NOAA Teacher at Sea
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
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.
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.
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.
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.
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.
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!