||Abstract of "The stock assessment of the shark resources off Taiwan waters":
1. "Analysis and investgation on shark fisheries activities and stock assessment of the shark resources off Taiwan waters" :
2. "Study on Endangered Large Chondrichthyan fishes" :
There were 46 whale sharks barged into set nets in 2013, and 15 of them were tagged and released. In addition, the first record of a neonatal whale shark was tagged and released in Green Island waters, suggested that eastern Taiwan waters might be breeding ground of the northwest Pacific stock. In 47 individuals, there were 16 (34%) from Yilan, 10 (21.3%) from Hualien, 10 (21.3%) from Taitung, 5 (10.6%) from Pingtung, 4 (8.5%) from Penghu, and 2 (4.3%) from Hsinchu and Miaoli; there were 36 (76.6%) from the east, and 11 (23.4%) from the west, converted to catch per unit effort were calculated to be 0.77 individual per set net per year in the east and 0.86 individual per set net per year, respectively. The amount of male whale sharks was significant bigger than which of female in sex structure analysis. Both the mean TL and median TL in 2013 were larger than which in 2012, and most whale sharks which occurred in Taiwan waters were near 10 years old based on age structure analysis.
One of 16 released whale sharks entered into another near set net indicated that re-sight rate was calculated to be 6.3%, and 2.9% for total of released individuals. Two SPOTs were tagged on a 6.7 m TL immature female caught in Penghu on Oct 30 and the other 5.1 m TL female also caught in Penghu on Nov. 27. The first one swam southward to the western waters off Philippines after release and remained there for many days. This individual usually moved to higher temperature as near surface regions in dusk time, and sometimes moved to lower temperature (7～10 °C) regions based on time at temperature data. No signals were received from the other one until now.
Report system for catching the basking, white, and megamouth sharks was implemented in 2013, and not any basking shark was caught this year. But there was a 550 kg and 365 cm TL female white shark caught by a drift gill net on Nov. 14, and its muscles, vertebrae and intestinal parasites samples were collected. Since the megamouth shark was found and named, there were 77 individual records until now, and 33 of them were from Taiwan as top one region of the world, even 22 were reported this year. All megamouth sharks were caught by drift gill nets in Hualien and the locations were gathered in coastal and inshore waters. All of 22 individuals were measured and recorded, but 5 of them were not sampled, and one whole body was bought by NMMBA to be reserved sample. Remained 16 megamouth sharks were collected their reproductive organs, muscles, vertebrae, stomach contents, parasites, etc. There were more females as 15 individuals (71.4%) with 250-710 cm TLs, 6 males with 363-484 cm TLs, and one 500 cm TL sex unknown individual for megamouth sharks caught in Hualien waters with sex ratio (male/totall) of 0.29. For 16 individuals records, there were 2 mature but non-pregnant females, 11 maturing sharks, and others were immature. Keeping on collecting information and data further is needed, and the most complete megamouth shark data bank in the world could be hoped to be built.
In other endangered large chondrichthyan fishes, this study focused on investigation and sample collection for the scalloped hammerhead shark only. Total of 833 specimens were sampled/recorded from fish markets of Nanfanao, Tahsi, and northwest regions. Median and large specimens were caught mainly by coastal and inshore long-liners of Nanfanao, few median specimens were from bottom trawlers of Tahsi, and small specimens were collected from drift gill nets of the west. Sample lengths range distributed from 45.6 to 344 cm in TL, and from 31.5 to 246 cm in PCL. TW-TL relationships differed significantly between sexes, and as to be TW=4.26 PCL3.25 for male and TW=5.00 PCL3.23 for female respectively.
Vertebrae were sampled from 229 individuals. Growth band pairs could be read clearly from X-radiography of processed vertebrae. Periodicity of growth band pair formation is still unverified due to insufficient summer samples.
3. "Species identification of shark fin using DNA barcode" :
Shark conservation and effective fisheries management is an important and worldwide issue. Many chondrichthyan species are listed in the World Conservation Union (IUCN) Red List and Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendices II. Ample studies had used DNA barcode technique to identify the shark species from the parts of the shark body e.g., shark fin when the morphological feature was removed. Previous studies have accumulated sufficient genetic information of chondrichthyan species in the database, which enables us to apply DNA barcode as a method to identify shark species from the shark fins landed in the harbors of Taiwan as well as from the shark fins products in the retail shops. We have identified 16 species from 173 samples collected in 3 harbors and 28 species from 170 dry fins purchased from retail stories. Totally, 33 species of shark and ray were identified, which belong to 17 genera, 12 families. According the IUCN list, 3 species are in the status of Least Concern: Rhizoprionodon acutus, Rhizoprionodon taylori, and Hemigaleus australiensis, 15 species in the status of Near Threatened: Carcharhinus falciformis, Carcharhinus brevipinna, Carcharhinus melanopterus, Carcharhinus albimarginatus, Carcharhinus limbatus, Carcharhinus amblyrhynchos, Carcharhinus sorrah, Carcharhinus dussumieri, Carcharhinus galapagensis, Carcharhinus macloti, Galeocerdo cuvier, Prionace glauca, Deania quadrispinosa, Chiloscyllium punctatum, Mobula japanica, 11 species in the status of Vulnerable: Alopias pelagicus, Alopias superciliosus, Carcharhinus longimanus, Hemipristis elongata, Stegostoma fasciatum, Sphyrna zygaena, Isurus oxyrinchus, Isurus paucus, Lamna nasus, Squalus acanthias, Rhynchobatus australiae, 2 species in the status of Endangered: Sphyrna lewini, Sphyrna mokarran, 1 species in the status of Critically Endangered: Anoxypristis cuspidate.