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.

Otolith

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.