Introduction

Tongan Bay is located in the northern Bay of Xiamen sea area, which is rich in fishery resources. However, in recent years, fish resources have been seriously damaged by human activities, such as overfishing, chemical pollution and non-native species. Therefore, the Length‐Weight Relationship (LWR) is important data for fishery research [1-3]. Chinese Sea supports highly diverse and endemic species of fishes [4]. Meanwhile, Length-Weight Relationship (LWR) is a basic tool in fish science and fisheries management [5]. This paper introduces the relationship between body length and body weight of three kinds of fishes.

Material and Methods

Working with local fishermen, from July 2018 to July 2019, fish samples were collected using commercial trawls (mesh size: 10 mm), once every four months, three times in total. The weight and body length of the three kinds of fish were measured immediately after catching, in the laboratory. The body weight and body length of the three kinds of fish were measured to 0.1g and 0.1cm respectively. Then the morphological method was used to identify the three kinds of fish. The expression of the relationship function between body length and body weight is W = aLb, where W is the weight (g) and L is the total length (cm), was fitted with a simple linear regression model using log-transformed data [2]. The 95% Confidence Interval (CI) was determined for parameters a and b [3].

Results

The analysis results of the three kinds of fishes were showed in Table 1. These kinds of fish have commercial value, which is very common in the local area, and the most abundant species was Johnius fasciatus. The values of parameter b varied between 2.90 and 3.51 and the coefficient of determination values (r2) ranged from 0.835-0.961.

N: Number of Individuals; a: Intercept; b: Regression Coefficient; CI: Confidence Limits. r2: Coefficient of Determination (Adjusted R-Squared).

Discussion

In our study, parameter b ranged from 2.89 for Johnius fasciatus to 3.41 for Sillago sihama, and the range of parameter a is 0.0029 for Sillago sihama to 0.342 for Gerres japonica. The r² values in all LWRs of all fish species were >0.95 and the values of parameter b remained within the expected range of 2.5-3.5 [3]. In a word, this study provides basic LWR data of three kinds of fish species and provides a certain reference value for the reasonable development and protection of Fisheries in Tongan Bay of China.

Acknowledgement

This study was supported by the National Natural Science Foundation of China (NSFC) (NO. 41806156); Zhejiang Provincial Natural Science Foundation of China (LY15D060004); Starting Research Fund from the Zhejiang Ocean University; Open Foundation from Marine Sciences in the First-Class Subjects of Zhejiang Province; Natural Science Foundation of Zhejiang Province (LY17C200010); Fundamental Research Funds for Zhejiang Provincial Universities and Research Institutes [No.2019J00048].

References

1. Le Cren ED (1951) The length‐weight relationship and seasonal cycle in gonad weight and condition in the Perch (Perca fluviatilis). Journal of Animal Ecology 20(2): 201-219.
2. Lei J, Su JY, Xiong W, Ling LY, Zhang D (2018) Length-weight relationships of two fish species from sanniang bay of guangxi, china. Journal of Applied Ichthyology 34(4): 990-991.
3. Froese R (2006) Cube law, condition factor and weight‐length relationships: History, meta‐analysis and recommendations. Journal of Applied Ichthyology 22(4): 241-253.
4. Xiong W, Zhu GP, Wang ZL, Ye N (2018) Length-weight relationships of four fish species from mangrove of Zhanjiang, China. Journal of Applied Ichthyology 34(1): 167-168.
5. Xiong W, Tao J, Zhang DC, Liu C, He DK, et al. (2015) Length-weight relationships for four small fish species caught in wetland of central Y angtze River, China. Journal of Applied Ichthyology 31(1): 219-220.