shark cradle – NOAA Teacher at Sea Blog

NOAA Teacher at Sea

Kathy Schroeder

Aboard NOAA Ship Oregon II

September 15-October 2, 2019

Mission: Shark/Red Snapper Longline Survey

Geographic Area of Cruise: Gulf of Mexico

Date: 9/30/19

Weather Data from the Bridge

Latitude: 29.47408
Longitude: 85.34274
Temperature: 85°F
Wind Speeds: E 5 mph

Science and Technology Log

Retrieving the Longline

One hour after the last highflyer is entered into the water it is time to retrieve the longline. The ship pulls alongside the first highflyer and brings it on board. Two people carry the highflyer to the stern of the ship. The longline is then re-attached to a large reel so that the mainline can be spooled back onto the ship. As the line comes back on board one scientist takes the gangion removes the tag and coils it back into the barrel. The bait condition and/or catch are added into the computer system by a second scientist. If there is a fish on the hook then it is determined if the fish can be brought on board by hand or if the cradle needs to be lowered into the water to bring up the species.

*Retrieving the high flyer on the well deck*

Protective eye wear must be worn at all times, but if a shark is being brought up in the cradle we must all also put on hard hats due to the crane being used to move the cradle. Once a fish is on board two scientists are responsible for weighing and taking three measurements: pre-caudal, fork, and total length in mm. Often, a small fin clip is taken for genetics and if it is a shark, depending on the size, a dart or rototag is inserted into the shark either at the base of the dorsal fin or on the fin itself. The shark tag is recorded and the species is then put back into the ocean. Once all 100 gangions, weights and highflyers are brought on board it is time to cleanup and properly store the samples.

*Taking the measurements on a sandbar shark (*Carcharhinus plumbeus) Measurements: 1080 precaudal, 1200 fork, 1486 total (4’10”)l, 20.2 kg (44.5 lbs)

tagging smoothhound — *Placing a rototag in a Gulf smooth-hound (*Mustelus sinusmexicanus)

Tiger shark on cradle — *Tiger shark* (Galeocerdo cuvier) *on the cradle getting ready for a dart tag*

data station — *Data station for recording measurements, weight, sex, and tag numbers*

Fish Data: Some species of snapper, grouper and tile fish that are brought on board will have their otoliths removed for ageing, a gonad sample taken for reproduction studies and a muscle sample for feeding studies and genetics. These are stored and sent back to the lab for further processing.

red snapper samples — red snapper *(Lutganidae campechanus)* samples: gonad (top), muscle (middle), otoliths (bottom)

Personal Log

It has been a busy last few days. We have caught some really cool species like king snake eels (Ophichthus rex), gulper sharks (Centrophorus granulosus), yellow edge grouper (Hyporthodus flavolimbatus) and golden tile fish (Lopholaatilus chamaeleontiiceps). There have been thousands of moon jelly fish (Aurelia aurita) the size of dinner plates and larger all around the boat when we are setting and retrieving the longline. They look so peaceful and gentle just floating along with the current. When we were by the Florida-Alabama line there were so many oil rigs out in the distant. It was very interesting learning about them and seeing their lights glowing. One of them actually had a real fire to burn off the gases. There were also a couple sharks that swam by in our ship lights last night. One of the best things we got to witness was a huge leatherback sea turtle (Dermochelys coriacea) that came up for a breath of air about 50 feet from the ship.

yellow-edge grouper — *yellow edge grouper* (Hyporthodus flavolimbatus) *891 mm (2′ 11″), 9.2 kg (20.3 pounds)*

king snake eel close-up — *king snake eel* (Ophichthus rex)

NOAA Teacher at Sea

Stephen Kade

Aboard NOAA Ship Oregon II

July 23 – August 10, 2018

Mission: Long Line Shark/ Red Snapper survey Leg 1

Geographic Area: 31 41 010 N, 80 06 062 W, 30 nautical miles NE of Savannah, North Carolina

Date: August 8, 2018

Weather Data from Bridge:

Wind speed 11 knots,
Air Temp: 30c,
Visibility 10 nautical miles,
Wave height 3 ft.

Science and Technology Log

Normally you wouldn’t hear the words shark and cradle in the same sentence, but in our case, the cradle is one of the most important pieces of equipment we use each day. Our mission on the Oregon II is to survey sharks to provide data for further study by NOAA scientists. We use the long line fishing method where 100 hooks are put out on a mile long line for about an hour, and then slowly hauled up by a large mechanical reel. If a shark is generally three feet and weighs 30lbs or less, it is handled by hand to carefully unhook, measure and throw back. If the shark is much larger and cannot be managed safely by hand, it is then held on the line by the ships rail until it can be lifted on deck by the cradle to be quickly measured, tagged, and put back into the ocean.

The shark cradle is 10 ft. long, with a bed width of roughly 4 feet. It is made from thick aluminum tubing and strong synthetic netting to provide the bed for the shark to lie on. It is lifted from the ship’s deck by a large crane and lowered over the ships rail into the ocean. The shark is still on the line and is guided by a skilled fisherman into the cradle. The crane operator slowly lifts the cradle out of the water, up to the rail, so work can begin.

Hammerhead shark in the cradle

Nurse shark in the cradle

A team of 3 highly skilled fishermen quickly begin to safely secure the shark to protect it, and the team of scientists collecting data. They secure the shark at 3 points, the head, body and tail. Then the scientists come in to take 3 measurements of the shark. The precaudal measurement is from the tip of nose to the start of the tail. The fork measurement is from the tip of the nose to the fork of the tail (the place where the top and bottom of the tail meet). Finally there is a total length taken from the tip of the nose to the furthest tip of the tail.

Measuring tools

Data sheet

Yellow tags

When all measurements are complete, a tag is then placed at the base of the first dorsal (top) fin. First a small incision is made, and then the tagger pushes the tag just below the skin. The tag contains a tracking number and total length to be taken by the person who finds the shark next, and a phone number to call NOAA, so the data can recorded and compared to the previous time data is recorded. The yellow swivel tags, used for smaller sharks, are identical to ones used in sheep ears in the farming industry, and are placed on the front of the dorsal fin. The measurements and tag number are collected on the data sheet for each station. The data is input to a computer and uploaded to the NOAA shark database so populations and numbers can be assessed at any time by NOAA and state Departments of Natural Resources.

removing hook — A skilled fisherman removes the hook so the shark can be released.

The longline is mile long and carries up to 100 hooks.

The shark is then unhooked safely by a skilled fisherman while the other two are keeping the shark still to protect both the shark and the fishermen from injury. The cradle is then slowly lowered by crane back into the ocean where the shark can easily glide back into its environment unharmed. The cradle is then raised back on deck by the crane operator, and guided by the two fishermen. All crew on deck must wear hardhats during this operation as safety for all is one of NOAA’s top priorities. This process is usually completed within 2 minutes, or the time it took you to read this post. It can happen many times during a station, as there are 100 hooks on the one mile line.

Personal Log

It is amazing for me to see and participate in the long line fishing process. I find it similar to watching medical television shows like “ER” where you see a highly skilled team of individually talented members working together quickly and efficiently to perform an operation. It can be highly stressful if the shark is not cooperating, or the conditions aren’t ideal, but each member always keeps their cool under this intense work. It’s also amazing to see the wealth of knowledge each person has so when an issue arises, someone always knows the answer to the problem, or the right tool to use to fix the situation, as they’ve done it before.

Animals Seen Today: Sandbar shark, Tiger shark, Sharpnose Shark, Sea Robin, Toadfish, Flying Fish

Tag: shark cradle

Kathy Schroeder: Retrieving the Longline, September 30, 2019

Stephen Kade: The Shark Cradle and Data Collection, August 8, 2018