed.
Tiger Shark-Galeocerdo cuvier Adult Tiger sharks average between 10 -14 feet in length and weigh up to 1,400 lbs. The largest sharks can grow to 20 feet and weigh nearly 2,000 lbs. They mature between 5 and 10 years, and their life span is 30 years or more. Tiger sharks are named for the brown stripes and patches they have on their sides when they are young. As they get older, they stripes eventually fade away.
juvenile tiger shark
juvenile tiger shark
They will eat almost anything they come across, and have been referred to as the “garbage cans of the sea”. Their habitat ranges from shallow coastal waters when they are young, to deep waters over 1,500 feet deep. They swim in shallow waters to hunt lobster, squid, fish, sea turtles, birds, and smaller sharks.
They migrate with the seasons to follow prey and to give birth to young. They swim in cool waters in the summer, and in fall and winter they migrate to warm tropical waters. Their young grow in eggs inside the mother’s body and after 13 months the sharks hatch. The mother gives birth to a litter of 10 – 80 pups. Their current status is currently Near Threatened.
Sharpnose Shark-Rhizoprionodon terraenovae Atlantic sharpnose sharks are small for sharks and have a streamlined body, and get their name from their long, pointy snout. They are several different shades of gray and have a white underside. Atlantic sharpnose sharks can grow to up to 32 inches in length. Atlantic sharpnose sharks have been observed to live up to 18 years. Females mature at around 2 years old in the Atlantic when they reach approximately 24 inches in length. Atlantic sharpnose sharks are commonly found in the western Atlantic from New Brunswick, Canada, right through the Gulf of Mexico. They are commonly caught in U.S. coastal waters from Virginia around to Texas.
Atlantic sharpnose sharks eat small fish, including menhaden, eels, silversides, wrasses, jacks, toadfish, and filefish. The lower and upper jaws of an Atlantic sharpnose shark have 24 or 25 rows of triangular teeth. Atlantic sharpnose sharks mate annually between mid-May and mid-July in inshore waters, and after mating, they migrate offshore to deeper waters. They also eat worms, shrimp, crabs, and mollusks.
Sandbar Shark on long line
Sandbar Shark in cradle
Sandbar Shark-Carcharhinus plumbeus. The most distinctive feature of this stocky, grey shark is its huge pectoral fins, and long dorsal fin that increases its stability while swimming. Females can grow between 6 – 8.5 feet, and males grow up to 6ft. Its body color can vary from a blue to a light brown grey with a pale white underside. The sandbar shark lives in coastal waters, living in water that is 20 to 200 feet deep. Rarely is its large dorsal fin seen above the water’s surface, as the sandbars prefer to remain near the bottom. It commonly lives in harbors, lagoons, muddy and sandy bays, and river mouths, but never moves into freshwater. The sandbar shark lives in warm and tropical waters in various parts of the world including in the Western Atlantic, from Massachusetts down to southern Brazil.
The sandbar shark spends the majority of its time near the ocean floor, where it looks continuously for prey, such as small fish, mollusks, and various crustaceans. Their main diet consists largely of fish. Sandbar sharks give birth to between 1 and 14 pups in each litter. The size of the litter depends on the size of the mother, with large females giving birth to larger litters. Pregnancy is estimated to last between 8- 12 months. Females move near shore to shallow nursery areas to give birth. The females leave coastal areas after giving birth, while the young remain in the nursery grounds until winter, when they move into warmer and deeper water.
remora sucker pad
remora being weighed
Fun Fact- Remoras, or shark suckers, live in tropical oceans around the world. They have a rigid oval- shaped sucker pad on top of their head that it uses to attach itself to sharks and rays. It is symbiotic relationship where both animals gain something from their temporary union. Remoras mouths are at the top front of the body so while attached to a shark’s body, they do their host a favor by nibbling off skin parasites. They can also eat scraps of leftover food the shark leaves behind while they also enjoy a free ride. The shark gains a day at the spa for a body scrub, and can rid itself of parasites in a way it couldn’t have before!
It was certainly an unforgettable experience being able to work with the scientific and fishing team for this shark survey. The opportunity to see and handle these sharks up close for two weeks has informed me of so many interesting things about these wonderful and vital members of the ocean. I can now take this information and share it first hand with students in my classroom, and members of my community. I also want to work to bring a positive awareness to these vital members of the ocean food web so they can thrive well into the future. As an artist, this trip has been invaluable for me, as now I’ve seen the how colorful and varied sharks are and other various anatomy details you just can’t see in books or television. This new awareness will help to make my future paintings more accurate than before.
Latitude 2848.37 N
Longitude 09247.66 W
Winds at 11 KTS
Waves at 2-4 FT
Science and Technology Log
Sometimes when a shark or fish is brought on board it has a “hitchhiker’ attached. We caught a blacknose shark that had a common remora, often referred to as a sucker fish, or shark sucker, attached to it. Scientist Kevin Rademacher placed this sharksucker (Echeneis naucrates) on my arm. I couldn’t really feel it but he was stuck there until I peeled him off. It was like peeling a piece of tape off. You can see from the photo how he is designed to attach to host species. Their head is actually a modified dorsal fin that has an oval shaped sucking disk with slat-like structures that open and close to create suction and take a firm hold against the skin of its host animal such as a shark, turtle, whale, or ray. By sliding backward, the remora can increase its suction, or it can release itself by swimming forward. They can be small like the one attached to my arm or they can grow to over two feet in length. The remora can move around on the host, removing parasites while at the same time gaining protection provided by the host. This relationship is often looked at as one of commensalism where both the host and the remora benefit.
The remora’s modified dorsal fin provides suction ability
Remora on TAS Karen Grady’s arm
Photos of the remora that was attached to a black-nosed shark.
When one hears that this is an experimental long-line survey of sharks and reef fish, all you think of is catching these creatures and collecting data. However, scientists are collecting data about the environment as well. It is very useful to obtain information about the water where they catch large numbers of a species and areas where they may not catch anything. One way they can do this is by using a Conductivity Temperature Depth Profiler (CTD).
The CTD gives scientists a profile of the water column where we just put out our line. The CTD has sensors that collects information on oxygen levels, temperature, water clarity, chlorophyll concentration, and salinity. The CTD is placed in the water and allowed to sit for three minutes to let the oxygen sensors soak and adjust from being on the deck and lowered into the water. The crew lowers it to a depth that is decided based upon the depth to the ocean floor. They like to take it as close to the bottom as possible in order for the information they gather to be as complete as possible. It is allowed to settle, run its scans and then is brought back up to the surface and the sensors are flushed with fresh water. The data is automatically loaded into the database. This information is collected at each station. It takes a joint effort of the deck, science and bridge crews to place the CTD in the water. Walkie talkies are utilized for communicating between all the crew involved in the operation.
Scientist James Sulikowski prepares the CTD for deployment
Scientists can review the data from the CTD immediately
Being at sea with Easter approaching had its moments when I thought of family and friends. We have our Easter traditions and I would be missing them this year. The Easter Bunny (Field Party Chief, Kristin Hannan) decided we needed an early visit this year. I think she was right. The surprise and the treats perked all the science staff up.
FPC Kristin Hannan asks me often if I have any questions about what they are doing or anything in general. I will be honest… I have gotten so caught up in what we are doing, trying to do my best at whatever job I am working on, and being in awe that I am actually out here that I forget to ask questions about the details. I love the anticipation of what might be on the next hook, I am mesmerized by the sleek lines of the sharks when we have them on board.
When we had one come onboard that was dead due to low oxygen levels in the water where we caught it, we did a dissection on the deck while we waited to put out another line. The animal science nerd in me came to life! I had no idea the liver was the largest organ inside a shark. Think about it …these creatures have no body fat and they store their energy in the liver. Then we looked at the intestines. There is not a lot of room in there so the shark we looked at the intestines are rolled up like you would roll a piece of paper. This gives them maximum absorption area but takes up a limited space.
One thing I think of as we are catching these species is that very few people stop and think about the actual research scientists do to help understand what is needed to maintain healthy populations. It is necessary to do these surveys, catch the species, tag some, draw blood, take fin clips, keep whole specimens, and dissect some. On our cruise we were lucky enough to ultrasound a few pregnant sharks and see the pups inside.
Now stop and think about all those things I just listed that we do at times. When a hook comes up and there is a fish or shark on it is handed off to one of the science crew. It is noted in the computer that there was a something caught. The science crew member will take measurements and weight of the fish or shark. If it is a shark, the sex will be noted and some species may be tagged, have a fin clip taken and blood drawn. While all of these activities are taking place, the next hooks keep being brought up. The deck can get pretty crazy if there are several hooks in a row with something on them. The data collector has to keep tag numbers, species, measurements, samples and weights all written in the correct spot while having two or three people calling them out for different fish and or sharks. I had experience working cattle which would mean filling syringes, writing down tag numbers, filling taggers, etc. But this is even crazier than that could get at times. And everything stops if someone calls “hardhats” because that means we have one big enough for the cradle. Working back writing down data or taking measurements you can’t see what is on the next line so you sneak up for a peak when they say it’s a big one then you get out of the way. One of the best experiences so far was almost getting a big tiger shark in the cradle. I was lucky enough to get a video of her, so stay tuned! Unfortunately, when the big shark brushed against the cradle she snapped the line and was gone with a huge spray of water.
This second leg of the experimental long-line survey is winding down. There have been long days but they are filled with laughter, giggles, anticipation, excitement, teachable moments (I can finally get the circle hooks out by myself…sometimes) , and the dreaded words “snapper.” I mean nothing against the Red Snapper, they are a bright colorful and tasty fish, but when you are hoping for a shark to be on the hook…. let’s just say the sets where we get 12 snapper and two sharks are not our favorites.
Photos: “Shark!” or “Fish on!” means a busy deck.
When the guys at the rail grab the hard hats it means it is time for the cradle and we get to see things like this gorgeous scalloped hammerhead. Things move very quickly when one is in the cradle. Safety for those on deck comes first and everyone is focused on getting measurements, fin clip and a tag on the shark and getting it safely back in the water as quickly as possible.
Baby tiger shark in the cradle. They warned me that they were cute and they were so right. Yes, a shark can be “cute” when your referring to baby tiger sharks and baby hammerheads!
Did You Know
Sharks store energy in their liver. It is the largest organ in their body. The heart on the other hand is extremely small in comparison to the size of the shark.
Look at the liver of this scalloped hammerhead. It is amazing how big it is in relation to the body of the shark. This is just one way these amazing creatures are designed to be efficient and survive in their underwater world.
Sharks have a nictitating membrane that they can close over their eye for protection. When a shark is brought on deck you can touch near the eye and the membrane will automatically move to close.
Rough Seas and bad weather have delayed our sampling. I’m getting use to walking sideways.
Today we reached the northernmost sampling station of our cruise, just off the North Carolina coast. The latest stations have been further off shore than those previous and we’ve caught fewer sharks. However, the sharks we have caught have been much larger. Our catch included Sandbar Sharks, Scalloped Hammerhead, Spinner, Nurse and Black Nose.
Sharks have a number of reproductive strategies ranging from egg laying to placental formation. Oviparous sharks produce and release egg cases made of a collagen (protein). The case surrounds the developing embryo and a large yolk with the vital nutrients required for shark development. This is called lecithotrophic (all nutrients from yolk). Oviparous sharks can take to 2 years to develop within the egg case.
Sharks that give birth to live young are considered Viviparous. Within this category there are two major types. Those that produce eggs with large yolks with all required nutrients, but remain in the uterus for gestation, are called yolk-sac vivipores (ovoviviparous, or aplacental viviparity). In some cases, offspring will consume other eggs (oophagy) in the uterus to gain additional nutrients. An advantage to this type of reproduction is that the young sharks are larger when they are born and have a higher survival rate.
The last group, considered to be the most advanced, is the Placental Group. As with the other types, a yolk is produced that can initially provide some nutrients to the developing pup. However, in the uterus the yolk sac after it is depleted is modified into a placenta through which nutrients can pass from parent to offspring. While fewer offspring are produced at one time, they are typically more robust and have a higher survival rate. Most of the sharks we have caught on this cruise are placental vivipores.
Career Spotlight: Dr. Ian Davenport, Ph.D., Research Scientist
Ian hails from Manchester, England, and his path to becoming a scientist was quite unusual. Similar to others on board, he always had an interest in Marine Science, and sharks in particular, but school was not a priority early on. He spent time travelling and learned a trade as well. He finally decided to return to school, but being accepted was a challenge. Fortunately Ian’s academic ability was recognized and he was accepted to the University of Newcastle upon Tyne where he studied Marine Biology, but a course in Developmental Biology particularly resonated. He went on to earn his Ph.D. in shark developmental biology at Clemson University.
Ian’s research focus is in evolution of “live bearing.” As noted above, shark species employ a number of reproductive strategies. Placentals are considered to be the most advanced. Ian is studying the eggs of placental sharks and the structure of the cells that surround the egg. His research has revealed some interesting cell features that may aid in nutrient delivery to the developing embryo. If a female shark is caught during the cruise and does not survive, Ian collects the eggs for later study.
Career Spotlight: Chuck Godwin, Deck Crew and Environmental Compliance officer
Chuck has a B.A. in History and has also studied Wildlife Management. Chuck spent 10 years in the Coast Guard and left in 2000, but he was recalled to active service on two occasions – after 9/11 and after Hurricane Katrina. In addition to his work as part of the deck crew, where he is involved in all deck operations, Chuck is also the Environmental Compliance Officer. As such, he manages hazardous waste compliance.
It’s apparent that Chuck enjoys his work. He is all business when he needs to be, but has a knack for adding a note of levity when appropriate. He keeps me laughing, even when the fish aren’t biting. Chuck notes that as a member of the Coast Guard, part of his job was to enforce U.S. fisheries laws. With NOAA he plays an important role in establishing those regulations and this makes the work that much more rewarding.
The weather has been poor since yesterday. Lightning caused a five-hour delay in setting the longline in the night; the ship traversed back and forth over the sampling area waiting for the worst of the storm to pass. Sleeping was a challenge – I think some of us were airborne a few times. Thank goodness for the patch and a few saltine crackers. I took the video below in my bunk as I was nodding off to sleep.
Today’s rough seas and high winds prevented us from using the cradle to bring sharks up to deck height. Ken’s dual laser device, mentioned in my last blog post, was put to good use to estimate the size of the large sharks before they were released.
I need to give shout out to the ship’s cook Walter Coghlan and the second cook O.C. (Otha) Hill. The food has been great and plentiful. ( Homemade Mac n’ Cheese – need I say more?) Walter takes special care to set aside a plate for us if we are on duty during mealtime. The ice cream sandwiches are much appreciated too.
New species seen since last posting: Sharksucker (a type of Remora, Echeneis naucrates), Blacktip (Carcharhinus limbatus)
NOAA Teacher at Sea Lynn M. Kurth Aboard NOAA Ship Oregon II July 25 – August 9, 2014
Mission: Shark/Red Snapper Longline Survey Geographical area of cruise: Gulf of Mexico and Atlantic Date:July 31, 2014
Lat: 30 11.454 N Long: 80 49.66 W
Weather Data from the Bridge: Wind: 17 knots
Barometric Pressure: 1014.93 mb
Temperature: 29.9 Degrees Celsius
Science and Technology Log: It would be easy for me to focus only on the sharks that I’ve encountered but there is so much more science and natural phenomena to share with you! I have spent as much time on the bow of the boat as I can in between working on my blogs and my work shift. There’s no denying it, I LOVE THE BOW OF THE BOAT!!! When standing in the bow it feels as if you’re flying over the water and the view is splendid.
From my prized bird’s eye view from the bow I’ve noticed countless areas of water with yellowish clumps of seaweed. This particular seaweed is called sargassum which is a type of macroalgae found in tropical waters. Sargassum has tiny chambers which hold air and allow it to float on or near the water’s surface in order to gather light for photosynthesis. Sargassum can be considered to be a nuisance because it frequently washes up on beaches and smells as it decomposes. And, in some areas it can become so thick that it reduces the amount of light that other plant species need to grow and thrive. However, the floating clumps of sargassum provide a great habitat for young fish because it offers them food and shelter.
We have hauled in a variety of sharks and fish over the past few days. One of the more interesting species was the remora/sharksucker. The sharksucker attaches itself to rays, sharks, ships, dolphins and sea turtles by latching on with its suction cup like dorsal fin. When we brought a sharksucker on board the ship it continued to attach itself to the deck of the boat and would even latch on to our arm when we gave it the chance.
The largest species of sharks that we have hauled in are Sandbar sharks which are one of the largest coastal sharks in the world. Sandbar sharks have much larger fins compared to their body size which made them attractive to fisherman for sale in the shark fin trade. Therefore, this species has more protection than some of the other coastal shark species because they have been over harvested in the past due to their large fins.
Thankfully finning is now banned in US waters, however despite the ban sandbar sharks have continued protection due to the fact that like many other species of sharks they are not able to quickly replace numbers lost to high fishing pressure. Conservationists remain concerned about the future of the Sandbar shark because of this ongoing threat and the fact that they reproduce very few young.
Did you Know?
Sargassum is used in/as:
fertilizer for crops
food for people
Personal Log: I continue to learn a lot each day and can’t wait to see what the next day of this great adventure brings! The folks who I’m working with have such interesting tales to share and have been very helpful as I learn the ropes here on the Oregon II. One of the friendly folks who I’ve been working with is a second year student at the University of Tampa named Kevin Travis. Kevin volunteered for the survey after a family friend working for NOAA (National Oceanic and Atmospheric Administration) recommended him as a volunteer. Kevin enjoys his time on the boat because he values meeting new people and knows how beneficial it is to have a broad range of experiences.
NOAA Teacher at Sea
Onboard NOAA Ship Oregon II
July 27 – August 8, 2012
Mission: Longline Shark Survey
Geographic area of cruise: Gulf of Mexico and Atlantic off the coast of Florida
Date: August 7, 2012
Weather Data From the Bridge:
Air Temperature (degrees C): 28.4
Wind Speed (knots): 8.62
Wind Direction (degree): 183
Relative Humidity (percent): 080
Barometric Pressure (millibars): 1015.41
Water Depth (meters): 43.4
Salinity (PSU): 35.660
We are getting close to wrapping up this first leg of a four-leg survey. Speaking of wrapping things up, one very important skill you must know when on a ship is how to tie a knot. Not just any knot, but the right knot for the job, or things might not turn out. Got it?
There are three knots, which we used every day. The Blood Knot (sometimes called the Surgeon’s Knot), the Double Overhand Loop (sometimes called a Surgeon’s End Loop), and the Locking Half-Hitch on a Cleat.
The blood knot is used to tie two ropes together. When we return a longline, it has to be tied back on to the main spool. Watch Tim and Chris demonstrate how to tie this knot.
The double overhand loop is used, as the name implies, to put a loop on the end of a line. It is used at each end of the longline to secure the highflier.
The locking half hitch knot is tied on to a ship’s cleat in order to secure the mainline after it has been sent out. This gives us the opportunity to tie a double overhand loop on to the end in order to clip on the highflier.
We have also been seeing some more different animals during the past couple of days. We saw a green sea turtle surface twice. The first time was right in front of us on the starboard side of the ship. The second time was several minutes later at the stern. Just when I thought I would not get a picture of a dolphin, a trio of Atlantic spotted dolphins followed along the Oregon II as we let out the longline. Dolphins and all sea turtles are protected.
We have also been catching more sharks. Again, the most common species caught has been the sharpnose shark. We finally caught a silky shark, Carcharhinus falciformes on our shift. The ridge that runs along their back and the smooth, silky look to their skin can be used to identify them.
A 93.6 kilogram nurse shark, Ginglymostoma cirratum was caught and brought up using the cradle. These are bottom-feeding sharks and have an unusual texture to their skin. It feels like a basketball!
It is always nice when you witness the rare or unusual. Such was the case with the next shark we caught. Many photographs were taken in order to document this rare occurrence. After releasing the shark, it was identified as a Caribbean reef shark, Carcharhinus perezi. Mark Grace, who started this survey 18 years ago, believes this is only the third Caribbean reef shark ever caught on the longline survey! Rare indeed! Unbelievable–the very next longline we caught a second Caribbean reef shark!
Another first for the first leg of the 300th mission was a dusky shark, Carcharhinus obscurus. This is another rare shark to be found. This one was even bigger than the nurse shark weighing in at 107.3 kilograms! We keep the larger sharks in the cradle while data is collected before releasing them.
While cleaning up, this little remora was found on the deck. It is easy to see the suction disc on the top of its head. This is used to hold onto a larger fish and tag along for the ride, cleaning up bits of food missing the mouth of the host fish.
This amazing journey is winding down and coming to an end. I would be remiss not to thank the crew and scientists of the Oregon II. Their hospitality, professionalism, friendly dispositions, and patience (LOTS of patience) have made me feel more than welcome. They have made me feel as though, for a brief moment, I was a part of the team. Thank you and may the next 300 missions be as safe and successful as the first 300.
Lat: 18 40 N
Long: 158 14 W
Sky: Sunnny with widely scattered cumulus
Air temp: 26.4 C
Wind: 172 degrees at 12 knots
Relative humidity: 61.4%
Sea temp: 26.4 C
Depth: 888.5 m
Sea: A few white caps out there; swells in 1-3 foot range — easy going today.
Science and Technology Log
A fairly exciting morning on the longline. Several escolar, a barracuda, and a pomfret (a laterally flattened fish about 30cm long but only 2-3 cm in width with a fine set of sharp teeth). Samples taken from all. We also had a blue shark from which samples were taken and an oceanic white tip shark which was tagged and released. I got to wrestle both. Picked up a few remoras from the sharks. We think we have at least two species of remoras.
This afternoon we passed over Cross Seamount and traversed it several times as we trolled but to no avail. There will be no longline set tonight since we have a date in Kona to drop off one of the current scientific party.
I want to fill in with more of the vision story this evening if I can stay coherent long enough to convey it sensibly. I will touch on the work of Steven, Kerstin, and Rickard.
I have been collecting samples of fish lenses. They vary in size, as you would expect, among different sized fishes. What makes the lenses different from those of most vertebrates is that they are spherical rather than oval in cross section. The cornea of fish is also optically non-functional. Since it has the same refractive index as water, focusing is done by moving the lens back and forth in the eye rather than by changing the shape of the lens as our eye muscles do.
Steven uses laser light to determine the focal point for different colors of light. He suspends lenses in a fluid medium then turns on a laser beam that makes two vertical passes through the diameter of the lens. You can watch light’s path change as the beam migrates. Computer analysis then determines focal point.
Kerstin and Rickard must have live cells from the retina for their studies. Among other things, they are looking at the sensitivity of these cells to different light intensities. Live retina cells convert light to electrical signals which travel via the optical nerve to the brain to produce an image. By attaching electrodes to tissue samples about 1 cm square in size and subjecting the cells to different intensities of light electrical responses of different strengths can be detected and measured. They appear as a wave pattern on a screen. As light intensity is increased, the amplitude of the wave pattern increases. So a flat line (no response) becomes one with small amplitude waves which grow as light intensity increases to a point where more light produces no greater effect.
Lets compare two species, mahi mahi, which stay nearer well lit surface and bigeye tuna which like deeper environs. Which eye would you expect to be more light sensitive? The bigeye. Their cells are stimulated by much lower intensities of light than the mahi’s. They (bigeye) have to be able to detect their prey under minimal light conditions and need the more sensitive eye to do that. Big eyes, big pupils (fish pupil size is fixed) and a “super” sensitive set of retinal cells are adaptations of these fish to their deep environment.
I’ve had enough (as I suppose you have too). I will wrap up the vision story tomorrow or Sunday.
We are headed for Kona. Although we probably will not get any shore time, it has been suggested that there might be an excursion to a place where we can swim/snorkel for awhile. I am hoping very much this it true as are others. A plunge into this element (I guess I should say compound) that we have bobbed around on top of for the past 13 days would be a pleasant change in the routine and scenery.
Reading E.O. Wilson’s The Diversity of Life.
I would like to thank, Ron, a fellow teacher from Michigan who I have never met, for writing a note to tell me that he has been enjoying the logs and also to pose a question. Much appreciated!
Sunrise here today is at 6AM and the great yellow ball sets here at 7PM. What time is it rising and setting in your area at this time of year? Find out sunrise and sunset times for the solstices for Honolulu and your area. From that determine A) how much longer the sun is above the horizon for each place in summer vs winter B) which place, Honolulu or your home has more sun time at each solstice? If you find that there are differences explain why they exist.