*2.5. Muscle Chemical Analysis*

According to AOAC method [21], the contents of total nitrogen, crude protein, moisture, and ash were analyzed. The moisture of the sample was weighed after desiccating to a constant weight at 105 ◦C in an oven (DHG-9240A, Keelrein Instrument Co., Ltd., Shanghai, China). The ash content was indicated after samples were incinerated in a muffle furnace (SX2-12-12N, Jinwen Instrument Co., Ltd., Nanjing, China) at 550 ◦C for 12 h. The crude protein was analyzed by single acid digestion in the Kjeldhal apparatus (Kelplus DISTYL-BS, Pelican Equipment Pvt. Ltd., Chennai, India). After extraction with chloroform-methanol (2:1, *v*/*v*), the crude lipids were measured following previously methods as indicated [22,23].

#### *2.6. Data Calculation and Statistical Analyses*

The parameters were determined based on the following calculations:

Survival rate (SR, %) = (final quantity of fish)/(initial quantity of fish) ∗ 100%;

Weight gain rate (WGR, %) = (Wt − Wi)/Wi ∗ 100%;

Feed conversion ratio (FCR, %) = feed intake/(Wt − Wi) ∗ 100%;

Visceral index (VSI, %) = visceral weight/body weight ∗ 100%;

Condition factor (CF, g/cm3) = body wet weight/body length3 ∗ 100%;

Stocking density (SD, kg/m3) = (quantity of fish ∗ body wet weight)/volume of culture;

where Wi and Wt referred to the initial body weight and final body weight of large yellow croaker, respectively.

SPSS version 24.0 (IBM, Armonk, New York, NY, USA) was used for the statistical analyses. Data are expressed as the mean ± SD. Different groups were considered as significant at *p* < 0.05 by *T*-test and a one-way analysis of variance (ANOVA) and Duncan multiple comparative analysis. GraphPad Prism 8 was utilized to create plots of the data.

#### **3. Results**

#### *3.1. Culturing Sites and Transfer Routes*

The transfer route and anchorage seas of the ship Gouxin 101 and the site of the cage are shown in Figure 2. The ship could obtain the best culturing conditions by moving according to the demand, and the cage was fixed in the Sandu Bay. At the end of May, the temperature of water rose to more than 25 ◦C in Ningde Sea area in Fujian Province rapidly, and the aquaculture ship shifted from Sandu Bay to the Zhoushan Sea area in Zhejiang Province. Due to the occurrence of the red tide in anchorage seas of Lvhua Island in Zhoushan during the culturing, it was transferred to Peach Blossom Island for a short

time. In mid-July, to avoid super typhoon "Yanhua", it moved to the waters off Qingdao, Shandong Province. While in Qingdao, due to short-term gale weather, the ship was temporarily transferred to the inner Bay of Jiaozhou Bay.

**Figure 2.** Location of experiment area in traditional aquaculture cages (marked with an orange star) and the anchorage location (marked with a red dot) and sailing route (marked with red lines) of the offshore aquaculture ship <http://www.gissky.net/map/ChinaZQYW.html, accessed on 8 November 2022>.
