NOAA Teacher at Sea Dave Grant Aboard NOAA Ship Ronald H. Brown February 15 - March 5, 2012
Mission: Western Boundary Time Series Geographical Area: Gulf Stream waters Date: March 1, 2012 Weather Data from the Bridge Position: 26.30N Latitude – 79. 23W Longitude Wind speed: Calm Wind direction: Calm Air Temperature: 76E F Atm Pressure: 1013. mb Water Depth: 750 meters Cloud Cover: 20% Cloud Type: Cumulus Personal Log Our most persistent travel companions on the cruise are the flying fish and today they are the most abundant in the entire trip. Sit at the bow while we are plunging into the swells and it is impossible not to be mesmerized by what issues from the sea surface when old Triton blows his wreathed horn. Over the eons, fishes have experimented with many different avenues of escape from predators and competition, and soaring out of the water is arguably the most dramatic and effective. There are scores of species in the family Exocoetidae, which comes from Greek roots and refers to “sleeping outside” - which was logical to ancient mariners who believed the flying fishes left the ocean to sleep on the shoreline. I check the Ron Brown’s deck each morning, hoping one has inadvertently landed on it, but without luck so far. We flush them from both sides of the ship while underway. Like birds of a feather flocking together, some escaping groups are about a foot long with a wing span (Oversized pectoral fins to be exact) about the same spread. Juveniles in other schools look no larger than the silver dollar George Washington threw across the Delaware River(Or did he skip it for greater distance like these little fishes do off the crests of waves?). Between the sky, sea and sunsets, I thought I had seen all the shades of blue on this cruise, up to the moment we had a perfect view of a flying fish that soared past the railing and then steered off towards the horizon. Flying fish exhibit all the colors of the near end of the spectrum as their attitude and altitude change in flight. Taking advantage of the mesoscale winds generated between swells, the fishes launch off wave crests and can soar farther than a football field; sustaining the flight time by sweeping their tail laterally in the water. Flying fish are harvested throughout the warmer waters of the ocean by man and beast, and are an important staple to island cultures. Barbados - to our south - is called the “land of the flying fish" and on the reverse side of a dollar coin that I kept after a Caribbean trip, one finds the fish in flight. When we are closer to land, I hope to see one of their main aerial opponents flying out to meet us – frigate birds.
Flying fish off the bow!
Mahi-Mahi
Our British colleagues remembered to bring fishing poles and the mahi-mahi is the most sought after and elusive creature out here when the ship is “on-station” doing sampling. Fishes and squid routinely come to the surface and congregate under the stern lights, and occasionally a large mahi will lurk in the shadows and dart in close to us chasing prey.
Also called dolphin-fish, our fishermen have learned only that the Hawaiian name Mahi-Mahi (Many Polynesian words are repeated) means “strong” since the hooked fishes have broken their fishing lines and escaped. Mahi is popular in restaurants and is a light, mild tasting fish. Swimming under the lights they look pale and eel-like, but when landed in a boat they exhibit a range of shades from blue and green that fades to golden – hence the Spanish name Dorado.
A Mahi rises to the surface alongside the Ron Brown
Fish ON!
Finally the fishermen had some luck and landed a jack - but without a fish guide, that’s as far as I can go in identifying it (Although the term “tuna” is loosely applied to most things that swim by.) Fortunately, I was able to get off an email and photo to Jeff Dement of the American Littoral Society (www.littoralsociety.org).
When not fishing, Jeff runs the largest independent fish tagging program in the country; distributing tags to recreational fishermen and analyzing their thousands of returns to document where fishes migrate to and how fast they grow. His quick analysis directs us towards the lesser amberjack (Seriola fasciata) “based upon the shape of the snout, and the eye stripe length.” Fast swimming and hard fighting, the amberjacks are popular gamefish on the line and in the skillet. Like most fish, they are tasty fried, broiled, baked, or grilled (I like fried…my doctor demands boiled, baked or grilled) Like barracudas and some other apex predators of the reef, amberjacks are implicated in Ciguatera poisoning in humans. They acquire contaminants from eating herbivorous reef fishes that have ingested and accumulated Ciguatoxins produced by Dinoflagellates attached to marine algae they have been grazing upon. Harmless to the fishes, the poison is a neurotoxin in humans who are exposed to a concentrated dose from a top predator like the amberjack through the process called bioaccumulation. This is the same process that concentrates Mercury spewing into the atmosphere from coal-fired power plants, into the sea, then into plankton and forage fishes, and finally tuna.
An amberjack gets a close look at people before returning to the sea.
"You strange astonished-looking, angle-faced, Dreary-mouthed, gaping wretches of the sea, Gulping salt-water everlastingly, Cold-blooded, though with red your blood be graced, And mute, though dwellers in the roaring waste... What is't you do? what life lead? eh, dull goggles? How do ye vary your dull days and nights? How pass your Sundays? Are ye still but joggles, In ceaseless wash? Still sought, but gapes and bites, And drinks and stares, diversified with boggles."
(Leigh Hunt - The Man to the Fish)
It pays to be clear.
For me, the catch of the day is a leptocephali - a larval fish as long as my index finger, that I almost overlooked in the samples.
A number of species go through this inconspicuous stage as zooplankton, and the most famous and intensely studied are the eels. American eels spend a year drifting to East Coast estuaries from their birthplace in the Sargasso Sea. The European species takes a more leisurely two-year tour of the North Atlantic on the Gulf Stream.(Images from the Ron Brown, by Dave Grant)