Cape Horse Mackerel
Species is currently under revision for offshore trawl component.
1. What is it?
Cape Horse Mackerel (Trachurus capensis) is a pelagic, shoaling species found at depths of 300m. They are widespread over the continental shelf in areas with sandy bottoms; they tend to feed in the surface waters at night and remain close to the bottom during the day. The stock status is presently unknown and there are substantial concerns due to declining catch rates in recent years. The cause for the poor catch rates is not presently known.
2. How was it caught or farmed?Mid-water trawl
Cape horse mackerel are fished using mid-water trawls. These nets are very large with a minimum mesh size of 75 mm when stretched to maximum size. Trawling takes place in the pelagic zone between the seabed and surface of the sea and the net is dragged through the water with minimal touching the seabed. As a result, there is very little impact on the benthic habitat or species other than the occasional bottom contact. Mid-water trawls tend to target large schools of fish of the same species so bycatch tends to be a relatively small portion of the total catch. For some vulnerable species such as sharks, sunfish and seals, however, the number of individuals caught might be significant enough to affect population levels.Offshore trawl
Cape Horse Mackerel are caught as bycatch within the within the offshore demersal trawl industry for hake using trawl nets that are dragged along the seabed at depths typically ranging from 110 m to 800 m (known as “demersal trawl nets”). This type of trawling is known to damage the seabed; the extent and impact of damage remains unknown. Trawling is not a very selective fishing method and a number of other species are often caught in the nets (fish, sharks and rays). Seabird interactions with trawl cables near the surface are also a major concern. A success story in the fishery has been the implementation of effective seabird mitigation strategies developed in connection with the MSC-certification process. These strategies have resulted in a dramatic reduction in seabird-fishery interactions through the introduction of tori lines (lines covered in coloured streamers making trawl attachment lines more visible to birds) and improved disposal of offal (discards that attract seabirds).
3. Where is it from?Mid-water trawl
Cape Horse mackerel are fished from southern Angola to the Wild Coast. In South Africa, management is considered partly effective due to a lack of recent scientific surveys required to update the stock assessment. Horse mackerel is managed through a TAC allocation for the directed mid water trawl sector, a bycatch reserve for the hake trawl sector and a Precautionary Upper Catch Limit (PUCL) for the small pelagic purse seine fisheries. An effort control restriction is in place to reduce the potential for overfishing in light of the uncertain stock status.Offshore trawl
Cape Horse Mackerel are caught as bycatch on the continental shelf edge and upper slope along the West Coast from the Namibian border southwards and on the South Coast primarily around the Agulhas Bank. Management is mainly focused on the target species (hake) in the form of Total Allowable Catch (TAC) and permit limitations. There are some ecosystem-based management measures in place such as precautionary catch limits on monkfish and kingklip, tori lines to reduce sea bird interactions, and limited fishing areas (i.e. fishing within a “footprint” to limit seabed disturbance). Research is underway to better understand impacts to seabed habitats. There is however, little information on impacts to sensitive shark, skate and ray populations.