Jeff Miller: Sharks and Dead Zones, September 12, 2015

NOAA Teacher at Sea
Jeff Miller
Aboard NOAA Ship Oregon II
August 31 – September 14, 2015

Mission: Shark Longline Survey
Geographical Area: Gulf of Mexico
Date: September 12, 2015

Data from the Bridge
Ship Speed:  9.2 knots
Wind Speed:  8.8 knots
Air Temp: 27,7°C
Sea Temp: 30.2°C
Seas: 1-2 meters
Sea Depth:  457 meters

GPS Coordinates
Lat:  27 47.142 N
Long:  094 04.264 W

Science and Technology Log
On September 8 – 9, we surveyed a number of stations along the Texas and Louisiana coasts that were in shallow water between 10-30 meters (approximately 30-100 feet).  Interestingly, the number of sharks we caught at each station varied dramatically.  For example, we pulled up 65 sharks at station 136 and 53 sharks at station 137, whereas we caught only 5 sharks at station 138 and 2 sharks at station 139.  What could account for this large variance in the number of sharks caught at these locations?

Weighing a bonnethead shark

Weighing a bonnethead shark caught off the coast of Texas.

One key factor that is likely influencing shark distribution is the amount of dissolved oxygen in the water.  Oxygen is required by living organisms to produce the energy needed to fuel all their activities.  In water, dissolved oxygen levels above 5 mg/liter are needed for most marine organisms to thrive. Water with less than 2 mg/liter of dissolved oxygen is termed hypoxic, meaning dissolved oxygen is below levels needed by most organisms to thrive and survive.  Water with less than 0.2 mg/liter of dissolved oxygen is termed anoxic (no oxygen) and results in  “dead zones” where little, if any, marine life can survive.

As part of several missions, including the ground fish and longline shark surveys, NOAA ships sample the levels of dissolved oxygen at survey stations in coastal waters of the Gulf of Mexico.  Measurements of dissolved oxygen, salinity, and temperature are collected by a device called the CTD.   At each survey station, the CTD is deployed and it collects real-time measurements as it descends to the bottom and returns to the surface.


Standing with the CTD, which is used to measure dissolved oxygen, salinity, and temperature.

Data collected by the CTD is used to produce maps showing the relative levels of dissolved oxygen in coastal regions of the Gulf of Mexico.    For more environmental data go to the NOAA National Centers for Environmental Information.

2015 Gulf Hypoxia Map

Map showing dissolved oxygen levels in the coastal areas of the Gulf of Mexico. Red marks anoxic/hypoxic areas with low dissolved oxygen levels.  Source: NOAA National Centers for Environmental Information.

Environmental surveys demonstrate that large anoxic/hypoxic zones often exist along the Louisiana/Texas continental shelf.  Because low dissolved oxygen levels are harmful to marine organisms, the anoxic/hypoxic zones in the northern Gulf of Mexico could greatly impact commercially and ecologically important marine species.  Overwhelming scientific evidence indicates that excess organic matter, especially nitrogen, from the Mississippi River drainage basin drives the development of anoxic/hypoxic waters.  Although natural sources contribute to the runoff, inputs from agricultural runoff, the burning of fossil fuels, and waste water treatment discharges have increased inputs to many times natural levels.

Runoff in the Mississippi basin

Map showing sources of nitrogen runoff in the Mississippi River drainage basin. Source NOAA National Centers for Coastal Ocean Science.

Nitrogen runoff from the Mississippi River feeds large phytoplankton algae blooms at the surface.  Over time, excess algae and other organic materials sink to the bottom.  On the bottom, decomposition of this organic material by bacteria and other organisms consumes oxygen and leads to formation of anoxic/hypoxic zones.  These anoxic/hypoxic zones persist because waters of the northern Gulf of Mexico become stratified, which means the water is separated into horizontal layers with cold and/or saltier water at the bottom and warmer and/or fresher water at the surface. This layering separates bottom waters from the atmosphere and prevents re-supply of oxygen from the surface.

Since levels of dissolved oxygen can  greatly influence the distribution of marine life, we reasoned that the high variation in the number of sharks caught along the Louisiana/Texas coast could be the result of differences in dissolved oxygen.  To test this idea, we analyzed environmental data and shark numbers at survey stations along the Louisiana/Texas coast.  The graphs below show raw data collected by the CTD at stations 137 and 138.

CTD 137

Dissolved oxygen levels at station 137 (green line; raw data). At the surface: dissolved oxygen = 5.0 mg/liter. At the bottom: dissolved oxygen = 1.5 mg/liter.  Notice the stratification of the water at a depth of 7-8 meters.


CTD 138

Dissolved oxygen levels at station 138 (green line; raw data).  At the surface: dissolved oxygen = 5.5 mg/liter. At the bottom: dissolved oxygen = 0 mg/liter.  Notice the stratification of the water at a depth of 7-8 meters.

Putting together shark survey numbers with environmental data from the CTD we found that we caught very high numbers of sharks in hypoxic water and we caught very few sharks in anoxic water.  Similar results were observed at station 136 (hypoxic waters; 65 sharks caught) and station 139 (anoxic waters; 2 sharks caught).

Data table

Relationship between dissolved oxygen levels and numbers of sharks caught at stations 137 and 138.

What can explain this data?  One possible answer is that sharks will be found where there is food for them to eat.  Thus, many sharks may be moving in and out of hypoxic waters to catch prey that may be stressed or less active due to low oxygen levels.  In other words, sharks may be taking advantage of low oxygen conditions that make fish easier to catch.  In contrast, anoxic waters cannot support marine life so there will be very little food for sharks to eat and, therefore, few sharks will be present.  While this idea provides an explanation for our observations, more research, like the work being done aboard the NOAA Ship Oregon II, is needed to understand the distribution and movement of sharks in the Gulf of Mexico.

Personal Log
My time aboard the Oregon II is drawing to a close as we move into the last weekend of the cruise.  We have now turned away from the Louisiana coast into deeper waters as we travel west to Galveston, Texas.  The weather has changed as well.  It has been sunny and hot for much of our trip, but clouds, rain, and wind have moved in.  Despite this change in weather, we continue to set longlines at survey stations along our route to Galveston.  The rain makes our job more challenging but our catch has been relatively light since we moved away from the coast into deeper waters.  Hopefully our fishing luck will change as we move closer to Galveston.  I would like to wrestle a few more sharks before my time on the Oregon II comes to an end.

Jeff Miller: Wrestling Sharks for Science, September 9, 2015

NOAA Teacher at Sea
Jeff Miller
Aboard NOAA Ship Oregon II
August 31 – September 14, 2015

Mission: Shark Longline Survey
Geographical Area: Gulf of Mexico
Date: September 9, 2015

Data from the Bridge
Ship Speed: 9.4 knots
Wind Speed: 6.75 knots
Air Temp: 29.4°C
Sea Temp: 30.4°C
Seas: <1 meter
Sea Depth: 13 meters

GPS Coordinates
Lat:  N 29 25.103
Long:  W 092.36.483

Science and Technology Log
The major goal of our mission is to survey shark populations in the western Gulf of Mexico and collect measurements and biological samples.  The sharks are also tagged so if they are re-caught scientists can learn about their growth and movements.

Sharks are members of the class of fishes called Chondrichthyes,which are cartilaginous fishes meaning they have an internal skeleton made of cartilage.  Within the class Chondricthyes, sharks belong to the subclass Elasmobranchii together with their closest relatives the skates and rays.  There are about 450 species of living sharks that inhabit oceans around the world.

Sharks, or better put their ancient relatives, have inhabited the oceans for approximately 450 million years and have evolved a number of unique characteristics that help them survive and thrive in virtually all parts of the world.  The most recognizable feature of sharks is their shape.  A shark’s body shape and fin placement allow water to flow over the shark reducing drag and making swimming easier.  In addition, the shark’s cartilaginous skeleton reduces weight while providing strength and flexibility, which also increases energy efficiency.

Blacktip shark

Measuring a blacktip shark on deck. The blacktip shark shows the typical body shape and fin placement of sharks. These physical characteristics decrease drag and help sharks move more efficiently through water.

When I held a shark for the first time, the feature I noticed most is the incredible muscle mass and strength of the shark.  The body of a typical shark is composed of over 60% muscle (the average human has about 35-40% muscle mass).  Most sharks need to keep swimming to breathe and, therefore, typically move steadily and slowly through the water.  This slow, steady movement is powered by red muscle, which makes up about 10% of a sharks muscle and requires high amounts of oxygen to produce fuel for muscle contraction.  The other 90% of a sharks muscle is called white muscle and is used for powerful bursts of speed when eluding predators (other sharks) or capturing prey.

Since sharks are so strong and potentially dangerous, one lesson that I learned quickly was how to properly handle a shark on deck.  Smaller sharks can typically be handled by one person.  To hold a small shark, you grab the shark just behind the chondrocranium (the stiff cartilage that makes up the “skull” of the shark) and above the gill slits.  This is a relatively soft area that can be squeezed firmly with your hand to hold the shark.  If the shark is a bit feisty, a second hand can be used to hold the tail.

Holding a sharpnose shark

Smaller sharks, like this sharpnose shark, can be held by firmly grabbing the shark just behind the head.

Larger and/or more aggressive sharks typically require two sets of hands to hold safely.  When two people are needed to hold a shark, it is very important that both people grab the shark at the same time.  One person holds the head while the other holds the tail.  When trying to hold a larger, more powerful shark, you do not want to grab the tail first.  Sharks are very flexible and can bend their heads back towards their tail, which can pose a safety risk for the handler.  While holding a shark sounds simple, subduing a large shark and getting it to cooperate while taking measurements takes a lot of focus, strength, and teamwork.

Holding a blacktip shark

Teamwork is required to handle larger sharks like this blacktip shark, which was caught because it preyed on a small sharpnose shark that was already on the hook.


Measuring a blacktip shark

Collecting measurements from a large blacktip shark.


Holding a blacktip shark

Holding a blacktip shark before determining its weight.

When a shark is too big to bring on deck safely, the shark is placed into a cradle and hoisted from the water so it can be measured and tagged.  We have used the cradle on a number of sharks including a 7.5 foot tiger shark and a 6 foot scalloped hammerhead shark.  When processing sharks, we try to work quickly and efficiently to measure and tag the sharks to minimize stress on the animals and time out of the water.  Once our data collection is complete, the sharks are returned to the water.

Tiger shark in the cradle

Large sharks, like this tiger shark, are hoisted up on a cradle in order to be measured and tagged.

Personal Log
We are now in full work mode on the ship.  My daily routine consists of waking up around 7:30 and grabbing breakfast.  After breakfast I like to go check in on the night team to see what they caught and determine when they will do their next haul (i.e. pull in their catch).  This usually gives me a couple hours of free time before my shift begins at noon.  I like to use my time in the morning to work on my log and go through pictures from the previous day.  I eat lunch around 11:30 so I am ready to start work at noon.  My shift, which runs from noon to midnight, typically includes surveying three or four different stations.  At each station, we set our baited hooks for one hour, haul the catch, and process the sharks and fishes.  We process the sharks immediately and then release them, whereas we keep the fish to collect biological samples (otoliths and gonads).  Once we finish processing the catch, we have free time until the ship reaches the next survey station.  The stations can be anywhere from 6 or 7 miles apart to over 40 miles apart.  Therefore, our downtime throughout the day can vary widely from 30 minutes to several hours (the ship usually travels at about 10 knots; 1 knot = 1.15 mph).  At midnight, we switch roles with the night team.  Working with fish in temperatures reaching  the low 90°s will make you dirty.  Therefore, I typically head to the shower to clean up before going to bed.  I am usually in bed by 12:30 and will be back up early in the morning to do it all over again.  It is a busy schedule, but the work is interesting, exciting, and fun.  I feel very lucky to be out here because not many people get the opportunity to wrestle sharks.  This is one experience I will always remember.

Jeff Miller: Fishing for Sharks and Fishes, September 6, 2015

NOAA Teacher at Sea
Jeff Miller
Aboard NOAA Ship Oregon II
August 31 – September 14, 2015

Mission: Shark Longline Survey
Geographical Area: Gulf of Mexico
Date: September 6, 2015

Data from the Bridge
Ship Speed: 9.7 knots
Wind Speed: 5.6 knots
Air Temp: 30.9°C
Sea Temp: 31.1°C
Seas: <1 meter
Sea Depth: 52 meters

GPS Coordinates
Lat:  N 28 06.236
Long:  W 095 15.023

Science and Technology Log
Our first couple days of fishing have been a great learning experience for me despite the fact that the fish count has been relatively low (the last three sets we averaged less than 5 fish per 100 hooks).  There are a number of jobs to do at each survey station and I will rotate through each of them during my cruise. These jobs include baiting the hooks, numbering and setting the hooks on the main line, hauling in the hooks, measuring and weighing the sharks/fish, and processing the shark/fish for biological samples.

Numbering the baited hooks

Each gangion (the baited hook and its associate line) is tagged with a number before being attached to the main line.


Number clips

A number clip is attached to each gangion (baited hook and its associated line) to catalog each fish that is caught.

After the line is deployed for one hour, we haul in the catch.  As the gangions come in, one of us will collect empty hooks and place them back in the barrel to be ready for the next station.  Other members of the team will process the fish we catch.  The number of fish caught at each station can vary widely.  Our team (the daytime team) had two stations in a row where we caught fewer than five fish while the night team caught 57 fish at a single station.

Collecting empty hooks

Empty hooks are collected, left over bait is removed, and the gangion is placed back in the bucket to be ready for the next station.

So far we have caught a variety of fishes including golden tilefish, red snapper, sharpnose sharks, blacknose sharks, a scalloped hammerhead, black tip sharks, a spinner shark, and smooth dogfish.  The first set of hooks we deployed was at a deep water station (sea depth was approx. 300 meters or 985 feet) and we hooked 11 golden tilefish, including one that weighed 13 kg (28.6 pounds).

Golden tilefish

On our first set of hooks in deep water, we caught a number of golden tilefish including this fish that weighed nearly 30 pounds.

We collect a number of samples from fishes such as red snapper and golden tilefish.  First we collect otoliths, which are hard calcified structures of the inner ear that are located just behind the brain.  Scientists can read the rings of the otolith to determine the approximate age and growth rate of the fish.


Otoliths can be read like tree rings to approximate the age and growth rate of bony fishes.  Photo credit: NOAA Marine Fisheries.

The answer to the poll is at the end of this post.

You can try to age fish like NOAA scientists do by using the Age Reading Demonstration created by the NOAA Alaska Fisheries Science Center.  Click here to visit the site.

When sharks are caught, we collect information about their size, gender, and sexual maturity.  You may be wondering, “how can you determine the sex of a shark?”  It ends up that the answer is actually quite simple.  Male sharks have two claspers along the inner margin of the pelvic fins that are used to insert sperm into the cloaca of a female.  Female sharks lack claspers.

Male female shark

Male and female sharks can be distinguished by the presence of claspers on male sharks.

Personal Log
After arriving at our first survey station on Thursday afternoon (Sep. 3), everyone on the ship is in full work mode.  We work around the clock in two groups: one team, which I belong to, works from noon to midnight, and the other team works from midnight to noon.  The crew and science teams work very well together – everyone has a specific job as we set out hooks, haul the catch, and process the fishes.  It’s a well oiled machine and I am grateful to the crew and my fellow science team members for helping me learn and take an active role the process.  I am not here as a passive observer.  I am truly part of the scientific team.

I have also learned a lot about the fishes we are catching.  For example, I have learned how to handle them on deck, how to process them for samples, and how to filet them for dinner.  I never fished much my life, so pretty much everything I am doing is new to me.

I have also adjusted well to life on the ship.  Before the cruise, I was concerned that I may get seasick since I am prone to motion sickness.  However, so far I have felt great even though we have been in relatively choppy seas (averaging about 1-2 meters or 3 to 6 feet) and the ship rocks constantly.  I have been using a scopolamine patch, an anticholinergic drug that decreases nausea and dizziness, and this likely is playing a role. Whether it’s just me or the medicine, I feel good, I’m sleeping well, and I am eating well.  The cooks are great and the food has been outstanding.  All in all, I am having an amazing experience.

Poll answer:  This fish is approximately nine years old (as determined by members of my science team aboard the Oregon II).

Jeff Miller: Cruising to the Survey Stations, September 2, 2015

NOAA Teacher at Sea
Jeff Miller
Aboard NOAA Ship Oregon II
August 31 – September 14, 2015

Mission: Shark Longline Survey
Geographical Area: Gulf of Mexico
Date: September 2, 2015

Data from the Bridge
Ship Speed: 11.6 knots
Wind Speed: 7 knots
Air Temp:  24.7°C
Sea Temp:  29.6°C
Seas:  3-4 ft.
Sea Depth: 589 meters

GPS Coordinates
Lat: 28 01.364 N
Long: 091 29.104 W

Cruising Map

Map showing our current location and the site of our first survey station

Science and Technology Log
After a one day delay in port at Pascagoula, MS we are currently motoring southwest towards our first survey station in the Gulf of Mexico near Brownsville, TX. Our survey area will include random stations roughly between Brownsville and Galveston, TX.

Survey stations are randomly selected from a predetermined grid of sites.  Possible stations fall into three categories: (A) stations in depths 9-55 meters (5-30 fathoms), (B) stations in depths between 55-183 meters (30-100 fathoms), and (C) stations in depths between 183-366 meters (100-200 fathoms).  On the current shark longline surveys, 50% of the sites we survey will be category A sites, 40% will be category B sites, and 10% will be category C sites.  Environmental data is also collected at each station including water temperature, salinity, and dissolved oxygen.

Several questions you may have are why do a shark survey, how do you catch the sharks, and what do you do with the sharks once they are caught?  These are great questions and below I will describe the materials and methods we will use to catch and analyze sharks aboard the Oregon II. 

Why does NOAA perform shark surveys?
Shark surveys are done to gather information about shark populations in the Gulf of Mexico and to collect morphological measurements (length, weight) and biological samples for research.

How are shark surveys performed?
At each collection station, a one mile line of 100 hooks baited with Atlantic Mackerel is used to catch sharks. The line is first attached to a radar reflective highflyer (a type of buoy that can be detected by the ship’s radar).  A weight is then attached to the line to make it sink to the bottom.  After the weight is added, about 50 gangions with baited hooks are attached to the line.  At the half mile point of the line, another weight is attached then the second 50 hooks.  After the last hook, a third weight is added then the second highflyer.  The line is left in the water for one hour (time between last highflyer deployed and first highflyer retrieved) and then is pulled back on to the boat to assess what has been caught.  Small sharks and fishes are brought on deck while larger sharks are lifted into a cradle for processing.

Longline equipment

Sampling gear used includes two highflyers, weights, and 100 hooks


Longline hooks

Longline hooks used for the shark survey


Longline hooks

Longline hooks used in the shark survey


Shark cradle

Shark cradle used to collect information about large sharks


What data is collected from the sharks?
Researchers collect a variety of samples and information from the caught sharks.  First, the survey provides a snapshot of the different shark species and their relative abundance in the Gulf of Mexico.  Second, researchers collect data from individual sharks including length, weight and whether the shark is reproductively mature.  Some sharks are tagged to gather data about their migration patterns.  Each tag has an identification number for the shark and contact information to report information about where the same shark was re-caught.  Third, biological samples are collected from sharks for more detailed analyses.  Tissues collected include fin clips (for DNA and molecular studies), muscle tissue (for toxicology studies), blood (for hormonal studies), reproductive organs (including embryos if present), and vertebrae (for age and growth studies).

Personal Log
One of the desired traits for participants in the Teacher at Sea program is flexibility – cruising schedules and even ports can change.  I have now experienced this first-hand as we were delayed in port in Pascagoula, MS for an extra day.  Though waiting an extra day really isn’t a big deal, it is hard to wait since myself and the rest of the scientific crew are all anxious to begin the shark survey.  Since we also have two days of cruising to reach our first survey site, this means we all have to find ways to pass the time.  I have used some of my time trying to learn about the operation of the ship as well as the methods we will be using to perform the longline survey.  I also watched a couple movies with other members of the science team.  The ship has an amazing library of DVDs.

The Oregon II

Getting ready to leave Pascagoula aboard the NOAA Ship Oregon II

Safety is very important aboard the Oregon II so today we performed several drills including an abandon ship drill.  This drill requires you to wear a survival suit.  Getting mine on was a tight squeeze but I got the suit on in the required time.

Safety suit

In my safety suit during an abandon ship drill

Did You Know?
The NOAA Commissioned Officer Corps is one of the seven uniformed services of the United States.  Can you name the other six uniformed services?  Think about this and check the answer at the bottom of this post.

NOAA Corps Officers perform many duties that include commanding NOAA’s research and survey vessels, flying NOAA’s hurricane and environmental monitoring planes, and managing scientific and engineering work needed to make wise decisions about our natural resources and environment.

Answer: The seven uniformed services of the United States are: (1) Army, (2) Navy, (3) Air Force, (4) Marine Corps, (5) Coast Guard, (6) NOAA Commissioned Officer Corps, and (7) Public Health Service Commissioned Corps.

Jeff Miller: Getting Ready to Sail, August 19, 2015

NOAA Teacher at Sea
Jeff Miller
(Almost) Aboard NOAA Ship Oregon II
August 31 – September 14, 2015

Mission: Shark Longline Survey
Geographical Area: Gulf of Mexico
Date: August 19, 2015

Personal Log

Hello from Phoenix, Arizona.  My name is Jeff Miller and I teach biology at Estrella Mountain Community College (EMCC) in Avondale, AZ.  EMCC is one of ten community colleges in the Maricopa Community College District, which is one of the largest college districts in the United States, serving more than 128,000 students each year.  I have been teaching at EMCC for eight years.  I currently teach two sections of a general biology course for non-majors (that is students who are majoring in subjects other than biology) and one section of a human anatomy and physiology course primarily taken by students entering healthcare-related fields.

Jeff Miller

A photo of me at Tuolomne Meadow in Yosemite National Park

EMCC is an outstanding place to teach because of all the truly wonderful students.  EMCC serves a diverse set of students from recent high school graduates to adults seeking a new career. EMCC students are also ethnically diverse. Thus, students bring a wide range of knowledge, ideas, and talents to our classrooms. Despite this diversity, one thing most students lack is real world experiences with marine organisms and environments. We are, after all, located in the heart of the Sonoran Desert.  Arizona does, however, possess many unique and amazing environments and when I’m not in the classroom, hiking and exploring nature with my family is one of my favorite things to do.

Cathedral Rock

Cathedral Rock in Sedona, AZ

Great Horned Owl

A Great Horned Owl perches on a log in the desert near Tucson, AZ


A saguaro cactus in the Sonoran desert near Tucson, AZ

White Mountains

Arizona is home to the largest unbroken Ponderosa Pine forest in the world. My wife (Weiru), daughter (Julia), and dog (Maya) in the White Mountains of Arizona

I applied to the Teacher at Sea program to deepen my knowledge of marine systems as part of my sabbatical.  A sabbatical is a period of time granted to teachers to study, travel, acquire new skills, and/or fulfill a personal dream. I have always loved the ocean and even worked with sea urchin embryos in graduate school.  However, my knowledge and experience of marine organisms and ecosystems is  limited.  Therefore, participation in the Teacher at Sea program will give me the opportunity to learn how marine biologists and oceanographers collect and analyze data and how their investigations can inform us about human impacts on marine ecosystems. I plan to use the knowledge and experiences I gain to develop curriculum materials for a marine biology course at EMCC that to helps my students gain fundamental knowledge of and appreciation for our world’s oceans. I hope to foster greater curiosity and excitement about marine science and the scientists who explore our oceans and help students see why it is so important to protect and conserve the oceans resources for future generations.

To help fulfill my dream of learning more about the oceans, I have the opportunity of a lifetime – to sail on the NOAA Ship Oregon II.  I will be working with the crew and scientists aboard the Oregon II to perform part of an annual longline shark survey.  The goal of the mission is to gather data about shark populations in the Gulf of Mexico and along the Atlantic coast.  Some of the data collected includes length, weight, and sex of each individual, collection of tissues samples for DNA analysis, and collection of environmental data.  Please visit the main mission page or the Oregon II Facebook page for more detailed information and images, videos, and stories from recent cruises.  Also check out a recent article from the Washington Post featuring Kristin Hannan, a fisheries biologist for the National Marine Fisheries Services describing the shark research being conducted aboard the Oregon II.

Longline Shark Survey Map

Map showing the region of the Gulf of Mexico where I will participate in the longline shark survey aboard the NOAA Ship Oregon II

Needless to say, I am extremely excited, though a bit nervous, about my upcoming cruise.  I have little experience sailing on the open ocean and have never been up close to a shark let alone actually handled one in person.  All that will change soon and I know that I will treasure the knowledge and experiences I gain aboard the Oregon II.  I am currently packing up my gear and preparing myself for the experience of a lifetime.

The next time you hear from me I will be in the Gulf of Mexico on my mission to learn more about sharks.

Kathleen Gibson, Preparing to Leave for the Mississippi Coast, July 10, 2015

NOAA Teacher at Sea
Kathleen Gibson
Aboard NOAA Ship Oregon II
July 25 – August 8, 2015

Mission: Fisheries – Conduct longline surveys to monitor interannual variability of shark populations of the Atlantic coast and the Gulf of Mexico.
Geographical Area of Cruise: Gulf of Mexico and Atlantic Ocean off the Florida coast.
Date: July 10, 2015


Town of Trumbull, Fairfield County , CT

Town of Trumbull, CT

My name is Kathleen Gibson and I bring you greetings from Trumbull, CT where live and teach. In two weeks I will travel to Pascagoula, MS, located on the Gulf of Mexico, to join NOAA Corps members, research scientists, and the crew aboard NOAA Ship Oregon II, as a  2015 NOAA Teacher at Sea.

I work at Trumbull High School and currently teach Biology to sophomores and two elective courses for seniors–Marine Science and AP Environmental Science.  I’m passionate about environmental education and am always looking for opportunities to engage students in the world outside of the classroom.  Trumbull has a large amount of protected green space, wetlands, streams and a river, and while we aren’t on the coast, we are only a few miles from Long Island Sound.  The woods and the shoreline have become our laboratory.

Pequonnock River, Trumbull, CT

Pequonnock River, Trumbull, CT

I’m open to adventures and new experiences that help me grow both personally and professionally.  I’m fortunate to have an awesome family, terrific colleagues and open-minded students who are willing to go along with my ideas; whether it be be hiking around volcanoes and rift zones, looking for puffins, or wading in nearby streams looking for life below.

About NOAA and Teacher at Sea

NOAA Ship Oregon II Photo Credit:

NOAA Ship Oregon II
Photo Credit:

The National Oceanic and Atmospheric Administration (NOAA) is an agency within the United States Department of Commerce that seeks to enrich life through science.  While NOAA is somewhat familiar to many of us– thanks to the abundance of weather data that is collected and disseminated to the public–that’s not all that is happening  there. NOAA is working to increase our understanding of climate, weather and marine ecosystems, and to use this knowledge to better manage and protect these crucial ecosystems.  In addition to the abundant educational resources available to all teachers, NOAA provides unique opportunities for teachers and students.  The Teacher at Sea Program  brings classroom teachers into the field to work with world-renowned NOAA scientists.

The Mission

The Mission of the cruise I will be a part of is to monitor Shark and Red Snapper populations in the Gulf of Mexico in the Atlantic Ocean off the Florida coast. Data collected will be compared to findings from previous years, as a part of the ongoing research studying inter-annual variability of these populations. We are scheduled to embark on July 25, 2015 and plan to sail from Pascagoula, MS, down the west coast of Florida and up the Atlantic Coast as far as Mayport, FL.

I am honored to have been selected to be a Teacher at Sea for the 2015 Season  and look forward to a number of “firsts”. I’ve never been to Mississippi nor have I been at sea for more than 24 hours. Also, I’ve only experienced sharks as preserved specimens or through aquarium glass.  I’m also looking forward to meeting my shipmates and learning about career opportunities and the paths that led them to be a part of this Oregon II cruise. I’ll share as much as I can through future posts. I’m excited to bring my students and others along with me on this journey.

Trumbull to Pascagoula.  Longline survey area is marked in blue.

Trumbull to Pascagoula. Longline survey area is marked in blue.

Next Up?

My next post to you should be coming later this month from off the Mississippi coast.  However, the first rule of being on board is FLEXIBILITY, so things may change.  Either way, I’ll keep you posted. In the meantime, please check out some of the TAS 2015 blogs written by my fellow NOAA Teachers at Sea, and spread the word. There is so much to learn.

Did You Know?

  • While some sharks release eggs into the water where they will later hatch, as many as 75% of shark species give birth to live young.
  • Shark babies are called pups.

David Walker: Florida, Speciation, and Learning All Over Again (Days 13-15), July 8, 2015

NOAA Teacher at Sea
David Walker
Aboard NOAA Ship Oregon II
June 24 – July 9, 2015

Mission: SEAMAP Bottomfish Survey
Geographical Area of Cruise: Gulf of Mexico
Date: July 8, 2015

Weather Data from the Bridge

Weather Log 7/7/15

NOAA Ship Oregon II Weather Log 7/7/15

The seas have remained incredibly calm, again with waves normally no higher than 1 ft.  July 7, 2015 was a beautiful day, with few (FEW, 1-2 oktas) clouds in the sky (see above weather log from the bridge).  Visibility from the bridge was 10 nautical miles (nm) throughout the day.

Science and Technology Log

After a run of around 16 hours, we finally arrived on the west coast of Florida to continue the survey.

Wow!  The organisms caught on the west coast of Florida were entirely different from those caught west of the Mississippi.  In our first trawl catch, I almost didn’t recognize a single species.

Fisheries biologist Kevin Rademacher shared with me an article, “Evidence of multiple vicariance in a marine suture-zone in the Gulf of Mexico” (Portnoy and Gold, 2012), that offers a potential explanation  for the many differences observed.  The paper is based on what are called “suture-zones.”  A suture-zone, as defined previously in the literature, is “a band of geographic overlap between major biotic assemblages, including pairs of species or semispecies which hybridize in the zone” (Remington, 1968).  In other words, it is a barrier zone of some kind, allowing for allopatric speciation, yet also containing overlap for species hybridization.  As noted by Hobbes, et al. (2009), such suture-zones are more difficult to detect in marine environments, and accordingly, have received less attention in the literature.  Such zones, however, have been discovered and described in the northern Gulf of Mexico, between Texas and Florida (Dahlberg, 1970; McClure and McEachran, 1992).

Portnoy and Gold note that “at least 15 pairs of fishes and invertebrates described as ‘sister taxa’ (species, subspecies, or genetically distinct populations) meet in this region, with evidence of hybridization occurring between several of the taxa” (Portnoy and Gold, 2012).  The below table delineates these sister taxa.  On this table, I have highlighted species that we have found on this survey.

Sister Taxa

Sister taxa found in the northern Gulf of Mexico. Highlighted are species we have encountered on this survey (Portnoy and Gold, 2012).

The figure below geographically illustrates distribution patterns of two pairs of sister species within the northern Gulf of Mexico.  We have seen all four of these species on this survey, and our observations have been consistent with these distribution patterns.

Distributions of sister taxa within the northern Gulf of Mexico

Distributions of “sister taxa” within the northern Gulf of Mexico (Portnoy and Gold, 2012)

Prior to Portnoy and Gold, hypothesized reasons for the suture-zone and allopatric speciation in the northern Gulf included “(1) a physical barrier, similar to the Florida peninsula, that arose c. 2.5 million years ago (Ma) during the Pliocene (Ginsburg, 1952), (2) an ecological barrier, perhaps a river that drained the Tennessee River basin directly into the Gulf, that existed approximately 2.4 Ma (Simpson, 1900; Ginsburg, 1952), (3) a strong current that flowed from the Gulf to the Atlantic through the Suwanee Straits approximately 1.75 Ma (Bert, 1986), and (4) extended cooling during early Pleistocene glaciations occurring c. 700–135 thousand years ago (ka) (Dahlberg, 1970)” (Portnoy and Gold, 2012).  Another explanation has been offered by Hewitt (1996), involving marine species being forced into different areas of refuge during the glacial events of the Pleistocene, allowing for allopatric speciation.  Following the retreat of the glaciers, according to this hypothesis, these species would have been allowed to come into contact again, allowing for hybridization.

Portnoy and Gold used mitochondrial and microsatellite DNA sequence data from Karlsson et al. (2009) to “determine if estimated divergence times in lane snapper were consistent with the timing of [the above] hypothesized variance events in the suture-zone area, in order to distinguish whether the Gulf suture-zone is characterized by a single or multiple vicariance event(s)” (Portnoy and Gold, 2012).

Their results suggest that the divergence of lane snapper in the northern Gulf occurred much more recently than the hypothesized events described by Ginsberg (1952), Bert (1970), and Dahlberg (1970).  These results also suggest that the explanation offered by Hewitt (1996) is an unlikely explanation for the divergence of lane snapper, for even though the time of multiple glaciations is consistent with the time of lane snapper divergence, water temperatures across the Gulf are estimated to have been within the thermal tolerance of lane snapper during these glaciations.  Evidence also suggests that a shallow shelf existed during these glaciations, representing a habitat in which lane snapper could have lived.

The explanation that Portnoy and Gold favor, in terms of explaining lane snapper divergence, is one suggested by Kennett and Shackleton (1975), as well as by Aharon (2003).  This explanation involves “large pulses of freshwater from the Mississippi River caused by a recession of the Laurentide Ice Sheet between 16 and 9 ka” (Portnoy and Gold, 2012).  This explanation would have also allowed for potential sympatric or parapatric speciation, because it contains multiple lane snapper habitat types (carbonate sediment, as well as mud and silt bottom).

Notably, the fact that the above explanation is favored by Portnoy and Gold for lane snapper divergence does not discount the explanations of Ginsberg (1952), Bert (1970), Dahlberg (1970), and Hewitt (1996), in terms of explaining the many other examples of species divergence exhibited within the northern Gulf.  It is most probable that many geological and ecological causes worked, sometimes in confluence, to create the divergences and hybridizations in species observed today.  A geographical depiction of many of the hypothesized explanations described by Portnoy and Gold is below.

Geographic Depiction

Geographical depiction of hypothesized triggers of species divergence in the northern Gulf of Mexico (Portnoy and Gold, 2012)

In addition to the species divergence observed in our survey, another interesting difference noted in our catches along the western coast of Florida was the emergence of lionfish.  These invasive species are native to the Indian Ocean and southwest Pacific Ocean, and they were most likely introduced by humans into the waters surrounding Florida.  There are two lionfish species that are invasive in Florida, P. miles and P. volitans (Morris, Jr. et al., 2008), and the earliest records of their introduction into Florida’s waters are from 1992 (Morris, Jr. et al., 2008).  Many characteristics have allowed these species to be successful alien invaders in these waters – (1) they are formidable, with venomous spines and an intimidating appearance, (2) they reproduce incredibly quickly, breed year-round, and mature at a young age, (3) they outcompete native predators for food and habitat, (4) they are indiscriminate feeders with voracious appetites, and (5) they take advantage of a sea that is over-fished, in which many of their predators are regularly being eliminated by humans (Witherington, 2012).

Life cycle of the lionfish

Life cycle of the lionfish

This invasion mechanism hauntingly reminds me of that of the Cane Toad, a very famous alien invader which has decimated the flora and fauna of Australia.  One of the main worrisome effects of lionfish around Florida is on coral reefs.  Lionfish “can reduce populations of juvenile and small fish on coral reefs by up to 90 percent…[and] may indirectly affect corals by overconsuming grazing parrotfishes, which normally prevent algae from growing over corals” (Witherington, 2012).

One of the ways in which Floridians are trying to eliminate this problem is through lionfish hunting tournaments.  CJ Duffie, a volunteer on this survey from Florida, has participated in these tournaments and also participates in lionfish research directed by the Florida Fish and Wildlife Commission.  CJ harvested the gonads of the lionfish we caught on Day 13 to take back to the lab for further analysis.  Floridians also actively promote the lionfish as a delicacy, in an attempt to encourage more people to eat the invasive species.  CJ described the fish as the best he has ever tried, so I was very easily intrigued.  A fillet was prepared from the large lionfish caught on Day 13 fish, and Second Cook (2C) Lydell Reed was able to cook it on the spot.  I agree with CJ – white, flakey, slightly sweet, this is the best fish I have ever tasted.

Personal Log

The survey is nearly over, and this will be my last post.  We are in transit back to Pascagoula, Mississippi, the ship’s home port.  I leave by plane from Mobile, Alabama for Austin on Friday, July 10, 2015.  I am eagerly anticipating walking on land, as I’ve heard it’s strange at first after being on a boat for awhile.  Apparently this weird feeling has a semi-formal name — “dock rock”.

This experience has truly been one of the best of my life, especially in terms of the raw amount I have learned every day.  Coming in, the sole knowledge of fish life I had derived from my stints fly fishing with my father, and most of this knowledge concerns freshwater fish.  I now feel as though I have a much more comprehensive knowledge of the biodiversity that exists in the Gulf of Mexico and a much greater appreciation for the diversity of life as a whole.  I have taken over 200 photos to document this biodiversity, accumulated a diverse collection of preserved specimens, and collected a wide variety of resources (textbooks, scientific papers, etc.) on marine life in the Gulf of Mexico.  These resources will surely make the preparation of a project-based activity for my students focused on this research a much easier feat.

Sharksucker (Echeneis naucrates)

Having fun with a sharksucker (Echeneis naucrates) during analysis of the last trawl catch

I have also learned how a large portion of marine field research is conducted.  We have surveyed dissolved oxygen levels in the water, plankton biodiversity, and bottomfish biodiversity throughout the northern Gulf, using established (and quite popular) research methods.  The knowledge I have gained here can be applied to the biodiversity project portion of my geobiology class, in which students conduct biodiversity surveys in local Austin-area parks and preserves.  I anxiously await the comprehensive results of this summer’s NOAA survey – the complete dissolved oxygen contour map, the biodiversity indexes for different regions of the Gulf, and plankton biodiversity data from Poland.  These data will definitely help me come to even more conclusions about the marine life in the Gulf and the factors affecting it.

Through this experience, I have also gained much appreciation for the diversity of careers that exist on board a NOAA research vessel.  I have learned about the great work of the NOAA Corps, a Commissioned Service of the United States.  I have learned from the fisherman, engineers, stewards, and other personnel on the boat, all required for a successful research survey.

First and foremost, I have to thank the science team on the night watch – fisheries biologists Kevin Rademacher and Alonzo Hamilton, FMES Warren Brown, and volunteer CJ Duffie.  These individuals were instrumental in helping me identify organisms, label my photos, and craft my blog posts and photo captions.  Kevin Rademacher provided me with most of the papers which I have referenced in this blog, and with no internet connectivity on the boat for around half of the trip, his library of information was essential.  For the “Notable Species Seen” section of this blog, Kevin also individually went through all of my species photos with me to help me add common and scientific names in the photo captions.  This took a great deal of his time, almost every day, and I am incredibly appreciative.

Night Watch

The rest of the night watch. From left to right — FMES Warren Brown and NOAA Fisheries Biologists Kevin Rademacher and Alonzo Hamilton

I also definitely need to thank Lead Fisherman Chris Nichols and Skilled Fisherman Chuck Godwin for their mentorship with CTD data collection and plankton sampling.  In addition, many thanks to Field Party Chief Andre Debose and Lieutenant Commander Eric Johnson for proofreading my blog entries and ensuring that my experience on the ship was a good one.  I enjoy learning from people much more than I enjoy learning from books, and these have been some of best (and most patient) teachers I have ever had.

Lastly, thanks so much to the NOAA Teacher at Sea staff for your work on this great program.  It truly makes a difference for many teachers and many students.  I have had an amazing time, and I am positive my students will benefit from what I have learned.

Survey Plot

The ship’s path during the survey, thus far. I have been on the boat for Leg 2, drawn in black.

Did You Know?

Lionfish venom is not contained within the tips of the fish’s spines.  Rather, glandular venom-producing tissue is located in two grooves that run the length of  each spine.  When skin is punctured by a spine, this glandular tissue releases the venom (a neurotoxin), which travels up the spine and into the wound by means of the grooves (Witherington, 2012).

Venomous Spines

Anatomy of the lionfish spine

Notable Species Seen