Kate Schafer: The Importance of Science, October 4, 2017

NOAA Teacher at Sea

Kate Schafer

Aboard NOAA Ship Oregon II

September 17 – 30, 2017

 

Mission: Shark/Red Snapper Longline Survey

Geographic Area of Cruise: Gulf of Mexico

Date: October 4, 2017

 

Weather Data from the San Francisco Bay area:

Latitude: 37o 38.4’ N
Longitude: 122o 08.5’ W

Visibility 16 km

Winds 5-10 mph

San Francisco Bay Water Temperature 16 oCelsius

Air Temperature 17 o Celsius

 

Science and Technology Log:

Well, I’m back on dry land, with lots of great memories of sharks, big and small, and all the interesting people who I spent two weeks with on the Oregon II.  And let’s not forget the red snappers either.

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The largest shark we caught: 10 foot tiger shark

 

CubanDogfish

Cuban dogfish: The smallest species we caught

On our last day, we fished at a couple of sites right off the coast of Alabama and caught lots of sharks, plus a new species of grouper for the trip.  The scamp grouper (Mycteroperca phenax) is apparently not frequently found on the longlines along the coast of Texas but becomes more common along the coasts of Mississippi and Alabama and up the Eastern Atlantic coast as well.

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Tail of a Scamp Grouper

The groupers are mostly protogynous, meaning that when they become sexually mature, they are always females.  Only later in life, when they have grown bigger (and have the right environmental influences), do they transition to males.  This species can live for more than 30 years, but that’s actually relatively short for a lot of the grouper species, some of which can live to 60 years or more. Scamp grouper come together in groups to reproduce, so this makes them vulnerable to overfishing.  The management councils take this into consideration when making a management plan and will close off areas known to be spawning grounds during the reproductive season.  These are also great areas to target as Marine Protected Areas.

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Scamp Grouper being measured

All of this knowledge about the scamp grouper (and other species we encountered on this survey) was gained through careful scientific research.  As mentioned before, the long line survey was started in 1995 and has been conducted using the same methods every year since then.  These data are used by fisheries managers to set catch limits and detect changes that might indicate problems for the species living in these areas.  In other words, the science forms the basis for decision making and planning.

This is true for the various surveys that NOAA conducts in the Gulf each year.  The Groundfish Survey, for example, provides vital information about the extent of the Dead Zone off the coast of Louisiana, by measuring dissolved oxygen levels on the sea floor as part of the survey.  This data tells us that we need to continue to work on controlling nutrient inputs into the Mississippi River from agriculture lands and cities that span much of the eastern United States.  Scientific research also tells us that we need to be planning for and mitigating the effects of the looming problem of climate change.

Climate change will certainly bring about significant change to the Gulf.  As ocean temperatures rise, water becomes less dense and therefore takes up more space.  Along with continued melting of land-supported ice in the polar regions, this is contributing to a cumulative increase in sea level of 3.2 mm per year (https://oceanservice.noaa.gov/facts/sealevel.html).  In the Gulf, this increase will particularly impact estuarine ecosystems that are rich nurseries for many fish species and are extremely productive habitats.

One of the predictions of many climate models is that increased global temperatures are likely to bring about more frequent and more intense hurricanes.  This 2017 hurricane season is a stark reminder of the devastating impacts that hurricanes can have, even when we have the scientific tools to predict approximately where and when the storm will make landfall.

Finally, the increase in global temperatures will make the regions surrounding the Gulf less pleasant places for people to live.  The summers are already very hot and humid, and a degree or two hotter will make a lot of difference in the livability of the region.

We know all of this through careful scientific research, and there is a consensus amongst scientists that this is happening.  To prepare for the effects of climate change and to know how to best minimize those effects, we must continue to collect data and do science.  After all, what is the point of scientific research if we don’t use the results to make better choices and to address the problems that are facing us?

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At the end of my time on the Oregon II

Personal Log:  I am so grateful for the opportunity to go on this research survey and for the Teacher at Sea program as a whole.  I strongly encourage any teacher thinking of applying to the program to do so.  Thanks to NOAA and everyone at the TAS office for all your help and support.

 

 

 

 

 

 

 

Kate Schafer: A Day in the Life… September 29, 2017

NOAA Teacher at Sea

Kate Schafer

Aboard NOAA Ship Oregon II

September 17 – 30, 2017

 

Mission: Shark/Red Snapper Longline Survey

Geographic Area of Cruise: Gulf of Mexico

Date: September 29, 2017

Weather Data from the Bridge:

Latitude: 29o 11.3′ N
Longitude: 88o 18.3′ W

Few clouds

Visibility 10 nautical miles

Wind speed 8 knots

Sea wave height 1 foot

Temperature Seawater 29.4 o Celsius

Science and Technology Log:

So, as my time on the Oregon II is winding down, I thought I’d share a bit about what it is like to do science on a boat.  First of all, there is a tremendous amount of planning that must go into a successful survey in the weeks and months beforehand.  In addition to all the logistics of going to sea for two weeks, there is the challenge of putting together a crew of scientists that can be away from their day to day jobs and lives, and agree to work 12 hour days, for weeks on end.  Lisa Jones is the Field Party Chief for this survey and must figure out those logistics plus organize the science part as well.  This survey has been going since 1995, and one of the keys to longitudinal data sets is that they keep standard methods throughout, or else the data aren’t comparable.

This can be challenging in all sorts of unforeseen ways.  For example, a few years ago, it became difficult to find the mackerel used as bait on the longlines.  During an experimental survey in the spring, they tried out squid as an alternative and caught a totally different composition of species.  Fortunately, the mackerel became more available again, and the problem is no longer an issue, for now.

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Hooks baited with mackerel

Lisa is also the one responsible for working with the captain and his crew to determine sampling locations and a plan for getting to those locations.  There’s a plan at the beginning, but, of course, that changes frequently, due to weather, the locations of other ships and a myriad of other unforeseen circumstances.  The goal is to reach 200 sites per year, with 50% between 5-30 fathoms (1 fathom=6 feet), 40% between 30-100 fathoms, and 10% between 100-200 fathoms.  These percentages reflect the depths of the continental shelf area throughout the sampling region. Below is a sampling map for the 2015 longline survey.

SamplingStations

Sampling stations for 2015 Longline survey from 2015 Cruise report

During a longline set, the line is deployed for one hour before retrieval, with 100 baited hooks.  As the line comes in, each fish is given three to four measurements (depending on the species) and is weighed.  Many of the sharks are tagged, as this provides the possibility of someone finding the tagged shark in the future.  With a tag retrieval, we can learn about how far the organism has traveled and how much and how quickly it has grown.

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Measuring and tagging shark in the cradle

As I mentioned in my post about the red snappers, the snappers, groupers and tilefish are dissected for their otoliths and gonads.  They can’t be successfully released in most circumstances anyway, due to barotrauma from pulling them quickly to the surface from depth.

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A Yellowedge Grouper weighing nearly 20 kg

Sharks are less affected by barotrauma because they don’t have swim bladders to maintain their buoyancy like the bony fishes we’ve been catching.

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Caught on the longline

Here are a couple examples of our data sheets.  As you can see, some sets have more fish than others (in fact the full one, was only one of three pages).  Once all the data are collected, they have to be entered in the computer for later summary and analysis.  Some days it can be a big challenge to get all the data entered before it’s time to start all over again.  Other days, like today, include lots of travel time.

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Only a tilefish on this set…

 

DataSheetFull

Many more on this one…in fact this is only one of three pages

 

Personal Log:

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Tiger shark filling the 10 foot cradle

For me, it has been truly wonderful to get to work as a scientist again, if just for a couple of weeks, especially with such an amazing group of scientists.  I’ve learned so much from my fellow day crew members (Lisa, Christian, Nick and Jason).  They have patiently answered all my questions, even when it was keeping them from getting to dinner.  Lisa Jones has gone above and beyond in her support of me, even though she has had many other responsibilities on her plate.  I also appreciate being made to feel welcome lurking around the night crew’s catches.  Thanks especially to Christophe, Vaden, and Eric for allowing me to hang out in the measuring pit.  I love my job as a teacher, but part of me definitely misses working as a field biologist.  I am grateful for the opportunity and especially thankful for my wonderful family.  I can’t tell you how much I appreciate your support and love.

 

Kate Schafer: So Many Snappers… September 24, 2017

NOAA Teacher at Sea

Kate Schafer

Aboard NOAA Ship Oregon II

September 17 – 30, 2017

 

Mission: Shark/Red Snapper Longline Survey

Geographic Area of Cruise: Gulf of Mexico

Date: September 24, 2017

Weather Data from the Bridge:

Latitude: 28o 25.1’ N
Longitude: 94o 50.3’ W

Broken sky

Visibility 10 nautical miles

Wind speed 13 knots

Sea wave height 2-3 feet

Temperature Seawater 28.8 o Celsius

Science and Technology Log:

This is a shark and red snapper longline survey, and the sharks tend to steal the stage.  They are bigger (for the most part), more diverse and definitely have more of a reputation.  I have been surprised, however, by how much I’ve been drawn to the snappers.  They are a beautiful color, and tend to come up in groups that are pretty similar in size.

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Red snapper (Lutjanus campechanus) ready to be measured

The Northern Red Snapper (Lutjanus campechanus) is commonly fished in the Gulf of Mexico, both recreationally and commercially.  It turns out that the commercial fishers get 51% of the catch quota and the recreational fishers get 49%.  The methods for dividing up those two basically equal pieces of the pie is different between the commercial and recreational fishers. In addition, the commercial fishing catch is monitored very closely, while the recreational fishing catch numbers are largely unknown.  Plus, the states have their own waters that extend out to different distances, depending on the state, and the federal waters extend from the state water boundary to 200 nautical miles offshore.  So, in other words, managing the fishery is quite complicated.

So, how do all these fishing rules and regulations get established and modified over time?  A law was passed in 1976, called the Magnuson-Stevens Fishery Conservation and Management Act, and one of the key parts of the act established eight regional management councils for regulating fishing in federal waters (more information on the act here: http://www.nmfs.noaa.gov/sfa/laws_policies/msa/).  It also established the 200 nautical mile extension of federal waters from land.  The Gulf of Mexico Fishery Management Council (GMFMC) is responsible for creating Fisheries Management Plans (FMPs) for fisheries within the U.S. federal waters of the Gulf of Mexico, from southern Texas, along Louisiana, Mississippi, and Alabama, and down the west coast of Florida.  This graphic shows the catch limits for red snapper and other species for 2017 set by the GMFMC.  For red snapper, the catch limit is close to 14 million pounds.

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Annual Catch Limits as set by the Gulf of Mexico Fishery Management Council (http://gulfcouncil.org/fishing-regulations/federal/)

The data that we are collecting helps scientists and policy makers to determine what the annual catch limit for a particular season should be.  For each fish that we bring on board, we measure the fish length and weight, as well as the weight of the gonads.  In addition, we collect their otoliths (ear bones) and samples of the ovaries of females.  These both help managers to estimate the age and size of the population, and future populations as well.

Otoliths are calcium carbonate hardened structures and are present in the part of the inner ear that is responsible for balance.  Humans and other vertebrates have them too, and they can be used to tell the age of the fish.  The otoliths of Lutjanus campechanus are quite large.  There seems to be an overall relationship between the habitat of the fish species and the size of the otolith.  Species like Lutjanus campechanus that live along reefs and rocky structures have much larger otoliths than species like tuna that swim up in the water column.  Flying fish, which we’ve seen a lot of, also have large otoliths, given their body size, probably aiding them in knowing where they are as they glide through the air.

Otoliths

Otoliths taken from one of the red snappers we collected

Well, we have been collecting a lot of data over the past couple of days to help inform these policies in the future!  Each line we’ve pulled in lately has had a dozen or more snappers on it,  and they are a lot of extra work as compared with the sharks, due to all the samples we have to collect once we’re done.  A couple times, we’ve barely finished before it was time to start baiting lines again.

Personal Log:

As I mentioned earlier, I’ve really come to love the red snappers.  Their eyes are the same color as their skin and I’m just awed by their size.  I am used to snappers that I’ve watched on coral reefs, and even the largest species I’ve seen on reefs are nothing compared with these guys.

SnapperEye

Red snapper (Lutjanus campechanus) eyes

I’ve also adjusted to the shift in my day, as evidenced by the fact that I’m finishing this up at 1 a.m.  It has been a long time since I’ve been on this kind of late night schedule.  I’m enjoying it, especially because I know when I return to California, I’ll be getting up at 5:30 a.m. again.

 

Did You Know?

That snappers eat a wide variety of different foods, including fish and various types of crustaceans? Here are a couple of items we’ve found in the ones we’ve caught.  Can anyone identify them?  I studied the second group for my Ph.D. dissertation!

MoleCrab

Mystery snapper food

Stomatopod

More snapper food

 

 

 

 

 

And We’re Fishing…

NOAA Teacher at Sea

Kate Schafer

Aboard NOAA Ship Oregon II

September 17 – 30, 2017

 

Mission: Shark/Red Snapper Longline Survey

Geographic Area of Cruise: Gulf of Mexico

Date: September 21, 2017

 

Weather Data from the Bridge:

Latitude: 27o 15.5’ N

Longitude: 97o 01.3’ W

Haze

Visibility 6 nautical miles

Wind SE 15 knots

Sea wave height 3-4 feet

Sea Temperature: 29.6o Celsius

Note: Just a month ago Hurricane Harvey was bringing 20 foot seas to this area, but today we’re enjoying the 3-4 foot swell.

Science and Technology Log:

Well, we’ve gotten to the fishing grounds, and we’ve gone from waiting to very busy!  We put out the first lines starting at around 8 pm on Tuesday evening.  The process involves first baiting 100 hooks with Atlantic mackerel.  When it’s time for the line to be deployed, first there is a tall buoy with a light and radar beacon (called a high flyer) on it that gets set into the water, attached to the monofilament fishing line.  Then there’s a weight, so the line sinks to the bottom, a series of 50 baited hooks then get clipped onto the line as the monofilament is being fed out.

Those 50 hooks are referred to as a “skate”.  This confused me last night when I was logging our progress on the computer.  I kept thinking that there was going to be some kind of flat, triangular shaped object clipped on to help the line move through the water…not really sure what I was imagining.  Anyway, Lisa Jones, the field party chief and fisheries biologist extraordinaire, has so kindly humored all my questions and explained that skate is just a term for some set unit of baited hooks.  In this case, the unit is 50, and we’ll be deploying two skates each time.

After the first skate comes another weight, the second skate, another weight and then the last high flyer.  Then the line is set loose and we wait.  It’s easy to locate the line again, even at night, because of the radar beacons on the high flyers.

Why are we collecting this data?

As mentioned in my previous post, one of the tasks of NOAA, especially the National Marine Fisheries Service Line Office, is to collect data that will help with effective fisheries management and assist with setting things like catch quotas and so forth.  A catch quota refers to the amount of a particular species that can be harvested in a particular year.  Fisheries management is incredibly complicated, but the basic idea is that you don’t want to use up the resource faster than it is replenishing itself.  In order to know if you are succeeding in this regard, you must go out and take a look at how things are going.  Therefore, the Oregon II goes out each year in the fall and samples roughly 200 sites over about eight weeks.  The precise locations of the sampling sites change each year but are spread out along the SE Atlantic Coast and throughout the U.S. waters in the Gulf of Mexico.

We’ve put out three long lines so far.  Last night, we caught a single fish, but it was a really cool one.  It’s called the Golden Tilefish but has an even better species name: Lopholatilus chamealeonticeps.  As Lisa was explaining that they dig burrows in the sea floor, I realized that I had seen their cousins while snorkeling around coral reefs but would never have made the connection that they were related. This guy was big!

 

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Golden tilefish (Lopholatilus chamealeonticeps) caught in first longline of the trip

This afternoon, things got really hectic.  Of our 100 hooks, 67 had a fish on it, and 60 of those were sharks.  As we were pulling in the last bit of line, we pull on a shark that was missing its back half!  Another had a bite taken out of it.  And then on hook number 100, was a bull shark.  This shark had been snacking along the line and got caught in the process.

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Bull shark caught on the last hook of a very productive bout of fishing (Photo courtesy of Lisa Jones, NOAA)

And I haven’t even mentioned the red snappers.  I will save them for another post, but they are absolutely beautiful creatures.

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Red snapper being measured

 

Personal Log:

I definitely continue to feel out of my element at times, especially as we were pulling in all these hooks with sharks on them, and I could barely keep up with my little job of tracking when a fish came on the boat.  All the sharks started running together in my mind, and it was definitely a bit stressful.  Overall, I feel like I’ve adjusted to the cadence of the boat rocking and have been sleeping a lot more soundly.  I continue to marvel at how amazing it is that we’re relatively close to shore but, except for a few songbirds desperate for a rest, there is no evidence of land that my untrained eyes can detect.  Lastly, I’ve realized that a 12-hour sampling shift is long.  I have a lot of respect for the scientists and crew that do this for months on end each year with just a few days break every now and then. Well, it time to pull in another line.  Next time, we’ll talk snapper.

 

Kate Schafer: Setting off for Brownsville, TX, September 18, 2017

NOAA Teacher at Sea

Kate Schafer

Aboard NOAA Ship Oregon II

September 17 – 30, 2017

 

Mission: Shark/Red Snapper Longline Survey

Geographic Area of Cruise: Gulf of Mexico

Date: September 18, 2017

 

Weather Data from the Bridge:

Latitude: 27o 02.5’ N
Longitude: 94o 32.6’ W

Scattered clouds

Visibility 14 nautical miles

Wind speed 10 knots

Sea wave height 1 foot

Temperature Seawater 29.9 o Celsius

 

Personal log

Sunday afternoon, September 17

I arrived in Pascagoula, Mississippi in the late afternoon on Saturday after a long day of travel.  Things were so quiet on the ship that evening as most of the crew had gone home during the break between legs of the survey.  It was great to be met and shown around by a friendly face, the Officer on Duty (OOD) David Reymore.  I definitely was feeling a bit like a fish out of water, even though we hadn’t even left the dock yet. As people start to arrive back on the ship, they all know their role and are busy getting ready for our departure later on today. It’s a good experience to feel like you’re out of your element every now and again and I guess a small part of why I decided to apply for a Teacher at Sea position in the first place.

NOAA

As I was preparing to depart on this adventure and was explaining that I was going to be a NOAA Teacher at Sea, I had a number of people ask me what NOAA stood for, so I thought I’d provide a bit of information about what they are and what they do.  First, NOAA stands for the National Oceanic and Atmospheric Administration, and the name definitely suggests the broad mission that the agency has.  Their mission involves striving to understand the oceans, atmosphere, climate, coastlines and weather and making predictions about how the interactions between these different entities might change over time.

That is a tall order, and the agency is divided up into different offices that focus on different aspects of their mission.  The National Weather Service, for example, is focused on forecasting the weather and makes predictions about things like where hurricanes will travel and how intense they will be when they get there.  The National Marine Fisheries Service is tasked with studying the ocean resources and habitats in U.S. waters and to use that understanding to create sustainable fisheries.

So far, I’ve met many people that I’ll be sharing the boat with over the next two weeks.  They have all taken time to introduce themselves and talk for a bit, even though I know that they’ve got tons to do before we sail.

Sunday evening

Well, we’re underway towards our first sampling sites off the coast of Brownsville, Texas.  The seas are really calm, and I’m sitting up on the deck enjoying the light breeze and digesting the delicious dinner of jambalaya, vegetables and blackberry cobbler.  On our way out from Pascagoula, we saw a few dolphins, beautiful white sand barrier islands and mile after mile of moon jellies, but now we’re no longer in sight of land.

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Barrier island off the coast of Mississippi

We’ve passed an occasional oil rig off in the distance but haven’t seen much else.  The sun just set behind just enough clouds to make the colors spectacular and then as I was climbing down the stairs, I saw a handful of dolphins playing in the boat’s wake.

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Sunset over the Gulf of Mexico

Monday, September 18

Today will be a full day of travel to reach our fishing grounds.  Assuming we continue to make steady progress, we should arrive in the late afternoon or early evening on Tuesday to begin fishing.  We will be baiting 100 hooks that, once deployed, will remain in the water for an hour before we pull them back in.  We’ll be fishing in a variety of depths while working our way back towards Pascagoula.  We practiced some drills this afternoon, including a “man overboard” simulation, using a couple of orange buoys.  They deployed a rescue boat and had retrieved the buoys in a matter of minutes.  I have to admit that watching them get out there with such speed and skill put me at ease.

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Rescue boat deployed during the “man overboard” drill

 

 

Kate Schafer: Off to the Gulf, September 16, 2017

NOAA Teacher at Sea

Kate Schafer

Aboard NOAA Ship Oregon II

September 17 – 30, 2017

Mission: Shark/Red Snapper Longline Survey

Geographic Area of Cruise: Gulf of Mexico

Date: September 16, 2017

Introduction

Welcome to my Teacher at Sea blog!  My name is Kate Schafer, and I am a teacher at the Upper School at the Harker School in San Jose, California, right in the middle of Silicon Valley.  I teach biology, marine biology and food science to mostly juniors and seniors.  This may seem like an odd mix of courses, but I am so fortunate to be able to teach students about all my favorite topics.  I have heard that the food is delicious on the Oregon II, and I’m interested in learning more about the challenges of keeping a crew fed when you can’t pop down to the corner grocery store when you realize that you forgot to order that crucial ingredient.  I have spent many hours on the ocean, and spent six years studying coral reefs in Belize, Central America, but I’ve never been to sea on a research vessel.  I’m thrilled to have that opportunity and to share it with my students.

My husband, daughter and I ready to tour the Atlantis in Woods Hole, MA this summer

Weather Data

The weather has been a big topic of conversation of late here in San Jose.  Two weekends ago set all-time record high temperatures throughout the Bay Area, even along the coast.  Living in close proximity to the ocean, we expect relief from that rare hot day to come rather quickly, but the heat lingered for days.  We’re back to normal fall weather as I head off, though.  This morning is cool and seasonable.  I know from growing up in Atlanta, Georgia, that I’m heading to warm and humid conditions on the other end of my travels.

Science and Technology Log

On this research cruise, we will be conducting long line surveys, looking at shark and red snapper populations in the Gulf of Mexico.  I will report more on where we are going and what we’re studying once the leg of the survey begins. There are multiple legs to the survey, and I’ll be joining in for the fourth and final leg.  It has been a tumultuous time in the Gulf over the past few weeks, and it will be interesting to learn about how this has impacted the coastal waters in the area we will be surveying.

Personal Log

I am sitting in the airport in San Jose, ready to board my flight to Dallas, en route to Gulfport and my final destination of Pascagoula, Mississippi.  Wow! It’s been a frantic week of getting all sorts of last minute pieces put together to allow things to, hopefully, run smoothly in my absence.  It’s early morning, so I’m still in a bit of a groggy cloud, making the fact that I’m actually heading off on this adventure all the more unreal.

Even the grogginess cannot stifle my excitement, though, as I head off for two weeks of working with scientists and collecting data.  As I was packing last night, I couldn’t help but be reminded of all the previous trips I packed for more than 15 years ago to conduct field research on coral reefs in Belize.  I was studying a type of crustacean called the stomatopod and learning about the role that they play in coral reef ecosystems, how they interact with other species like pygmy octopus and crabs, their main source of prey.

I am thrilled to be heading out on this research trip and feel so fortunate for the opportunity.  I look forward to questions from you about what we are doing and learning on our voyage.  Check in frequently for updated blog posts once the trip commences.

Did You Know?

That the Oregon II has been part of the NOAA fleet since 1977?

Susan Brown: Who Needs Sharks Anyway? September 13, 2017

 

NOAA Teacher at Sea

Susan Brown

Aboard NOAA Ship Oregon II

September 3 – 15, 2017

 

Mission: Snapper/Longline Shark Survey

Geographic Area of Cruise: Gulf of Mexico

Date: September 13, 2017

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sunset through jaws of a blacktip shark

 

Science and Technology Log

We have been sampling along the coast of Florida, Alabama, Mississippi, Louisiana, and Texas at varying depths – “A” stations ( 5- 30 fathoms), “B” stations (30 -100 fathoms) and “C” stations (100 – 200 fathoms). A fathom is six feet or approximately 2 meters. The longlines are baited the same – mackerel on 100 hooks spread out across one nautical mile and then set on the bottom of the ocean. As we reel in the long line, the click and whine of the line as it’s being spooled, we wait in anticipation of what it may bring. Each station yields something different and you never know what you are going to get. Below is a list of some of the animals we have encountered.

 

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baby hammerhead

Shark species: blacktip, sharpnose, blacknose, scalloped hammerhead, great hammerhead, bull, tiger, spinner and bonnet head (to learn more about each of these species, select it for a NOAA fact sheet).

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Scallop Hammerhead in cradle

Other animals: southern ray, cownose ray, roughtail stingray, red snapper, black drum, sharksuckers, catfish, red drum, yellowedge grouper, king snake eels and even some blue crabs.

So why survey sharks? Did you know that people are one of only a few species that prey on sharks — killer whales and other sharks are the others– killing over a hundred million per year?* Sharks are apex or top predators in an ocean food web and play a vital role in keeping this food web in balance. With the hunting of sharks as well as over fishing the prey that sharks eat we are disturbing the natural balance. This survey is used determine the number of sharks and other species that are present in the Atlantic Ocean including the Caribbean Sea and the Gulf of Mexico. With these numbers, the National Marine Fisheries Service (NOAA Fisheries) regulate how many sharks, swordfish and tuna can be harvested without impacting the total population. In the Pacific Ocean, NOAA fisheries work with fisheries in developing how to best manage sharks.

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red snapper

Apex predators in any ecosystem are vital to the health of that ecosystem. These top predators keep numbers down on the more abundant prey species and keep their numbers in check. Here is a simplified illustration of what happens when we lose apex (top) predators in an ocean ecosystem.

If the number of sharks goes down then the food the sharks eat goes up (forage fish) because they are not being eaten by the sharks. With more of those forage fish around their need for food – the zooplankton – increase. With more forage fish eating the zooplankton there are less zooplankton and their numbers begin to decrease. If there are less zooplankton then the phytoplankton numbers increase because the zooplankton aren’t around the eat them. Removing top predators from any ecosystem can have an impact on the entire food web and this phenomena is called a trophic cascade.

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Removing Hook

Personal Log

When people think of sharks, they think of the movie Jaws. Unfortunately this has given sharks a bad reputation and has vilified these animals that are essential to the ocean food webs. Sure, there have been shark attacks, but did you know that more people are killed each year by electrocution by Christmas tree lights than by shark attacks? When people imagine sharks, they think of enormous sharks that eat everything in sight. The reality is that sharks come in all sizes and shapes. A mature Atlantic sharpnose shark will only get to be 3.5 feet long with the world’s smallest shark being the dwarf lantern shark that can fit in the palm of your hand. The largest shark is the harmless-to-human whale sharks that feeds primarily on plankton and can grow up to 60 feet!

IMG_6084

Smooth-hound (Mustelus Sinusmexicalis)

Did You Know?

Scientists can tell the age of a shark by counting the rings on its vertebrae (similar to how they can tell how old a tree is by counting its rings!)

Question of the day:

What is an example of a terrestrial (land) apex predator that has been over hunted impacting the entire ecosystem?

hint: watch this video clip: https://www.youtube.com/watch?v=ysa5OBhXz-Q