The concept of "state fishes of India": Current status, knowledge gaps, and strategic plans for conservation and sustainable utilization.

The concept of "state fishes of India" highlights the importance and significance of the prioritized fish species distributed across various states within the country. This review article systematically documents the current status of state fishes from various perspectives, identifies the prevailing knowledge gaps, and also highlights the issues and strategic plans essential for the conservation and sustainable utilization of these valuable genetic resources. A total of 8357 publications were checked for the consolidated information on state fish species, and the appropriate items were selected under eight categories: biology, physiology and nutrition, aquaculture, habitat and environmental parameters, genetics and biotechnology, harvest and postharvest, fish health management, and others. The synthesized information was used to present the current status of research and development on state fish species. The knowledge gaps that are to be addressed are also depicted under the perspectives of fisheries management and conservation aquaculture. Based on the findings, strategic plans for the targeted conservation programmes are proposed and discussed under various in situ and ex situ conservation measures. Further, the departmental processes involved in the declaration, the importance of stakeholder involvement, namely, local communities and policymakers, in fostering effective conservation measures, and planning for utilization of these valuable fish genetic resources are also indicated.

The AutoSpawner system - Automated ex situ spawning and fertilisation of corals for reef restoration.

The restoration of reefs damaged by global and local pressures remains constrained by the scale of intervention currently feasible. Traditional methods for ex situ sexual propagation of corals produce limited materials, typically of limited genetic diversity and only sufficient for small field trials. The development and validation of new technologies to upscale and automate coral propagation is required to achieve logistically and financially feasible reef restoration at ecologically relevant scales. To address the need for upscaled production of genetically diverse material for use in reef restoration we designed an automated system (the AutoSpawner) for harvesting, fertilising and washing gametes from tropical broadcast-spawning corals. The system includes a novel high density dynamic fertilisation process, which enables the production of large numbers of fertilised coral eggs (>7 million per night for highly fecund species) without any downstream negative effects on larval quality. The functionality of the system and the quality of the produced larvae was assessed using multiple species from two coral families (Acroporidae and Merulinidae) across a range of spawning and gamete characteristics. We present the schematics and protocols required for automated sexual propagation of high-quality coral larvae using this novel system; and demonstrate that the time demands, and labour costs, associated with traditional manual-based sexual propagation of corals can be reduced by up to 113-fold using the AutoSpawner.

Genetic diversity and phenotypic variation within hatchery-produced oyster cohorts predict size and success in the field.

The rapid growth of the aquaculture industry to meet global seafood demand offers both risks and opportunities for resource management and conservation. In particular, hatcheries hold promise for stock enhancement and restoration, yet cultivation practices may lead to enhanced variation between populations at the expense of variation within populations, with uncertain implications for performance and resilience. To date, few studies have assessed how production techniques impact genetic diversity and population structure, as well as resultant trait variation in and performance of cultivated offspring. We collaborated with a commercial hatchery to produce multiple cohorts of the eastern oyster (Crassostrea virginica) from field-collected broodstock using standard practices. We recorded key characteristics of the broodstock (male : female ratio, effective population size), quantified the genetic diversity of the resulting cohorts, and tested their trait variation and performance across multiple field sites and experimental conditions. Oyster cohorts produced under the same conditions in a single hatchery varied almost twofold in genetic diversity. In addition, cohort genetic diversity was a significant positive predictor of oyster performance traits, including initial size and survival in the field. Oyster cohorts produced in the hatchery had lower within-cohort genetic variation and higher among-cohort genetic structure than adults surveyed from the same source sites. These findings are consistent with "sweepstakes reproduction" in oysters, even when manually spawned. A readily measured characteristic of broodstock, the ratio of males to females, was positively correlated with within-cohort genetic diversity of the resulting offspring. Thus, this metric may offer a tractable way both to meet short-term production goals for seafood demand and to ensure the capacity of hatchery-produced stock to achieve conservation objectives, such as the recovery of self-sustaining wild populations.

Influence of a dynamic rearing environment on development of metabolic phenotypes in age-0 Lake Sturgeon, Acipenser fulvescens.

Environment-phenotype interactions are the most pronounced during early life stages and can strongly influence metabolism and ultimately ecological fitness. In the present study, we examined the effect of temperature [ambient river temperature (ART) vs ART+2°C], dissolved oxygen (DO; 100% vs 80%) and substrate (presence vs absence) on standard metabolic rate, forced maximum metabolic rate and metabolic scope with Fulton's condition factor (K), energy density (ED) and critical thermal maximum (CTmax) in age-0 Lake Sturgeon, Acipenser fulvescens, before and after a simulated overwintering event. We found that all the environmental variables strongly influenced survival, K, ED and CTmax. Fish reared in elevated temperature showed higher mortality and reduced K pre-winter at 127 days post-hatch (dph). Interestingly, we did not find any significant difference in terms of metabolic rate between treatments at both sampling points of pre- and post-winter. Long-term exposure to 80% DO reduced ED in Lake Sturgeon post-winter at 272 dph. Our data suggest that substrate should be removed at the onset of exogenous feeding to enhance the survival rate of age-0 Lake Sturgeon in the first year of life. Effects of early rearing environment during larval development on survival over winter are discussed with respect to successful recruitment of stock enhanced Lake Sturgeon, a species that is at risk throughout its natural range.

Genetic Diversity of an Imperiled Neotropical Catfish and Recommendations for Its Restoration.

The long-whiskered catfish Steindachneridion parahybae (Family Pimelodidae) is endemic to the Paraíba do Sul River basin in southeastern Brazil. This species was heavily exploited by artisanal fisheries and faces challenges posed by dams, introduced species, and deterioration of critical habitat. The remaining populations are small and extirpated from some locales, and the species is listed as critically endangered in Brazil. Screening variation at a partial mitochondrial control region sequence (mtCR) and 20 microsatellite loci, we: (i) describe the patterns of genetic diversity along its current distributional range; (ii) test the null hypothesis of panmixia; (iii) investigate the main factors driving its current population structure, and (iv) propose management of broodstock for fostering recovery of wild populations through genetically cognizant restocking. Our microsatellite data for 70 individuals from five collections indicate moderate levels of heterozygosity (HO = 0.45) and low levels of inbreeding (FIS = 0.016). Individual-based cluster analyses showed clear genetic structure, with three clusters of individuals over the collection area with no mis-assigned individuals, suggesting no recent migration among the three clusters. Pairwise DEST values showed moderate and significant genetic differentiation among all populations so identified. The MUR population may have suffered a recent demographic reduction. mtCRs for 70 individuals exhibited 36 haplotypes resulting from 38 polymorphic sites. Overall, mitochondrial haplotype diversity was 0.930 (±0.023) and nucleotide diversity was 0.011 (±0.002). Significant population structure was observed, with ϕST = 0.226. Genetic markers could be used in a hatchery-based restoration program emphasizing breeding of pairs with low kinship values in order to promote retention of genetic diversity and avoid inbreeding. Individual average kinship relationships showed 87.3% advised matings, 11.0% marginal matings, and 1.7% advised against. While these results comprise a contribution toward planning better breeding management and monitoring, parallel actions to be undertaken include surveying healthy riverine habits for reintroduction and continued searching for wild individuals to introduce new variation into the captive broodstock to avoid adaptation to captivity and to minimize inbreeding.

Osmoregulation of juvenile marine goliath grouper (Epinephelus itajara) in low-salinity water / Osmorregulación de juveniles del mero guasa juvenil (Epinephelus itajara) en aguas de baja salinidad / Osmorregulação de juvenis do peixe garupa (Epinephelus itajara) em águas de baixa salinidade

Background: goliath grouper (Epinephelus itajara) is an economically valuable marine species and an excellent candidate for domestication for aquaculture purposes. If this grouper can osmoregulate in lowsalinity water, its cultivation can provide socio-economic benefits, for both coastal communities and the mainland agricultural sector. Objective: to evaluate the osmoregulatory capacity of juvenile goliath grouper when exposed to low-salinity water. Methods: juvenile goliath grouper (Epinephelus itajara) were either directly or gradually transferred from seawater to freshwater to test osmoregulatory ability. Body weight was assessed during acclimation and blood samples were taken to measure total osmolality and electrolytes. Results: all fish survived the transfer to freshwater and were maintained for up to 12 days after termination of the acclimation trials which lasted 72 hours. Juvenile goliath grouper were hyposmotic (342-462 mosmol/kg) to seawater and hyperosmotic (272-292 mosmol/kg) to freshwater. The gills and kidneys were found to have principal roles in the osmoregulatory processes. Numerous chloride cells were found on superficial regions of the gill filament epithelium, most likely serving to eliminate the excess of electrolytes while in seawater. The kidneys had numerous nephrons to make urine and retain electrolytes while in freshwater. Conclusions: these observations lead to the conclusions that juvenile goliath grouper have the ability to osmoregulate in freshwater and should be considered a marine euryhaline species. Such adaptability opens for consideration the possibility that goliath grouper could be successfully farmed in brackish water or even in freshwater.

Antecedentes: el mero guasa Epinephelus itajara es una especie marina de gran valor comercial y un excelente candidato a domesticar con fines acuícolas. Si el mero guasa puede osmoregular en agua de baja salinidad, su cultivo puede proporcionar beneficios socio económicos, tanto para las comunidades costeras, como al sector agropecuario en tierra firme. Objetivo: evaluar el efecto en la osmoregulación de juveniles de mero guasa expuestos a aguas de baja salinidad. Métodos: juveniles de mero guasa mantenidos en agua de mar fueron transferidos directamente o de manera gradual a agua dulce para poner a prueba su capacidad osmorreguladora. Durante el proceso de aclimatación se les evaluó el peso corporal y se extrajo sangre para medir la osmolalidad total y electrolitos. Resultados: todos los peces sobrevivieron la transferencia al agua dulce y durante 12 días más, después de la finalización de los ensayos de aclimatación que tuvieron una duración de 72 horas. Juveniles de mero guasa fueron hiposmóticos (342-462 mosmol/kg) respecto al agua de mar e hiperosmóticos (272-292 mosmol/kg) respecto al agua dulce. La histología de branquias y riñones reveló que estos órganos son de gran importancia en los procesos osmorregulatorios. Un gran número de células de cloruro fueron localizadas como parte del epitelio de los filamentos branquiales; estas células trabajan para librar al cuerpo del exceso de electrolitos mientras los peces se encuentran en el mar. En el riñón se observaron numerosas nefronas y túbulos colectores para la formación de orina y retención de electrolitos; tejidos esenciales si estos peces permanecen en agua dulce. Conclusión: estas observaciones llevan a la conclusión de que los juveniles de mero guasa tienen la capacidad de osmorregular en agua dulce y debe ser considerada una especie marina eurihalina. Tal adaptabilidad supone la posibilidad de que el mero guasa podría ser cultivado en agua salobre o incluso en agua dulce.

Antecedentes: o peixe garoupa Epinephelus itajara é uma espécie marinha de muito valor comercial a qual seria ótimo ter domesticada para sua produção industrial na aquicultura. Se o peixe garoupa pode osmoregular em água de baixa salinidade, sua cultura pode proporcionar benefícios socioeconômicos, tanto para as comunidades costeiras, quanto para o sector agrícola no interior do continente. Objetivo: avaliar a osmoregulação de juvenis do peixe garoupa expostos a águas de baixa salinidade. Métodos: juvenis do peixe Garoupa mantidos no mar foram transferidos direta ou gradualmente para água doce testando assim sua capacidade osmorregulatória. Durante o processo de aclimatização, foi avaliado o peso corporal e amostras de sangue foram coletadas para medir a osmolalidade total e alguns eletrólitos. Resultados: todos os peixes sobreviveram à transferência para água doce 12 dias mais após a conclusão dos estudos de aclimatação que se fizeram durante um período de 72 horas. Juvenis do peixe garupa foram hiposmoticos (342-462 mosmol/kg) com respeito à água marinha e hiperosmóticos (272-292 mosmol/kg) com respeito à água doce. Histologia das brânquias e os rins revelaram que estes órgãos são de grande importância nos processos de osmoregulaçao. Um grande número de células de cloreto foi localizado como parte do epitélio dos filamentos branquiais; estas células trabalham no organismo para livrar o corpo do excesso de eletrólitos enquanto os peixes estão no mar. Nos rins foram observados numerosos néfrons e ductos recoletores para a formação de urina e retenção de eletrólitos; tecidos essenciais no caso de que estes peixes permaneçam em água doce. Conclusão: estas observações levam à conclusão de que os juvenis do peixe garupa tem a capacidade de osmoregular em água doce e deve ser considerado uma espécie marinha eurialina. A adaptabilidade deste peixe em água doce supõe a possibilidade de que o peixe garupa poderia ser cultivado nesta água em criadouros no interior do continente.