It is important to maintain contact (hydrobiological)
During monitoring in the Teva Hula Nature Reserve, species of fish were found climbing upstream, and their presence indicates that the fish ladder built in the reserve has re-established its natural hydrological connection to the Jordan system. In the Upper Jordan they are working to remove more hydrological barriers.
At the beginning of the summer of 2024, the fish company was monitored in the Teva Hula Nature Reserve and among the species found were also a large midge scaly and an Israeli flounder. These species have not been found in the reserve since Lake Hula dried up in the 50s and cut off the connection between it and the Jordan system, and were found there again after the reconnection between them in 2015.
Connectivity was interrupted due to the height difference between the Hula Reserve and the Jordan system: while the reserve remained in its original height, the Jordan system dropped by about 2 m due to soil erosion caused by the drying up of Lake Hula. In the last decade, the Hula reserve underwent physical restoration and a change in the water interface, and an area of 400 dunams in its northwestern part was flooded, and a fish ladder was built there to renew the connection between the reserve and the Jordan system.
Indeed, today, the fish community in the flooded area is similar to the fish community in the canals of the Jordan system, and it includes ten species: Israeli flounder, large scaly flounder, long-headed flounder, Lebanese galilean, common yablas, Jordan flounder, Lebanese lisner, common tilapia, blue flounder, and common catfish.
The return of the Israeli Hephaf and the large scaly female species, which migrate up streams to breed and are able to climb up fish ladders, indicates that the fish ladder is what made it possible to renew the hydrobiological connectivity between the reserve and the Jordan system, and illustrates the great importance of removing barriers in continuous water systems, especially in streams.
Barriers in the upper Jordan system
The upper Jordan system, including the Hula nature reserve, extends from the sources of the Jordan - from the rivers Dan, Hermon, Shenir and Eyon - to the Sea of Galilee, and is a very significant flowing habitat in Israel. Every year about 430 million cubic meters of rainwater and springs flow through it in permanent streams, seasonal streams and artificial canals, the total length of which is about 400 km.
However, the streams and canals are riddled with artificial barriers created for human needs. Dams, water diverters, measuring stations with a waterfall and other artificial structures built along the course of the streams - all of these allow the passage of water, but hinder the free passage of aquatic animals along the streams and even block it altogether.
These hydrobiological barriers harm nature:
They cause biological fragmentation, affect the size of the populations and threaten the biological diversity in the streams. It is understood that most of their damage is evident in the sections of the streams upstream of the barrier: the more barriers there are in the stream, the poorer the upstream becomes in abundance and variety of species.
Several years ago, the Nature and Parks Authority began to restore aquatic habitats and remove hydrobiological barriers in the Jordan system in cooperation with the Drainage Authority.
In 2018, a comprehensive survey was conducted in the upper Jordan system to map the barriers in all the channels where water flows all year round: the mountainous Jordan, the Jordan canals in the center of the valley, the Hula Nature Reserve, the Dopan springs (basalt streams and small flat streams), the Jordan, mountain streams, the Dan tributaries and Nahal Eyon .
235 hydrobiological barriers were found in the survey. The facilities that constitute a biological barrier in the streams are intended for different needs - for crossing roads and agricultural roads over waterways, for measuring water flow in the stream and for diverting water. About a quarter of the facilities surveyed completely block the passage of aquatic animals up or down the stream or in both directions. The highest number of barriers is in Nahal Dan and its tributaries - more than 70.
Following the survey, several barriers were removed:
Two in historic Jordan in the center of the Hula Valley, and five more will be removed soon; A roadblock was removed in Jordan near the traffic jam bridge; Another fish ladder was built in the Hula Reserve at the outlet of the water to the Jordan; And a full block was removed at the outlet of Nahal Oravim to the Jordan.
Outlines for the future were also outlined: there are budgeted plans for the treatment of measuring stations of the hydrological service, which block the flow of water in the Meshus, Dalit and Zalmon streams, which feed the Kinneret; There are plans to remove barriers at two important dams in the Jordan system - Kfar Blum Dam and Kfar Hanasi Dam; And in the Dan system there is a plan to restore connectivity in the Tal segment within the Tal Horesh area.