Wednesday 29 August 2018

We’re going on a sponge hunt! Blog #2

It’s our third shift at Faroe Shetland Sponge Belt NCMPA and we’re on the hunt for sponges.
Technical issues have delayed us by a day and have persisted. Offshore surveys are never straightforward, but work is now well underway.

Faroe Shetland Sponge Belt NCMPA is designated to protect deep-sea sponge aggregations but currently we lack information on where they occur within the site. This survey will help us to understand how this habitat is distributed across the site. We will collect this information using two different pieces of equipment, the video chariot and the drop-down camera.

The video chariot being deployed 

The video chariot can be towed above the seabed at a relatively high speed (2 knots). By towing the video chariot in long transects, we can quickly scan our survey area for sponge aggregations.

Later in the cruise, once we know where sponge aggregations occur, we plan to return to Faroe Shetland Sponge Belt NCMPA with a drop-down camera. The drop-down camera is towed slowly and close to the seabed to provide us with more detailed information about the sponge aggregations.

Example image of sponges seen at Faroe Shetland Sponge Belt NCMPA (laser scale 30cm)

During daylight hours, Marine Scotland Science colleagues are undertaking trawl surveys in the Faroe-Shetland Channel between 1100m and 1400m. While the primary objective is to delimit the distribution of Greenland Halibut (Reinhardtius hippoglossoides) in the area and provide stock indices, the catch weights and length frequencies of all other fish species will also be recorded. This will aid understanding of how fish assemblages vary in relation to environmental factors such as depth and temperature.

Survey Fun Fact:
The main deep-sea sponge aggregation found at the Faroe Shetland Sponge Belt NCMPA is boreal ‘ostur’. They are abundant with the giant sponge species Demospongia referred to locally by the fishermen as ‘Osterbunds’ or ‘cheese-bottoms’ relating to their appearance (with cheese translating to ‘ostur’ in Icelandic). In UK waters, the boreal ‘ostur’ sponge aggregations are only found to occur in the biogeographic region which encompasses the Faroe-Shetland Channel (JNCC, Oct 2017). 

Written by Jessica Taylor & Jim Drewery
Images copyright JNCC/MSS.