Estimating peak breeding season, size at first maturity and variation in fecundity and egg-size at different sizes of Hilsa (Tenualosa ilisha).

Hilsa shad, Tenualosa ilisha, has recently gained momentum due to its taste, nutrition and demand. Imposing ban at peak breeding and setting up a minimum capture size are two of the most effective tools for conservation and management of any fish species. Although, Bangladesh government has been imposing ban on a particular time and set the minimum legal size, there is still contradictory information on these two issues. That is why, a study was carried out to determine peak season of breeding and first maturity of Hilsa collected across the natural habitats in Bangladesh. Variation in fecundity and egg-size at different sizes were also investigated. Peak breeding season was identified observing gonadosomatic index of female Hilsa all the year round. First maturity was estimated with Probit analysis. Based on the gonadosomatic index of gravid females, peak breeding season was identified as late October to early November in this study. However, another minor peak was found in February-March. The highest GSI value (12.1) was observed in October-November, which indicates the peak time of spawning. The size at maturity (M50) of female Hilsa was estimated as 31 cm total length. A significant variation was observed in egg sizes between the left and right lobes of the fish (t (24) = 2.42, p = 0.02), and between the parts of the same lobe (p = 0.03). However, fish length and weight had no effect on egg size(for egg-size vs. fish length, r = -0.009, p = 0.966; and for egg size vs. body weight, r = 0.132 and p = 0.530). The average egg count from left lobe and right lobe were recorded as 0.375 ± 0.16 million, 0.371 ± 0.17 million. Total fecundity was counted as 0.745 ± 0.33 million. A significant positive correlation was noticed between length, weight, and total fecundity (r = 0.7 for total fecundity vs. body weight; r = 0.6 for of total fecundity vs. length). No significant variation was observed in fecundity between the left and right lobe (p = 0.6) and among three parts of a lobe (p = 0.3). The size of eggs varied between two lobes and among different parts of a lobe. The eggs from middle part were bigger in size than the other parts. The findings of our study will help conserve and manage the natural population of Hilsa (T. ilisha) in Bangladesh and contribute to the wider scientific community.

Comparative growth and morphometric assessment between cultures of wild and hatchery-produced mud crabs.

This paper reports the comparative growth, nutritional performance, and morphometric variation between wild and hatchery-reared juvenile mud crabs (Scylla olivacea) in earthen ponds. The crabs were fed daily with boiled tilapia paste at a feeding rate of 5-8% body weight for the first two weeks, followed by feeding with chopped eviscerated tilapia until termination of the experiment. Selected phenotypic trains, including carapace width (CW), carapace length (CL) and abdominal width (AW), were measured weekly. The protein content of the muscle (21.13%), gill (13.51%) and egg (43.28%) were significantly higher in the hatchery-sourced compared to wild female crabs (muscle = 19.15%; gill = 10.09%; egg = 38.15%). Likewise, the hatchery sourced crabs exhibited higher lipid content in the muscle (2.45-2.51%) and eggs (7.51%) compared to the wild counterparts (muscle = 1.45-1.47%; egg = 6.15%). These findings suggested a superior nutritional quality of the hatchery-reared compared to the wild-sourced crabs. Although some selected phenotypic traits did not vary among the wild and hatchery-reared crabs (p < 0.05), their survival rates varied significantly depending on the stocking density (p < 0.05). Overall, the findings suggest that the growth characteristics of the hatchery produced and wild-sourced crab were similar, which will help to remove the misconception among the crab farmers about the hatchery seeds and promote diversification of the crab production system for long-term sustainability.

Identifying peak breeding season and estimating size at first maturity of mud crab (Scylla olivacea) from a coastal region of Bangladesh.

Recently mud crab (Scylla olivacea) has emerged as a potential export commodity. Its farming is increasing rapidly in Bangladesh because of its lucrative price and high demand in international market. However, the farming or fattening of mud crab is totally dependent on capture of wild crablets. A huge quantity of mud crabs is being caught indiscriminately from nature and thus putting intense pressure on its wild stock, which is a major concern of conservation. Imposing ban at peak breeding season and setting a legal capture size are considered effective management tools for safe migration and spawning of berried females. There is contradictory information on breeding season of mud crab in Bangladesh. Thus, it is crucial to identify the peak breeding season of it and to formulate conservation policies to protect the berried crabs. Live crabs were collected year-round from the river adjacent to southwest part of Sundarbans. Although mud crab breeds throughout the year, March-April was identified as the peak breeding season of it. The second peak was observed in August-September. The highest abundance of crablets (1-2 months age) was recorded in May-June, and the lowest in January-February. Immature crablets were found all through the year that proves that mud crab is a continuous breeder. The highest amount of GSI value (11.6) was observed in February-March, which indicates that the breeding is very near. The size at first maturity (M50) was estimated as 95.5 mm CW which lied at size class 91-100 mm (CW). The findings from the study will assist in fixing up the banning time and thus protecting the mother crabs; and will assist in formulating police to conserve and protect juvenile crabs in the sense that the minimum legal capture size of crabs will allow the adults to mate and spawn at least once before their capture.

COVID-19 (Coronavirus) Pandemic: Information Sources Channels for the Public Health Awareness.

The main purpose of this paper is to highlight the important information sources of the Public Health awareness used by the library and information sources in this Pandemic situation. Social distancing phase Information professional used a different medium to connect with their patron and try to serve the best manner. The role of the information professional in health information and health literacy is very vital. Information professional public health awareness information with the library patrons and the general public. In this paper, the researchers provide a brief introduction to different information channel support in information dissemination.

The COVID-19 (Coronavirus) pandemic: reflections on the roles of librarians and information professionals.

This Regular Feature explores the role of health science librarians in the coronavirus pandemic. COVID-19 has spread rapidly all over the world. All major cities around the globe are in lockdown. In Pakistan, the first case was diagnosed on 26 February 2020, and currently, there are more than 2039 diagnosed cases and 26 deaths as on 31 March 2020. Across the country, there are further 12 000 suspected cases. This will undoubtedly increase if precautionary measures are not taken. Pakistani universities, colleges and schools were in lockdown. The role of university librarians in this emergency included raising awareness through public health education, providing support to medical staff, researchers and providing ongoing traditional services to regular library patrons in Pakistan. The Regular Feature also provides links to useful resources. JM.

Transcriptome analysis and characterisation of gill-expressed carbonic anhydrase and other key osmoregulatory genes in freshwater crayfish Cherax quadricarinatus.

The pH and salinity balance mechanisms of crayfish are controlled by a set of transport-related genes. We identified a set of the genes from the gill transcriptome from a freshwater crayfish Cherax quadricarinatus using the Illumina NGS-sequencing technology. We identified and characterized carbonic anhydrase (CA) genes and some other key genes involved in systematic acid-base balance and osmotic/ionic regulation. We also examined expression patterns of some of these genes across different sublethal pH levels [1]. A total of 72,382,710 paired-end Illumina reads were assembled into 36,128 contigs with an average length of 800 bp. About 37% of the contigs received significant BLAST hits and 22% were assigned gene ontology terms. These data will assist in further physiological-genomic studies in crayfish.

Analysis, characterisation and expression of gill-expressed carbonic anhydrase genes in the freshwater crayfish Cherax quadricarinatus.

Changes in water quality parameters such as pH and salinity can have a significant effect on productivity of aquaculture species. Similarly, relative osmotic pressure influences various physiological processes and regulates expression of a number of osmoregulatory genes. Among those, carbonic anhydrase (CA) plays a key role in systemic acid-base balance and ion regulation. Redclaw crayfish (Cherax quadricarinatus) are unique in their ability to thrive in environments with naturally varied pH levels, suggesting unique adaptation to pH stress. To date, however, no studies have focused on identification and characterisation of CA or other osmoregulatory genes in C. quadricarinatus. Here, we analysed the redclaw gill transcriptome and characterized CA genes along with a number of other key osmoregulatory genes that were identified in the transcriptome. We also examined patterns of gene expression of these CA genes when exposed to three pH treatments. In total, 72,382,710 paired end Illumina reads were assembled into 36,128 contigs with an average length of 800bp. Approximately 37% of contigs received significant BLAST hits and 22% were assigned gene ontology terms. Three full length CA isoforms; cytoplasmic CA (ChqCAc), glycosyl-phosphatidylinositol-linked CA (ChqCAg), and ß-CA (ChqCA-beta) as well as two partial CA gene sequences were identified. Both partial CA genes showed high similarity to ChqCAg and appeared to be duplicated from the ChqCAg. Full length coding sequences of Na(+)/K(+)-ATPase, V-type H(+)-ATPase, sarcoplasmic Ca(+)-ATPase, arginine kinase, calreticulin and Cl(-) channel protein 2 were also identified. Only the ChqCAc gene showed significant differences in expression across the three pH treatments. These data provide valuable information on the gill expressed CA genes and their expression patterns in freshwater crayfish. Overall our data suggest an important role for the ChqCAc gene in response to changes in pH and in systemic acid-base balance in freshwater crayfish.

Comparative analysis of gill transcriptomes of two freshwater crayfish, Cherax cainii and C. destructor.

We undertook deep sequencing of gill transcriptomes from two freshwater crayfish, Cherax cainii and Cherax destructor, in order to generate genomic resources for future genomics research. Over 83 and 100 million high quality (quality score (Q)≥30) paired-end Illumina reads (150 bp) were assembled into 147,101 and 136,622 contigs in C. cainii and C. destructor, respectively. A total of 24,630 and 23,623 contigs received significant BLASTx hits and allowed the identification of multiple gill expressed candidate genes associated with pH and salinity balance. These functionally annotated transcripts will provide a resource to facilitate comparative genomic research in the genus Cherax, and in particular allow insights into respiratory and osmoregulatory physiology of this group of animals.