Chondrichthyes (cartilaginous fish, including sharks, rays and chaemeras) >

Fishing of cartilaginous fish

Note: This was written in the late 1980's and some of the figures are out-of-date.

Cartilaginous fishes are increasingly important fisheries species in many areas of the world as evidenced by a three-fold increase in the total catch since 1947. The catch statistics published by the Food and Agriculture Organization of the United Nations (FAO) for 1986 show that 627,000 tonnes of cartilaginous fishes were caught world-wide. This represents about 0.7 % of the total world fisheries catch which was about 92 million tonnes in 1986. Between 1947 and 1986 over 420 million tonnes of cartilaginous fishes were taken in fisheries. This does not include the millions of tonnes taken as a by-catch of other fisheries then discarded. India, Pakistan, Indonesia, Taiwan, Japan, and China are among the leading countries that catch and market cartilaginous fishes. Among African countries, Nigeria has the highest reported catches of cartilaginous fishes, and landed between 11,000 and 36,000 tonnes of cartilaginous fishes between 1970 and 1986, according to FAO catch statistics. However, catch statistics for most African countries either go unreported or the information is so scattered that an accurate assessment of the fishery is impossible.

In southern Africa cartilaginous fish fisheries have been slow to develop because of the misconception that cartilaginous fishes are `inedible'. The flesh of many species is quite palatable and can be eaten fresh or dry salted as `biltong' (jerky). Elsewhere than southern Africa, many species of sharks and rays are the basis of substantial fisheries for food, and relatives of the St Joseph (family Callorhinchidae) are fished wherever they occur. A large industry formerly existed for liver oil from various coastal sharks, which has a high vitamin A content. Soupfin sharks (Galeorhinus galeus) and several other species were heavily fished for liver oil off Australia, the United States, South America, and southern Africa. Today synthetically produced vitamin A has replaced the demand for liver oil, except for some countries where shark liver oil is cheaper to produce than synthetic vitamin A.

Several directed and by-catch fisheries for cartilaginous fishes operate in southern Africa, but only a small portion of the catch is utilized as food for the domestic market. In St. Helena Bay on the west coast dried shark meat or biltong is exported to several central African countries, most notably DRC. Gillnetters take a sizable catch of St Joseph (Callorhinchus capensis) off the western Cape, some 640 tonnes as reported by FAO in 1986, which is eaten locally. The fishery for Soupfin shark at Gans Bay once processed sharks for vitamin A liver oil, but today their operation is mainly restricted to the biltong (jerky) market, which is sold domestically.

Another fishery for small sharks, situated on the east coast, utilizes both the flesh for food and the liver oil for vitamin A. The flesh is exported to several European countries, the liver oil is processed and sold locally, fins are dried and exported for the oriental fin trade, jaws are sold for curios, and vertebrae and viscera are utilized locally for traditional medicine. There is some movement to develop a local market for leather from sharks, which is more durable and commands a higher price than ordinary leather from cattle. Preparation of hides requires much time and effort, however.

Probably the best publicized small shark fishery is that conducted by the Natal Sharks Board (NSB) to protect the bathing beaches of Natal from shark attack. The NSB catches about 1,000 large sharks per year, and currently costs about USA $4,000,000 a year to run. This is not a commercial operation but a heavily subsidized fishery where the cost to catch each shark (possibly up to $4000 at present) is considerably more than the value of the catch. The catch can only be utilized to a limited extent because of operational constraints with shark netting, which may leave sharks in the nets for long periods. Meat, hides, and fins are often unusable and carcasses must be disposed by burying them. The jaws and teeth are sold as jewelry and curios, and some fins are marketed locally. Official NSB figures are not available, but the actual catch weight is small compared to other fisheries. If the average shark caught weighs about 68 kg (about as much as a human being), multiplying this by the average annual shark catch of the NSB between 1978 and 1984 (1151 individuals), the annual catch of the NSB is about 78 tonnes. This small fishery is ecologically significant, however, because it targets sharks near or at the apex of the food web and has steadily operated for over three decades.

There are buyers of dried shark fins for the oriental fin market in major cities in southern Africa, which export them to Taiwan and Hong Kong. The value of shark fins, which are used to make the gelatinous base for shark-fin soup, has soared in the past few years: prices of USA $100.00 per kg for large fins and $25.00 per kg for small fins were recently quoted to us. This has stimulated sport anglers as well as commercial fishermen to collect and save shark fins from otherwise unwanted sharks. Offshore foreign longliners targeting billfish and tuna also collect shark fins as a major low-volume, high-value bycatch, and the effects of this largely unstudied but world-wide and pervasive fishery is virtually unknown. Local blue-water anglers and trawlermen in the western Cape suspect that blue sharks have been heavily depleted by the longline fishery in the past twenty years.

The post-JAWS media publicity on sharks has helped to stimulate a market for the jaws and teeth of sharks, which are locally sold as curios, decorations, and as jewelry or shipped overseas. Large shark jaws are valuable, and the jaws of large Great white sharks command an inordinately high value, particularly in the United States. Spot commercial fisheries for large white sharks, targeting their jaws or entire frozen carcasses for display have occured in the western Cape.

The sport angling community of southern Africa, including rock and surf and skiboat anglers, comprises another directed but largely non-utilized fishery. Up to seven tonnes of sharks and rays are sometimes landed in a single day in major angling competitions. Competitive anglers target specifically for cartilaginous fishes since points are awarded based on the total weight and sharks and rays on the average weigh more than bony fish. Unfortunately most of this catch is usually discarded or processed into fish meal. However, there is an increasing tendency for anglers to release sharks and rays after weighing and tagging them. There are specialist anglers in Natal who seek large rays for the sport they give when hooked, but release them afterwards. Many of the angling clubs maintain detailed records on their catches for the purposes of scoring in local and regional competitions. This represents an ideal database for scientists to study the long-term effects of fishing pressure for a given area and hence assist anglers in helping to maintain and manage their fishing stocks. It is essential, however, that the species being caught are accurately identified to increase the value of the information.

Trawler fleets operating off the southwest and west coast of southern Africa from Cape Agulhas to Namibia conduct the single largest fishery for cartilaginous fishes in the area. In addition to trawling vast quantities of hake and other bony fishes they catch substantial amounts of cartilaginous fishes as an untargeted bycatch. Dogfish (family Squalidae), skates (family Rajidae), houndsharks (family Triakidae), catsharks (family Scyliorhinidae), and St Joseph are the most important components of this bycatch. Most of these cartilaginous fishes are wasted because they have a low value in the trawlfish market and are generally discarded to make room for commercially valuable bony fish. A small quantity of Biscuit skates (Raja straeleni) are processed for skate wings and utilized locally. Probably most if not all of the cartilaginous fishes that are discarded are dead after being in the trawl for several hours, so these animals are essentially being exploited without being used. The catch weight of cartilaginous fishes discarded from this by-catch fishery is uncertain since no statistics are kept, and the impact of this fishery on the demersal community is presently unknown.

Using data from a research cruise of RV Africana (046) off the western Cape, we derived a weight ratio of hake to cartilaginous fishes caught on the cruise. By multiplying the ratio by the total hake catch in southern African waters, we obtained a rough estimate of about 22,000 tonnes of cartilaginous fishes caught per year in the trawl fishery. This represents about 11 million individuals assuming a weight of about 2 kg per shark, ray, or chimaera.

Text by Leonard J.V. Compagno, David A. Ebert and Malcolm J. Smale

  Iziko Museums of Cape Town, 2008

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