Cape Horse Mackerel

(Trachurus capensis)

Carapau, Maasbanker

1. What is it?

Cape horse mackerel (Trachurus capensis) are semi-pelagic, shoaling species that ranges through the water column. In recent years, overall catches of horse mackerel have declined. The exact cause of the decline remains unknown; therefore stock is considered uncertain. Horse mackerel are targeted by the midwater trawl fishery and certain vessels in offshore trawl fishery. Horse mackerel is also caught as bycatch in the inshore and offshore trawl fishery for hake (MSC certified) and sole (inshore trawl only).

2. How was it caught or farmed?

Midwater trawl

Cape horse mackerel are fished using mid-water trawls. These nets are very large with a minimum mesh size of 75mm 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.

Inshore demersal trawl

Cape horse mackerel are caught as bycatch using trawl nets that are dragged along the seabed at depths up to the 110 m isobath or 20 nautical miles from the coast. This type of trawling is known to damage the seabed; however 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). Substantial effort has been made to reduce seabird deaths through the use of tori lines (bird-scaring lines) and work is underway to better understand impacts on endangered, threatened or protected species.

Offshore demersal 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 were also a major concern. However, the implementation of effective seabird mitigation strategies such as tori lines (lines covered in coloured streamers making trawl attachment lines more visible to birds) and improved disposal of offal (discards that attract seabirds) has resulted in a dramatic reduction in seabird-fishery interactions.

3. Where is it from?

Midwater trawl

Cape horse mackerel is currently fished along the South Coast. In South Africa, stock levels are managed based on a fluctuating annual Total Allowable Catch (TAC) implemented in 2013. The TAC is slowly increased until negative effects are observed. The majority of the TAC is allocated directly to the sector whilst a small portion is available for the hake trawl sector (when horse mackerel is caught as bycatch). Management is considered effective.

Inshore demersal trawl

Cape horse mackerel are caught as bycatch mainly on the Agulhas Bank off the South Coast. Management measures are considered to be largely effective and mainly focused on the target species (hake and sole) in the form of Total Allowable Catch (TAC) and permit limitations. Additional measures in place include precautionary catch limits and fishing only in historical fishing grounds. More effort is required to improve at-sea scientific observation of fishing activities to better understand ecosystem impacts.

Offshore demersal trawl

Cape horse mackerel are caught along 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 monkfish, kingklip and horse mackerel, 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.