Analysis of long-term data-sets of limnological and ichthyological features of the Lake Kinneret ecosystem structure revealed evidence that the decline of fish landings during 2007-2008 was not an unpredicted crisis a...Analysis of long-term data-sets of limnological and ichthyological features of the Lake Kinneret ecosystem structure revealed evidence that the decline of fish landings during 2007-2008 was not an unpredicted crisis and included only Tilapias, and mostly S. galilaeus. Several factors were found to be responsible for the decline and recovery afterwards: decline of stocking, enhancement of population size of food competitors (Bleaks), the use of smaller mesh size of fishing nets, increase of predation pressure by Cormorants, the burst of Viral Disease, natural cyclic oscillation of ENSO event and its higher frequencies and intensities during the 2000’s. Therefore, recommendations aimed at ceased fishing are not justified and fishery continuation is correct: renewal of Bleaks fishing effort, improvement of fishing legislations, enforcement and management of fish stocking, and efficient implementation of Cormorants deportation.展开更多
Silver Carp (SC) (Hypophthalmichthys molitrix, Valenciennes, 1844) is a worldwide common fish for aquaculture and stocking in lakes and reservoirs. The fish is distributed through rivers, aquaculture and stocking in a...Silver Carp (SC) (Hypophthalmichthys molitrix, Valenciennes, 1844) is a worldwide common fish for aquaculture and stocking in lakes and reservoirs. The fish is distributed through rivers, aquaculture and stocking in about 90 countries around the world. SC was first introduced into Lake Kinneret in 1969 and continues onwards. Total number of stocked fingerlings (1969-2013) was 18.5 × 106 (average: 441 × 103 per year). The total catch (tons) of SC in Lake Kinneret was 3218 tons, average: 75 t/year. Studies on SC in East Lake, China, revealed that the fish was a phytoplanktivorous and percentage of consumed phytoplankton varied between 83% - 91% where Microcystis was the major item. In Lake Kinneret, the effects of SC and the Cichlid, Galilee St. Peters Fish (S. galilaeus) on Plankton resources are not independent and potentially competitors. SC is also known as efficient consumer of Microcystis. It was found that environmental conditions in Lake Kinneret were optimal for reasonable growth and recruitment of this fish to commercial fishery. The SC did not reproduce in Lake Kinneret and we recommended introducing annually 600 - 1000 × 103 fingerlings for the benefit of water quality protection and fishermen income.展开更多
Stocking of Lake Kinneret by exotic fish species (Mugilids: Mugil cephalus and Liza ramada) started in 1958. The rational stocking of Lake Kinneret with Mugilids was double functioned: To improve fishermen income and ...Stocking of Lake Kinneret by exotic fish species (Mugilids: Mugil cephalus and Liza ramada) started in 1958. The rational stocking of Lake Kinneret with Mugilids was double functioned: To improve fishermen income and the water quality in the lake. Mugilids are chosen as introduction target because their market value is high, the fish cannot reproduce in the lake and fingerlings are low cost available. During 1960-2015, 56.2 million fingerlings were introduced into the lake approximately averaged one million per year of M. cephalus (MC) and L. ramada (LR). The study of the Mugilids food composition has indicated consumption of suspensoids, mostly detritial organic particles. Therefore no damage to water quality is suggested. The best fitness between recruitment to Dock on Side landings and stocking capacity was evaluated at 3 years interval. Differences were found between recruitments of MC and LR to commercial catches by individual averaged age and weight. The long term success of Mugilid introduction to Lake Kinneret is confirmed.展开更多
文摘Analysis of long-term data-sets of limnological and ichthyological features of the Lake Kinneret ecosystem structure revealed evidence that the decline of fish landings during 2007-2008 was not an unpredicted crisis and included only Tilapias, and mostly S. galilaeus. Several factors were found to be responsible for the decline and recovery afterwards: decline of stocking, enhancement of population size of food competitors (Bleaks), the use of smaller mesh size of fishing nets, increase of predation pressure by Cormorants, the burst of Viral Disease, natural cyclic oscillation of ENSO event and its higher frequencies and intensities during the 2000’s. Therefore, recommendations aimed at ceased fishing are not justified and fishery continuation is correct: renewal of Bleaks fishing effort, improvement of fishing legislations, enforcement and management of fish stocking, and efficient implementation of Cormorants deportation.
文摘Silver Carp (SC) (Hypophthalmichthys molitrix, Valenciennes, 1844) is a worldwide common fish for aquaculture and stocking in lakes and reservoirs. The fish is distributed through rivers, aquaculture and stocking in about 90 countries around the world. SC was first introduced into Lake Kinneret in 1969 and continues onwards. Total number of stocked fingerlings (1969-2013) was 18.5 × 106 (average: 441 × 103 per year). The total catch (tons) of SC in Lake Kinneret was 3218 tons, average: 75 t/year. Studies on SC in East Lake, China, revealed that the fish was a phytoplanktivorous and percentage of consumed phytoplankton varied between 83% - 91% where Microcystis was the major item. In Lake Kinneret, the effects of SC and the Cichlid, Galilee St. Peters Fish (S. galilaeus) on Plankton resources are not independent and potentially competitors. SC is also known as efficient consumer of Microcystis. It was found that environmental conditions in Lake Kinneret were optimal for reasonable growth and recruitment of this fish to commercial fishery. The SC did not reproduce in Lake Kinneret and we recommended introducing annually 600 - 1000 × 103 fingerlings for the benefit of water quality protection and fishermen income.
文摘Stocking of Lake Kinneret by exotic fish species (Mugilids: Mugil cephalus and Liza ramada) started in 1958. The rational stocking of Lake Kinneret with Mugilids was double functioned: To improve fishermen income and the water quality in the lake. Mugilids are chosen as introduction target because their market value is high, the fish cannot reproduce in the lake and fingerlings are low cost available. During 1960-2015, 56.2 million fingerlings were introduced into the lake approximately averaged one million per year of M. cephalus (MC) and L. ramada (LR). The study of the Mugilids food composition has indicated consumption of suspensoids, mostly detritial organic particles. Therefore no damage to water quality is suggested. The best fitness between recruitment to Dock on Side landings and stocking capacity was evaluated at 3 years interval. Differences were found between recruitments of MC and LR to commercial catches by individual averaged age and weight. The long term success of Mugilid introduction to Lake Kinneret is confirmed.
