# Assessment of Potential Yield and Sustainable Management of Burbot, Lota lota (L.1758), in the Upper Heilongjiang River, China, Based on Population Parameters

## TL;DR

This study assesses the burbot population in the Upper Heilongjiang River, China, and suggests sustainable fishing limits to protect the species and ecosystem.

## Contribution

The study provides updated population parameters and proposes specific sustainable yield limits for burbot in the Upper Heilongjiang River.

## Key findings

- Burbot population in the Upper Heilongjiang River has recovered significantly but not fully.
- Suggested sustainable fishing limits are a minimum size of 251 mm and an annual catch of less than 14.69 tons.
- The estimated maximum sustainable yield is 14.69 tons with a current exploitation rate of 24.39%.

## Abstract

As the only freshwater species of Gadidae in the world, burbot, Lota lota, has a unique biological value. The uncontrolled utilization of burbot without knowing the current status of the stock will have a great impact on the whole inland cold-water fish community structure and ecosystem. We estimated and analyzed the data from our fieldwork in combination with mathematical modeling. We found that the burbot population in the upper Heilongjiang River has been seriously damaged. However, with the protection policies introduced by the local governmental departments in the past 10 years, the population has recovered considerably. Although the population has not recovered to its optimal state, we believe that it is appropriate to control the fishing size and the annual catch yield to more than 251 mm and less than 14.69 tons, respectively.

We evaluated growth, mortality, and resource utilization of burbot, Lota lota, in the upper reaches of Heilongjiang River, China. The population has experienced significant decline, and, despite substantial recovery, concerns regarding resource management have arisen. A total of 638 specimens collected from October 2022 to October 2023 were used to calculate the relationship between body length and weight, which ranged from 107 to 529 mm and from 8.91 to 1474.17 g, respectively. FAO FiSAT II software was used to estimate population parameters based on body length frequency distribution of the samples. The calculated progressive body length value and the growth coefficient were 551.25 mm and 0.16, respectively. The natural mortality rate of burbot is 0.31 a−1. Assuming a total mortality rate of 0.41 a−1, the estimated current exploitation rate is 24.39%. Total biomass (94.76 t) and maximum sustainable yield (14.69 t) were estimated based on length-structured virtual population analysis. Burbot, of the upper reaches of Heilongjiang River, is a fast-growing fish that is well-suited to the ecology of the investigated area. The current research yielded suggestions for utilization of resources to ensure the preservation of the species, as well as the development of the local economy.