Spencer Cody: Sea of Life, June 4, 2014

NOAA Teacher at Sea

Spencer Cody

Aboard NOAA Ship Pisces

May 27 – June 11, 2014

Observational Data:

Science and Technology Log:

The degree to which the Gulf of Mexico is rich in sea life is truly stunning.  The Gulf produces more fish, shrimp, and shellfish than the waters of New England, the Chesapeake, mid- and south-Atlantic combined; consequently, the SEAMAP survey area includes a wide variety of sea life with great abundance.  A lot is riding on our ability to understand and manage the Gulf of Mexico.  According to a 2010 National Marine Fisheries Service report, the five U.S. Gulf states harvested 1.3 billion pounds of commercial shellfish and fish.  In that same year, the Gulf produced 82% of the U.S. shrimp harvest, and 59% of the U.S. oyster harvest, and over a billion pounds of fish.  Maintaining the Gulf as a productive fishery for years into the future is essential to the U.S. economy and its food production.  So, what is going on with reef fish in the Gulf?  In general, many commercially valuable species in the Gulf are showing signs of strain due to over harvesting and various environmental factors.  However, compared to waters in some parts of the neighboring Caribbean that have had commercially valuable reef fish devastated by lax regulation and enforcement, some parts of the Gulf appear relatively pristine.

One area of concern is our red snapper stocks.  It can be a difficult population to maintain since major swings in reproduction occur from year to year.  This can give both recreational and commercial fishermen a false sense that a population is doing well; however, with red snappers one thirty-year-old female lays more eggs than 30 one-year-old females.  Therefore, it is in our best interests to ensure some older fish survive for reproduction. This same trend can be applied to other commercial fish in the Gulf further complicating management efforts.

The populations of both red snapper and vermillion snapper are showing signs of recovery since setting harvesting restrictions. Red snapper still has a ways to go to get to the targeted sustainable population.  Currently, the red snapper population is only 13% of the target population level while the vermillion snapper is now at 92% of its target population.  Both populations are well below levels documented early in the 20^th century. We see a similar problem with some of the grouper in the Gulf.

Species such as the gag grouper and red grouper have faced similar declines due to overfishing, and both have shown signs of recovery while the gag grouper is still under a population rebuilding plan.  While the bandit reels are targeting fish stocks that often have commercial or recreational value, the camera array reveals the context to the rest of the story about the habitat that is up to several hundred feet below our feet.

Just as freshwater fish back home are often attracted to some sort of structure, reef fish exhibit the same tendencies.  Survey areas where we catch few, if any, fish using the bandit reels often appear as barren, flat muddy or sandy bottoms.  This stands in stark contrast with the rich communities that congregate around structure.

Areas in the Gulf that have structure often have a remarkable array of fish and an even wider ranging variety in invertebrates.  So far on this cruise, we have viewed dozens of species of fish representing groups as diverse as snapper, grouper, sharks, eels, triggerfish, pufferfish, anglefish, damselfish, jacks, porgies, and tilefish.

The invertebrate diversity at these sites spans many phyla including sea fans, sea sponges, crabs, brittle stars, sea lilies, shrimp, tunicates, and various types of algae.  One may wonder why structure is found in these places.  In many cases these communities thrive on ancient coral reefs.  These reefs are no longer living themselves since the 150 to 300 feet we often find them in is too deep for the colonial animals that make up coral to have symbiotic algae living with them.  There is simply not enough light at that depth for the types of algae normally associated with coral to carry out photosynthesis.  Then how did corals get to such depths in the first place?  Twelve thousand years ago large ice sheets existed across much of the northern hemisphere.  These continental glaciers locked up approximately 100 feet of ocean sea level into ice at the peak of glaciation.  Therefore, many of our survey sections are directly over where the Gulf coast once was in very recent geological time.  Once the global climate warmed, the glacial ice sheets collapsed and filled the ocean basins to their present day sea levels leaving the existing coral reefs in near darkness.

Personal Log:

In addition to all of the sea life that I have seen directly relating to the survey, I have seen numerous species as a result of incidental catches or just from casual observations from the ship.  The Gulf is home to more than a dozen shark species.  A hammerhead and possibly a bull shark were spotted from the Pisces during the cruise.  Several unidentified sharks were attracted to the mackerel that we were using for bait on our bandit reels and the fish that we were reeling in on our lines.  Trying to reel in your catch and pull off ten hooks from your line before the sharks get a hold of it really adds a whole new element of excitement to fishing that I had never had to deal with before.  Other sea life that I have seen include barracuda, a wahoo, a bottlenose dolphin, Atlantic spotted dolphins, large mats of brown algae called Sargassum, and the many living things that live among the Sargassum, which I will talk more about in future posts.

Did You Know?

Fish stocks throughout the ocean are threatened by over-harvesting and environmental issues.  You can learn more about the status of key marine species and issues relating to our seafood supply at the NOAA FishWatch.gov site.