Cruise GU-03-04, Leg I
October 8 - October 22, 2003

Once again we are ‘combing’ the waters of the northern Gulf of Mexico. This time, we are in search of bottom dwellers in depths of 100 to 500 meters. Finding and retrieving these creatures is a detail-oriented procedure.

One hundred and fifty stations were randomly generated by computer to cover the entire northern Gulf. A survey is conducted at each station to find an obstruction-free stretch of seafloor. Realtime graphic displays of data from acoustic sensors and equipment onboard are used to determine the characteristics of the seafloor and help in selecting the best site to trawl. Below are screen captures of "suitable" and "unsuitable" sites.

Unsuitable bottom for trawling. Note the gas seepage from the top knolls.

A more suitable bottom for trawling. Obstruction-free bottom at 86 fathoms (about 156 m).

When a suitable stretch of seafloor is found, a net shaped like a long sleeve, is sent to the bottom. In this particular case, the scientists use one of the biggest fishing nets available for this type of research. With its ‘mouth’ wide open the net measures 90 ft. wide (~30 m) by 15 ft. high (~5 m) by a length of over 200 ft. (~70 m). Once the net is on the bottom, it is towed at a slow speed for 30 minutes. At the end of the trawl, the net is carefully recovered and the catch is weighed, sorted and cataloged while the ship transits to the next station.

The photos below depict the trawling operation.

(Click on image for larger view)

Deck crew deploy the net.	Wire winch and port side 'door' are basic components of the trawling gear.
Weighing the catch (this one broke the cruise record!)	Sorting the catch - looking for different species.
Sending the catch to the Lab in baskets. Shown here are interesting creatures caught at a depth of almost 500 meters.	The catch is cleaned, identified and cataloged by the scientists.
SF Barbosa and F Ropiak show off the catch of the day - a 6 ft. eel.	Final step - Chief Steward Ted Obcena presents: "Big Eyed Scad" cooked to perfection.

The acoustic data collected while the ship is trawling is correlated with the various species caught. “The long term goal” says Chief Scientist Walter Ingram, “is to develop an ‘acoustic signature’ for each species. In the future, a commercial fishing boat will be able to locate its target fish by using acoustics before sending nets down and thus, cutting operating costs as well as causing less environmental harm to bottom features and by-catches”. There are more than 10,000 different species, of which, approximately 400 are considered common species in waters less than 100 meters and at least as many in deeper waters. “It’ll take 30 to 40 years to complete the ‘acoustic signature’ project which is why it is classified as the ‘long term’ goal” says Ingram.

Acoustic display of bottom features and fish.

“The ‘short term’ goal, to hopefully be accomplished within a decade or two” continues Ingram, “is to build a model of the relationship between the different species. In recent years, fisheries management has shifted from ‘single species’ to ‘ecosystem’ management, i.e.: understanding and managing fish as a community. All fish, big and small, are part of the same food chain. Therefore, learning their basic characteristics of age, growth and mortality, reproduction, food habits and distribution will clarify their role in the whole system. This model will give fisheries management the tools to predict the depletion or recovery of fish by electronically removing a certain fish from the model. Predicting the future of a target fish will help the commercial fisheries with their long term planning as well as protect the overall balance of the environment."

With this hopeful thought, we conclude the report from Leg I of the Deep Water/Small Pelagics Survey. We will be back with more stories and photos after we complete the next leg of this cruise in mid-November. Until then, here are photos of a few not often seen creatures from the depths of the Gulf of Mexico.

(Click on image for larger view)

See the pictures and read about Legs II and III of the Deep Water/Small Pelagics Survey.

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