Bycatch management
Trawling is an unselective fishing method and consequently the South African hake trawl fishery may be considered a multispecies fishery; although Cape hakes are the target species, approximately 20 other species are regularly caught in trawl nets.
Bycatch is considered to be a valuable part of the trawl catch and a number of bycatch species are important for food security. For instance, horse mackerel, snoek, ribbon fish, panga and angelfish are a good source of affordable animal protein for lower income groups, particularly in the Western Cape. Other bycatch species, most notably kingklip and monk, are highly prized on export markets.
In recent years, SADSTIA has worked with scientists and conservationists to institute measures aimed at better managing the bycatch component of the deep-sea trawl fishery.
The effort limitation, or “sea days” regulation plays an integral role in curbing fishing strategies that result in excessive targeting or catching of bycatch species. Effort limitation caps fishing effort and eliminates opportunities to use excess effort to target bycatch species once quotas for hake have been exhausted.
Precautionary upper catch limits have been set for kingklip and monk.
The Bycatch Fishery Conservation Project
Between 2016 and 2019, the South African Offshore Trawl Bycatch Fishery Conservation Project worked with SADSTIA members to improve the management of non-target species in the deep-sea trawl fishery.
The non-target species are kingklip (Genypterus capensis), monk (Lophius vomerinus), angelfish (Brama brama), Cape dory (Zeus capensis), gurnard (Chelidonichthys capensis), horse mackerel (Trachurus capensis), jacopever (Helicolenus dactylopterus), octopus (Octopus vulgaris), panga (Pterogymnus laniarus), ribbonfish (Lepidopus caudatus), snoek (Thyrsites atun) and a number of skate species.
Although these species are collectively referred to as “non target species” or “by-catch”, they are retained and processed by trawl operators and many of the lower value species, for example panga, snoek and angelfish, are valued as a source of good quality animal protein by lower income groups, particularly in the Western Cape.
In spite of their importance, the management of these species has traditionally taken a back seat to the management of the Cape hakes that are the target of the deep-sea trawl fishery. The FCP has improved knowledge about non-target species and enhanced the systems used for their management.
Some of the most common
bycatch species of the deep-sea trawl fishery
Kingklip
Genypterus capensis
Other names: Ling or Cusk Eel (in Australia and New Zealand)
Although a kingklip resembles an eel, its body is not round in cross section. It is tinged with a light pink colour and covered in irregular brown blotches. Kingklip can grow to 150cm in length.
Kingklip has always formed part of the catch of both the deep-sea and inshore hake trawl fisheries. Until a precautionary upper catch limit of 3 500 tons per year was applied to kingklip, catches averaged about 4 500 tons per annum. Because kingklip mainly occur on rocky terrain that is difficult to trawl, only small volumes are caught throughout the year, except for a window period during late August, September and October. Certain trawl grounds are seasonally closed to protect spawning aggregations of kingklip.
The name “kingklip” comes from the old Dutch word “koningklipvisch” which translates as “king of the rock fishes”.
Snoek
Thyrsites atun
Other names: Cape snoek; Barracouta (New Zealand and Australia)
The snoek is an elongated, silvery fish that is widely distributed in southern Africa, from northern Angola to Port Elizabeth. However, most fish are found between the Cunene River and Cape Agulhas. The snoek is a medium-sized fish that reaches a maximum length of 2m, corresponding to a mass of 9kg. In South Africa, adult fish prey mainly on sardine, anchovy and mantis shrimps.
Snoek is caught in trawl nets with hake and is a common “by-catch” species of the South African deep-sea and inshore trawl fisheries. Snoek is also an important catch of the traditional linefishery, particularly in the western and southwestern Cape and the species is targeted by recreational linefishers, usually from ski-boats.
Monk
Lophius vomerinus
Other names: Monk fish, mock crayfish
Monk is endemic to southern Africa. It is a demersal (bottom dwelling) species that occurs in deep water, usually between 90 and 500m in depth. It has a large, flattened head with a huge mouth, spanning the full width of the head. This allows the fish to swallow prey (usually small fish) as large as itself.
Monk is a classical by-catch of the hake trawl fishery, especially on the west coast. Specific trawling techniques and an experienced crew are required to fish for monk, yet the hake component always remains the major portion of the catch. As such, monk has always been accepted as an important component of the hake trawling business, averaging about 4% of the total hake catch across the entire fleet. Today monk catches are controlled by a 7 000 ton precautionary upper catch limit.
Horse mackerel
Trachurus capensis
Other names: Maasbanker; Cape horse mackerel; Carapau (in Portugal)
Horse mackerel is a pelagic fish species, meaning the fish form large schools in the surface layers of the ocean – the pelagic zone. The fish is silver with green markings and similar in shape and appearance to other pelagic species, such as sardine and anchovy. Although the horse mackerel can grow to 50cm in length, most adult fish are between 25 and 30cm long.
Horse mackerel occurs along the entire coast of South Africa and Namibia, with the biggest concentrations found between the west coast and the Agulhas Bank. It is a common by-catch of the deep-sea trawl fishery and is mostly produced and packaged whole, in frozen form. There are markets in rural South Africa and other African countries where horse mackerel is a staple source of protein.
Buttersnoek
Lepidopus caudatus
Other names: Ribbonfish; Silver scabbardfish
Angelfish
Brama brama
Other names: Atlantic pomfret
Jacopever
Helicolenus dactylopterus
Other names: Jacks, Blackbelly Rosefish (in the Northern hemisphere);
Sea Perch (Japan and New Zealand)
The Jacopever is a red-orange fish with a white belly and chest. It is caught on soft seabeds at depths of between 50 and 500m. False Bay is an important breeding ground and large numbers of Jacopever are found off the southern and western Cape coast.
John Dory
Zeus capensis
Other names: Cape Dory
John Dory are endemic to southern Africa, occurring in deep water (140 to 400 m) on the west coast. The grey-green fish are very easy to identify because they are almost scaleless and have mournful looking faces. The prominent round blotches on their sides are much less distinctive than they are on Zeus faber, a species that occurs in deep water off KwaZulu-Natal, but is not caught in the nets of the deep-sea trawl fishery.
The Ring Fence Initiative
The ring fence initiative is a voluntary undertaking on the part of SADSTIA members to only trawl on currently used grounds, prevent damage to lightly trawled areas, and to preserve natural refuges for hake.
The ring fenced area represents approximately 4.4 percent of South Africa’s territorial waters. Trawling outside the ring fenced zone requires the completion of an environmental impact assessment.
The ring fence initiative has been systematically implemented by SADSTIA. A brochure and navigational software was circulated to the entire trawling industry. The software is compatible with the plotting system used by skippers to track their trawling activities. As such, it is possible for each skipper to quickly and easily identify the boundaries of the trawl grounds, outside of which trawling is prohibited.
Image: Nozipho Mkhabela, I&J.
SADSTIA’s seabed research
Read more about SADSTIA’s seabed research: Wilkinson, S. & Japp, D. 2005. Description and evaluation of hake-directed trawling intensity on benthic habitat in South Africa. Prepared by Fisheries and Oceanographic Support Services on behalf of SADSTIA.
