Chapter 8: Human Uses of Bigheaded Carps
Bigheaded carps are sometimes grown in reservoirs as a type of aquaculture where market-sized fish are caught using gill nets or triangular nets from fishing vessels (Chang 1966). A few countries (e.g., Albania, Czech Republic, India, Italy, Mozambique, Slovakia) have also imported these fishes to augment wild fisheries. Li and Xu (1995) described capture fisheries for bighead Hypophthalmichthys nobilis and silver H. molitrix carps in Chinese reservoirs. The Chinese use a combination of methods to catch these fishes. Blocking nets (designed to trap and funnel, rather than entangle, the fish) are deployed in defined areas to funnel fishes into a harvesting basin or chamber also made of nets. The fishes are driven into the harvesting chamber using either seining, bubble curtains, electricity, or driving the fishes with boats. Weighted wooden boards painted white are dragged behind boats on ropes to assist in the driving of fishes. Sometimes trammel or gill nets are also used in the driving of fishes, and some fishes are caught in these entanglement gears during the process. Fishes are targeted during their spawning migrations up tributaries or in areas where abundant food sources exist. Chapman has observed that, although driving fishes into nets is an effective method of catching Asian carps, the jumping behavior of silver carp make this method dangerous for fishers and can result in bodily injury.
Most capture fisheries for bighead carps in American waters are done using trammel or hoop nets, essentially the same gear used by most freshwater commercial fishers. Commercial fishers on the Illinois and Missouri rivers often use trammel nets to catch bighead and silver carps, driving the fishes into the net with a motorboat. On the Illinois River, the fishes were sometimes periodically emptied from the boat into “live nets” in several places in the river, to be retrieved later for transport in livehaul trucks to a distributor, but this practice has now been outlawed. Commercial fisheries for bighead and silver carps exist on the Mississippi, Missouri, and Illinois rivers, and probably in other locations where bighead carps occur in large numbers and commercial fishing is legal. Fishes are sold live or dead—although increased state regulation of the possession, transportation, and sale of live bighead carp has shifted the market more toward dead fish. Live fish have a higher value but have more difficult handling requirements.