24. July


Bottom trawl being launched. Photo: D. Shale


A medusa selected for onboard experiments. Photo: D. Shale


A ctenophore, member of a common group of gelatinous zooplankton. Photo: D. Shale

Todays Highlights

Date:24 July 2004
Author:  Odd Aksel Bergstad (IMR)

We crossed the main east-west directed channels of the Charlie-Gibbs Fracture zone where depths reach 3500-4500 m. Between two deep channels lies a series of seamounts, of which the one known as Hecate Seamount is the most prominent. The shallowest areas of this seamount is no more than 750m. Commercial fisheries have been conducted here, primarily for roundnose grenadier, one of the many macrourid fishes that are abundant in deep-sea areas. Our attempt to fish on the seamount failed completely as the trawl came up badly damaged. This shows how difficult seamount fisheries are, despite modern mapping and gear monitoring tools.

We had to move on to our next station located north of the main fractures at about 3200 m. The remainder of the cruise will be spent in this area where we will have 6 stations in pre-determined locations.

On the deep first station a mid-water dive was carried out with the ROV Aglantha. The zooplankton team is looking for gelatinous animals in the water column. They try to identify species and count their numbers, and they use the suction sampler on Aglantha to collect specimens to be used for onboard respiration experiments. Today’s dive was successful in that they captured several live medusae in good condition.

 

Weather Conditions

Overcast, but not windy. Good working conditions.

 

Tomorrows expected highlights

We will complete another very deep station, and the trawl catch from great depths is always exciting.