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This study investigates the reproductive seasonality variation in Indian Major Carps (IMC), specifically Rohu (Labeo rohita) and Catla (Labeo catla). Utilizing field observations and analysis of gonadosomatic index (GSI), distinct reproductive patterns were observed among these species. The findings highlight that, in the absence of scientific interventions such as photoperiod manipulation and feeding management, a significant portion of Rohu and Catla fish reach maturity and breed after and before monsoon period (December and March). Understanding these reproductive variations is crucial for the identification of genetically distinct stocks suitable for line development that can reproduce during the winter seasons. This knowledge contributes to the strategic management of year-round seed availability. By elucidating the natural reproductive cycles of these economically important species, researchers can optimize breeding programs to align with environmental conditions, potentially identifying genetically different stock for line development, which can breed during winter seasons. [ABSTRACT FROM AUTHOR]

Flatback turtles (Natator depressus) are endemic to northern Australia, but their movements at sea have remained understudied. Here, we compiled one of the world's largest single‐species satellite tracking datasets (n = 280 transmitters, deployed between 2005 and 2020) to investigate the movements and level of spatial protection afforded to five flatback genetic stocks across Western Australia during different behavioral phases (i.e., inter‐nesting, migration, and foraging). Flatbacks spent 99.5% of their time in Australian waters and are provided with a very high level of spatial protection (>98% overlap with Biologically Important Areas) during the inter‐nesting phase of their life cycle. Up to 85.6% and 59.1% overlap between marine reserves and the foraging and migratory ranges for flatback stocks, respectively, was found. However, our results identified additional foraging and migratory areas where protective measures would benefit multiple stocks at once. The detailed flatback distribution maps produced here will be key resources for managers and researchers and highlight the benefits of collaborative multi‐agency studies. Additionally, this work provides a useful analytical framework for future studies endeavoring to complete large‐scale, multi‐stock spatial distributions and overlap assessments for populations of conservation concern. [ABSTRACT FROM AUTHOR]

Background: Butter catfish (Ompok bimaculatus) is a preferred species in South East Asia, with huge aquaculture potential. However, there is limited information about genetic stock composition due to insufficient markers. The goal of this study was to develop de novo microsatellite markers. Methods and results: For sequencing, genomic SMRT bell libraries (1.5 Kbp size) were prepared for O. bimaculatus. A total of 114 SSR containing sequences were used for primer designing. Polymorphic loci were validated by genotyping 83 individuals from four distant riverine populations, viz., Brahmaputra, Bichiya, Gomti and Kaveri. A total of 30 microsatellite loci were polymorphic, of which five were found to be associated with functional genes and eight (four positive and four negative) loci were found to be under selection pressure. A total of 115 alleles were detected in all loci and PIC ranged from 0.539 to 0.927 and pair-wise FST values from 0.1267 to 0.26002 (p < 0.001), with an overall FST value of 0.17047, indicating the presence of population sub-structure. Cross-species transferability of 29 loci (96.67%) was successful in congener species, Ompok pabda. Conclusion: The novel SSR markers developed in this study would facilitate stock characterization of natural populations, to be used in future selection breeding programs and planning conservation strategies in these species. Identified non-neutral markers will give insights into the effect of local adaptation on genetic differentiation in the natural population of this species. [ABSTRACT FROM AUTHOR]

The scalloped hammerhead shark Sphyrna lewini is a migratory shark species, highly valued commercially for its meat and fins. Although this species has been listed on the CITES Appendix II, its genetic structure in the West Pacific is still little known. In this study, shotgun sequencing technique was used to sequence millions of small fragmented DNA sequences simultaneously. Nine novel polymorphic microsatellite markers were isolated from sequencing reads and then tested on 54 individuals collected from the western North Pacific. The number of alleles detected in each locus ranged from seven to 21. Observed and expected heterozygosity of these loci were from 0.370 to 0.870 and from 0.505 to 0.724, respectively. These nine novel polymorphic loci can further be used to reveal genetic connectivity patterns among S. lewini in the West Pacific. [ABSTRACT FROM AUTHOR]

Gymnogobius isaza is a freshwater goby endemic to ancient Lake Biwa, the largest lake in Japan. The species is now listed as ‘Critically Endangered’ in the Red Data Book of Japan. Nevertheless, it remains subject to fishing without any specific management strategies. Previous studies using mitochondrial DNA markers showed that this fish species has two cryptic lineages. However, little is known about spatial genetic structure and ecological differences across the broad lakescape. In this study, we collected fish samples at nine locations along the lakeshore during the breeding season and tested for the presence of spatial heterogeneity in the lineage’s composition while measuring body size as the most fundamental biological trait. The results showed that the major lineage dominated all the sampling locations whereas the minor lineage consisted of only 11% (16/143) of samples. Furthermore, although their spatial distributions overlapped (i.e. the two lineages may be well mixed), we found it possible that the minor lineage may have a potentially narrower distribution than the major lineage. In addition, we found that the two lineages differ in body size; specifically, the minor lineage is smaller in size. From the viewpoint of genetic diversity conservation and sustainable resource use, this fish should be managed as two genetic stocks and spatial and/or body size-based fishery management is desirable, with particular attention to the minor (smaller sized) lineage. [ABSTRACT FROM AUTHOR]

Abstract: Estuarine habitats provide rearing opportunities for the juvenile life stage of anadromous fishes. Because survival is positively correlated with juvenile performance, these estuarine habitats play an important role in population abundance and productivity. To provide information for the recovery of several depressed stocks of Chinook salmon in the Columbia River Basin, we sought to identify the factors that explain variability in performance. Using otolith‐derived estimates of juvenile somatic growth rate as an index of recent performance, we observed a negative nonlinear relationship between growth rate and day of year, and a decreasing and increasing trend of growth rate over the 8 years of this study and distance from the river mouth respectively. Using a generalised linear modelling approach, we found that variability in juvenile somatic growth rate was best explained by where and when individuals were collected, their body size, contaminant loads, stock of origin, and whether a fish was hatchery produced or unmarked. Lastly, we argue that a considerable improvement to the growth rate of juveniles in estuarine habitats is physiologically possible. The results of this 8‐year study provide a baseline of the performance of juvenile Chinook salmon to evaluate habitat restoration programs and to compare against future anthropogenic conditions. [ABSTRACT FROM AUTHOR]

Octopus minor (Sasaki, 1920) is an important economic fishery resource in China. In order to explore the stock information and the phylogeographic status of O. minor, mitochondrial DNA cytochrome c oxidase subunit I (COI, 565 bp) and 16S rRNA (493 bp) genes were amplified from 11 different sampling locations. Genetic diversity evaluated by haplotypic and nucleotidic diversity implied high diversity in Lianjiang, and relatively low diversity in Rongcheng, which suggests that effective measures to protect the O. minor resource in this area are urgently required. Private haplotypes and remarkable higher pairwise ΦST in Yilan are responsible for the deep genetic divergence between Yilan and the 10 other populations. Haplotypes networks and two clusters’ topological structure also support the distinct subgroups (lineages A and lineages B), which apparently possess smaller genetic variation than mean interspecies distance. Taiwan island and its strait may act as a natural barrier that restricts the gene flow from the mainland. Deep genetic divergence between mainland and Taiwanese east coasts suggests different genetic stock, indicating that different management strategies are required. [ABSTRACT FROM AUTHOR]

Sandy beach surf zones serve as alternative nursery habitats for juvenile Chinook salmon (0 age) during their early marine residency, a period considered critical due to high and variable mortality rates. Despite the importance of early marine residence, the extent of juvenile salmon surf zone use and movement along sandy beaches is not well understood. Juvenile Chinook salmon distribution and movement were studied in shallow surf zone habitats by sampling from 2006 to 2010 with a beach seine 11 beaches adjacent and distant to four estuary mouths in Oregon and Washington, USA. The estuary of origin of each juvenile was determined using genetic stock identification methods and coded wire tags. Surf zones sampled were within littoral cells, which are stretches of the coastline bordered by rocky headlands, and included estuaries with and without Chinook salmon populations. Juvenile salmonids were only collected at littoral cells with Chinook-inhabited watersheds. Most juveniles (95 %) were present at sandy beaches adjacent (<500 m from estuary mouth) to their estuary of origin. Few Chinook salmon (5 %) were collected at littoral cells that contained non-natal estuaries. These results indicate that juvenile Chinook salmon inhabiting surf zones mostly use beaches adjacent to their estuaries of origin, but some juveniles may reside in beaches distant from their point of ocean entry. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Heredity is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Heredity is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we have reviewed the population genetic structure of eleven tuna species (albacore, bigeye, yellowfin, Pacific bluefin, Atlantic bluefin, southern bluefin, blackfin, longtail, skipjack, frigate, and little tuna) with a global perspective. Based on the studies using molecular markers, there are 50 genetically distinct populations of tuna species worldwide (12 albacore, 4 bigeye, 9 yellowfin, 4 bluefin, 2 blackfin, 2 longtail, 12 skipjack, 2 little tuna, and 3 frigate tuna). It is evident that some tunas (albacore, bigeye, yellowfin, bluefin, and skipjack) have got more attention of researchers than the others (longtail tuna, blackfin tuna, little tuna, and frigate tuna), possibly because of their higher commercial importance. So, the larger number of studies on some species of tuna might be the reason for the higher number of population structure observed. Also, relying on the results of a single molecular marker, which were used in some studies, may produce misleading conclusions. Therefore, complementary sets of markers should be used in assessing population structure. Still, the number of to date revealed genetically distinct populations in some tunas species (albacore, yellowfin, and skipjack) is higher than number of stocks managed by authorities grouped in tuna regional fisheries management organizations. It might be a signal for reevaluation of fishery management of such tunas. [ABSTRACT FROM AUTHOR]

In parts of the Indo-Pacific, large-scale exploitation of the green turtle Chelonia mydas continues to pose a serious threat to the persistence of this species; yet very few studies have assessed the pattern and extent of the impact of such harvests. We used demographic and genetic data in an age-based model to investigate the viability of an exploited green turtle stock from Aru, south-east Indonesia. We found that populations are decreasing under current exploitation pressures. The effects of increasingly severe exploitation activities at foraging and nesting habitat varied depending on the migratory patterns of the stock. Our model predicted a rapid decline of the Aru stock in Indonesia under local exploitation pressure and a shift in the genetic composition of the stock. We used the model to investigate the influence of different types of conservation actions on the persistence of the Aru stock. The results show that local management actions such as nest protection and reducing harvests of adult nesting and foraging turtles can have considerable conservation outcomes and result in the long-term persistence of genetically distinct management units. [ABSTRACT FROM AUTHOR]