Skate wings, Twineyes, Skate
1. What is it?
Twineye (Raja miraletus) are long-lived, slow growing, late maturing, low fertility skates making them vulnerable to heavy fishing pressure. There is no directed fishery for skates as they are commonly caught as bycatch. No stock assessment has been done on them but there are some indications of them being over fished due to substantial declines in catch abundances.
2. How was it caught or farmed?
Twineye skates are caught as bycatch in the inshore trawl fishery for hake (MSC certified) and sole using trawl nets. In the inshore zone, trawl nets are dragged along the sea bed at depths in the area from the coast to the 110m isobath or to 20 nautical miles from the coast, whichever is the greater distance. Demersal trawling is known to damage the seabed; the extent and impact of this damage remains unknown. This methodology is not selective, however, and a number of other benthic species are often caught in the nets as well. Seabird bycatch was highlighted as an issue and the subsequent introduction of tori lines (lines covered in coloured streamers making attachment lines more visible to birds) has led to a decrease in bird mortalities.
3. Where is it from?
Twineye skates are caught between Cape Agulhas and the Great Kei River at depths shallower than 110 m. Management is considered to be partly effective. Management is mainly directed at the target species hake (MSC certified) and sole in the form of Total Allowable Catch (TAC) and permit limitations. Some ecosystem-based management measures have been implemented, such as the use of tori lines to minimize seabird interactions and limited fishing areas. There is a fishery conservation project (FCP) presently underway seeking to test a co-management approach that would bring under management 10 non-target species in the sector. Additional ecological concerns are little information on impacts to sensitive shark, skates and ray populations as well as impacts to the seabed. Efforts are underway to improve the scientific observer coverage at sea for this sector to better understand ecosystem impacts.