The Cape horse mackerel, Trachurus capensis, is a mackerel-like species in the family Carangidae.^[1] Their maximum reported length is 60 cm, with a common length of 30 cm.^[2]

Fisheries

Capture of Cape horse mackerel in tonnes from 1950 to 2009 ^[3]

Summary

Cape horse mackerel (Trachurus capensis) is a pelagic species, usually found up to a depth of 300m. They are mostly found over the continental shelf, often over sandy bottoms. The shoals rise to feed in surface waters at night but can be found close to the bottom during the day. Horse Mackerel are very abundant in South African and Namibian waters, though much of the catch is exported. The stock status of Cape Horse Mackerel is uncertain but expert opinion is that the stock is most likely under-fished.

Cape horse mackerel is a bycatch species in the offshore demersal trawl, which operates mainly off the waters of the Western Cape at depths of 110m and deeper. The offshore demersal trawl fishery operates using trawl nets which are dragged behind the boat along the ocean floor at depths from 110 – 800 m. Cape horse mackerel caught in the midwater trawl fishery are considered to be more sustainable than those caught in the offshore trawl fishery (see Cape horse mackerel assessment for midwater trawl). This fishery primarily targets deepwater hake (Merluccius paradoxus) on soft, sandy bottoms as well as commercially valuable bycatch species such as kingklip (Genypterus capensis) and monkfish (Lophius vomerinus). Although trawling is a highly unselective fishing method, offshore fishing grounds are not generally very biodiverse (i.e. they are only inhabited by a few species) and the discard rate for this fishery is estimated to be 10% of the total catch. However, this fishing method is likely to have significant impacts on bottom habitats and there are concerns around the number of seabird mortalities caused during trawling (estimated at 8000 per year). The hake component of the offshore demersal trawl fishery has been certified by the Marine Stewardship Council (MSC) since 2004 and the current management system for this fishery employs a number of ecosystem-based management measures which address issues such as bycatch, closed areas and benthic habitat impacts.. Horse mackerel managed in terms of a Maximum Precautionary Catch Limit (MPCL). The MPCL has been maintained at 44 000 tonnes in recent years and accommodates both mid-water-directed and bycatch in the hake-directed demersal trawl sector. Juvenile horse mackerel are occasionally targeted on the West Coast where a 5 000 tonnes precautionary catch limit is enforced (the whole small pelagic sector is closed if the limit is exceeded). Despite the absence of direct evidence of ecosystem change, there is potential for ecosystem impact as this is an important small pelagic species, and fills a similar ecosystem niche to other small pelagic species such as sardine and anchovy.

Notes

v t e Mackerel True mackerels (tribe Scombrini) Scomber (4 species) Atlantic mackerel Atlantic chub mackerel Blue mackerel Chub mackerel Rastrelliger (3 species) Short mackerel Indian mackerel Island mackerel Spanish mackerels (tribe Scomberomorini) Acanthocybium (1 species) Wahoo Grammatorcynus (2 species) Double-lined mackerel Shark mackerel Scomberomorus (18 species) Atlantic Spanish mackerel Australian spotted mackerel Broadbarred king mackerel Cero mackerel Chinese mackerel Indo-Pacific king mackerel Japanese Spanish mackerel King mackerel Korean mackerel Monterey Spanish mackerel Narrow-barred Spanish mackerel Pacific Sierra Papuan Spanish mackerel Queen mackerel Queensland school mackerel Serra Spanish mackerel Streaked Spanish mackerel West African Spanish mackerel Non-Scombrid mackerels Jack mackerels (10 species) Atlantic horse mackerel Blue jack mackerel Cape horse mackerel Chilean jack mackerel Cunene horse mackerel Greenback horse mackerel Japanese horse mackerel Mediterranean horse mackerel Pacific jack mackerel Yellowtail horse mackerel Snake mackerels (5 species) Black snake mackerel Blacksail snake mackerel Snake mackerel Violet snake mackerel White snake mackerel Hexagrammidae (2 species) Okhostk Atka mackerel Atka mackerel Family Scombridae Subfamily Scombrinae Other Scombrids: Butterfly kingfish (butterfly mackerel) Tunas (tribe Thunnini) Bonitos (tribe Sardini)