The Role of Environmental Factors on the Fishery Catch of the Squid Uroteuthis chinensis in the Pearl River Estuary, China

Abstract

The Pearl River Estuary (PRE) is one of the major fishing grounds for the squid Uroteuthis chinensis. Taking that into consideration, this study analyzes the environmental effects on the spatiotemporal variability of U. chinensis in the PRE, on the basis of the Generalized Additive Model (GAM) and Clustering Fishing Tactics (CFT), using satellite and in situ observations. Results show that 63.1% of the total variation in U. chinensis Catch Per Unit Effort (CPUE) in the PRE could be explained by looking into outside factors. The most important one was the interaction of sea surface temperature (SST) and month, with a contribution of 26.7%, followed by the interaction effect of depth and month, fishermen’s fishing tactics, sea surface salinity (SSS), chlorophyll a concentration (Chl a), and year, with contributions of 12.8%, 8.5%, 7.7%, 4.0%, and 3.1%, respectively. In summary, U. chinensis in the PRE was mainly distributed over areas with an SST of 22–29 °C, SSS of 32.5–34‰, Chl a of 0–0.3 mg × m−3, and water depth of 40–140 m. The distribution of U. chinensis in the PRE was affected by the western Guangdong coastal current, distribution of marine primary productivity, and variation of habitat conditions. Lower stock of U. chinensis in the PRE was connected with La Niña in 2008.

Modeling of swordtip squid (Uroteuthis edulis) monthly habitat preference using remote sensing environmental data and climate indices

“…Our data indicated that swordtip squid preferred SSTB ranges of 15-18°C and SST of 24-28°C. Temperature is a dominant factor affecting the distribution of different species of squid (Postuma and Gasalla, 2010;Yu et al, 2015;Yamaguchi et al, 2020a;Fang et al, 2021;Wang et al, 2021;Yamaguchi et al, 2022;Fang et al, 2023;Wang et al, 2023, Yu et al, 2019b and fish (Vayghan et al, 2016;Teng et al, 2021;Mammel et al, FIGURE 5 Correlation between various environmental parameters.…”

“…Notably, temperature changes influence the growth and development of the squid reproductive system (Boavida-Portugal et al, 2010;Wang et al, 2013;Pang et al, 2020). Embryo development, hatching, and juveniles' growth depend on water temperature (Moreno et al, 2012), thus regulating the recruitment capacity of the squid population (Challier et al, 2005) and affecting the CPUE for squid (Wang et al, 2021) and fish stock (Wang et al, 2013;Porcaro et al, 2014). In winter, squid migrates to warmer environments to ensure their feeding and growth in southern Taiwan (Wang et al, 2021;Cheng et al, 2022;Yamaguchi et al, 2022;Fang et al, 2023;Yu et al, 2019c), and this species moves back northward in summer.…”

“…Embryo development, hatching, and juveniles' growth depend on water temperature (Moreno et al, 2012), thus regulating the recruitment capacity of the squid population (Challier et al, 2005) and affecting the CPUE for squid (Wang et al, 2021) and fish stock (Wang et al, 2013;Porcaro et al, 2014). In winter, squid migrates to warmer environments to ensure their feeding and growth in southern Taiwan (Wang et al, 2021;Cheng et al, 2022;Yamaguchi et al, 2022;Fang et al, 2023;Yu et al, 2019c), and this species moves back northward in summer. Overall, seawater temperature strongly influences swordtip squid habitat, growth, maturation, and fishing ground, and this variable should be highly considered in future habitat studies in relation to climate change.…”

“…Forage fish play a pivotal role in marine ecosystems and are highly valuable worldwide, both directly as a landed commodity and indirectly as prey for other harvested species (Hunsicker et al, 2010;Pikitch et al, 2014). Squid (Cephalopoda: Loginidae) plays a critical role in sustaining trophic webs, is fast growing, has a short life span, lives in warm continental shelf waters, is a highly reproductive species, and is sensitive to changes in ambient oceanic variables, which result in its wide distribution in the Pacific Ocean from the South China Sea to Japan and through the Java Sea and coastal waters of Indonesia, Malaysia, and Thailand as well as the waters of the tropical and equatorial regions of Latin America (Roper et al, 1984;Liao et al, 2006;Wang et al, 2021;Fang et al, 2023). These characteristics rapidly increase the population size of this commercially important species in suitable habitats.…”

Spatial–Temporal Distribution of Fish Larvae in the Pearl River Estuary Based on Habitat Suitability Index Model

“…Therefore, chl-a can be one of the major reference indicators in the analysis of larvae habitat. Studies have shown that the spawning grounds and major fishing grounds of major commercial fishes in the northern SCS may vary with the distribution of chlorophyll concentration [ 51 , 52 ]. This study indicated that the larvae in the PRE inhabited in the waters with Chl-a of 0–10 mg/m 3 , and the optimum Chl-a for larvae in April, June, July, August and September was 2–4 mg/m 3 based on the SI model.…”