Seasonal Fish Research Articles

Современный состав ихтиофауны водохранилищ Москворецкой водной системы и водораздельного бьефа канала имени Москвы

Based on the results of long-term research on reservoirs of the Moskvoretsky water system and the watershed of the Moscow canal, information is provided on the features of their hydrological, hydrochemical and hydrobiological regimes, as well as on the current composition of the ichthyofauna. The article presents the long-term dynamics of catches of fishing nets and small fry. Changes in the structure of net catches are shown depending on the mesh step of the applied nets and the depth of setting the net orders. It is established that during the period of operation of reservoirs of the Moskvoretsky water system and the watershed of the Moscow canal, the fish part of the community of this group of reservoirs is quite stable and is represented mainly by eurybiont species of the limnophilic ecological group. The similarity of the species composition of the ichthyofauna of reservoirs in the Moscow canal watershed is explained by the exchange of species and seasonal fish migrations between these reservoirs through the channel. A greater number of fish species in the reservoirs of the channel. Compared to the moskvoretskiye reservoirs, this is due to their connection through the migration corridor - channel with the Volga, a more favorable oxygen regime, and the hydrological isolation of the moskvoretskiye reservoirs. The results of long-term measures for acclimatization of fish in this group of reservoirs are described. The issue of the state of Amateur fishing in reservoirs near Moscow is considered.

Strengthening climate change adaptation strategy of fishermen (a case study in Peatland River, Kerumutan Sub District, Riau, Indonesia)

This research aimed to find out the peatland river fishermen’s adapting strategy against the climate change and the effects of strengthening the strategy. This study was an action research using participatory rural appraisal. The results showed that so far the fishermen employed local wisdom in predicting the fish output of the peatland river. The method considered the rainy days rate in mapping the quantity of tuakang, pelumpung, toman, and snakehead freshwater fish species. Local flood occurrences became the main indicator of the initiation for high fish production period. The water hyacinths preservation in pandanus forest to support fish reproduction and sunlight-dependence manual fish processing indicated the naturefriendly behaviour of fishermen community. Several attempts have been taken to reinforce the adaptation strategy of fishermen, i.e.: (1) developing the capacity of fishermen group, including preparing the fish season calendar and, fishermen time map, also fishermen institution relation map; (2) conducting training for fish processing verification; and (3) advising on the processing of water hyacinth for alternative products.

Hydroacoustic evaluation of the spatial and temporal distribution of fish in the upstream proximity of a dam in a Neotropical reservoir

Background. Construction of dams alters the physical, chemical, and ecological characteristics of the aquatic environment and modifies fish behaviour and the community composition. Few studies have shown the diel and seasonal fish distribution in tropical reservoirs, mainly in the proximity of the dam, where the risk of injury and death of fishes, which try to migrate downstream, is high. Thus, the data obtained in these regions can encourage actions that may attenuate the impacts on ichthyofauna. Hydroacoustic sampling is an effective tool to study fish behaviour and their spatial distribution in water bodies. In this context, the aim of this study was to evaluate the spatial and seasonal distribution of fish in the reservoir of Três Marias (Minas Gerais, Brazil), immediately upstream of the dam, using hydroacoustic and gillnet sampling. Materials and methods. Hydroacoustics and gillnet sampling were carried out both during the day and at night, and during the rainy and dry seasons. For the acquisition of hydroacoustic data, we employed an echosounder (BioSonics DT-X Digital Scientific) with a split-beam digital transducer. For the biological data, gillnets of different mesh sizes were set. Results. Hydroacoustic data showed significant differences in fish depth between day and night surveys, with fish remaining in deeper water during the day, a phenomenon known as Diel Vertical Migration. Furthermore, hydroacoustic data showed that smaller fish (estimated by “target strength”) concentrate at smaller depths. There was no significant difference in the size of fish between seasons. Limnological and operation variables were not related to the fish  abundance. Distribution maps showed that during the day fishes were distributed in areas more distant from the dam, while at night they were closer to the dam. Gillnets sampled 127 individuals of 22 species and 57.5% of the collected specimens were migratory species. Conclusion. These results can contribute to the understanding of fish behaviour in reservoirs, as well as provide an empirical basis for the development of novel fish management measures for Neotropical dams.

A Return to the Ghanaian Cultural Values of Closed Fishing Season in Ghana’s Artisanal Marine Fishing: An Essential Means of Restoring Small Pelagic Fish Stocks

Abstract Closed fishing season for artisanal and inshore fishing is an effective management measure for restoring the fish stock. The study aimed at assessing the impacts of the closed fishing season observed in the Sekondi harbour in Ghana. The findings revealed that the one month closure period was too short and/or lack of strict supervision to realize any significant change in fish population and sizes. A more transparent discussion on the period for the closure, longer closure period up to three months as well as provision of alternative sources of livelihood were suggested to ensure more cooperation from the fisher folks.

Annual Reproductive Cycle of Acheilognathus rhombeus, in Korea.

In this study, an experiment was conducted to investigate the annual reproductive cycle of a Korean flat bittering, Acheilognathus rhombeus, from Ogok-myeon located in Seomjin River. The reproductive cycle was examined histologically regarding water temperature and day length of the habitat, the gonadosomatic index (GSI), and developmental characteristics of female and male gonads. The maximum GSI was found to be 3.50±0.53 and 1.36±0.14 for females and males, respectively, when the water temperature and day light was 16.9°C and 11.3 hours, respectively in October 2018. On the other hand, the minimum GSI was found to be 0.16±0.09 and 0.69±0.15 for males and females in December 2018 and February 2019, respectively. The ovipositor of females appeared from August to November 2018. We compared and calculated the stages of germ cell developmental characteristics in the testis and ovaries to determine the reproductive cycle. According to the result, we classified the female A. rhombeus reproductive cycle into four phases, which are ripe and spawning phase (October), degenerative phase (November to December), growing phase (January to March) and mature phase (April to September). The annual reproductive cycle of male A. rhombeus was categorized into four phases: mature phase (June to October), degenerative phase (November to March), resting phase (April) and growing phase (May). The Korean flat bittering is an autumn-spawner as the main spawning season in October. In male, testicular spermatogonia appeared all year-round, and the ripe and releasing phase, which is characteristics of the spawning season in other fish, did not appear.

Tuning in to the male: evidence contradicting sexually antagonistic coevolution models of sexual selection in Leucauge mariana (Araneae Tetragnathidae)

Male courtship signals often stimulate female sense organs whose sensitivities originally evolved under natural selection. In classic female choice models of sexual selection, females can benefit from increasing their sensitivity and responsiveness to male stimuli; but in sexually antagonistic models, increased female sensitivity or responsiveness to males could increase the costs that females are thought to suffer from male stimulation. We tested these contrasting expectations in a previously discovered sexually dimorphic trait in the spider Leucauge mariana: 12 elongate setae on the female’s sternum that are deflected by movements of the male’s cheliceral fangs during copulation. By removing these setae, we tested whether this stimulation induces female responses that favor the male’s chances of paternity. We found that these stimuli induced females to add a product crucial to the formation of copulatory plugs. These results do not fit expectations from sexually antagonistic coevolution models of sexual selection. This conclusion resembles the heretofore unappreciated implications of specialized female sense organs in other species, and of the temporary increases in female sensitivities and responsiveness to male stimuli during the breeding season in female fish and frogs.

Influence of seasonal factors on carp fish immune reactivity

The article presents data about influence of seasonal factors on immune reactivity in carp scaly, carp framey, and carp. We studied the blood that was taken from the heart of fish in different seasons: spring (May), summer (August) and autumn (October). The research was carried out at the Lviv department of the Institute of Fisheries of the National Academy of Agrarian Science, Velykyj Ljubin in three groups of two-year-old fish. The received data give reason to think that the number of T- and B-lymphocytes in the blood of carp fish and their functional activity to a large extent depends on the influence of seasonal factors (temperature of the medium, oxygen concentration, duration of light day). This is points to the probable increase in the number of T-lymphocytes (common, active, theophylline-sensitive and theophylline-resistant) and a decrease in B-lymphocytes in the blood of investigated fish in the summer and, especially in the autumn period of research. In this case, an increase in the functional activity of T-lymphocytes was revealed due to the redistribution of the receptor apparatus of the immunocompetent cells. In particular, a reduction in the number of blood of inactive T-lymphocytes in functionally and an increase in cells with low and medium receptor density. Regarding the degree of differentiation of B-lymphocytes, the decrease in their amount in the blood of the studied individuals occurred due to the increase of “zero” and low-conductivity EAS-RUL and reduction of the subpopulation with average receptor density. We suggested that the abiotic factors can modulate the immune response of carp fish.

Interannual variation of bycatch assemblages of artisanal bottom shrimp-trawling on the Patos Lagoon estuary, Brazil

One of the most concerning problems of trawl fisheries today is the bycatch, especially given that over the last decade the Ecological Approach to Fisheries (EAF) has increased in importance. Bycatch variation is an important issue in fisheries management, since non-representative assessments of this topic can lead to the implementation of inadequate legislation. The assemblages of bycatch species in shrimp trawlings on the Patos Lagoon estuary and their relation to salinity, the size of the main species captured, and the bycatch to shrimp ratio were studied. Samples were taken between January 2011 and May 2014, encompassing four fishing seasons. We analyzed a total of 173 trawls, containing a joint total of 32,835 individuals. Sixty-one different types of bycatch species were captured, which were mostly (>80%) juveniles/non-mature individuals of commercial species. Eleven species dominated the captures, the most abundant of which were Micropogonias furnieri (FO > 82%), Callinectes sapidus (FO > 90%) and Genidens barbus (FO between 1.30–66.7%). There was a shift in assemblage structure according to salinity, which was reflected in the presence or absence of the lesser abundant species, but also in shifts on the density of the dominant species. Temperature was similar throughout the studied fishing seasons (23.9 ±3.3∘C), but salinity varied between 8.6 and 21.9. The bycatch to shrimp ratio was very high during the studied period (2011 = 3.3:1; 2012 = 2.6:1; 2013 = 8.7:1; 2014 = 65:1), but highest values were recorded when salinity was lower. However, even when environmental conditions favored pink shrimp abundance (high salinity), the ecological impact of this fishery was high, confirmed by the higher richness of species in the samples. Results call for a better fisheries management and supervision of illegal trawls.

Prevalence of Kudoa thyrsites (Myxozoa) in South African sardine Sardinops sagax, kingklip Genypterus capensis, and Cape hakes Merluccius capensis and M. paradoxus

Prevalence of infection with the myxozoan parasite Kudoa thyrsites is not well documented in sardine Sardinops sagax, the Cape hakes Merluccius capensis and M. paradoxus, and kingklip Genypterus capensis. Quantitative polymerase chain reaction assays were used to determine the prevalence of K. thyrsites in wild-caught S. sagax (n = 296), Merluccius spp. (n = 162) and G. capensis (n = 70), harvested in 2015. Sardinops sagax were harvested from the east, south and west coasts of South Africa, whereas M. capensis, M. paradoxus and G. capensis were taken from the west coast only. Relationships between K. thyrsites infection prevalence and fish capture locality, season, sex and size were determined with Chi-square tests. Prevalence was highest in S. sagax (91%), followed by M. capensis and M. paradoxus (87%) and G. capensis (40%). Prevalence was independent of sex of the host for all fish species. In the case of S. sagax only, the prevalence of infection was independent of locality of capture but depended on season, with prevalence lowest during spring and highest during autumn. No significant relationship (p > 0.05) was found between infection prevalence and host size for any of the fish species.

Economic impact of predatory piscivorous birds on small-scale aquaculture farms in Kenya

This study assessed the economic loss due to pond-fish predation by piscivorous birds in small-scale aquaculture systems in western Kenya. Piscivorous birds were surveyed in the field through daily focal scan sampling to record abundance and species richness. Overall fish damage by birds was quantified from known daily feeding rates, and economic-loss estimates were projected for a six-month production season. The influence of farm habitat features on bird diversity and frequency was also evaluated. These features included hedgerow characteristics, size of fallow areas, presence of woodlots, tree density and pond proximity to dwellings. Thirteen piscivorous bird species were identified. Their abundances increased with increasing tree density and pond distance from houses, except when exotic hedgerows were present. Total seasonal fish damage by birds, mainly large waders, across all farms was estimated at 2.141 tonnes per production season valued at USD 12,845, representing 15% of the projected production. This corresponded to an average loss of 33 kg of fish (worth USD 165) per pond, and is a substantial and challenging setback for rural aquaculture. Urgent action through habitat management and capital support is required as a necessary step for reducing investment losses and sustaining the local food supply while at the same time protecting wildlife.

Fish fauna of Obueyinomo River, Edo State, Nigeria

The fish faunal studies of Obueyinomo River, Edo state, Nigeria was carried out between May 2015 and April 2017. Fishes were caught by hired fishermen using fish trap, bagnet and hook and line. One thousand, seven hundred and twenty four fishes (1724) were caught belonging to 17 families, 25 genera, and 38 species. Clariidae and Channidae were the most abundant families with 25.2% and 16.7%, and the least abundant families were Osteoglossidae with 0.06%. The fish biomass investigation showed Channidae (31.2%), Clariidae (35%) and Malapteruridae (11.1%) as the most dominant families. Thirty one (31), (40.7%), 25 (27.2%) and 27 (32.3%) species were caught in stations 1, 2 and 3. The families with the highest number of species (7) were Cichlidae and Mormyridae. The dominant fish species were Auchenoglanis monkei, Parachanna obscura, Clarias gariepinus: and Malapterurus electricus. The seasonal fish abundance determinations showed higher catches during the rainy season (52.2%) than dry season (47.8%). The Chi-square test showed no significant difference (P>0.05) between the seasons. Findings from this study will be a useful document of the fish fauna of Obueyinomo River for prospects of harnessing the fisheries of this water body and facilitate formulation of development plan in the fishing industry.Keywords: fauna, fishermen, fish composition, fish abundance, biomass

Seasonal Fish Assemblage Structure Using Environmental DNA in the Yangtze Estuary and Its Adjacent Waters

The fisheries resources of the Yangtze Estuary and its adjacent waters have undergone dramatic declines as a consequence of environmental changes and human activities, with traditional ecological investigations demonstrating progressive decreases in species diversity and annual numbers in the fisheries resource. Environmental DNA (eDNA) technology has been demonstrated as an effective tool by many studies for detecting fish species, monitoring fish biodiversity and indicate the fish abundance. In the present study, we chose the Yangtze Estuary and its adjacent waters as a primary research area to investigate fish assemblage structure using eDNA technology. A total of 50 eDNA samples were collected in the estuary in 2018. The results showed that 41 operational taxonomic units were identified from three seasons, with 18, 12 and 33 fish species associated specifically with spring, summer and autumn, respectively. The fish assemblage differed significantly among seasons. Canonical correspondence analysis showed that water temperature, salinity, and dissolved oxygen were the main environmental factors affecting structure of the seasonal assemblages. Results of the present study indicate that eDNA technology can be an effective tool not only for fisheries monitoring, but might also importantly assist marine resources conservation, sustainable exploitation of fisheries, the aquatic products processing industry, eco-friendly development, and socioeconomic stability.

State-space modeling of multidecadal mark–recapture data reveals low adult dispersal in a nursery-dependent fish metapopulation

Quantifying connectivity within fish metapopulations is an important component in understanding population dynamics and providing an evidence base for assessment and management. We investigate metapopulation connectivity of the common sole (Solea solea) in the Eastern English Channel (EEC). The EEC common sole stock is currently assessed as a single and spatially homogeneous population, but connectivity induced through adult movements within this stock and with nearby stocks remains unknown. To fill this knowledge gap, we developed a state-space mark–recovery model, designed to estimate adult connectivity using mark–recapture data from multiple release experiments from 1970 to 2018 across the EEC and adjacent management areas. The model estimates seasonal fish movements between five predefined areas, Western English Channel, Eastern English Channel (split into three discrete sub-areas), and North Sea. Over 32 000 fish were tagged, 4036 of which were recovered via fisheries. Our results suggest minimal large-scale adult movements between these areas; movements among spatial units within the EEC were very low with even lower levels of immigration from areas adjoining the EEC. Our results support the hypothesis of segregated populations within the EEC. The importance of accommodating population substructure in the fisheries management is considered.

Business pattern and mini purse-seine fishing (pajeko) season in South Tobelo District, North Halmahera Regency, North Maluku Province

Title (Bahasa Indonesia): Pola usaha dan musim penangkapan mini purse-seine(pajeko) di Kecamatan Tobelo Selatan, Kabupaten Halmahera Utara, Provinsi Maluku Utara The study uses a descriptive method and was carried out for 5 months. Data collection covered primary and secondary data. Primary data was carried outthrough direct observation on production planning, production process, and control on the mini purse-seine fishing unit and through direct interviews with mini purse-seine owner and fishermen. Secondary datawas obtained from Marine and fisheries Service of North Halmahera. Literature study was conducted as well. The data were analyzed to find outthe business pattern practiced by mini purse-seine fishermen by usinginteractive model of analysis and time series analysis-based average percentage methodwas usedto get the fishing season.This study concluded that business pattern of fishermen in South Tobelo district was done by imposingthe operational cost on the investment owner in both peak and lowfishing seasons. Moreover, the profit sharing is divided by50% for townersand 50% for fishermen after operational cost, and 20% for the FAD if other FAD was used. The fishing season of the mini purse-seine in South Tobelo district occurrsin March, August and September, while the lowseason occursin January, February, June, November, and December.Penelitian ini menggunakan metode deskriptif dan dilakukan selama 5 bulan. Pengumpulan data dilakukan baik pada data primer maupunsekunder. Data primer dilakukan dengan pengamatan langsung terhadap perencanaan produksi, proses produksi dan pengawasan produksi unit penangkapan pajekodan wawancara terhadap nelayan dan pemilik kapal pajeko. Data sekunder dikumpulkan dari Dinas Kelautan dan Perikanan Kabupaten Halmahera Utara disamping itu dilakukan juga study pustaka. Untuk mengetahui pola usaha yang dijalankan oleh nelayan pajekodigunakan interactive model of analysis. Untuk analisis pola musim penangkapan ikan menggunakan metode persentase pata-rata (The Average Percentage Methods) yang didasarkan pada Analisis runtun raktu (Times Series Analysis). Dari hasil Penelitian ini dapat disimpulkan bahwa pola usaha yang digunakan oleh nelayan di Kecamatan Tobelo Selatan dilakukan dengan membebankan biaya operasional pada pemilik baik musim puncak maupun musim paceklik tiba. Disampaing itu system bagi hasil dibagi 50% untuk pemilik dan 50% untuk nelayan setelah dikeluarkan biaya operasional dan 20% untuk rumpon apabila menggunakan rumpon milik orang lain. Musim penangkapan dengan pajekodi Kecamatan Tobelo Selatan terjadi pada bulan Maret, Agustus, dan September, sedangkan pada bulan Januari, Februari, Juni, November, sedangkan musim paceklik terjadi pada bulan Januari, Februari, November, dan Desember.

Arctic charr brain transcriptome strongly affected by summer seasonal growth but only subtly by feed deprivation

BackgroundThe Arctic charr (Salvelinus alpinus) has a highly seasonal feeding cycle that comprises long periods of voluntary fasting and a short but intense feeding period during summer. Therefore, the charr represents an interesting species for studying appetite-regulating mechanisms in fish.ResultsIn this study, we compared the brain transcriptomes of fed and feed deprived charr over a 4 weeks trial during their summer feeding season. Despite prominent differences in body condition between fed and feed deprived charr at the end of the trial, feed deprivation affected the brain transcriptome only slightly. In contrast, the transcriptome differed markedly over time in both fed and feed deprived charr, indicating strong shifts in basic cell metabolic processes possibly due to season, growth, temperature, or combinations thereof. The GO enrichment analysis revealed that many biological processes appeared to change in the same direction in both fed and feed deprived fish. In the feed deprived charr processes linked to oxygen transport and apoptosis were down- and up-regulated, respectively. Known genes encoding for appetite regulators did not respond to feed deprivation. Gene expression of Deiodinase 2 (DIO2), an enzyme implicated in the regulation of seasonal processes in mammals, was lower in response to season and feed deprivation. We further found a higher expression of VGF (non-acronymic) in the feed deprived than in the fed fish. This gene encodes for a neuropeptide associated with the control of energy metabolism in mammals, and has not been studied in relation to regulation of appetite and energy homeostasis in fish.ConclusionsIn the Arctic charr, external and endogenous seasonal factors for example the increase in temperature and their circannual growth cycle, respectively, evoke much stronger responses in the brain than 4 weeks feed deprivation. The absence of a central hunger response in feed deprived charr give support for a strong resilience to the lack of food in this high Arctic species. DIO2 and VGF may play a role in the regulation of energy homeostasis and need to be further studied in seasonal fish.

The influence of body size and season on the feeding ecology of three freshwater fishes with different diets in Lake Erie

Isotopic niche and length-isotope relationships were quantified across the body size of three similarly-sized fish species with different feeding strategies as adults (benthivore: freshwater drum, Aplodinotus grunniens; piscivore: walleye, Sander vitreus; and omnivore: white perch, Morone americana) in Lake Erie's western basin using δ13C, δ15N and δ34S. Stable isotopes demonstrated that resource utilization changed with body size for all three species and length-isotope relationships varied with season. Isotopic niche overlap was lower when modelled with three isotopes (δ13C, δ15N, and δ34S) than with two (δ13C and δ15N), providing greater resolution of feeding ecology among the species. Based on isotopic niches, there was significant overlap in resource use among species and size classes in spring, but overlap decreased in the fall for both. In this study, freshwater fish species with different adult feeding strategies partition resources through different mechanisms that vary through body size and season. Isotopes supported the generally identified feeding ecology of each species but demonstrated that each species underwent significant changes in feeding ecology with increasing body size. Changes in isotopes across season, and body size for each species demonstrate the need for a more thorough understanding of how resource use changes with body size and season in freshwater fish.

Warm, dry winters truncate timing and size distribution of seaward-migrating salmon across a large, regulated watershed.

Ecologists are pressed to understand how climate constrains the timings of annual biological events (phenology). Climate influences on phenology are likely significant in estuarine watersheds because many watersheds provide seasonal fish nurseries where juvenile presence is synched with favorable conditions. While ecologists have long recognized that estuaries are generally important to juvenile fish, we incompletely understand the specific ecosystem dynamics that contribute to their nursery habitat value, limiting our ability to identify and protect vital habitat components. Here we examined the annual timing of juvenile coldwater fish migrating through a seasonally warm, hydrologically managed watershed. Our goal was to (1) understand how climate constrained the seasonal timing of water conditions necessary for juvenile fish to use nursery habitats and (2) inform management decisions about (a) mitigating climate‐mediated stress on nursery habitat function and (b) conserving heat‐constrained species in warming environments. Cool, wet winters deposited snow and cold water into mountains and reservoirs, which kept the lower watershed adequately cool for juveniles through the spring despite the region approaching its hot, dry summers. For every 1°C waters in April were colder, the juvenile fish population (1) inhabited the watershed 4–7 d longer and (2) entered marine waters, where survival is size selective, at maximum sizes 2.1 mm larger. Climate therefore appeared to constrain the nursery functions of this system by determining seasonal windows of tolerable rearing conditions, and cold water appeared to be a vital ecosystem component that promoted juvenile rearing. Fish in this system inhabit the southernmost extent of their range and already rear during the coolest part of the year, suggesting that a warming climate will truncate rather than shift their annual presence. Our findings are concerning for coldwater diadromous species in general because warming climates may constrain watershed use and diminish viability of life histories (e.g., late springtime rearing) and associated portfolio benefits over the long term. Lower watershed nurseries for coldwater fish in warming climates may be enhanced through allocating coldwater reservoir releases to prolong juvenile rearing periods downstream or restorations that facilitate colder conditions.

Community Mangrove Aqua-Silviculture (CMAS Culture): An Innovation and Climate Resilient Practice by the Sundarbans Mangrove Forest Dependent Rural Communities of Bangladesh

To adapt to the emergent global climate impacts, the local communities of Khulna, Satkhira and Bagerhat districts in South-Western Bangladesh have spontaneously promoted a number of social innovation using their innovative ideas and traditional knowledge. The present study highlights on this practice called as Community Mangrove Aqua-Silvi-Culture (CMAS) to cultivate some floral and faunal species of the Sundarbans mangrove ecosystem. CMAS is a plot of swampy land with 1 to 1.5 feet deep water bordered by a dyke of 0.5 to1.5 feet height from the water level. The mangrove plant species in CMAS includes Goalpata (Nypa fruticans), Goran (Ceriops tagal), Keora (Sonnerata species), Hargoza (Alanthus ilicifolius), and Baen (Avicennia Species). Besides, there is a canal of about 2-2.5 feet depth that runs along the farm dykes where fish (Telapia, Vetki, Amadi, Tengra, Carps), shrimp (Bagda) and crabs are cultured. For in depth analysis of CMAS, face-to-face interview was conducted in 18 CMAS farms to know about the cultivation method, cost-benefit aspects, environmental and social impact of this unique culture. The farm owners opined that after 13 to 14 months of plantation, which is the shortest in comparison with traditional practice, Golpata and Goran can be harvested usually in January to February. On the other hand, farming seasonality of fish and shrimps varies species to species. However, most of the fish species can be harvested in between May to June in each year. Interestingly, CMAS culture doesn’t need much care and maintenance costs. It is expected that the detailed analysis of CMAS will help the Sundarbans depended local communities more climate resilient.

Seasonal variation of water transport through the Karimata Strait

Four trawl-resistant bottom mounts, with acoustic Doppler current profilers (ADCPs) embedded, were deployed in the Karimata Strait from November 2008 to June 2015 as part of the South China Sea-Indonesian Seas Transport/Exchange and Impact on Seasonal Fish Migration (SITE) Program, to estimate the volume and property transport between the South China Sea and Indonesian seas via the strait. The observed current data reveal that the volume transport through the Karimata Strait exhibits significant seasonal variation. The winteraveraged (from December to February) transport is–1.99 Sv (1 Sv=1×106 m3/s), while in the boreal summer (from June to August), the average transport is 0.69 Sv. Moreover, the average transport from January 2009 to December 2014 is–0.74 Sv (the positive/negative value indicates northward/southward transport). May and September are the transition period. In May, the currents in the Karimata Strait turn northward, consistent with the local monsoon. In September, the southeasterly trade wind is still present over the strait, driving surface water northward, whereas the bottom flow reverses direction, possibly because of the pressure gradient across the strait from north to south.

An overview of 10-year observation of the South China Sea branch of the Pacific to Indian Ocean throughflow at the Karimata Strait

Besides the Indonesian throughflow (ITF), the South China Sea throughflow (SCSTF) also contributes to the water transport from the Pacific to the Indian Ocean. However, this South China Sea (SCS) branch at the Karimata Strait is poorly observed until 2007, even though its importance has been suggested by numerical studies for decades. In this paper, we review the nearly 10-year field measurement in the Karimata Strait by the execution of the projects of “SCS-Indonesian Seas Transport/Exchange (SITE) and Impacts on Seasonal Fish Migration” and “The Transport, Internal Waves and Mixing in the Indonesian Throughflow regions (TIMIT) and Impacts on Marine Ecosystem”, which extend the observations from the western Indonesian seas to the east to include the main channels of the ITF, is introduced. Some major achievements from these projects are summarized.