Evaluation of multi-scale climate effects on annual recruitment levels of the Japanese eel, Anguilla japonica, to Taiwan.

Long-term (1967-2008) glass eel catches were used to investigate climatic effects on the annual recruitment of Japanese eel to Taiwan. Specifically, three prevailing hypotheses that potentially explain the annual recruitment were evaluated. Hypothesis 1: high precipitation shifts the salinity front northward, resulting in favorable spawning locations.

Origin of the mass mortality of the flathead grey mullet (Mugil cephalus) in the Tanshui River, northern Taiwan, as indicated by otolith elemental signatures.

A massive fish kill of approximately 50 tons of flathead grey mullet (Mugil cephalus) occurred in August 2006 in the Tanshui River, northern Taiwan. To clarify the origin of these mullets, 42 individuals were randomly collected to determine their ages by reading otolith annuli and to measure the trace elements in the otolith. The total lengths of the fish averaged 32.

Plio-Pleistocene sea level and temperature fluctuations in the northwestern Pacific promoted speciation in the globally-distributed flathead mullet Mugil cephalus.

Background: The study of speciation in the marine realm is challenging because of the apparent absence of physical barriers to dispersal, which are one of the main drivers of genetic diversity. Although phylogeographic studies using mitochondrial DNA (mtDNA) information often reveal significant genetic heterogeneity within marine species, the evolutionary significance of such diversity is difficult to interpret with these markers. In the northwestern (NW) Pacific, several studies have emphasised the potential importance of sea-level regression during the most recent glaciations as a driver of genetic diversity in marine species.

Serum estradiol-17beta and testosterone levels during silvering in wild Japanese eel Anguilla japonica.

To understand the changes of serum levels of sex steroids in the wild Japanese eel Anguilla japonica during silvering process, eels collected from the Kaoping River of Taiwan from August 2000 through June 2001 were examined. The maturational stages of female eels before and during silvering were divided into four stages: juvenile, sub-adult, pre-silver and silver stages based on skin coloration and oocyte diameter. Male eels were investigated only in the silver stage.

Profiles of PGH-alpha, GTH I-beta, and GTH II-beta mRNA transcript levels at different ovarian stages in the wild female Japanese eel Anguilla japonica.

The complete complementary DNA (cDNA) encoding pituitary gonadotropin II-beta subunit (GTH II-beta) of Japanese eel Anguilla japonica was cloned and sequenced, and the profiles of pituitary glycoprotein hormone alpha subunit (PGH-alpha), GTH I-beta, and GTH II-beta mRNA transcript levels at different stages of ovarian development before vitellogenesis in the wild females were investigated. The maturity of female eels was divided into four stages: juvenile, sub-adult, pre-silver, and silver stages based on ovarian development and skin color. The GTH II-beta cDNA was cloned by reverse transcription and polymerase chain reaction (RT-PCR) amplification from total pituitary RNA.