Horseshoe crab conservation reflects the country’s commitment to endangered species protection.
These 10-month-old tri-spine horseshoe crab babies are examples of the only variety of the arthropod endemic to Taiwan. (Courtesy of Su Yin-ten)
There was good news for horseshoe crab conservationists over the past year. In March the government of the outlying county of Penghu announced a ban on fishing for the only species endemic to Taiwan—Tachypleus tridentatus, the tri-spine horseshoe crab—across its territory. In May a juvenile of the species was spotted in Taijiang National Park, a first for the wetland area in southern Taiwan since the park’s establishment in 2009. Subsequently another three crabs were found there over the next three months, indicating a possible viable population. In August the southern Taiwan-based nongovernmental organization (NGO) Chiayi County Ecological Conservation Association (CECA) bred and released 250 juveniles into coastal Budai Township’s Haomeiliao Wetland. “The association will become even busier as awareness of horseshoe crab conservation is raised further in Taiwan, ” said CECA Executive Secretary Su Yin-tien (蘇銀添).
Known as living fossils due to unchanged specimens dating back 400 million years, the family Limulidae are in fact not crabs or crustaceans; they are chelicerates, most closely related to arachnids like spiders and scorpions, and were once common in coastal waters around the world. Adults lay eggs in sand and the juveniles live in intertidal zones. Four species of the animal have been identified globally and Taiwan’s tri-spine variety is also found elsewhere in East and Southeast Asia. Increasing industrialization and commercial net fishing have led to a significant global population decline in all species.
These 10-month-old tri-spine horseshoe crab babies are examples of the only variety of the arthropod endemic to Taiwan. (Courtesy of Su Yin-ten)
Conservation Areas
According to the Ocean Conservation Administration (OCA) under the Cabinet-level Ocean Affairs Council (OAC), in 1996 the first horseshoe crab research and conservation projects in Taiwan were initiated by marine ecologists Chen Chang-po (陳章波) and Hsieh Hwey-lian (謝蕙蓮) in outlying Kinmen County. Then in 2000 the local Kinmen government created Taiwan’s first horseshoe crab-themed education and exhibition center as well as the first reserve for the arthropod in Guningtou intertidal area.
NGOs like CECA played a positive early role in the species’ protection. In 2012 the association, with skills and knowledge provided by Chen, set up a conservation center in Budai to collect the creatures from local fishing industry bycatch and rehabilitate them. “We encouraged individual fishermen to hand in any horseshoe crabs they caught in nets as otherwise they would die,” Su said. In the same year, the Chiayi County Government designated the summertime Lunar Valentine’s Day as Horseshoe Crab Conservation Day because the species is known for performing courtship displays in pairs. CECA and the local government then jointly organized themed events to educate the public. The association also raised juvenile horseshoe crabs provided by Kinmen’s Fisheries Research Institute (FRI) and released them into Haomeiliao Wetland in 2013.
Chiayi County Ecological Conservation Association staff and volunteers board a raft to Haomeiliao Wetland to examine the horseshoe crabs’ habitat. (Courtesy of Su Yin-ten)
Yang Ming-che (楊明哲), a horseshoe crab expert currently working at southern Taiwan’s National Sun Yat-sen University, said conservation started in earnest in 2019 when the tri-spine species was listed as endangered on the Red List of Threatened Species compiled by the International Union for Conservation of Nature (IUCN), a Switzerland-based organization recording declining global levels of biodiversity. At the quadrennial International Workshop on the Science and Conservation of Horseshoe Crabs that took place just three months after the designation, attendees, who were mostly members of the Horseshoe Crab Specialist Group (HCSG) under IUCN’s Species Survival Commission, jointly declared June 20 International Horseshoe Crab Day in a statement calling to protect all species of the animal. HCSG’s three Taiwan members are Chen, Hsieh and Yang, who all play a crucial part in the arthropod’s domestic conservation.
Protection Plans
The tri-spine horseshoe crab is not yet categorized as a legally protected species in Taiwan, but the OCA is attempting to integrate resources for its conservation while raising public awareness. Cai Ya-ru (蔡雅如), an associate technical specialist at OCA, hopes that the species can be protected by conserving its habitat. This includes national-level protected wetlands in outlying counties as well as locations like Budai. Cai noted the OCA is also searching for as-yet unrecorded populations to integrate into future conservation measures.
An adult horseshoe crab at outlying Kinmen County’s Fisheries Research Institute is marked for release into the wild. (Courtesy of Ocean Conservation Administration, Ocean Affairs Council)
In a move to raise the profile of horseshoe crab conservation, in 2021 the OCA funded a project co-led by Yang to review the latest status of the creatures in Taiwan. The results of this investigation constitute much of the content of the Draft Conservation and Recovery Plan for Horseshoe Crab published last April. It is the most comprehensive report to date on the tri-spine species in Taiwan, covering subjects such as threats to coastal habitat due to industrialization as well as existing measures to protect the arthropods. The OCA made the draft public to encourage general awareness of the issue while seeking opinions from all stakeholders to ensure the viability of any future conservation plan. Notably, the draft indicated that the Marine Wildlife Conservation Advisory Committee, whose members are recruited by OAC, will debate whether to categorize the tri-spine horseshoe crab as a legally protected species.
Before that happens, there is an urgent need to further research the size of the population in Taiwan as there is not yet sufficient data. Cai expects to have a better estimate by the end of 2023. Yang has seen the population decline in Kinmen, according to field studies he and other researchers have conducted. For example, Yang’s 2018 survey found 0.2 juveniles per square meter around Chienkung Islet, down from 0.75 in a 2003 study by FRI. These survey results became part of the data IUCN referred to in its decision to label the tri-spine horseshoe crab as endangered on its Red List. Last year the OCA started to fund training for both the government agency’s marine inspectors and volunteers to conduct on-site surveys using methodology established by Yang. The trainees undertook their first surveys in northern Taiwan’s Hsinchu County and outlying Penghu and Lienchiang Counties. All this contributes to the ongoing evaluation of the total endemic population size.
CECA conservation center, where the association's Executive Secretary Su Yin-tien feeds oysters to horseshoe crabs being rehabilitated (Photos by Chin Hung-hao)
The OCA is also tapping Taiwan’s vibrant civil society, funding private groups dedicated to conservation as part of its Community-based Marine Conservation Program launched in 2019. CECA used part of the subsidy to purchase and care for horseshoe crabs caught by fishermen. The Chiayi organization is one of the two facilities in Taiwan proper collecting and rehabilitating the arthropods, the other being the National Museum of Marine Science and Technology located in northern Taiwan’s Keelung City. CECA keeps any living horseshoe crabs found in southern and central Taiwan, and from 2019 the Keelung facility has handled any from that area. In August 2022 a conservation facility started construction in Budai with a budget of around NT$100 million (US$3.1 million). It is scheduled to open by 2024 and will comprise education and exhibition spaces as well as a rehabilitation section. Over the past two years CECA has additionally used a subsidy to train 40 volunteers on the creatures’ rehabilitation and guide visitors on ecotours. The volunteers will also design teaching materials and board games to educate schoolchildren about conservation. This prepares trainees for the task of helping run the horseshoe crab conservation complex when it opens.
For his part, Yang has found himself increasingly busy promoting civil science related to the arthropod’s conservation in schools and communities. “The decision to categorize horseshoe crabs as a protected species will enforce stringent safeguards nationwide and give society a better understanding of its status,” he explained. Currently he is preparing a horseshoe crab conservation association comprising members from NGOs, academia and natural science museums. For horseshoe crab conservationists in Taiwan, 2022 was an exciting year, and they are optimistic about the future.
Write to Oscar Chung at mhchung@mofa.gov.tw