scholarly journals Reproductive Biology and Fishery-Related Characteristics of the Malabar Grouper (Epinephelus malabaricus) Caught in the Coastal Waters of Mafia Island, Tanzania

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Lydia Gaspare ◽  
Ian Bryceson
Keyword(s):  
Reproductive Biology ◽  
Spawning Season ◽  
Small Scale ◽  
Northeast Monsoon ◽  
Independent Research ◽  
Spawning Aggregations ◽  
Gonadal Histology ◽  
Management And Conservation ◽  
Sexually Mature ◽  
Epinephelus Malabaricus

The reproductive biology and fishery-related characteristics of the Malabar grouper (Epinephelus malabaricus) (Bloch and Schneider, 1801) specimens were investigated. The size of females ranged from 25 to 113 cm total length (LT), with 50% sexually mature at 79 cmLT, and the males (97 cm to 114 cmLT) were larger than the females. Due to the sex ratios and size distribution of the sample, it appeared that the groupers change sex between 97 and 113 cmLT. However, the gonadal histology data lacked specimens in the transitional stage. The spawning peak occurred in November, as defined by the presence of ripe females, and the spawning season lasted from September to February. The size of the fish correlated positively with the water depth at capture, which is also related to oxygen levels in deep water being more favourable for larger fish. Larger specimens (>100 cmLT) were targeted by fishers between December and February, when the northeast monsoon coincides with calmer weather and the spawning season. Fishers were interviewed, and observations were made on fishing gear, vessels, and grounds. There was no indication that small-scale fishers targeted spawning aggregations; therefore, fisheries independent research is recommended in order to verify the time, location, and behaviour of the spawning of Malabar groupers for management and conservation purposes.

Spawning season influences on commercial catch rates: computer simulations and Plectropomus leopardus, a case in point1

1999 ◽  
Vol 56 (6) ◽  
pp. 1096-1108 ◽  
Author(s):  
Elizabeth Fulton ◽  
David Kault ◽  
Bruce Mapstone ◽  
Marcus Sheaves
Keyword(s):  
Fishery Management ◽  
Spawning Season ◽  
Small Scale ◽  
Test Case ◽  
Model Output ◽  
Commercial Catch ◽  
Spawning Aggregations ◽  
Spawning Stock ◽  
Plectropomus Leopardus ◽  
Catch Rates

Spatial and temporal closures of sections of the marine environment are proposed frequently as fishery management devices, particularly when specific areas, such as spawning aggregations, can be identified. The ultimate effectiveness of spawning area closures is unknown, as spawning-related determinants of catch rate have not been studied. A simulation model, based on existing biological and fisher information, was constructed to examine the most important determinants of the spawning season catch rates using the protogynous aggregative spawner Plectropomus leopardus (Family Serranidae, Subfamily Epinephelinae) as a test case. Model output indicated that spawning season catches rose as long as catchability of spawners was equal to or greater than that of nonspawners. Greatest increases in catch were produced by fish moving from habitats inaccessible to fishers into regularly fished locations during migrations to spawning aggregations. Elevated catches were not simply dependent on the targeting of aggregations by fishers. Small-scale spatial closures around spawning aggregation sites would not be sufficient to protect the spawning stock of fish such as P. leopardus, but larger scale closures during the spawning season may be useful even when fishers are not targeting spawning aggregations.

scholarly journals Reproductive biology of Haemulon plumieri (Teleostei: Haemulidae) in Ceará state, Northeastern Brazil

2013 ◽  
Vol 73 (2) ◽  
pp. 391-396 ◽  
Author(s):  
RA Shinozaki-Mendes ◽  
J Santander-Neto ◽  
JRF Silva ◽  
FHV Hazin
Keyword(s):  
Reproductive Biology ◽  
Fishing Effort ◽  
Northeastern Brazil ◽  
Tropical Species ◽  
Stock Management ◽  
Western Atlantic ◽  
Total Fecundity ◽  
Maturation Stages ◽  
First Maturity ◽  
Management And Conservation

The Haemulon plumieri is a typical reef-associated and tropical species found in warm and temperate waters of the Western Atlantic. Due to the large fishing effort directed to H. plumieri, the knowledge about its reproductive biology is essential for correct stock management and conservation. The aim of this study was to characterise reproductive biology with a focus on its seasonal variation of gonadal maturation stages, first maturation size and fecundity. Specimens were monthly collected and a total of 119 females and 136 males were analysed. The reproductive cycle of Haemulon plumieri is seasonal, with higher activity between March and May. Size at first maturity (L50) was estimated at 16.86 and 18.55 cm for females and males, respectively. The total fecundity ranged between 17,816 and 120,333 mature oocytes per female and relative fecundity was 235 ± 63 oocyte.g−1 whereas batch fecundity varied between 20 and 25% from total fecundity. Since the species is widely caught, we suggest a closed season from March to May and to establish a minimum catch size of 18.5 cm for both sexes, since there is no evident sexual dimorphism.

scholarly journals Seasonal variations in the population biology of Salmostoma bacaila (Cyprinidae) from a tributary of the Payra River, Bangladesh

2019 ◽  
pp. 113-119
Author(s):  
Ahamed Ahamed ◽  
Faruque Ahmed Zoarder ◽  
Jun Ohtomi
Keyword(s):  
Sex Ratio ◽  
Seasonal Variations ◽  
Population Biology ◽  
Sexual Maturity ◽  
Condition Factor ◽  
Gonadosomatic Index ◽  
Spawning Season ◽  
Frequency Distributions ◽  
Size At Sexual Maturity ◽  
Management And Conservation

Some biological parameters of Salmostoma bacaila – including sex ratio, length-frequency distributions (LFDs), size at sexual maturity, spawning season, length-weight relationships (LWRs) and condition factor – were studied. Samples were collected seasonally during June 2017 to May 2018 from a tributary of the Payra River. The overall sex ratio was significantly different from the expected value of 1:1 (p < 0.001), in favour of male specimens. Females were significantly larger than males. Size at sexual maturity was estimated at 7.6~7.7 cm total length. Seasonal variations in the gonadosomatic index (GSI) indicate that the main spawning season is from spring to summer. The LWRs showed negative allometric growth in both sexes, but with clear seasonal variation. Fulton’s condition factor varied in both sexes and was attributed to variations in GSI with maturity. The fin¬dings of this study will be helpful for management and conservation of S. bacaila populations.

scholarly journals Low Discounting Behavior among Small-Scale Fishers in Fiji and Sabah, Malaysia

2011 ◽  
Vol 3 (6) ◽  
pp. 897-913 ◽  
Author(s):  
Louise S. L. Teh ◽  
Lydia C. L. Teh ◽  
U. Rashid Sumaila
Keyword(s):  
Experimental Approach ◽  
Small Scale ◽  
Economic Factors ◽  
Discount Rates ◽  
Cultural Economic ◽  
Conservation Policies ◽  
Management Interventions ◽  
Tropical Reef ◽  
Management And Conservation ◽  
Socio Economic Factors

Understanding the socio-economic factors that are associated with fishers’ willingness to delay gratification may be useful for designing appropriate fisheries management and conservation policies. We aim to identify the predictors of low discounting behaviour among fishers, which is analogous to having a longer-term outlook. We base our empirical study on two small-scale tropical reef fisheries in Sabah, Malaysia, and Fiji. We use an experimental approach to identify fishers with low discount rates, and then use a logistic regression model to identify predictors of low discount rates. We find that 42% of the respondents have low discount rates, and that site and village level variables are significant predictors of low discount rates. Within Sabah and Fiji, boat ownership and relative catch differentiate low discounting from non-low discounting fishers, but these variables have contradictory effects in Sabah and Fiji. Overall, our results imply that a substantial proportion of reef fishers may be willing to engage in conservation initiatives; however, local socio-cultural, economic, and ecological conditions have to be considered first during the process of designing management interventions.

Vulnerability of spawning aggregations of a coastal marine fish to a small-scale fishery

2017 ◽  
Vol 164 (5) ◽  
Author(s):  
Brad E. Erisman ◽  
Juan José Cota-Nieto ◽  
Marcia Moreno-Báez ◽  
Octavio Aburto-Oropeza
Keyword(s):  
Marine Fish ◽  
Small Scale ◽  
Spawning Aggregations ◽  
Coastal Marine

scholarly journals Some Aspects of Reproductive Biology of the Mudskipper Apocryptes Bato From the Coast of Chitagong

2018 ◽  
Vol 44 (1) ◽  
pp. 91-99
Author(s):  
Mohammed Sadequer Rahman ◽  
Md Sohel Parvez ◽  
Mohammad Mizanur Rahman ◽  
Md Rashed Un Nabi ◽  
Md Wahidul Alam
Keyword(s):  
Reproductive Biology ◽  
Coastal Waters ◽  
Spawning Season ◽  
Gonad Weight ◽  
Male And Female ◽  
Length Standard ◽  
Significant Coefficient ◽  
The Right ◽  
T Values ◽  
Relationship Of

Some aspects of reproductive biology of the mudskipper Apocryptes bato (Hamilton 1822) from the coastal waters of Chittagong, Bangladesh was conducted. Disproportionate occurrence of male and female (1.20 : 1) was observed in the number of two sexes. A prolonged spawning season was found from June to early October with a single peak. The aspects in the ovary indicate one complete spawning of females in a single spawning season. The fecundity was found to vary from 7453 - 31195 with an average of 17590 ± 6867. Significant coefficient of correlation between the diameters of the eggs of corresponding anterior, middle and posterior regions of the right and left ovaries indicated the simultaneous release of eggs from both the ovaries. A much closer relationship of fecundity and the significant ‘t’ values indicated fecundity increases with the increase of total length, standard length, body weight and gonad weight. Asiat. Soc. Bangladesh, Sci. 44(1): 91-99, June 2018

scholarly journals Histology of Tritia mutabilis gonads: using reproductive biology to support sustainable fishery management

2021 ◽  
Vol 34 ◽  
pp. 6
Author(s):  
Alicia Mallet ◽  
Jean-Yves Jouvenel ◽  
Morgane Broyon ◽  
Nelly Pirot ◽  
Benjamin Geffroy
Keyword(s):  
Reproductive Biology ◽  
Fishery Management ◽  
Shell Height ◽  
Management Plan ◽  
Small Scale ◽  
Breeding Period ◽  
Management Measures ◽  
Baseline Information ◽  
Sustainable Fishery ◽  
First Maturity

The mutable nassa, Tritia mutabilis, a marine gastropod that is widely exploited on the Adriatic coast is an important source of income for small-scale fishermen in the Mediterranean Sea, particularly in the Gulf of Lion. However, the lack of knowledge on the ecology and biology of this species limits our capacities to propose and produce an effective management plan. As a result, stocks are currently declining, especially in Italy. In order to optimize a management plan for this fishery, we designed a study to better characterize the reproductive biology of T. mutabilis, using gonad histology and performing a regular monitoring of population size frequency. The average shell height of individuals during the breeding period was 24 ± 2.7 mm for males and 30 ± 3.7 mm for females. The presence of small females (10 mm) and large males (32 mm) in the whole sample challenged previous assumptions regarding protandry (sex change from male to female). The size at first maturity was estimated for males and females at 17.5 mm and 24.4 mm shell height, respectively. In Italy, current management measures include a minimum conservation reference size of 20 mm in shell height. Therefore, it is likely that many individuals that did not reproduce are being caught, which could partly explain the decline observed, despite conservation measures introduced more than ten years ago. Overall, our study provides some baseline information to establish, in consultation with fishermen, management measures for this small-scale fishery in France.

scholarly journals Assessment of small-scale variability of rainfall and multisatellite precipitation estimates using a meso-rain gauge network measurements from southern peninsular India

2015 ◽  
Vol 12 (10) ◽  
pp. 10389-10429
Author(s):  
K. Sunilkumar ◽  
T. Narayana Rao ◽  
S. Satheeshkumar
Keyword(s):  
High Resolution ◽  
Spatial Variability ◽  
Diurnal Cycle ◽  
Rain Gauge ◽  
Spatiotemporal Variability ◽  
Small Scale ◽  
Northeast Monsoon ◽  
Peninsular India ◽  
Precipitation Estimates ◽  
Rain Gauge Network

Abstract. This paper describes the establishment of a dense rain gauge network and small-scale variability in rain storms (both in space and time) over a complex hilly terrain in southeast peninsular India. Three years of high-resolution gauge measurements are used to evaluate 3 hourly rainfall and sub-daily variations of four widely used multisatellite precipitation estimates (MPEs). The network consists of 36 rain gauges arranged in a near-square grid area of 50 km × 50 km with an intergauge distance of ~ 10 km. Morphological features of rainfall in two principal monsoon seasons (southwest monsoon: SWM and northeast monsoon: NEM) show marked seasonal differences. The NEM rainfall exhibits significant spatial variability and most of the rainfall is associated with large-scale systems (in wet spells), whereas the contribution from small-scale systems is considerable in SWM. Rain storms with longer duration and copious rainfall are seen mostly in the western quadrants in SWM and northern quadrants in NEM, indicating complex spatial variability within the study region. The diurnal cycle also exhibits marked spatiotemporal variability with strong diurnal cycle at all the stations (except for 1) during the SWM and insignificant diurnal cycle at many stations during the NEM. On average, the diurnal amplitudes are a factor 2 larger in SWM than in NEM. The 24 h harmonic explains about 70 % of total variance in SWM and only ~ 30 % in NEM. The late night-mid night peak (20:00–02:00 LT) observed during the SWM is attributed to the propagating systems from the west coast during active monsoon spells. Correlograms with different temporal integrations of rainfall data (1, 3, 12, 24 h) show an increase in the spatial correlation with temporal integration, but the correlation remains nearly the same after 12 h of integration in both the monsoons. The 1 h resolution data shows the steepest reduction in correlation with intergauge distance and the correlation becomes insignificant after ~30 km in both monsoons. Evaluation of high-resolution rainfall estimates from various MPEs against the gauge rainfall indicates that all MPEs underestimate the weak and heavy rain. The MPEs exhibit good detection skills of rain at both 3 and 24 h resolutions, however, considerable improvement is observed at 24 h resolution. Among different MPEs, Climate Prediction Centre morphing technique (CMORPH) performs better at 3 hourly resolution in both monsoons. The performance of TRMM multisatellite precipitation analysis (TMPA) is much better at daily resolution than at 3 hourly, as evidenced by better statistical metrics than the other MPEs. All MPEs captured the basic shape of diurnal cycle and the amplitude quite well, but failed to reproduce the weak/insignificant diurnal cycle in NEM.

scholarly journals Reproductive biology of silurid catfishes Ompok miostoma (Vaillant 1902) in Mahakam River East Kalimantan

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
. Jusmaldi ◽  
Dedy Duryadi Solihin ◽  
Ridwan Affandi ◽  
MF Rahardjo ◽  
Rudhy Gustiano
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Spawning Season ◽  
Spawning Period ◽  
Male And Female ◽  
Gonad Maturity ◽  
East Kalimantan ◽  
Fish Samples ◽  
Total Fish ◽  
Somatic Index

Reproductive biology of silurid catfish O.miostoma(Vaillant 1902)as one of endemic species in Mahakam River East Kalimantan is not yet known. This study aimed to analysisreproductive aspect related to changing seasons, including sex-ratio, spawning season, spawning location, length at first gonad maturity, gonado-somatic index, and fecundity. Total fish samples (n=1214)were collected monthly from November 2013 to October 2014 at four locations in the Mahakam River, using many fishing gears.The results of this research showthe total length of fish ranged from 132.19 to 227.30 mm and weight ranged from 20.00 to 70.40 g. The overall sex ratio of male and female was1: 1.56, while at gonad maturity stages were1:1.77. The spawning season range from November to January and peak spawning occurs in December. The highest spawning location was found at swamp flood Semayang Lake. The length at first gonad maturity of male ranged of 191.05-202.60 mm, while it was in 179.56-198.50 female. Maximum average gonado-somatic index (GSI) values obtained for male and female were 0.32 and 2.07 respectively during spawning period in November and declined to minimum in February. The total fecundity and eggs diameter rangedfrom 2648 to 12495 eggsind-1and 0.61 to 1.30 mm respectively. There was a positive correlation between fecundity andtotal length and weightof fishes.AbstrakBiologi reproduksi ikan lais O. miostoma (Vaillant 1902)sebagai salah satu spesies endemik di Sungai Mahakam Kalimantan Timur belum pernah diketahui. Tujuan penelitian ini adalah menganalisisaspek reproduksi ikan laisberkaitan dengan perubahan musimyang mencakupnisbah kelamin, musim pemijahan, lokasi pemijahan, ukuran kali pertama matang gonad, indeks kematangan gonad dan fekunditas.Total ikan contoh 1214 ekor telah dikumpulkan setiap bulan mulai dari bulan November 2013 sampai Oktober 2014di empat lokasi perairan Sungai Mahakam, menggunakan berbagai alat tangkap. Hasil penelitian menunjukkanukuran panjang total ikan berkisar dari 132,19-227,30 mm dan bobot berkisar dari  20,00-70,40 gram.Nisbah kelamin seluruh ikan jantan dan betina yang diamati 1 : 1,56, sedangkanpada tahap kematangan gonad 1:1,77. Musim pemijahan terjadi mulai dari bulan November sampai Januari dan puncak pemijahan pada bulan Desember. Lokasi pemijahan tertinggi ditemukan di rawa banjiran Danau Semayang. Ukuran ikan pertamamatang gonad pada jantan berkisar dari 191,05-202,60 mm dan betina berkisar dari 179,56-198,50 mm. Rata-rata indeks kematangan gonad (IKG)  tertinggi ditemukan pada jantan dan  betina berturut turut 0,32  dan 2,07 selama musim pemijahanpada bulan November dan menurun hingga terendah pada bulan Februari. Fekunditas total berkisar dari 2.648-12.495 butir telur per individu.Ada korelasi positif antara fekunditas dengan panjang total dan bobot ikan.

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