FISHERY BULLETIN: VOL. 72, NO. 2 



YEAR PRECIPITATION 



SHARE IN TRAWL CATCH 

 HAKE LIZARDFISH 



/qISIO 5 5 10 15 



l_-l L 



15 10 5 5 1015 /ft 



TEMPERATURE YEAR 

 SEA AIR 



50/51- 



52/53- 



54/55- 



56/57- 



58/59- 



60/61- 



62/63- 



64/65- 



66/67- 



68/69- 



70/61- 



RAINY YEAR 



DRIEST JAN-APR 

 SEASON 



VERY RAINY 

 YEAR 



V.RAINY YEAR 



DROUGHT 



RAINY YEAR 



DROUGHT 



RAINY YEAR 



BELOW 75M. 

 WARM IN AUTUMN 

 & SUMMER 



AIR EXTRA 

 WARM IN WIN. 



AIR iXTRA 

 COLD IN 

 WINTER 



-50/51 



AIR EXTRA 

 COLD IN 



WINTER 



SURF. EXTRA 

 WARM IN 

 WINTER 



-52/53 



-54/55 



-56/57 



58/59 



-60/61 



-62/63 



-64/65 



-66/67 



-68/69 



-70/71 



Figure 8. — Changes of the proportion of the hake and the Red Sea lizardfish in the Israel trawl landings and their 



relationship with environmental conditions, 1950-71. 



Hence, in the case of the lizardfish, the 

 population-growth logistic curve (Bodenheimer, 

 1966) would have been extremely steep in its cen- 

 tral part with extremely sharp flexes between the 

 first and the central sections and, again, between 

 the central and the third sections of the curve. It 

 can be, therefore, speculated that this invasion 

 and expansion were not only a product of a "nor- 

 mal" population growth but were also aided by 

 additional factors. 



370 



The Role of Environmental Factors 



The sudden buildup of the Red Sea lizardfish 

 population which occurred between 1954 and 1956 

 was accomplished by a series of unusual 

 phenomena: 1) unusually high temperatures, both 

 of air and water (Ben-Yami, 1955; Oren, 1957), 

 especially in winter (Figures 1, 2, 3); 2) the ex- 

 tremely dry January-April season of 1955 (Figure 

 4), as well as a very pronounced absence of winter 



