# The Seasonal Spatial Distribution Pattern and Migration of Kishi Velvet Shrimp Metapenaeopsis dalei in the Southern Yellow and East China Seas

## TL;DR

This study maps the seasonal movement and habitat of Kishi velvet shrimp in the Yellow and East China Seas to aid in their conservation and management.

## Contribution

The study identifies specific spawning and nursery areas and seasonal distribution patterns of Metapenaeopsis dalei in Chinese waters.

## Key findings

- The shrimp's biomass and abundance vary with depth, temperature, and salinity across seasons.
- Haizhou Bay–Lvsi and Zhoushan–Yushan are likely spawning grounds for M. dalei.
- The Yangtze River's diluted water mass supports spawning and nursery activities.

## Abstract

Metapenaeopsis dalei is an economically important shrimp species in Northeast Asia. However, very little ecological information is available about the seasonal spatial distribution and migration pattern of M. dalei in the Yellow and East China Seas of China. In this study, we assume that the parent cohorts spawned in the coastal waters of Haizhou Bay–Lvsi in the southern Yellow Sea and Zhoushan–Yushan in the East China Sea in May to August and the newborn recruitment cohorts migrate to adjacent offshore water areas for further nursery and overwintering in other seasons. The diluted water mass from the Yangtze River might play an important role in the spawning and nursery of M. dalei. The above findings can benefit the stock conservation and fisheries management of M. dalei in China.

It is important to understand the ecological information of Metapenaeopsis dalei to better conserve and manage the stocks in Asia. In this study, we employed research vessels to collect the field data including biomass and number of M. dalei in each survey stations along with environmental data including depth, water temperature, and salinity from November 2018 to September 2019 in the region of 26.50–35.00° N and 120.00–127.00° E in the southern Yellow and East China Seas of China. We found that the annual mean catch per unit effort of weight and number (CPUEw and CPUEn) was 15,235.89 g∙h−1 and 17,319.13 ind∙h−1, respectively. Metapenaeopsis dalei was found in 10–130 m. The greatest biomass occurred at 10–20 m in spring, 30–40 m in summer, 10–100 m in autumn, and 10–40 m in winter. The greatest abundance occurred at sea bottom temperature (SBT) 14–15 °C in spring, 19 °C in summer, 15–20 °C in autumn, and 10–12 °C in winter. The greatest abundance occurred at sea bottom salinity (SBS) 32–33 in spring, 32 in summer, 32–35 in autumn, and 31–32 in winter. We found the lowest SBT of M. dalei at 10–11 °C in spring and summer. The juveniles were found at SBT 21 °C and SBS 34 in autumn. The total CPUEw and CPUEn rankings were winter > spring > autumn > summer, and the mean average individual weight (AIW) ranking was summer > spring > winter > autumn. Fishing grounds of Haizhou Bay–Lvsi and Zhoushan–Yushan may be the spawning grounds for M. dalei. These findings can benefit fishery management action and planning in the future.