About This Project

Larimichthys crocea was one of China's three top commercial marine fishes. However, heavy fishing pressured lead to a rapid 90% decline in population by the 1980s, with the species now listed as critically endangered. Hong Kong’s L. crocea population status is currently unknown, though it has been documented by local fishermen. In this study, we collect fish eggs and eDNA water samples to determine the spatiotemporal spawning ecology to aid future local sustainable management plans.

Ask the Scientists

What is the context of this research?

During the 1950s and 1980s, Larimichthys crocea was a key China fisheries species, ranking in the top three for marine fisheries production. However, due to the heavy fishing exploitation, the wild population declined by over 90% by the 1980s, becoming a rare bycatch species (Liu & Sadovy de Mitcheson 2008), and was classified as critically endangered. Past management practice showed that the closing of the spawning season could improve its reproductive output and fishery catch. However, the current state of Hong Kong's population is largely unknown limiting management action plans. The key question I am trying to answer is where and when L. crocea spawn in Hong Kong waters. To achieve these goals for current and future assessments, non-invasive sampling methods will be utilized.

What is the significance of this project?

Currently, only 5% of Hong Kong waters are designated to be established as marine protected areas (MPA). However, this figure is lagging far behind the Global Biodiversity Framework's "30x30" target. Meanwhile, scientists, conservationists and NGOs in Hong Kong are calling for 10% of Hong Kong waters to be designated as MPA by 2030. However, the newly suggested MPA is mainly for protecting mammals, coral reefs, and horseshoe crabs, without any consideration for protecting the spawning grounds of highly valued critically endangered fishes. The goal of this project is to determine the spawning area and timing of a critically endangered species, Larimichthys crocea, in Hong Kong waters which can provide solid evidence to promote more MPA to conserve biodiversity on a fine scale.

What are the goals of the project?

To achieve the goals of this study, we identified 8 sampling sites in western Hong Kong waters which were previously determined as spawning grounds for our target species, based on reports from the 1970s. Sampling is currently underway since September 2023, and has been conducted on the second day of the high tide or full moon once per month. During sampling, 10 minutes of plankton trawl and 6 liters of middle seawater have been collected. Currently, we have 132 eDNA samples and around 2,400 fish egg samples that need to be extracted, and a relative number of qPCR and PCR that need to be conducted, respectively. The fund will be used to purchase DNA extraction kits and qPCR and PCR primers and reagents to complete the data generation from the already acquired samples.