| Cape horse mackerel | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Carangiformes |
| Family: | Carangidae |
| Genus: | Trachurus |
| Species: | T. capensis |
| Binomial name | |
| Trachurus capensis Castelnau, 1861 | |
The Cape horse mackerel (Trachurus capensis) is a mackerel-like species in the family Carangidae. [2] It is a pelagic species of the south eastern Atlantic Ocean which is a target of fisheries, mainly as bycatch.
The Cape horse mackerel has an elongated, slightly compressed, body with a large head. It has no distinctive markings apart from a small, black spot on edge of its operculum near the upper angle. The dorsal part of body and head are dark and can be dusky, almost black or grey, to bluish green in colour while the flanks, belly and head are usually paler, varying from whitish to silvery. [3] Their maximum reported length is 60 cm, with a common length of 30 cm. [4]
The Cape horse mackerel is found in the southeastern Atlantic from the Gulf of Guinea to eastern South Africa. It is largely restricted to the Benguela current from southern Angola to southern South Africa. [1]
Cape horse mackerel adults are found mainly over the continental shelf, especially where there is a substrate of sand. The shoals rise to the surface waters at night to feed and remain near to the bottom during the day. The juveniles prey mostly on copepods while the adults feed on fishes and a wider variety of invertebrates. [4]
Trachurus capensis is considered to be a subspecies of the Atlantic horse mackerel (Trachurus trachurus) by some authorities but it is thought that there is no adequate series of this specimens of these taxa along the coast of Africa available to confirm the validity of this taxon. [1]
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 concerns are expressed 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 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. The Cape horse mackerel is 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, a potential for ecosystem impact exists, as this is an important small pelagic species, and fills a similar ecosystem niche to other small pelagic species such as sardine and anchovy.[ citation needed ]
Hake is the common name for fish in the Merlucciidae family of the northern and southern oceans and the Phycidae family of the northern oceans. Hake is a commercially important fish in the same taxonomic order, Gadiformes, as cod and haddock.
Trawling is an industrial method of fishing that involves pulling a fishing net, that is heavily weighted to keep it on the seafloor, through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different species of fishes or sometimes targeted species. Trawls are often called towed gear or dragged gear.
Longline fishing, or longlining, is a commercial fishing angling technique that uses a long main line with baited hooks attached at intervals via short branch lines called snoods or gangions. A snood is attached to the main line using a clip or swivel, with the hook at the other end. Longlines are classified mainly by where they are placed in the water column. This can be at the surface or at the bottom. Lines can also be set by means of an anchor, or left to drift. Hundreds or even thousands of baited hooks can hang from a single line. This can lead to many deaths of different marine species. Longliners – fishing vessels rigged for longlining – commonly target swordfish, tuna, halibut, sablefish and many other species.
Bottom trawling is trawling along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is towing a net at the very bottom of the ocean and demersal trawling is towing a net just above the benthic zone. Bottom trawling can be contrasted with midwater trawling, where a net is towed higher in the water column. Midwater trawling catches pelagic fish such as anchovies and mackerel, whereas bottom trawling targets both bottom-living fish (groundfish) and semi-pelagic species such as cod, squid, shrimp, and rockfish.
Midwater trawling is trawling, or net fishing, at a depth that is higher in the water column than the bottom of the ocean. It is contrasted with bottom trawling. Midwater trawling is also known as pelagic trawling and bottom trawling as benthic trawling.
Fish stocks are subpopulations of a particular species of fish, for which intrinsic parameters are traditionally regarded as the significant factors determining the stock's population dynamics, while extrinsic factors are traditionally ignored.
The Atlantic horse mackerel, also known as the European horse mackerel or common scad, is a species of jack mackerel in the family Carangidae, which includes the jacks, pompanos and trevallies. It is found in the eastern Atlantic Ocean off Europe and Africa and into the south-eastern Indian Ocean. It is an important species in commercial fisheries and is listed as a Vulnerable species on The IUCN Red List of Threatened Species.
Thyrsites atun, known as the snoek in South Africa and as the barracouta in Australasia, is a long, thin species of snake mackerel found in the seas of the Southern Hemisphere, and a popular food fish in South Africa, particularly along the west and southwest coast. Despite its Australasian name, it is not closely related to the barracuda.
Unsustainable fishing methods refers to the utilization of the various fishing methods in order to capture or harvest fish at a rate which sees the declining of fish populations over time. These methods are observed to facilitate the destructive fishing practices that destroy ecosystems within the ocean, and more readily results in overfishing, the depletion of fish populations at a rate that cannot be sustained.
Emmelichthys nitidus, the Cape bonnetmouth, bonnetmouth, redbait, pearl fish, picarel, red baitfish, red herring or Southern rover, is a species of marine ray-finned fish belonging to the family Emmelichthyidae, the rovers and bonnetmouths. This species is found in the Indian and Pacific oceans. This species is of minor importance to commercial fisheries.
The yellowtail horse mackerel, also known as yakka, is a jack in the family Carangidae found around Australia and New Zealand at depths to 500 m. Its length is up to 50 centimetres (20 in).
The environmental impact of fishing includes issues such as the availability of fish, overfishing, fisheries, and fisheries management; as well as the impact of industrial fishing on other elements of the environment, such as bycatch. These issues are part of marine conservation, and are addressed in fisheries science programs. According to a 2019 FAO report, global production of fish, crustaceans, molluscs and other aquatic animals has continued to grow and reached 172.6 million tonnes in 2017, with an increase of 4.1 percent compared with 2016. There is a growing gap between the supply of fish and demand, due in part to world population growth.
The South East Atlantic Fisheries Organisation (SEAFO) is an organization that maintains controls over fishing and fishing related acts in the Southeastern Atlantic Ocean.
This is a glossary of terms used in fisheries, fisheries management and fisheries science.
Destructive fishing practices are fishing practices which easily result in irreversible damage to habitats and the sustainability of the fishery ecosystems. Such damages can be caused by direct physical destruction of the underwater landform and vegetation, overfishing indiscriminate killing/maiming of aquatic life, disruption of vital reproductive cycles, and lingering water pollution.
The false scad, also known as the spotfin scad, ten-finned horse mackerel and yellow horse mackerel, is a species of medium-sized marine fish classified in the jack family Carangidae. The false scad is distributed throughout the tropical and temperate waters of the eastern Atlantic Ocean from Namibia in the south to Spain and throughout most of the Mediterranean in the north. The species has an atypical body form compared to other species of Caranx, and can be distinguished from these on its elongate 'scad-like' body shape alone. Distinguishing the species from members of Decapterus and Trachurus is more difficult, requiring detailed anatomical analysis. The false scad is known to grow to a length of 60 cm and a weight of 1 kg. The species lives both pelagically and demersally in continental shelf waters, ranging from depths of 15 to 200 m. It is a predatory fish, taking small fishes, crustaceans including euphausiids and shrimps, and cephalopods as its main prey, with significant dietary shifts as it ages. The false scad reaches sexual maturity at 2 years of age, with spawning occurring between April and July in shallow inshore waters, where the juveniles remain. The species is of major importance to fisheries throughout its range, but particularly from Morocco to Senegal, with annual catches ranging from 500 to 19000 t. The species is caught using trawls, seine nets and gill nets and sold fresh, frozen or salted.
Merluccius capensis is a ray-finned fish in the genus Merluccius, found in the south-eastern Atlantic Ocean, along the coast of South Africa. It is a long, lean fish with a large head, similar in appearance to the European hake and the deep-water Cape hake. By day, it lives close to the bottom on the continental shelf and upper slope at depths not usually exceeding 400 m (1,300 ft); it makes a large, daily vertical migration rising at night to feed in the nectonic zone, and it also migrates southwards in spring and northwards in autumn. It is an important commercial fish species in southern Africa.
The Chilean jack mackerel, sometimes called the Inca scad or Peruvian jack mackerel, is a species of jack mackerel in the genus Trachurus of the family Carangidae. Since the 1970s, it has become one of the world's more important commercial fish species. High volumes have been harvested, but the fishery may now be in danger of collapsing.
The South African Deep-Sea Trawling Industry Association (SADSTIA) represents the trawler owners and operators active in the offshore demersal trawl fishery for hake, the most valuable of South Africa's commercial fisheries, contributing approximately 45 percent of the value of fishery production. Based in Cape Town, South Africa, SADSTIA currently has 32 members that catch, process and market the Cape hakes, Merluccius paradoxus and Merluccius capensis as well as several bycatch species.
Merluccius senegalensis, the Senegalese hake, is a species of fish from the family Merlucciidae, the true hakes. It is found in the sub tropical waters of the eastern Atlantic Ocean off the north western coast of Africa.
