Fishing about and about fishing

Ben-Yami Column- WORLD FISHING AND AQUACULTURE,  November 2014

 

THE JUMPING MULLETS

 

Grey mullets are funny fish. When fenced off - they'll just jump over the net corkline and laugh at you from the outside. They may also jump back and forth - just for fun. This is why fishermen, especially in Mediterranean, in China, and around Indian Ocean, have been using for ages "verandah" nets. Well, grey mullets are not the only fishes that jump to escape being fenced off. Carps and some other fishes, like tilapia, are also among the jumpers, and represent the main catch in verandah-styled gear in some Asiatic countries, but the mullet high-jumpers no doubt are in the top Olympic league in their size class.

 A veranda net (Italian "saltarello"), consists of a vertical net wall that all along its corkline is mounted an about 1.5-2 m wide strip of netting, bordered by another corkline. To keep it horizontal and well spread in water, bamboo sticks or, nowadays, plugged plastic tubes, are fit at intervals into the "verandah". In some areas the verandah is made of trammel netting, which keeps the fish entangled. Verandah nets come in two main forms: fixed setnets and floating. The setnets, usually fixed across known swimming path of the fish, may be hung on stakes, either in a straight line, or as a weir, in a semi-surrounding or spiral form, sometimes with "wings" guiding the fish into the verandah-net trap. The floating ones are set around spotted fish schools. Often fishermen in auxiliary small boats enter the surrounded or semi-surrounded space and create noise to scare the fish into the net.

  Verandah (FAO)

Grey mullets have served as an important source of food in Mediterranean Europe since Roman times. The family Mugilidae includes about 80 species in 17 genera, half of them in just two genera (Liza and Mugil). Mullets are distinguished by the presence of two separate dorsal fins, small triangular mouths, and the absence of a lateral line. They feed at the lowest trophic levels on plants, detritus and algae, and most mugilids have unusually muscular stomachs and a complex pharynx to help in digestion.

Mullet are grown in ponds and semi-enclosed water bodies in Egypt, China, Hawaii, Italy, Japan, Philippine, Taiwan, Russia, Israel, and other parts of the world. In most cases they're grown in polyculture with carps, tilapia, and milkfish. Mullets (Family Mugilidae), and especially the flathead grey mullet Mugil cephalus and thinlip mullet Liza ramada, while highly esteemed, and therefore, massively cultured in Egypt, represent worldwide the bulk of the farmed mugilids.

 

Flathead grey mullet is a common species in tropical and temperate waters of the Atlantic. It occurs at temperatures ranging from 8-24 deg.C, from the Bay of Biscay southward, in the whole of Mediterranean and Black Sea, as well as in the temperate Pacific, and in the Indian Ocean. Last century, it was introduced into the Caspian Sea, where it abounds since. It's usually found in schools in calm waters close to shore, around mouths of rivers, streams and inlets, and in brackish or hyper-saline (that's in waters saltier than seawater) bays, lagoons, and harbours, mainly over sand or mud. The flathead is an omnivorous feeder, feeding on zooplankton, small benthos including invertebrates, and algae. When food available it would feed also at the surface. 

 

It's caught with beach seines, gillnets, cast nets, liftnets, barrier nets, trammel nets, and other artisanal gear. It reaches maximum size of 120 cm, but is commonly caught at 35-50 cm. Apart from some limited induced breeding, grey mullets culture depends on fingerlings collected from coastal waters. Among the countries with the largest catches are Egypt, Korea, Republic of China, and Venezuela.

 

Grey mullets fetch the best prices, where marketed fresh or fresh-frozen. In certain areas, for lack of on-board refrigeration or well-equipped beach-landing installations, and also for lack of demand for the costly fresh fish, they are processed into dried, salted product. Their roe, which in some areas, such as Egypt and the Far East, is relatively highly valued, is sold fresh, salted and dried, or smoked.

 

Grey mullet farming and capture fisheries in Egypt.  Egypt uses wild-caught mullet seed for the annual restocking of inland lakes for at least 80 years. The world's mullet empire, it boasts over 90% of the world's grey mullet farming yield. The positive experience with collection of wild fingerlings, at low costs has inhibited the development of hatcheries. With 156,400 mt produced in 2005, mullets are very important in the national aquaculture production. Current legislation prohibits wild seed fisheries except under the direct supervision of the relevant authorities. In 2005, 69.4 million mullet fry were caught for both aquaculture and culture-based fisheries. A parallel illegal fry fishery exists, however, affecting management and statistical data. The effect of wild seed fisheries on the wild stocks of mullet is not well studied. The negative effect of the fingerlings collection activity is a matter of debate between fish farming and capture fisheries communities, although the capture of wild mullet fisheries shows no observable effect of fry collection on mullet yields during the last 25 years.

 

In Taiwan and in Israel. Taiwanese scientists and fish farmers have pioneered induced breeding and larval rearing of flathead grey mullet already in the 1960s, with the first success - in 1969. During the 1970s, the complete generation cycle was achieved, contributing to artificial breeding of grey mullet, as well as other marine finfishes. However eventually, artificial breeding of grey mullets has not been applied on a wide commercial basis, due to the great availability of fry at much less financial cost.

In Israel, where the artificial breeding of grey mullet has been achieved in parallel and in cooperation with the Taiwanese, the fingerlings for annual stocking in Lake Kinneret and the fish-ponds also come cheaper from the wild.

 

Still, the ability to induce spawning and the more difficult larval rearing in fast growing grey-mullet species should counterweigh their overfishing, and the jolly mullets would keep jumping.