Other studies and applications

The hidden diversity of fish otoliths in traditional Chinese medicine 

Fish otoliths have been used as medicine in many regions and cultures of the world. The history of using otoliths, so called "yu nao shi", in traditional Chinese medicine (TCM) can be trace back to the Song dynasty. A range of effects is reported for otoliths in TCM, including relieving nasal membrane inflammation. The source of these otoliths has been widely described as originating from the yellow croakers (Larimichthy spp., Sciaenidae), one of the intensively fished coastal fish in the waters off western Taiwan. Vendors claim efficacy only if the otoliths of yellow croakers are applied. However, our preliminary survey suggest that a wide variety of fish taxa are involved in the production of otoliths in TCM. Therefore, this project aims to describe the hidden diversity of otolith taxa that are sold as TCM in Taiwan. The significance of the study will improve the validation technique of biological product in TCM, as well as further revealing whether the specific fishery in TCM is sustainable. 

The significance of fish otoliths in the archaeological midden site in Tainan City, southwestern Taiwan

As a continuation of the previously described Pomadasys otoliths from an archaeological midden site in Tainan City, southwestern Taiwan, we explore the significance of other co-occurring otolith-based fish taxa. Materials from the related sites in the area over the past 3000 yrs will be discussed together. Taxonomy composition and size frequency data will be measured, and the implication of coastal adaptation of prehistoric inhabitants will be discussed. 

Application of otoliths in diet composition analysis: a case study of bigeye tuna from tropical Indian Ocean

Studies of piscivores feeding ecology have traditionally and routinely been known to identify otoliths. However, in most of the cases, otoliths are yet often ignored simply because their taxonomic work is usually challenging without well-trained specialist and specifically-built reference collections.

Using in-house otolith collection in the museum, we explicitly demonstrate that otoliths, together with fish remains, allow a more comprehensive interpretation for the diet composition of bigeye tuna, an economically and ecologically vital apex marine predator. 

We then analyzed the spatiotemporal and biological dynamics of the feeding habits in bigeye tuna using four variables, including capture site, capture depth, the month of catch, and fish FL. The results significantly indicated that there is a shift in both diet composition and prey size from small to large bigeye tuna. By measuring the dimension of otoliths, we found that larger bigeye tunas fed on larger preys in at least two prey species. This ontogenetic shift in diet suggests a rapid change in trophic level during the life history of bigeye tuna, and therefore understanding the diet composition of this species can potentially allude to a rough index of energetic flux in the region. READ THE PAPER