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Procambarus clarkii, as an invasive species, has proved to have an adverse impact on the Egyptian freshwater system, nevertheless, its fisheries could be one of many ecosystem services it can provide to society. This study aims to document the main fisheries characteristics of this species during 2014. Many fishing methods were found to capture P. clarkii including trammel nets (Estaquaza and extended nets), gill nets, and traps. About 70% of the individuals had carapace lengths between 39 and 52 mm and 95 % the individuals had a mean carapace length that exceeds the harvestable limit (35 mm). The length-weight relationship data of P. clarkii showed an allometric growth for weight more than for length (b > 3). The variations in male and female sex ratio with length classes showed that males of P. clarkii predominated all length classes except length classes 8 and 12 cm total length. The results of this study indicate that the crayfish grows considerably longer in the River Nile than it usually does in its original environment and that there is an assisted population, and high yields are expected when crayfish from the River Nile are to be utilized for commercial purposes.

Lake Nasser, a large man-made tropical reservoir, is located in the southern part of Egypt. The lakes’ fisheries have undergone a steady decrease during the last 10 years obscuring its potential for sustainability. Fisheries assessment study based on the fishing activities is essential to attain reliable information for construction a management plan to achieve rational and sustainable exploitation. Spatial and landing site surveys were conducted during the period from 2016 to 2017. More than 300 random fishing boats were examined to investigate their fishing gears characteristics, species composition, mean trophic level and catch per unit effort. More than 13,000 fish specimens from the catch were sampled and investigated for the gear selectivity study. The results indicate that trammel nets, gill nets and long-lines are the main fishing methods used. Thirty-four fish species were recorded in the lake, 6 of them were dominant, namely; Oreochromis niloticus, Sarothrodon galilaeus, Coptodon zillii, Lates niloticus, Alestes baramoze and Hydrocynus vittitus. The lake exhibits spatial variations in its productivity as the southern part is more productive. The time series of size and CPUE showed a high exploitation rate for the most important commercial fish species in the lake by the fishing gears used. Measures for fishery management based on gear selectivity are suggested for sustainability. Keywords: Lake Nasser, Fisheries management, Gear selectivity

The annual catch of bogue, Boops boops, in Egypt decreased from about 4000 MT to be 2000 MT in last 10 years. The present study provided information on the fisheries biology of B. boops, from Egyptian Mediterranean waters for management purpose. Monthly random samples of total 1367 specimens were collected from three landing sites front Alexandra during 2018. Results showed that, the total length of B. boops varied from 9.3 to 23 cm, while the total weight ranged between 7.4 and 133.1 g. The length-weight relationship revealed that “b” value (2.96) is indicating a tendency towards isometric growth with statistically highly significant coefficient. The longevity of B. boops was estimated to be 4 years and age groups I+ and II+ were the most abundant in the catch constituting more than 85%. The length at first capture and first maturity was 12.5 and 13.2 cm respectively. The mortalities rates were 0.671, 1.589 and 2.26 y-1 for natural, fishing and total mortalities, respectively. The bogue stocks in the Mediterranean waters front Alexandria was exposed to over exploitation (E= 0.70). For fisheries management, some measures were proposed for stock maintenance, fisheries development and catch sustainability.

Lake Manzala undergoes a decline in its fish production in recent two decades. The present work aims to assess the axes and constraints for development of its fisheries. Descriptive and quantitative analyses were conducted for its production during the period from 1995 to 2016. The results revealed that Manzala Lake produced 59.6 thousand MT (14.6% total fish production in Egypt) during 1995 and declined to 42.3 thousand MT (3.4%) during 2016. Statistically, data revealed that estimated model at 10% change in tilapia production led to 78% in the lake total production, 10% change in catfish led to change in 17% of the lake total production and about 93% of annual production leads to changes in fish species. The annual increment in productivity per boat was estimated as 1.14 MT, with estimated 6% rate of change during period from 1995 to 2016 based on the linear regression of average productivity per boat. In addition, productivity per fisherman indicated that there was a progress trend estimated at 7.5 MT per year, with a rate of change estimated at 4% during the study period. And, the average productivity was slightly increased from 313.7 to 384.6 kg between 1995 and 2016, respectively. In conclusion, this study suggests some solutions for constraints which are negative affecting the lake development.

The present study focused on the determination of the baseline data and correlations between biological and physicochemical variables, including the assessment of trophic conditions in Lake Qarun. The concentrations of nutrients were high, with the maxima usually in the east subarea (total nitrogen 6.40 mg dm-3, mineral nitrogen 2.34 mg dm-3, orthophosphates 0.22 mg dm-3). A total of 134 phytoplankton species were recorded. Bacillariophyceae and Dinophyceae co-dominated spatially and seasonally in phytoplankton assemblages. The highest phytoplankton density (935 × 104 cells dm-3) and chlorophyll a content (69.3 μg dm-3) were recorded in the east subarea of the lake, whereas the largest total and dominant fish (Mugil cephalus and Solea spp.) were in the west. Tilapia zillii and Engraulis encrasicolus were most abundant in the east and in the middle part, respectively. When phytoplankton density decreased from the east toward the west subarea, the Secchi disk depth increased. The TLI-based assessment indicated hypereutrophic waters at most sites of Lake Qarun. Statistically significant positive or negative correlations were found between the dominant fish species: T. zillii and Solea spp., and the phytoplankton density, Dinophyceae density, concentrations of TP, chlorophyll a, ammonium, nitrite and nitrate. Such correlations may be helpful to better understand how to enhance the sustainable fish production.

Qarun Lake is a closed salty basin located about 90km southern Cairo Egypt, cover an area of 230km 2 with annual production of about 3000 tonnes. The present study assessed the lake fishery for better management purpose. Data, information and samples were collected through 42 field trips and 311 fishermen interviews during fishing season (2010-2011). The lake was divided into three sub-areas, east, middle and west. It was found that the fishing gears used in the lake were; 1-Trammel nets with four types differed in their dimensions, mesh sizes and mainly targeting Mugil cephalus, Tilapia zillii, Solea spp. and Liza spp. 2- Seine nets with three types that were targeting M. cephalus, anchovy and shrimp. 3- Others fishing methods (Fishing aggregation system, traps and hooks) targeting mainly T. zillii. For each gear and methods used, the species composition (target and by-catch) and catch per unit effort were estimated according to sub-area and season. It is realized that middle area was more productive with higher species diversity. The present study recommends prohibiting traps in spring and all seine nets except Gahzl Zardina during summer in west and improving the fish catch and effort statistics for sustainable management of this valuable resource.