scholarly journals Impact of a ring net fishery in the inshore marine waters of Kilifi on the reproductive biology of six pelagic fish species

2021 ◽  
Vol 20 (1) ◽  
pp. 1-10
Author(s):  
David K. Bett ◽  
Mwakio Tole ◽  
Chrisestom M. Mlewa
Keyword(s):  
Monsoon Season ◽  
Sex Ratios ◽  
Stage Iv ◽  
Composition Analysis ◽  
Northeast Monsoon ◽  
Marine Waters ◽  
Environmental Implications ◽  
Spawning Aggregations ◽  
Catch Composition ◽  
Ring Net

Ring nets are modified purse seines used for pelagic fishing along the Kenya coast. This method is however associated with potential negative environmental implications in inshore and shallow fishing grounds. Biological impacts on selected pelagic species caught in the marine waters of Kilifi were investigated during the Southeast Monsoon season (SEM) in April, May and September 2014, and the Northeast Monsoon season (NEM) in October and November 2014, and March 2015. Amblygaster sirm, Rastrelliger brachysoma, Sardinella gibbosa, Rastrelliger kanagurta, Hemiramphus far and Sphyraena obtusata were the most abundant species caught by the ring nets and comprised 68.9 % of fish catch composition. Analysis of ring net impacts on the fish sizes and maturity status were conducted for the NEM and SEM seasons. The catch composition for A. sirm in October comprised of 53.3 % juveniles and 53.4 % juveniles for S. obtusata in November. High percentages of H. far (78.3%) and S. obtusata (58.9 %) were captured in September. Incidences of undersize fish for A. sirm, S. gibbosa, R. kanagurta and R. brachysoma were observed across the seasons. Sex ratios for A. sirm, R. brachysoma, R. kanagurta and S. obtusata in the NEM season deviated from a normal ratio of 1:1 with more males observed. Females were dominant in the catch for H. far (1: 1.28) but the ratio was not different for S. gibbosa (χ² = 5.564, df = 1, p = 0.21). Males were dominant for A. sirm (1: 0.8) and S. gibbosa (1: 0.7) in the SEM season but the ratios were not different for H. far, S. obtusata, R. brachysoma and R. kanagurta. Differences in sex ratios were attributed to fish migrations and reproductive processes. Ring nets fished relatively offshore during the NEM season and targeted mainly spawning aggregations in stage IV. Immature fish in stage I and II which comprised of juveniles were harvested within sheltered inshore waters in the SEM season. Use of ring nets to target juveniles and spawning aggregations may disrupt recruitment processes. To enhance sustainable management of the ring net fishery, there is a need to develop harvesting strategies based on the information on stock status of the target fish.

scholarly journals SPATIO-TEMPORAL ESTIMATION OF INTEGRATED WATER VAPOUR OVER THE MALAYSIAN PENINSULA DURING MONSOON SEASON

2017 ◽  
Vol XLII-4/W5 ◽  
pp. 165-175
Author(s):  
S. Salihin ◽  
T. A. Musa ◽  
Z. Mohd Radzi
Keyword(s):  
Water Vapour ◽  
Monsoon Season ◽  
Temporal Distribution ◽  
Southwest Monsoon ◽  
Northeast Monsoon ◽  
Path Delay ◽  
Zenith Path Delay ◽  
Temporal Estimation ◽  
Integrated Water Vapour ◽  
Spatio Temporal

This paper provides the precise information on spatial-temporal distribution of water vapour that was retrieved from Zenith Path Delay (ZPD) which was estimated by Global Positioning System (GPS) processing over the Malaysian Peninsular. A time series analysis of these ZPD and Integrated Water Vapor (IWV) values was done to capture the characteristic on their seasonal variation during monsoon seasons. This study was found that the pattern and distribution of atmospheric water vapour over Malaysian Peninsular in whole four years periods were influenced by two inter-monsoon and two monsoon seasons which are First Inter-monsoon, Second Inter-monsoon, Southwest monsoon and Northeast monsoon.

scholarly journals Spatiotemporal Variability of Lightning Flash Distribution over Sri Lanka

2019 ◽  
Vol 82 ◽  
pp. 1-13
Author(s):  
U.G.Dilaj Maduranga ◽  
Mahesh Edirisinghe ◽  
L. Vimukthi Gamage
Keyword(s):  
Sri Lanka ◽  
Monsoon Season ◽  
Tropical Rainfall Measuring Mission ◽  
Spatiotemporal Variability ◽  
Spatial And Temporal Variation ◽  
Lightning Flash ◽  
Northeast Monsoon ◽  
Time Period ◽  
Total Lightning ◽  
Imaging Sensor

The variation of the lightning activities over Sri Lanka and surrounded costal belt (5.750N-10.000N and 79.50E-89.000E) is studied using lightning flash data of Lightning Imaging Sensor (LIS) which was launched in November 1997 for NASA’s Tropical Rainfall Measuring Mission (TRMM). The LIS data for the period of 1998 to 2014 are considered for this study. The spatial and temporal variation of lightning activities is investigated and respective results are presented. The diurnal variation over the studied area presents that maximum and minimum flash count recorded at 1530-1630 Local Time (10-11UTC) and 0530-0630LT (00-01UTC) respectively. Maximum lightning activities over the observed area have occurred after the 1330LT (08UTC) in every year during the considered time period. The seasonal variation of the lightning activities shows that the maximum lightning activities happened in First inter monsoon season (March to April) with 30.90% total lightning flashes and minimum lightning activities recorded in Northeast monsoon season (December to February) with 8.51% of total lightning flashes. Maximum flash density of 14.37fl km-2year-1 was observed at 6.980N/80.160E in First inter monsoon season. These seasonal lighting activities are agree with seasonal convective activities and temperature variation base on propagation of Intra-Tropical Convection Zone over the studied particular area. Mean monthly flash count presents a maximum in the month of April with 29.12% of lightning flashes. Variation pattern of number of lightning activities in month of April shows a tiny increment during the time period of 1998 to 2014. Maximum annual flash density of 28.09fl km-2yr-1 was observed at 6.980N/80.170E. The latitudinal variation of the lightning flash density is depicted that extreme lightning activities have happened at the southern part of the county and results show that there is a noticeable lack of lightning activities over the surrounded costal belt relatively landmass.

scholarly journals Quantifying Landscape Structure of the Kelantan River Basin Before and After a Major Flood Event Using Landscape Metrics

2021 ◽  
pp. 61-67
Author(s):  
H.Y. Abdul
Keyword(s):  
River Basin ◽  
Land Use Planning ◽  
Landscape Structure ◽  
Monsoon Season ◽  
Integrated Approach ◽  
Flood Event ◽  
Northeast Monsoon ◽  
Flood Events ◽  
Kelantan River Basin ◽  
The Impact

Over the years, flood is one of the natural hazards which occur all over the world and it is critical to be controlled through proper management. Flood in Kelantan is mainly caused by heavy rainfall brought by the Northeast monsoon starting from November to March every year. It is categorized as annual flood as it occurs every year during the Monsoon season. Severe flood events in Kelantan, Malaysia cause damage to both life and property every year and understanding landscape structure changes is very important for planners and decision makers for future land use planning and management. This research aims to quantify the landscape structure near to Kelantan River basin during the flood event using integrated approach of remote sensing (RS), geographic information system (GIS) technique and landscape ecological approach. As a result, this study provide new knowledge on landscape structure that contributes to understand the impact of flood events and provide the best ways to mitigate flooding for helping to protect biodiversity habitat and dwellers. As conclusions, this kind of study will give more benefits to various stakeholders such as Department of Irrigation and Drainage, Department of Environment, state government, fisherman and communities.

An observational study of the Kanchipuram flood during the northeast monsoon season in 2015

Weather ◽  
2018 ◽  
Vol 73 (9) ◽  
pp. 300-301 ◽  
Author(s):  
Anoop Mishra ◽  
Sagarika Chandra ◽  
Mohammd Rafiq ◽  
N. Sivarajan ◽  
K. Santhanam
Keyword(s):  
Observational Study ◽  
Monsoon Season ◽  
Northeast Monsoon

Gonadal cycle of the blue crab Portunus segnis (Forskål, 1775) (Decapoda, Portunoidea) in the Mediterranean Sea off Alexandria, Egypt

Crustaceana ◽  
2021 ◽  
Vol 94 (1) ◽  
pp. 1-27
Author(s):  
Ibrahim Gaber ◽  
Mauro Luisetto ◽  
Oleg Latyshev
Keyword(s):  
Mediterranean Sea ◽  
Germ Cells ◽  
Vas Deferens ◽  
Gonadosomatic Index ◽  
Sex Ratios ◽  
Stage Iv ◽  
Hepatosomatic Index ◽  
Chi Square ◽  
The Mediterranean ◽  
Portunus Segnis

Abstract Adults of Portunus segnis were captured from Ras el Tin beach on the Mediterranean Sea at Alexandria, Egypt, from January to December 2017. Male crabs are present in higher density in the sea during fall and winter, while female crabs are more common during spring and summer. Sex ratios were calculated as follows: number of males or females/total number of crabs. The calculated sex ratios were subjected to a Chi-square test according to the equation: , where O represents the observed frequency and E the expected frequency. One-way analysis of variance shows differences in the carapace size (length and width) and the weight of males and females during the four seasons. The hepatosomatic index of male crabs ranges from 9.1-9.25 in winter months, 8.7-7.9 in fall, being lower, 3.12-2.25, in spring and 5.96-4.13 in summer. The hepatosomatic index of female crabs is 8.9-3.9 in spring, 9.2-7.9 in summer, shifts lower to 5.1-3.2 in fall and to 4.2-1.5 in winter. The gonadosomatic index of female crabs is 0.12-8.2 in spring, 0.20-13.9 in summer and decreases to 0.66-7.8 in fall and 0.18-4.7 in winter. Ovaries and testes were isolated, fixed, and prepared for histological examination. The testicular lobes are surrounded by simple epithelium with haemolymph filling the interspaces. Seminiferous ducts are inserted in the testicular lobes. Spermatogenesis and spermiogenesis are described. The vas deferens is usually filled with spermatophores. Spermatophore formation begins in the testis near the vas deferens. Near the base of the penes there is glandular tissue. This study proposes the classification of the ovarian maturation into five stages: Stage I, Immature ovary with primary and secondary oogonia; Stage II, early maturing ovary with germ cells in different maturation phases; Stage III, mature ovary with vitellogenic oocytes and germ cells; Stage IV, maturing ovary with oocytes I, II and fully mature oocytes; and Stage V, ovary in regeneration. The wall of the spermatheca consists of a stratified squamous epithelium.

scholarly journals Data on dissolved metals in Terengganu waters of South China Sea during pre-, post-, and Northeast Monsoon season

Data in Brief ◽  
2019 ◽  
Vol 27 ◽  
pp. 104806
Author(s):  
Marinah Mohd Ariffin ◽  
Ghazali Adiana ◽  
Joseph Bidai ◽  
Lee Siang Hing ◽  
Mohd Yusoff Nurulnadia ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Monsoon Season ◽  
Northeast Monsoon ◽  
Dissolved Metals ◽  
China Sea

scholarly journals Evaluation of bias-adjusted satellite precipitation estimations for extreme flood events in Langat river basin, Malaysia

2019 ◽  
Vol 51 (1) ◽  
pp. 105-126 ◽  
Author(s):  
Eugene Zhen Xiang Soo ◽  
Wan Zurina Wan Jaafar ◽  
Sai Hin Lai ◽  
Faridah Othman ◽  
Ahmed Elshafie ◽  
...  
Keyword(s):  
River Basin ◽  
Bias Correction ◽  
Monsoon Season ◽  
Rainfall Threshold ◽  
Careful Consideration ◽  
Northeast Monsoon ◽  
Satellite Precipitation ◽  
Extreme Floods ◽  
Extreme Flood ◽  
Langat River

Abstract Even though satellite precipitation products have received an increasing amount of attention in hydrology and meteorology, their estimations are prone to bias. This study investigates the three approaches of bias correction, i.e., linear scaling (LS), local intensity scaling (LOCI) and power transformation (PT), on the three advanced satellite precipitation products (SPPs), i.e., CMORPH, TRMM and PERSIANN over the Langat river basin, Malaysia by focusing on five selected extreme floods due to northeast monsoon season. Results found the LS scheme was able to match the mean precipitation of every SPP but does not correct standard deviation (SD) or coefficient of variation (CV) of the estimations regardless of extreme floods selected. For LOCI scheme, only TRMM and CMORPH estimations in certain floods have showed some improvement in their results. This might be due to the rainfall threshold set in correcting process. PT scheme was found to be the best method as it improved most of the statistical performances as well as the rainfall distribution of the floods. Sensitivity of the parameters used in the bias correction is also investigated. PT scheme is found to be least sensitive in correcting the daily SPPs compared to the other two schemes. However, careful consideration should be given for correcting the CMORPH and PERSIANN estimations.

scholarly journals Relationship between Lightning Activity over Peninsular India and Sea Surface Temperature

2010 ◽  
Vol 49 (4) ◽  
pp. 828-835 ◽  
Author(s):  
M. I. R. Tinmaker ◽  
Kaushar Ali ◽  
G. Beig
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Monsoon Season ◽  
Lightning Activity ◽  
Sea Surface ◽  
Lightning Flash ◽  
Northeast Monsoon ◽  
Monsoon Period ◽  
Peninsular India ◽  
Seasonal Time Scale

Abstract This paper presents a study of spatiotemporal variation of lightning activity over Peninsular India (8°–22°N, 72°–88°E) by using monthly satellite-based lightning flash grid (1° × 1°) data for a period of 10 yr (1998–2007). The data are examined in terms of spatial, annual, and seasonal distribution of the lightning activity. It is found that lightning activity is higher over south Peninsular India and eastern India. On a seasonal time scale, the lightning activity shows two maxima—first in the month of May and then in the month of September. The lightning activity in the monsoon period is noticed to be considerable because of the occurrence of the low-level jet and increase in the monsoon break period. During the postmonsoon, the activity is mainly due to the presence of the convective nature of the disturbed weather during the northeast monsoon season over most parts of the east coast of south Peninsular India. The relationship between lightning activity over Peninsular India and sea surface temperature in the bordering seas (Arabian Sea and Bay of Bengal) is also examined. The results disclose a significant link between them.

scholarly journals A review of microcystin detections in Estuarine and Marine waters: Environmental implications and human health risk

Harmful Algae ◽  
2017 ◽  
Vol 61 ◽  
pp. 31-45 ◽  
Author(s):  
Ellen P. Preece ◽  
F. Joan Hardy ◽  
Barry C. Moore ◽  
Michael Bryan
Keyword(s):  
Health Risk ◽  
Human Health ◽  
Human Health Risk ◽  
Marine Waters ◽  
Environmental Implications
Sign in / Sign up

Export Citation Format

Share Document