SUMMARYWe investigated the effects of embryonic temperature (ET) treatments (22, 26 and 31°C) on the life-time recruitment of fast myotomal muscle fibres in zebrafish Danio rerio L. reared at 26/27°C from hatching. Fast muscle fibres were produced until 25 mm total length (TL) at 22°C ET, 28 mm TL at 26°C ET and 23 mm TL at 31°C ET. The final fibre number (FFN) showed an optimum at 26°C ET (3600) and was 19% and 14% higher than for the 22°C ET (3000) and 31°C ET (3100) Supplementary material available online at

Background: Stac3, an uncharacterised gene, was identified by its high expression levels in vertebrate muscle. Results: Knockdown of stac3 inhibited zebrafish myofibrillar protein assembly and differentiation in C2C12 cells by perturbing Akt signaling and cell cycle exit. Conclusion: Stac3 is a novel regulator of myogenic differentiation. Significance: Identifying new genes controlling myogenic differentiation will allow greater understanding of processes leading to muscular diseases.

The cee (conserved edge expressed protein) gene was recently identified in a genome-wide screen to discover genes associated with myotube formation in fast muscle of pufferfish. Comparative genomic analyses indicate that cee arose some 1.6-1.8 billion years ago and is found as a single-copy gene in most eukaryotic genomes examined. The complexity of its structure varies from an intronless gene in yeast and tunicates to nine exons and eight introns in vertebrates. cee is particularly conserved among vertebrates and is located in a syntenic region within tetrapods and between teleosts and invertebrates. Low dN/dS ratios in the cee coding region (0.02-0.09) indicate that the Cee protein is under strong purifying selection. In Atlantic salmon, cee is expressed in the superficial layers of developing organs and tissues. These data, together with functional screens in yeast and Caenorhabditis elegans, indicate that cee has a hitherto uncharacterized role in normal growth and development.

The accuracy and efficiency of marker-assisted selection (MAS) has been proven for economically critical aquaculture species. The potato grouper (Epinephelus tukula), a novel cultured grouper species in Taiwan, shows large potential in aquaculture because of its fast growth rate among other groupers. Because of the lack of genetic information for the potato grouper, the first transcriptome and expressed sequence tag (EST)-derived simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers were developed. Initially, the transcriptome was obtained from seven cDNA libraries by using the Illumina platform. De novo transcriptome of the potato grouper yielded 51.34 Gb and 111,490 unigenes. The EST-derived SSR and SNP markers were applied in genetic management, in parentage analysis, and to discover the functional markers of economic traits. The F1 juveniles were identified as siblings from one pair of parents (80 broodstocks). Fast- and slow-growth individuals were analyzed using functional molecular markers and through their association with growth performance. The results revealed that two SNPs were correlated with growth traits. The transcriptome database obtained in this study and its derived SSR and SNP markers may be applied not only for MAS but also to maintain functional gene diversity in the novel cultured grouper.

Mixed fisheries refer to fishing activities that catch more than one species simultaneously, and a species may be fished using different gear. A trawl fishery shares these features to exploit multiple species simultaneously, with diverse fishing gear and strategies. The situation becomes more complex when interactions among fleet dynamics, fishing activities, and fishery resources are involved and influence each other. Information regarding the operational patterns may be hidden in a set of long-term big data. This study aims to investigate the fishery structure and fleet dynamics of trawl fisheries in Taiwan for spatial planning and management, based on a long-term dataset from a management system that collects information by using voyage data recorders (VDR) and dockside observers. We applied a two-step data mining process with a clustering algorithm to classify the main groups of fishery resources and then identified 18 catch métiers based on catch composition. The target species, operation pattern, and fishing season were determined for each métier, and associated with the relevant fishery resources and the fishing gear used. Additionally, fishing effects on target species were estimated using information on fishing grounds and trajectories from VDR. The métier-based approach was successfully applied to define the six major fishery resources targeted by trawlers. We examined the key features of fishing activity associated with catch composition and spatial-temporal fishing metrics, which could be used to provide suggestions for the spatial planning and management of the mixed trawl fishery in the offshore waters of Taiwan.

Stock enhancement is a method for replenishing depleted wild finfish populations by supplementing them with hatchery-raised fish. In Taiwan, silver sea bream (Rhabdosargus sarba) is a predominant commercial species involved in stock enhancement projects. Although management agencies conduct stock enhancement projects, there are a lot of private releases without records. Stock enhancement is performed by the private aquaculture sector without accurate genetic records, potentially leading to unintended consequences for wild populations. We analyzed the genetics of 459 wild and 701 hatchery-reared specimens from nine batches produced by various hatcheries. Wild and hatchery-reared samples could be considered two separate clades by using a set of stable and informative microsatellite markers including type I (from gene introns and 3′UTR) and type II markers (randomly picked up from genome). Type I microsatellite markers could more sensitively reflect the loss of genetic diversity more than type II markers in the domestication process. All specimens were considered native by using mtDNA COI and microsatellites. The genetic composition of the wild population is relatively simple, and the estimated low contribution rate of the hatchery stock (1.3–10.9%; 6–50/459) indicated a weak but significant genetic effect of stock enhancement. Therefore, establishing standards for the stock enhancement of silver sea bream for more effective supplementation of wild populations is imperative.

Laevistrombus canarium is a marine gastropod species with high economical value. The complete mitochondrial genome of L. canarium has been characterized in this study. The circular mitogenome is 15626 bp in length and comprises 13 protein-coding genes (PCGs), 22 transfer RNA genes, and two ribosomal RNA (rRNA) genes. The organization of these genes is consistent with that of other stromboidae species. The overall base composition of mitochondrial genome is 30.87% A, 38.99% T, 15.54% G, and 14.60% C, with 69.86% AT. Phylogenetic analysis further implies that L. canarium is placed within the Stromboidae.

Stock enhancement is considered to be a valuable approach for restoring fishery resources. Because no specific official institution in Taiwan is responsible for the production of fry, the released fry are purchased directly from the private sector. However, fishermen from the private industry have not established a genetic background, so the genetic composition for each batch of released fry is unclear. Mangrove red snapper (Lutjanus argentimaculatus), a prominent species released in Taiwan, was collected after its official release. One hundred and two field samples were compared with four batches of hatchery fry (n = 685) by using a microsatellite-based multiplex PCR assay. Four of the field samples (3.9%; 4/102) were revealed to be from a fish farm and most likely from a single batch. This study revealed that wild mangrove red snappers are genetically different from those originating from farms, and their origins can be traced through molecular markers, even without information on breeding stocks.