NOAA Teacher at Sea
Aboard NOAA Ship Oregon II
July 25 – August 8, 2015
Mission: Shark Longline Survey
Geographic Area of the Cruise: Atlantic Ocean off the Florida and Carolina Coast
Date: Aug 2, 2015
LAT 3428.300 N
LONG 07705.870 W
Weather Data from the Bridge:
Wind speed (knots): 11.2
Sea Temp (deg C): 29.1
Air Temp (deg C): 25.7
Science and Technology Log: Shark Reproductive Strategies
Rough Seas and bad weather have delayed our sampling. I’m getting use to walking sideways.
Today we reached the northernmost sampling station of our cruise, just off the North Carolina coast. The latest stations have been further off shore than those previous and we’ve caught fewer sharks. However, the sharks we have caught have been much larger. Our catch included Sandbar Sharks, Scalloped Hammerhead, Spinner, Nurse and Black Nose.
Sharks have a number of reproductive strategies ranging from egg laying to placental formation. Oviparous sharks produce and release egg cases made of a collagen (protein). The case surrounds the developing embryo and a large yolk with the vital nutrients required for shark development. This is called lecithotrophic (all nutrients from yolk). Oviparous sharks can take to 2 years to develop within the egg case.
Sharks that give birth to live young are considered Viviparous. Within this category there are two major types. Those that produce eggs with large yolks with all required nutrients, but remain in the uterus for gestation, are called yolk-sac vivipores (ovoviviparous, or aplacental viviparity). In some cases, offspring will consume other eggs (oophagy) in the uterus to gain additional nutrients. An advantage to this type of reproduction is that the young sharks are larger when they are born and have a higher survival rate.
The last group, considered to be the most advanced, is the Placental Group. As with the other types, a yolk is produced that can initially provide some nutrients to the developing pup. However, in the uterus the yolk sac after it is depleted is modified into a placenta through which nutrients can pass from parent to offspring. While fewer offspring are produced at one time, they are typically more robust and have a higher survival rate. Most of the sharks we have caught on this cruise are placental vivipores.
Career Spotlight: Dr. Ian Davenport, Ph.D., Research Scientist
Dr. Ian Davenport, Ph.D., is a Developmental Biologist at Xavier University, New Orleans, and has been a volunteer on this cruise for 7 years.
Ian hails from Manchester, England, and his path to becoming a scientist was quite unusual. Similar to others on board, he always had an interest in Marine Science, and sharks in particular, but school was not a priority early on. He spent time travelling and learned a trade as well. He finally decided to return to school, but being accepted was a challenge. Fortunately Ian’s academic ability was recognized and he was accepted to the University of Newcastle upon Tyne where he studied Marine Biology, but a course in Developmental Biology particularly resonated. He went on to earn his Ph.D. in shark developmental biology at Clemson University.
Ian’s research focus is in evolution of “live bearing.” As noted above, shark species employ a number of reproductive strategies. Placentals are considered to be the most advanced. Ian is studying the eggs of placental sharks and the structure of the cells that surround the egg. His research has revealed some interesting cell features that may aid in nutrient delivery to the developing embryo. If a female shark is caught during the cruise and does not survive, Ian collects the eggs for later study.
Career Spotlight: Chuck Godwin, Deck Crew and Environmental Compliance officer
Chuck has a B.A. in History and has also studied Wildlife Management. Chuck spent 10 years in the Coast Guard and left in 2000, but he was recalled to active service on two occasions – after 9/11 and after Hurricane Katrina. In addition to his work as part of the deck crew, where he is involved in all deck operations, Chuck is also the Environmental Compliance Officer. As such, he manages hazardous waste compliance.
It’s apparent that Chuck enjoys his work. He is all business when he needs to be, but has a knack for adding a note of levity when appropriate. He keeps me laughing, even when the fish aren’t biting. Chuck notes that as a member of the Coast Guard, part of his job was to enforce U.S. fisheries laws. With NOAA he plays an important role in establishing those regulations and this makes the work that much more rewarding.
The weather has been poor since yesterday. Lightning caused a five-hour delay in setting the longline in the night; the ship traversed back and forth over the sampling area waiting for the worst of the storm to pass. Sleeping was a challenge – I think some of us were airborne a few times. Thank goodness for the patch and a few saltine crackers. I took the video below in my bunk as I was nodding off to sleep.
Today’s rough seas and high winds prevented us from using the cradle to bring sharks up to deck height. Ken’s dual laser device, mentioned in my last blog post, was put to good use to estimate the size of the large sharks before they were released.
I need to give shout out to the ship’s cook Walter Coghlan and the second cook O.C. (Otha) Hill. The food has been great and plentiful. ( Homemade Mac n’ Cheese – need I say more?) Walter takes special care to set aside a plate for us if we are on duty during mealtime. The ice cream sandwiches are much appreciated too.
New species seen since last posting: Sharksucker (a type of Remora, Echeneis naucrates), Blacktip (Carcharhinus limbatus)
Check out these interesting shark facts.