**4.6 The impact of residence time on nutrients and phytoplankton dynamics**

Monthly changes of epilimnetic TN stock were found to be related to the length of Residence Time (RT; the ratio between inflows rate and Lake Volume): higher TN stock accompanied longer RT [23, 27, 28]. Lake Volume increase and shorter RT are correlated with the epilimnetic load decline of TN an increase of epilimnetic TP loads during January–April and gradual decline later on until December was correlated with the Hydrological parameters: RT elongation during January– September, became shorter later; The decline of TN/TP Mass ratio is respective to RT prolongation: The higher the RT value is, the lower is the Epilimnetic TN/TP mass ratio [24, 26, 27]. The biomass of Peridinium contributes Phosphorus and the headwater input are carriers of Nitrogen. The shortest RTs were recorded during the Peridinium bloom onset and later when RT length declines, P-mediated Peridinium dissipates, and Epilimnetic stock diminishes. Shortest RT's were recorded during winter, and later in the year RT becomes longer. Conclusively, external hydrology (water discharge) contribute Nitrogen and Peridinium bloom in addition to dust deposition, external inputs, and bottom sediments by microbial activity contribute Phosphorus. When Nitrogen supply was declined Peridinium bloom was deleted and Phosphorus fluxes were shortened and TN/TP mass ratio was lowered. The final result was enhancement of Peridinium replacement by Cyanobacteria [28].

**133**

**Figure 11.**

**Figure 10.**

**Figure 9.**

*Sustainable Utilization of the Lake Kinneret and Its Watershed Ecosystems: A Review*

*Fractional polynomial regression between RT length (years) and algal (Peridinium, Cyanophyta) biomass (g/m2*

*Fractional polynomial regression between annual means of monthly residence time (RT in years) and years.*

*Fractional polynomial regression between RT length (years) and monthly changes of water level (m).*

*).*

*DOI: http://dx.doi.org/10.5772/intechopen.93727*

*Sustainable Utilization of the Lake Kinneret and Its Watershed Ecosystems: A Review DOI: http://dx.doi.org/10.5772/intechopen.93727*

### **Figure 9.**

*Landscape Architecture - Processes and Practices Towards Sustainable Development*

Residence Time prolongation (Water exchange reduction) affected also Nitrogen and Phosphorus dynamics (**Figures 9**–**11**). The process of Peridinium decline and Cyanobacteria enhancement was also supported by RT prolongation. The climate change initiated a linkage of chain events. Discharge decline and water scarcity (dryness) resulted WL decrease, RT prolongation and nutrient supply reduction accompanied by the modification of algal community structure. Normally, the higher the discharge is the faster is the increase of the WL and the shorter is the RT. and vice versa. The decline of discharge and Nitrogen input was accompanied by decline of epilimnetic TN stock and decrease of TN/TP mass ratio. Optimal Ecosystem management is aimed at protecting sustainability and the operation tool is through hydrological control: desirable ranges of pumping, WL fluctuations, nutrient dynamics preventing water quality deterioration resulting adequate water quality. Before 2010 the majority of domestic water supply originated from Lake Kinneret but essential climate change condition constrains created the need for the construction of alternative water source - Desalinization. The decline of discharge and insufficient Nitrogen input caused the phytoplankton community change. The newly created ecosystem structure enforced management adaptation for sustainability protection. When water budget is positive accompanied by appropriate withdraw (pumping and/or open Dam options) RT become shorter and water exchange is high. Decline of Nitrogen availability accompanied by Phosphorus enhancement caused the decline of TN/TP mass ratio [23, 35]. Hydrological management of Lake Kinneret is creating a dilemma for future implementation: Water supply is done by desalinization, salinity and Microcystis are enhanced as supported by close dams that enhance RT prolongation and water quality deterioration. It is therefore likely that recently, WL regime is not the management key factors and other parameters should step forward on the scale of priorities such as: salinity, nutrients and toxic Cyanobacteria biomass. For example, during heavy rain a partial open of the Dam is recommended to remove salt, phosphorus and Cyanobacteria biomass while water

**4.6 The impact of residence time on nutrients and phytoplankton dynamics**

Monthly changes of epilimnetic TN stock were found to be related to the length of Residence Time (RT; the ratio between inflows rate and Lake Volume): higher TN stock accompanied longer RT [23, 27, 28]. Lake Volume increase and shorter RT are correlated with the epilimnetic load decline of TN an increase of epilimnetic TP loads during January–April and gradual decline later on until December was correlated with the Hydrological parameters: RT elongation during January– September, became shorter later; The decline of TN/TP Mass ratio is respective to RT prolongation: The higher the RT value is, the lower is the Epilimnetic TN/TP mass ratio [24, 26, 27]. The biomass of Peridinium contributes Phosphorus and the headwater input are carriers of Nitrogen. The shortest RTs were recorded during the Peridinium bloom onset and later when RT length declines, P-mediated Peridinium dissipates, and Epilimnetic stock diminishes. Shortest RT's were recorded during winter, and later in the year RT becomes longer. Conclusively, external hydrology (water discharge) contribute Nitrogen and Peridinium bloom in addition to dust deposition, external inputs, and bottom sediments by microbial activity contribute Phosphorus. When Nitrogen supply was declined Peridinium bloom was deleted and Phosphorus fluxes were shortened and TN/TP mass ratio was lowered. The final result was enhancement of Peridinium replacement by Cyanobacteria [28].

**4.5 Residence time (RT) prolongation**

**132**

supply is not critical.

*Fractional polynomial regression between annual means of monthly residence time (RT in years) and years.*

**Figure 10.**

*Fractional polynomial regression between RT length (years) and algal (Peridinium, Cyanophyta) biomass (g/m2 ).*

**Figure 11.** *Fractional polynomial regression between RT length (years) and monthly changes of water level (m).*

### *4.6.1 Peridinium*

Elongation of RT corresponds to the reduction of the Peridinium biomass. The RT elongation is a signal of Nitrogen availability deficiency. A slight increase of Peridinium biomass documented during the longest RT, is probably attributed to Nitrogen input by fixation carried out by Cyanobacteria.

### *4.6.2 Cyanobacteria*

A prominent increase of the Cyanophyta Biomass (from 1.9 to 6.3 g/m<sup>2</sup> ) was documented in response to RT elongation of 1 to 15 years accompanied by decline of Nitrogen availability. It is likely that the Nitrogen deficiency in lake water was compensated by Nitrogen fixation maintained by Cyanobacteria. It is assumed that the minor decline of Cyanobacteria biomass observed during the longest RT is due to the lack of Phosphorus when Peridinium is absent.

### **5. Fishery**

The Fishery management in Lake Kinneret is aimed at both, commercial income and water quality protection and ecosystem sustainability [34]. As a result, stocking of exotic fish species was confirmed just of those which cannot reproduce in the lake, their feeding habit improve water quality and their contribution to commercial fishery is essential. Final confirmation was given after a thorough investigation which confirm the implementation of those three objectives. The Tilapia *Sarotherodon galilaeus* was indicated as an optimal species target: the species is native, feed intensively on the bloom forming Peridinium and have a high commercial value. Therefore, fishing efforts are mostly aimed at this fish and the lake population is enhanced by commercial fingerlings production. Results in **Table 5** summarized annual landings of *S. galilaeus* [36–40].

Respective data of other stocked species indicates the followings: The stocking of *Oreochromis aureus* which is not pure native species in the lake was eliminated due to food competition with preferred *S. galilaeus*; Until the mid-1990s, stocking of Silver Carp (*Hypophthalmichthys molitrix*) was not recommended aimed at enhancement of zooplanktonic algal grazers whereas later on when Microcystis replaced Peridinium its stocking was recommended due to its efficient consumption of this algae. Three Gray mullet species (Marine origin) are successfully stocked because of ecological adaptation to improve water quality, not able to reproduce in Lake Kinneret and has high commercial value. Another 7 other species of exotic species were totally deleted from stocking program. Conclusively, stocking resources are invested toward fish species that has positive impact on water quality, fishermen income, and the exotics are unable to reproduce in the lake. The fishery (landing and stocking) management policy contribute strengthening of


**Table 5.**

*Periodical means (SD) of Sarotherodon galilaeus landings (t/year) and indication of trend of changes [36, 37].*

**135**

**5.1 Zooplankton dynamics**

*Sustainable Utilization of the Lake Kinneret and Its Watershed Ecosystems: A Review*

ecosystem sustainability. Peridinium was the major food source for *Sarotherodon galilaeus*. Several other constraints created additional pressures on the fish population: Increased population of the migratory fish predator, Great Cormorant (*Phalacrocorax carbo*), reduction of stocked *S. galilaeus* fingerlings, usage of illegal fishing gill-nets mesh size, the elimination of Bleaks (Sardine: *Mirograx terraesanctae terraesanctae, Acanthobrama lissneri*) fishing, enhanced piscivory of *S. galilaeus* by *Clarias gariepinus* and outburst of Viral diseases, which infected mostly Tilapias. Ecological structure with complicated interactions require informative record long enough to ensure appropriate management decision in response to actual and unusual developed changes. Inappropriate alerted conclusions were followed a fishery crisis in Lake Kinneret when annual landings of *S. galilaeus* in 2007–2008 were less than 10 tons while normally its varied between 100 and 300. Simultaneously, documentation of the total number of fish (>90% Bleaks) was gradually increasing between 1987 and 2005. A recommendation of a three-year total fishing ban in Lake Kinneret was concluded. This decision was alternatively replaced by a recommendation of normal continuation of fishing. The fishing ban decision was canceled, and fishing continuation was confirmed formally. During 2010–2016, the population of *S. galilaeus* and consequently their landings were recovered and came to its normal level. During 2007–2008, Tilapia fishery in Lake Kinneret collapsed [18, 19]. A governmental decision of 3 years total commercial fishing ban was undertaken. Nevertheless, as part of ecological sustainability clarification of potential reasons the resolution was canceled and within 3 years the *T. galilaeus* population recovered. [36, 39]. The changes of the Phytoplankton composition were also accompanied by a modification of the fish feeding habits. During its dominance, *Peridinium spp.* was the major food component of the most valued native fish (*Sarotherodon galilaeus*) in the lake. Zooplankton was the major food constituent of the endemic Bleak cyprinids (*Acanthobrama terraesanctae terraesanctae*, *Acanthobrama lissneri*). To ensure water quality, it is important to maintain high grazing pressure of zooplankton on nano-phytoplankton. Removal of the unwanted Bleaks by intensified fishery management and the introduction of the exotic Silver Carp *(Hyphophthalmichthis molitrix),* an efficient consumer of *Microcystis,* is therefore beneficial*.* Zooplankton biomass in Lake Kinneret declined from 1970 to the early 1990s but increased thereafter. Both, the biomass and size frequency of cladocerans were affected by fish predation. Under the modified food web structure, Tilapia became a competitor with Bleaks on Zooplankton consumption. Information given in previous studies including the long-term record of the Kinneret zooplankton [1–3, 6] distribution, population dynamics and physiological trait was re-evaluated in the present paper.

The Zooplankton compartment within the Kinneret ecosystem exemplify the necessity for multi targeted maintenance evaluation [1, 2, 5, 6]. The complex interaction relationships require a comprehensive implementation. Long term (1969–2001) averages of zooplankton biomass (WW) density in Lake Kinneret is

A deeper insight into the Zooplankton temporal distribution indicates long term decline since mid-1980s accompanied enhancement of Bleak populations. The Bleaks population increase was resulted by decline of fishing pressure. Therefore, a recommendation was submitted and accepted to subsidize Bleak fishing. The concept of sustainability included reduction of cascaded top-down pressure on algal grazers to improve water quality. Nevertheless, ecosystem sustainability protection requires a comprehensive approach of which only fishery was accounted. To achieve water quality improvement by algal biomass reduction in oligotrophic deep

given in **Table 6** as averages and ranges (Max-Min) of annual means.

*DOI: http://dx.doi.org/10.5772/intechopen.93727*

### *Sustainable Utilization of the Lake Kinneret and Its Watershed Ecosystems: A Review DOI: http://dx.doi.org/10.5772/intechopen.93727*

ecosystem sustainability. Peridinium was the major food source for *Sarotherodon galilaeus*. Several other constraints created additional pressures on the fish population: Increased population of the migratory fish predator, Great Cormorant (*Phalacrocorax carbo*), reduction of stocked *S. galilaeus* fingerlings, usage of illegal fishing gill-nets mesh size, the elimination of Bleaks (Sardine: *Mirograx terraesanctae terraesanctae, Acanthobrama lissneri*) fishing, enhanced piscivory of *S. galilaeus* by *Clarias gariepinus* and outburst of Viral diseases, which infected mostly Tilapias. Ecological structure with complicated interactions require informative record long enough to ensure appropriate management decision in response to actual and unusual developed changes. Inappropriate alerted conclusions were followed a fishery crisis in Lake Kinneret when annual landings of *S. galilaeus* in 2007–2008 were less than 10 tons while normally its varied between 100 and 300. Simultaneously, documentation of the total number of fish (>90% Bleaks) was gradually increasing between 1987 and 2005. A recommendation of a three-year total fishing ban in Lake Kinneret was concluded. This decision was alternatively replaced by a recommendation of normal continuation of fishing. The fishing ban decision was canceled, and fishing continuation was confirmed formally. During 2010–2016, the population of *S. galilaeus* and consequently their landings were recovered and came to its normal level. During 2007–2008, Tilapia fishery in Lake Kinneret collapsed [18, 19]. A governmental decision of 3 years total commercial fishing ban was undertaken. Nevertheless, as part of ecological sustainability clarification of potential reasons the resolution was canceled and within 3 years the *T. galilaeus* population recovered. [36, 39]. The changes of the Phytoplankton composition were also accompanied by a modification of the fish feeding habits. During its dominance, *Peridinium spp.* was the major food component of the most valued native fish (*Sarotherodon galilaeus*) in the lake. Zooplankton was the major food constituent of the endemic Bleak cyprinids (*Acanthobrama terraesanctae terraesanctae*, *Acanthobrama lissneri*). To ensure water quality, it is important to maintain high grazing pressure of zooplankton on nano-phytoplankton. Removal of the unwanted Bleaks by intensified fishery management and the introduction of the exotic Silver Carp *(Hyphophthalmichthis molitrix),* an efficient consumer of *Microcystis,* is therefore beneficial*.* Zooplankton biomass in Lake Kinneret declined from 1970 to the early 1990s but increased thereafter. Both, the biomass and size frequency of cladocerans were affected by fish predation. Under the modified food web structure, Tilapia became a competitor with Bleaks on Zooplankton consumption. Information given in previous studies including the long-term record of the Kinneret zooplankton [1–3, 6] distribution, population dynamics and physiological trait was re-evaluated in the present paper.

### **5.1 Zooplankton dynamics**

The Zooplankton compartment within the Kinneret ecosystem exemplify the necessity for multi targeted maintenance evaluation [1, 2, 5, 6]. The complex interaction relationships require a comprehensive implementation. Long term (1969–2001) averages of zooplankton biomass (WW) density in Lake Kinneret is given in **Table 6** as averages and ranges (Max-Min) of annual means.

A deeper insight into the Zooplankton temporal distribution indicates long term decline since mid-1980s accompanied enhancement of Bleak populations. The Bleaks population increase was resulted by decline of fishing pressure. Therefore, a recommendation was submitted and accepted to subsidize Bleak fishing. The concept of sustainability included reduction of cascaded top-down pressure on algal grazers to improve water quality. Nevertheless, ecosystem sustainability protection requires a comprehensive approach of which only fishery was accounted. To achieve water quality improvement by algal biomass reduction in oligotrophic deep

*Landscape Architecture - Processes and Practices Towards Sustainable Development*

Nitrogen input by fixation carried out by Cyanobacteria.

to the lack of Phosphorus when Peridinium is absent.

summarized annual landings of *S. galilaeus* [36–40].

Elongation of RT corresponds to the reduction of the Peridinium biomass. The RT elongation is a signal of Nitrogen availability deficiency. A slight increase of Peridinium biomass documented during the longest RT, is probably attributed to

) was

A prominent increase of the Cyanophyta Biomass (from 1.9 to 6.3 g/m<sup>2</sup>

documented in response to RT elongation of 1 to 15 years accompanied by decline of Nitrogen availability. It is likely that the Nitrogen deficiency in lake water was compensated by Nitrogen fixation maintained by Cyanobacteria. It is assumed that the minor decline of Cyanobacteria biomass observed during the longest RT is due

The Fishery management in Lake Kinneret is aimed at both, commercial income and water quality protection and ecosystem sustainability [34]. As a result, stocking of exotic fish species was confirmed just of those which cannot reproduce in the lake, their feeding habit improve water quality and their contribution to commercial fishery is essential. Final confirmation was given after a thorough investigation which confirm the implementation of those three objectives. The Tilapia *Sarotherodon galilaeus* was indicated as an optimal species target: the species is native, feed intensively on the bloom forming Peridinium and have a high commercial value. Therefore, fishing efforts are mostly aimed at this fish and the lake population is enhanced by commercial fingerlings production. Results in **Table 5**

Respective data of other stocked species indicates the followings: The stocking of *Oreochromis aureus* which is not pure native species in the lake was eliminated due to food competition with preferred *S. galilaeus*; Until the mid-1990s, stocking of Silver Carp (*Hypophthalmichthys molitrix*) was not recommended aimed at enhancement of zooplanktonic algal grazers whereas later on when Microcystis replaced Peridinium its stocking was recommended due to its efficient consumption of this algae. Three Gray mullet species (Marine origin) are successfully stocked because of ecological adaptation to improve water quality, not able to reproduce in Lake Kinneret and has high commercial value. Another 7 other species of exotic species were totally deleted from stocking program. Conclusively, stocking resources are invested toward fish species that has positive impact on water quality, fishermen income, and the exotics are unable to reproduce in the lake. The fishery (landing and stocking) management policy contribute strengthening of

**Period Trend of change Periodical averaged landing (t/year) (SD)**

*Periodical means (SD) of Sarotherodon galilaeus landings (t/year) and indication of trend of changes [36, 37].*

1959–1970 Stable 175 (28) 1970–1990 Increase 248 (112) 1990–2010 Decline 231 (154) 2011–2016 Increase 184 (99)

*4.6.1 Peridinium*

*4.6.2 Cyanobacteria*

**5. Fishery**

**134**

**Table 5.**


**Table 6.**

*Averages of annual (1969–2001) means and max-min ranges of zooplankton groups (Copepoda, Cladocera, Rotifera, Total) WW-biomass (g(ww)/m<sup>2</sup> ).*

lakes Phosphorus removal is ultimately required. Because Phosphorus removal was excluded Sustainability protection was only a partial success: zooplankton biomass was recovered but algal biomass was not reduced [36–39]. The suppression of the enhanced population winter migratory fish consumer Cormorants in Lake Kinneret became essential as a protector of ecosystem sustainability [36–39]. The deportation of Cormorant from Lake Kinneret is a useful implementation of water quality protection. The number of Great Cormorant *(Phalcocorax carbo*) wintering (from the end of October through March) in the Lake Kinneret Region is approximated as 6000 (5000–7000). The predation rate of the Cormorants indicates a daily ration varying between 300 and 1000 grams per bird with the more common value of 700 grams per bird [37, 38]. Six thousand Great Cormorants preying daily at 500 g fish per bird during 100 days removed 300 tons of sub-commercial-sized Tilapia (Mostly *S. galilaeus*) from the lake. However, we have to take into account that the fishes preyed on are below the commercial size of 100 g per fish, that is to say that the potential damage is bigger (legal size >200 g/fish). Individual Tilapia preyed on weighted 50-70 g; if not preyed on they might grow up to commercial size within 5–6 months to be marketed. Consequently, the commercial value of such losses is between 1.5 and 3.0 million US\$. Such a damage to fishermen's income and ecologically to the system can be reduced by aggressive deportation of the Cormorants from Lake Kinneret and simultaneously from their night station site. The ecological contribution of Tilapia to the ecosystem aimed at water quality protection is done through the consumption of *Peridinium* biomass gradually reappeared recently. The recommended accompanied operation is Bleaks removal aimed at releasing zooplankton food biomass to *S. galilaeus*. Predictive recommendations include, among others, is a practical design which is presently under consideration aimed at achieving reduction of fish predation by Cormorant without violating accepted legislations. In other words to protect nature items together with improvement of fishery and water quality in Lake Kinneret.

### **6. Shallows: beach vegetation interface**

The lake shallows/beach interface is a contradiction between public and eco-limnological services. The surface area of the inundation zone is about 11 km2 according to: Annual WL fluctuates between 209 with lake bottom area is 168.9 km<sup>2</sup> , and 213 mbsl with lake bottom area of 161.4 km2 , lake shoreline length is 55 km and adjacent beach belt width is 50 m. This nearby water beach area is potentially open for recreation service entitled "Aquatic Recreation Belt" (ARB) [41]. Nevertheless, under temporal long-term inundation regime the ARB allocation is not precisely predictive. During heavy precipitation season WL is high and major part of the ABR area is shrunk while after low rainfall season ABR area is wider

**137**

Sustainable trait: 50 × 103

*Sustainable Utilization of the Lake Kinneret and Its Watershed Ecosystems: A Review*

and immediately covered by beach aquatic vegetation. The fast grower aquatic plants create a nuisance for aquatic recreational activities such as water access and favored environmental conditions for unwanted animals like Venomous Snakes. Fox, Mongoose, Jackal, etc. Moreover, next year the aquatic plants would be flooded and decomposed forming optimal conditions for Mosquitoes reproduction accompanied by accumulation of rotten bad smell organic matters. Reasonable solution might be mowing of those plants which on the other hand probably create shortage of spawning ground for *S. galilaeus* [10]. The Kinneret shoreline length is 55 km of which only 12.7 km (23%) are legal open public beaches. So far, prognosis of damage is practically negligible while enhancing *S. galilaeus* population biomass is possible by commercial production of fingerlings. Conclusively, partial mowing of beach vegetation and *S. galilaeus* reproduction would not be interfered. These objectives are due to the high (212–213 mbsl) WL regime. A recent computation of lake water surface area in respect to WL obviously indicates close positive significant linear regression when WL was below 210 mbsl. Under higher WL the relation was insignificant. It is because WL came the Bethsaida lagoons altitude. Resulting lower elevation of WL with respect to wide flooding area. The Beteicha lagoons densely covered by aquatic plants (*Tamarix spp., Typha spp.,* and *Phragmites spp.*) are known as an optimal spawning ground, YOY care treatment for *S. galilaeus*. Conclusively [10], beach vegetation mowing as a compromise between fish reproduction interference and human recreation is relevant when WL altitude is lower than 212 mbsl.

**7. Hula valley farmers and Kinneret limnologists should be friends**

Since 1993 flocks of migratory Cranes (*Grus grus*) stay during 4 winter months in the Hula Valley. The Crane wintering provided the most attractive target for Eco-tourism [42]. The winter migrating of app. 50,000 Cranes in the Hula Valley during 4 months are very attractive, and the touristic visits were enhanced significantly from about 50,000 during the early 1990's to almost half a million presently. The Crane wintering flocks created severe difficulties, including damage of agricultural crop and nutrient (excretions) sources in Lake Agmon-Hula and further downstream into Lake Kinneret. It might be risky for the stability of the Kinneret

approximately 44.5 tons of TP [42] beside other TP sources in the Hula Peat soil,

Protection of aquatic Ecosystem sustainability require anthropogenic control throughout the entire watershed. The social, agricultural, hydrological and ecological activities of development in the Hula Valley justify a careful approach., The Crane case, among others, require a significant consideration. The Hula Valley contribute above 50% of the external nutrient inputs into Lake Kinneret and the agricultural management has an impact on nutrients merit to the lake. Ecotouristic management including Crane wintering as visitors' attraction is part of reasonable entire Valley management and Kinneret water quality protection. Therefore collaborative management by the farmers and tourism managers is vital. A collaborative solution between farmers, nature authorities, water managers, land owners, and regional municipalities was budgeted and implemented. Money was allocated for the renting of a 40 ha field block in the valley dedicated as "Feeding Station" where purchased Corn seeds are given to the cranes twice a day. Feeding start in late December and continue until early March when the Cranes fly back to Europe for breeding. Cranes which land prior to Mid-December are deported aimed at reducing number of potential feeders, prevention damage and reduction of the cost of Corn seeds. This

agricultural fertilization and ecological processes in Lake Agmon.

Cranes excrete 5.24 gP/Ind./day during 170 days produce

*DOI: http://dx.doi.org/10.5772/intechopen.93727*

*Sustainable Utilization of the Lake Kinneret and Its Watershed Ecosystems: A Review DOI: http://dx.doi.org/10.5772/intechopen.93727*

and immediately covered by beach aquatic vegetation. The fast grower aquatic plants create a nuisance for aquatic recreational activities such as water access and favored environmental conditions for unwanted animals like Venomous Snakes. Fox, Mongoose, Jackal, etc. Moreover, next year the aquatic plants would be flooded and decomposed forming optimal conditions for Mosquitoes reproduction accompanied by accumulation of rotten bad smell organic matters. Reasonable solution might be mowing of those plants which on the other hand probably create shortage of spawning ground for *S. galilaeus* [10]. The Kinneret shoreline length is 55 km of which only 12.7 km (23%) are legal open public beaches. So far, prognosis of damage is practically negligible while enhancing *S. galilaeus* population biomass is possible by commercial production of fingerlings. Conclusively, partial mowing of beach vegetation and *S. galilaeus* reproduction would not be interfered. These objectives are due to the high (212–213 mbsl) WL regime. A recent computation of lake water surface area in respect to WL obviously indicates close positive significant linear regression when WL was below 210 mbsl. Under higher WL the relation was insignificant. It is because WL came the Bethsaida lagoons altitude. Resulting lower elevation of WL with respect to wide flooding area. The Beteicha lagoons densely covered by aquatic plants (*Tamarix spp., Typha spp.,* and *Phragmites spp.*) are known as an optimal spawning ground, YOY care treatment for *S. galilaeus*. Conclusively [10], beach vegetation mowing as a compromise between fish reproduction interference and human recreation is relevant when WL altitude is lower than 212 mbsl.
