How New Quality Productivity Becomes a New Driving Force for Marine Economy High-Quality Development: An Empirical Analysis Based on New Technology, New Forms, and New Economy

Abstract

Exploring the development laws of new quality productivity and leveraging its role in empowering marine economy high-quality development (MEHQ) is of great significance for promoting the construction of a maritime power in China, achieving the goals of Chinese-style modernization and solidifying the country’s advantages in marine economic development. This paper systematically reviews the mechanisms and effects of new quality productivity (NQP) in empowering MEHQ. Using panel data from 17 cities along the Bohai Sea from 2010 to 2022, we comprehensively measure the combined levels of NQP and MEHQ. Employing various statistical analysis methods, including benchmark regression models, multiple mediation effect models, and spatial Durbin models, we empirically test the mechanisms and spatial spillover effects of NQP in empowering MEHQ. The results indicate that NQP has a significant positive driving effect on MEHQ, and this conclusion remains valid after a series of robustness tests. The empowering effect of NQP on MEHQ mainly occurs through three pathways: marine technological innovation, optimization of marine industrial structure, and improvement of marine resource allocation efficiency. There is a positive correlation between NQP and MEHQ, with significant agglomeration phenomena, reflecting the non-uniform characteristics of spatial distribution. NQP not only empowers MEHQ but also exhibits significant spatial spillover effects, promoting MEHQ in adjacent regions and releasing growth dividends.

1. Introduction

In September 2023, China’s General Secretary Xi Jinping emphasized during his inspection in Heilongjiang that “integrating technological innovation resources, leading the development of strategic emerging industries and future industries, and accelerating the formation of NQP” [1]. In January 2024, while presiding over the 11th collective study session, General Secretary Xi made profound explanations and important arrangements for accelerating the development of NQP and solidly advancing high-quality development [2]. These two important speeches not only pointed out the direction for the development of NQP but also provided fundamental guidelines for the new path of high-quality development in our marine sector. NQP, as a reflection of the integration of new technologies, new business formats, and new economies, is gradually becoming an important force driving the marine economy. In the marine field, the cultivation and development of NQP are not only related to the sustained growth of the marine economy but also concern the sustainable protection of the marine ecosystem and the in-depth implementation of the national marine strategy [3].

Research on the driving mechanism of NQP empowering MEHQ aligns with the demands of the times and is an important direction in current marine economy studies, holding significant theoretical and practical significance. However, discussions and progress on this topic are still in the initial stages, as reflected in the following aspects: First, the ocean serves as a resource treasure and strategic space for future development, increasingly becoming a ballast for economic growth, a center for national manufacturing, a frontier in building an innovative country, a leader in open economic construction, and a demonstration window for green development, all of which embody typical characteristics of high-quality development [4]. A healthy and robust model for MEHQ requires long-term advanced production momentum. However, there is currently a lack of research on the driving mechanisms that empower MEHQ through multi-factor and integrated production elements. Second, NQP signifies a departure from the old technological system, breaking away from traditional growth paths, and meeting the requirements for high-quality development. In the digital age, it exhibits greater integration and new connotations, promoting quality through innovation [5]. However, it is still in its early stages, with insufficient empirical research on the theoretical connotations, driving mechanisms, and optimization paths of NQP in the context of MEHQ. To better unleash the potential and vitality of blue economic development and create new momentum for blue development, there is an urgent need for in-depth research combining qualitative, quantitative, and positioning approaches from a comprehensive perspective. How to cultivate NQP and lead and support MEHQ, thereby measuring, optimizing, and regulating the level of the blue economy, is the focus of this study and the scientific problem that needs to be addressed.

Based on the above background, this study aims to achieve blue growth and green development of China’s marine economy by exploring the core elements and mechanisms of NQP empowering MEHQ, and to construct a new pattern of NQP empowering MEHQ. Using panel data from 17 cities along the Bohai Sea from 2010 to 2022, this study employs benchmark regression models, mediation effect models, and spatial Durbin models to empirically test the impact effects and realization paths of NQP on MEHQ. This not only enriches the theories and methods of marine economic geography but also provides guidance and suggestions for the construction of a maritime power in the new era, holding significant theoretical and practical implications.

2. Literature Review

2.1. Research on New Quality Productivity

As the core driving force leading future economic development and social progress, NQP has become the focus of researchers and decision makers, and a series of theoretical and practical viewpoints have been put forward [6]. First of all, the concept of NQP is deeply analyzed. From the perspective of different disciplines, this paper systematically studies the definition [7], characteristics [8], and formation mechanism of NQP [9]. At the same time, the relationship and differences between NQP and traditional productivity are also discussed in depth [10], which provides a theoretical basis for further research on NQP. Secondly, the driving factors of NQP are systematically sorted out. Scholars generally believe that scientific and technological innovation, institutional reform, and human resource training are important driving forces for the development of NQP [11,12]. On this basis, the interaction mechanism among various driving factors and their specific influence paths and effects on the development of NQP are discussed [13]. Finally, the practical application of NQP is studied. Scholars have explored the application and actual effects of NQP in various fields through case analysis and empirical research [14,15].

The research status of NQP shows the characteristics of diversification and deepening. Scholars not only comprehensively analyze the concept, characteristics, and formation mechanism of NQP from the theoretical level but also discuss its driving factors and application effects from a practical perspective. These studies provide valuable theoretical support and an empirical basis for us to understand the nature and development law of NQP. However, there are still some shortcomings in the current research. For example, the quantitative measurement and evaluation system of NQP has not yet formed a unified standard, which limits the accurate assessment of its development level and effect. In addition, the research on the development difference and adaptability of NQP in different fields and regions still needs to be strengthened. Future research should further explore the quantitative evaluation methods of NQP, strengthen cross-field and cross-region comparative research, in order to more comprehensively reveal the development law and practical application value of NQP.

2.2. Research on Marine Economy High-Quality Development

With the marine economy becoming more and more important in the national economy, the research on MEHQ is constantly enriched and perfected. These studies mainly focus on the connotation of MEHQ [16], evaluation system [17], influencing factors [18], and realization path [19]. First of all, scholars have conducted an in-depth discussion on the connotation of MEHQ and made it clear that it includes multiple dimensions, such as the sustained growth of the marine economy, optimization of industrial structure, improvement of innovation ability, efficient use of resources, and ecological environmental protection [20]. Secondly, an evaluation system for MEHQ has been established, and a series of key indicators have been selected to conduct quantitative evaluation and comparative analysis of the level of MEHQ [21]. In addition, the paper deeply analyzes the main factors affecting MEHQ, such as scientific and technological innovation, policy support, resource endowment, market demand, etc., and discusses the action mechanism and influence effect of these factors [22]. Finally, it puts forward specific paths and countermeasures to promote MEHQ, including strengthening the guidance of scientific and technological innovation; optimizing the layout of industrial structure; deepening the reform of the system and mechanism; and promoting the construction of ecological civilization, so as to provide strong support for the realization of MEHQ [23]. Therefore, on the basis of existing MEHQ achievements and theoretical research, we aim to accelerate the transformation, continue to stimulate the vitality of MEHQ, and promote the coordination of the blue growth and green development of the marine economy in order to provide effective information for the construction of marine power in the new era.

Research on MEHQ has formed a relatively complete and in-depth framework system. From the definition of the connotation to the construction of the evaluation system, to the analysis of influencing factors and the exploration of the realization path, scholars have carried out a comprehensive analysis of many aspects of MEHQ. These studies not only enrich the theoretical system of MEHQ, but also provide a scientific basis for policy formulation and implementation in practice. However, with the continuous changes in the internal and external environment of the marine economy, MEHQ still faces many challenges and problems, such as the slow conversion of old and new growth drivers, and increasing constraints on resources and the environment. Therefore, future research needs to pay further attention to these new problems and challenges, deepen the understanding of the internal mechanism and dynamic mechanism of MEHQ, and strengthen interdisciplinary and cross-field comprehensive research to provide more comprehensive and in-depth intellectual support for promoting MEHQ.

2.3. Research on New Quality Productivity and Marine Economy High-Quality Development

Oceans nurture life, connect the world, and foster development. The marine economy has transitioned from a focus on sustainability to one of high-quality development, elevating the strategic importance from “blue economy” to “marine power construction.” [24]. Consequently, its growth momentum has shifted from traditional factors such as land, labor, capital, and technology to low-carbon initiatives and technological innovation [25]. Digital economy products like data, green finance, and blockchain have emerged as new drivers for MEHQ [26,27]. In this new era, steady MEHQ requires continuous enhancement of productive forces. “NQP,” distinct from traditional productivity, involves advanced fields and high-tech content, representing an innovation-intensive form of productivity. Its core characteristics are innovation-driven, advanced, leading, and comprehensive aligning with the demands of the times for MEHQ [28].

Regarding research on the relationship between NQP and MEHQ, there is limited academic exploration and discussion. From an innovation-driven perspective, Liang et al. [3] analyzed how NQP promotes MEHQ through technological and model innovation, thereby driving MEHQ. Du et al. [29], from the perspective of industrial chain integration, discussed how NQP can enhance coordination between upstream and downstream sectors of the marine economic industry chain, improving overall competitiveness and promoting MEHQ. Although these studies differ in their approaches, they all underscore the critical role of NQP in advancing MEHQ. However, deeper research on this relationship remains insufficient, necessitating further theoretical exploration and practical analysis.

This paper examines 17 coastal cities around the Bohai Sea to explore the impact of NQP on MEHQ and to identify a new path for MEHQ under the backdrop of NQP. Theoretically, it aims to integrate NQP into the analytical framework of MEHQ, establishing a connection between the two. It also analyzes how technological innovation, industrial structure upgrades, and resource optimization can empower MEHQ. Empirically, it constructs indices for MEHQ and NQP levels for the 17 coastal cities from 2010 to 2022, empirically testing the influence and transmission mechanisms using regression models, intermediary effect models, and spatial Durbin models. Practically, it provides a scientific basis and decision-making reference for promoting MEHQ through NQP.

3. Theoretical Analysis and Enabling Mechanism

3.1. Influence Mechanism of New Quality Productivity on the Marine Economy High-Quality Development

As a pivotal force driving economic development in the new era, NQP has infused fresh vitality into MEHQ through its unique attributes and innovative advantages. In the realm of the marine economy, NQP is not only evident in the integration and innovation of emerging technologies, business models, and economies but also in its profound transformation of traditional marine industry patterns, thereby elevating the marine economy to higher levels and standards.

Firstly, advanced technology stands as one of the core elements of NQP. With continuous breakthroughs and applications of cutting-edge technologies, the marine industry is progressively achieving intelligent and digital transformations. These technologies not only enhance the efficiency of marine resource exploration, development, and utilization but also bolster capabilities in marine environmental monitoring and disaster early warning, providing robust technical support for MEHQ. Secondly, the emergence of new business models offers extensive opportunities for NQP to influence MEHQ. Industries like marine tourism, marine culture, and marine biomedicine are burgeoning, enriching the scope and depth of MEHQ while extending and expanding related industrial chains. Guided by market demand and driven by innovation, these new business models inject fresh impetus into MEHQ. Furthermore, the vigorous development of the new economy fosters deeper integration of NQP within MEHQ. Economic models represented by the digital economy, green economy, and sharing economy are profoundly altering MEHQ. Through digitalization, networking, and intelligence, the marine economy achieves more efficient, environmentally friendly, and sustainable growth. Additionally, these new economic models promote the marine industry with other sectors, facilitating the optimization and upgrading of the marine economic structure.

Through the five development concepts—innovation, coordination, green, openness, and sharing—NQP has significantly impacted MEHQ. Innovation, as the primary driver, propels continuous advancements in marine science and technology, improves the utilization efficiency of marine resources, develops competitive marine products, and infuses new vitality into MEHQ. Coordination emphasizes harmonious coexistence between ocean and land, economy and society, and humans and nature, ensuring comprehensiveness, coordination, and MEHQ. Green development underscores ecological and environmental protection, requiring balanced economic and ecological benefits during marine resource development. Openness advocates active participation in global economic cooperation and competition, leveraging both domestic and international resources and markets to expand the development space of the marine economy. Sharing embodies people-oriented development, ensuring that the fruits of marine economic development benefit all people and improve living standards and happiness.

In summary, NQP has profoundly influenced MEHQ through the five development concepts of innovation, coordination, green, openness, and sharing. It enhances the innovation capacity and competitiveness of the marine economy while promoting comprehensive, coordinated, and sustainable development, laying a solid foundation for building a maritime power.

3.2. Effect and Hypothesis of New Quality Productivity Empowering Marine Economy High-Quality Development

3.2.1. Direct Effect

The direct effect of NQP on MEHQ is primarily manifested in two key areas: technological innovation and industrial upgrading. Firstly, technological innovation is the core driving force for enhancing MEHQ. By introducing advanced technologies, processes, and materials, the marine industry can significantly boost production efficiency, reduce costs, improve product quality, and thereby enhance market competitiveness. For instance, the application of intelligent technology can facilitate the automation and intelligent upgrading of marine equipment, improving the efficiency of exploration, development, and utilization of marine resources. Secondly, industrial upgrading is a critical pathway through which NQP promotes MEHQ. The development of NQP has facilitated the optimization and upgrading of the marine industrial structure, shifting from traditional high-energy consumption and high-pollution industries to low-carbon, environmentally friendly, and efficient industries. This transformation not only enhances the overall benefits of the marine economy but also supports MEHQ and the ecological environment. In summary, the following hypothesis is proposed:

Hypothesis 1.

NQP positively drives the improvement of MEHQ.

3.2.2. Heterogeneous Effect

Given the heterogeneity across different regions in terms of geographical location, development stage, and NQP structure, this study posits that differentiated development strategies and policies should be implemented to promote the growth of NQP and foster MEHQ. Firstly, geographical location heterogeneity implies that the impact of NQP on MEHQ varies with different locations. Differences in geographical conditions lead to variations in the development speed and direction of NQP, consequently affecting MEHQ differently. Secondly, developmental stage heterogeneity indicates that the absorption and utilization capacity of NQP differ at various stages of development. The role and position of NQP vary across cities at different developmental stages, leading to distinct impacts on MEHQ. Finally, the structural heterogeneity of NQP highlights that different types of NQP have varying effects on MEHQ. For example, high-tech and green industries focus more on technological innovation and environmental protection, positively impacting regional economic transformation and sustainable development. Financial and business services emphasize infrastructure construction and business environment optimization, promoting diversified and international development of the urban economy.

Hypothesis 2.

The impact of NQP on MEHQ exhibits geographical location heterogeneity, developmental stage heterogeneity, and structural heterogeneity of NQP.

3.2.3. Indirect Effect

Marine science and technology innovation serve as the core driving force for the development of regional NQP. In the context of continuous global scientific and technological progress, it is imperative to strengthen scientific and technological innovation and enhance independent innovation capabilities. Increasing investment in research and development, building innovation platforms, and attracting and cultivating high-quality scientific and technological talents will continuously bolster scientific and technological strength, providing robust technical support for MEHQ. Industrial structure upgrading is a key approach to developing regional NQP. Accelerating the optimization of industrial structure and promoting diversified industrial development are necessary. By fostering emerging industries, improving traditional industries, and enhancing service industry levels, we can gradually reduce resource dependence and enhance regional economic stability. Rational allocation of marine resources is crucial for the development of regional NQP. Efficient resource utilization and management are essential for MEHQ. By strengthening resource planning and management, optimizing resource allocation, promoting recycling and economical use, we lay a solid material foundation for new urbanization. In summary, the following hypothesis is proposed:

Hypothesis 3.

NQP influences the dynamic change in MEHQ through three channels: marine science and technology innovation, marine industrial structure upgrading, and marine resource allocation.

3.2.4. Spatial Effect

As the core driving force for MEHQ, NQP not only promotes local EHQ but also exerts a far-reaching radiation impact on surrounding regions. Specifically, NQP, characterized by its unique integration features, effectively breaks regional restrictions, enhances inter-industry links, and improves the industrial structure for EHQ. Additionally, the introduction of NQP strengthens internal and external economic relations within cities, achieving common regional economic development through industrial chain synergy. The promotion of NQP ensures resource development while emphasizing ecological environmental protection, accelerating EHQ in surrounding areas. Moreover, NQP can significantly reduce marginal costs of economic activities in local and surrounding areas, making social governance of MEHQ more intelligent, promoting cross-regional market player linkage, and substantially increasing revenue. Therefore, the impact of NQP on MEHQ may exhibit spatial spillover effects. In summary, the following hypothesis is proposed:

Hypothesis 4.

NQP has a spatial spillover effect on the improvement of MEHQ.

4. Research Design

4.1. Model Construction

In order to assess the impact of NQP on MEHQ and reduce the deviation caused by collinearity, this study adopts the multiple regression method to analyze the panel data, and discusses the correlation between marine science and technology innovation, marine industrial structure upgrading, and marine resource element allocation on MEHQ. For Hypothesis 1, a panel benchmark regression model is constructed:

$$NQ{P}_{it}={\alpha }_0+{\alpha }_{1}MEH{Q}_{it}+\gamma contro{l}_{it}+u_{it}+{\lambda }_{it}+{\epsilon }_{it}$$

(1)

where i is the region; t is the year; NQP_it is the development level of new quality productive forces; MEHQ_it is MEHQ level; a is a constant term; ${control}_{it}$ is the control variable that affects the MEHQ level; μ_it is a regional fixed effect; λ_it is a time fixed effect; and ${\epsilon }_{it}$ is a random disturbance term.

According to the above theoretical analysis, the development of NQP may promote MEHQ through three ways: marine science and technology innovation, marine industrial structure upgrading, and marine resource element allocation. According to the above analysis, the following multiple intermediary effects model is established:

$$HST{I}_{\mathrm{it}}={\beta }_0+{\beta }_{1}MEH{Q}_{it}+{\beta }_{2}contro{l}_{it}+{\epsilon }_{it}$$

(2)

$$HIN{D}_{\mathrm{it}}={\beta }_0+{\beta }_{1}MEH{Q}_{it}+{\beta }_{2}contro{l}_{it}+{\epsilon }_{it}$$

(3)

$$HF{A}_{\mathrm{it}}={\beta }_0+{\beta }_{1}MEH{Q}_{it}+{\beta }_{2}contro{l}_{it}+{\epsilon }_{it}$$

(4)

$$NQ{P}_{it}={\gamma }_0+{\gamma }_{1}MEH{Q}_{it}+{\gamma }_{2}HST{I}_{it}+{\gamma }_{3}HIN{D}_{it}+{\gamma }_{3}HF{A}_{it}+{\gamma }_{5}contro{l}_{it}+{\mu }_{it}+{\lambda }_{it}+{\epsilon }_{it}$$

(5)

In the formula, HSTI, HIND, and HFA are the three variables of marine science and technology innovation, marine industrial structure upgrading, and marine resource factor allocation, respectively, whereas α, β, and γ are the parameters to be estimated, respectively, and other variables are the same as above. When α₁ is significant, it indicates that NQP has an impact on MEHQ. When β₁ is significant, it indicates that NQP will affect the mediating variable. Based on this, when γ₂ is significant and γ₁ is not significant or the coefficient is less than α₁, the intermediary effect is present.

In order to further examine the spatial spillover effect of NQP on MEHQ, a spatial Durbin model was constructed:

$$MEH{Q}_{it}={\theta }_0+{\theta }_{1}WMEH{Q}_{it}+{\theta }_{2}WNQ{P}_{it}+{\theta }_{3}NQ{P}_{it}+{\theta }_{3}Wcontro{l}_{it}+\theta {\gamma }_{3}contro{l}_{it}+{\mu }_{it}+{\lambda }_{it}+{\epsilon }_{it}$$

(6)

where θ₁ is the spatial autoregressive coefficient, and θ₂ represents the spatial spillover effect of NQP. W is the spatial weight matrix, and other variables are defined as above. Based on the model estimation results, the total effect, direct effect, and indirect effect of NQP on MEHQ are decomposed.

4.2. Measurement and Description of Variables

4.2.1. Explained Variable: MEHQ

Based on scientific and operational principles, this study comprehensively considers the development status of coastal cities around the Bohai Sea; selects multidimensional evaluation indicators covering time series and spatial distribution; and constructs an evaluation system covering 25 specific indicators based on the five dimensions of innovation, coordination, green, openness, and cooperation, with reference to the calculation method of Chen et al. and An et al. [30,31]. The entropy method is used to assign weight to each index and measure the level of the index. As an objective weighting method, the entropy weight method can reflect the amount of information contained in each index and determine the weight of each index by calculating the information entropy of each index. This method avoids the bias caused by subjective empowerment and makes the construction of a comprehensive index more scientific and reasonable (see

Table 1. Indicator system for the marine economy high-quality development.

Target Layer	System Layer	Indicator Layer	Attributes
Marine economy high-quality development	Innovation	Intensity of marine R&D expenditure	+
		Number of marine research papers published	+
		Number of marine research topics	+
		Marine scientific research personnel of Thurber accounted	+
		Marine productivity per shoreline	+
	Coordination	Proportion of marine tertiary industry	+
		Proportion of added value of marine scientific research, education, and management service industry	+
		Urbanization rate in coastal areas	+
		Coefficient of difference of disposable income between urban and rural residents in coastal areas	-
		Marine industry employment deviation	-
	Green	Massive industrial wastewater discharges per unit gross marine industrial product	-
		Exhaust emissions per unit of gross marine industrial product	-
		Proportion of good water quality points in coastal waters	+
		Electricity consumption per capita in coastal areas	-
		Energy consumption per unit gross marine industry product	-
	Open	Economic externality of coastal areas	+
		International container throughput of coastal ports	+
		Actual amount of direct utilization of foreign capital in coastal areas	+
		Proportion of overseas tourists in coastal areas	+
		Reception capacity of inbound tourism in coastal areas	+
	Share	Proportion of marine major students in school	+
		Coastal area per capita medical institutions of beds	+
		Disposable income of coastal urban residents	+
		Per capita green park area in coastal areas	+
		Proportion of sea-related employees	+

).

4.2.2. Core Explanatory Variable: NQP

The core feature of NQP is its ability to break through key disruptive technologies, which not only reflects the depth and breadth of scientific and technological innovation but also is an important pillar of the national strategic layout. In the process of promoting the development of China’s strategic emerging industries and future industries, NQP plays an irreplaceable role. At present, China still has shortcomings in some key technological fields and faces the challenge of the technological blockade of Western developed countries. Therefore, the development of NQP is of vital significance to enhance China’s competitive position in the global industrial chain, break through the technological blockade, and achieve independent technological innovation. NQP covers three aspects: new technology, new economy, and new business form [32,33,34]. Among them, the new technology focuses on promoting the progress of science and technology, especially emphasizing the breakthrough of key technologies to provide technical support for industrial development; the new economy relies on the deep integration of scientific and technological innovation and institutional innovation to promote the economic structure and inject new momentum into industrial development. The new business format is driven by digital technology, promotes the digital transformation of traditional industries, accelerates the industrial application of digital technology, and realizes the effective transfer of technology to high-end industries. By continuously promoting the development of NQP, it will provide solid support for the optimization and upgrading of China’s industrial system and MEHQ, and open up a new growth path. The core explanatory variable NQP represents the development level of NQP. Based on the definition and measurement indicators of NQP in the existing literature, evaluation indicators are selected from three key dimensions: new technology, new business form, and new economy (

Table 2. Indicator system for the new quality productivity.

Target Layer	System Layer	Dimension Layer	Indicator Layer	Attributes
New quality productivity	New technology	Educate structure	Per capita education level	+
			Structure of students in institutions of higher learning	+
		Human capital structure	Human capital structure	+
			Proportion of tertiary industry employees	+
		Technology Research and Development	Number of patents per capita	+
			R&D investment	+
	New formats	Entrepreneurial idea	Entrepreneurial activity	+
		Emerging sectors of strategic importance	Added value of emerging strategic industries	+
		Future industry	Number of robots	+
		Digital infrastructure	Fiber length	+
		Digital economy	Digital economy index	+
		Enterprise digitization	Enterprise digital economy level	+
	New economy	Economic strength	Per capita GDP	+
		Social security	Per capita wage	+
		Environmental governance	Industrial waste treatment	+
			Intensity of environmental protection	+
			Pollutant discharge	-
		Ecological protection	Forest coverage rate	+
			Energy consumption	-
		Infrastructure construction	Highway mileage	+

). After the standardization of the selected index data, the entropy weight method is used to calculate the comprehensive index of NQP, reflecting the overall development of China’s NQP. As an objective weighting method, the entropy weight method can reflect the amount of information contained in each index and determine the weight of each index by calculating the information entropy of each index. This method avoids the bias caused by subjective empowerment and makes the construction of the comprehensive index more scientific and reasonable.

4.2.3. Intermediary Variables

The intermediary variables include marine science and technology innovation, marine industrial structure upgrading, and marine resource factor allocation, in which marine science and technology innovation (STI) is represented by the number of marine patent applications per capita [34], and marine industrial structure upgrading (IND) is measured by Fu Linghui’s industrial structure upgrading index [35]. It is used to describe the transformation process of industrial structure from the primary stage to the advanced stage, and resource factor allocation (FE) is represented by marine factor allocation efficiency.

4.2.4. Control Variables

In order to better analyze the effect of NQP enabling MEHQ, this paper selected population growth (POP), transportation infrastructure (TI), government fiscal expenditure (GOV), number of industrial enterprises above designated size (ENT), and cultural industry strength (CUL) as control variables. Among them, population growth is represented by the natural population growth rate, transportation infrastructure is represented by the sum of road density and railway density, government fiscal expenditure is represented by the ratio of local government fiscal expenditure to GDP, and the number of industrial enterprises above a designated size is represented by the number of industrial enterprises above a designated size at the provincial level. The strength of the cultural industry is represented by the ratio of income from the cultural creation industry above a designated size to GDP.

4.3. Data Sources

This paper selects the annual data of 17 prefectural-level cities (Tianjin, Tangshan, Qinhuangdao, Cangzhou, Qingdao, Yantai, Binzhou, Dongying, Weifang, Weihai, Rizhao, Dalian, Jinzhou, Panjin, Yingkou, Dandong, and Huludao) in the coastal area around the Bohai Sea from 2010 to 2022 as the basic data. The data involved are mainly from the 2010 to 2022 China Urban Statistical Yearbook, China Marine Statistical Yearbook, China Port Yearbook, statistical yearbook, ecological environment bulletin, and marine environment bulletin of coastal provinces and cities around the Bohai Sea region; EPS database; China Economic Network database; and wind database. Some missing data were estimated by interpolation and analogy.

These data sources are authoritative statistics to ensure the reliability and accuracy of the data. The 17 prefecture-level cities in the coastal area around the Bohai Sea are selected as the research objects because this area is an important and representative area for MEHQ. At the same time, the data period covers from 2010 to 2022, which can better reflect the impact of NQP on MEHQ.

5. Result Analysis

5.1. Baseline Regression Analysis

According to the benchmark regression model (1) constructed above, the benchmark regression results of NQP enabling MEHQ can be calculated, as shown in

Table 3. Benchmark regression results.

Variable	MEHQ
	(1)	(2)	(3)	(4)	(5)	(6)
NQP	0.885 *** (0.055)	0.7621 *** (0.056)	0.692 *** (0.077)	0.661 *** (0.030)	0.582 *** (0.028)	0.556 *** (0.067)
POP		0.002 (0.003)	0.005 (0.003)	0.004 ** (0.004)	0.005 *** (0.002)	0.006 *** (0.001)
TI			−0.006 *** (0.001)	−0.003 ** (0.002)	−0.001 (0.002)	−0.002 (0.004)
GOV				0.009 *** (0.002)	0.004 (0.002)	0.005 (0.002)
ENT					−0.026 *** (0.009)	−0.027 *** (0.008)
CUL						0.002 (0.002)
_cons	0.031 *** (0.005)	0.022 ** (0.008)	0.072 *** (0.018)	−0.032 * (0.032)	0.251 *** (0.101)	0.298 *** (0.113)
N	221	221	221	221	221	221
R2_a	0.825	0.833	0.821	0.823	0.819	0.863
City FE	Yes	Yes	Yes	Yes	Yes	Yes
Year FE	Yes	Yes	Yes	Yes	Yes	Yes

Note: *, **, and *** are significant at the level of 10%, 5%, and 1%, respectively, and the values in brackets are standard deviations.

. NQP, as a new driving force of modern science and technology and economic development, not only provides strong technical support for MEHQ but also injects new vitality and possibilities into it. As can be seen from the data in Table 3, on the basis of excluding the influence of various control variables, the correlation between NQP and new urbanization is extremely high, and its impact coefficient reaches 0.885, which fully demonstrates the important role of NQP in promoting MEHQ. In the process of gradually introducing different control variables, the influence coefficient of the development of NQP on MEHQ not only remains at a significant level of 1%, but also shows a steady growth trend. Behind this trend is the increasingly close correlation and interaction between NQP and MEHQ. After controlling all potential disturbing variables, the influence coefficient of NQP on MEHQ reaches 0.556, which means that for every 1 percentage point increase in NQP, the MEHQ level is expected to increase by 0.556 units. Further in-depth analysis of this result shows that NQP plays a significant role in promoting MEHQ and shows a steady growth trend. This driving effect is not achieved overnight but is based on long-term accumulation and continuous innovation.

For population growth (POP), although its influence coefficient is positive, it does not pass the significance test, indicating that the increase in the natural population growth rate has limited direct impact on MEHQ. The influence coefficient of transportation infrastructure (TI) is significantly negative, and the value is small, indicating that the current construction and development of transportation infrastructure has no obvious promoting effect on MEHQ and may even have a certain restricting effect. This may be due to the fact that the layout, planning, and operational efficiency of transportation infrastructure cannot fully adapt to the needs of MEHQ, resulting in its supporting role in MEHQ not having been fully played. The influence coefficient of government financial expenditure (GOV) is also significantly positive, indicating that government financial support is an important force to promote MEHQ. The influence coefficient of the number of industrial enterprises above a designated size (ENT) is negative and has passed the significance test, which indicates that the excessive number or unreasonable structure of industrial enterprises above a designated size may have a certain negative impact on MEHQ. This may be due to the excess capacity of some industrial enterprises, lack of innovation capacity, environmental standards, and other problems, resulting in its role in promoting MEHQ not being obvious, and it may even become a restricting factor. Although the influence coefficient of cultural industry strength (CUL) is positive, the significance level is relatively low, reflecting that the current contribution of the cultural industry to MEHQ needs to be further improved.

5.2. Heterogeneity Test

5.2.1. Geographical Location Heterogeneity Test

According to the characteristics of administrative division, economy and society, and development history, the Bohai Rim region is divided into a western Economic zone (Tianjin, Tangshan, Qinhuangdao, Cangzhou), a southern Economic zone (Qingdao, Dongying, Binzhou, Weifang, Yantai, Weihai, Rizhao), and a northern economic zone (Dalian, Dandong, Yingkou, Panjin, Jinzhou, Huludao) in order to realize NQP and MEHQ in the region.

As one of the important regions of China’s economic development, the test results of geographical location heterogeneity in the Bohai Rim region are also worthy of attention. The overall results show that NQP in the north, south, and west of China’s coastal cities around the Bohai Sea has geographical location heterogeneity, showing a development pattern of “western region > Southern region > northern region”. The influence coefficient of NQP on MEHQ in the western region is 0.756. Relying on the radiative driving role of Tianjin and other cities, the economic development of the western economic zone is relatively fast, and the development of NQP is also relatively rapid, which has a more obvious role in promoting MEHQ. The influence coefficient of NQP on MEHQ in the southern region is 0.224. With the industrial advantages and innovative vitality of Qingdao, Yantai, and other cities in the southern economic zone, NQP has also achieved positive results in enabling MEHQ. Although the northern economic zone has Dalian and other port cities, it is relatively backward in the cultivation and development of NQP, and its role in promoting MEHQ needs to be further strengthened (see

Table 4. Grouped regression results based on different geographical locations.

Variable	MEHQ
	Western Economic Zone	Northern Economic Zone	Southern Economic Zone
NQP	0.756 *** (0.092)	0.224 *** (0.063)	0.426 *** (0.052)
POP	0.032 *** (0.003)	0.005 (0.006)	0.007 (0.001)
TI	0.006 (0.006)	0.005 (0.008)	−0.005 *** (0.002)
GOV	0.022 (0.008)	0.009 (0.006)	0.007 (0.003)
ENT	−0.065 ** (0.053)	−0.056 *** (0.032)	−0.052 *** (0.006)
CUL	−0.005 (0.006)	0.005 (0.002)	−0.005 (0.003)
_cons	0.356 * (0.333)	0.869 *** (0.436)	0.365 *** (0.068)
N	52	91	78
R2_a	0.835	0.894	0.866
City FE	Yes	Yes	Yes
Year FE	Yes	Yes	Yes

Note: *, **, and *** are significant at the level of 10%, 5%, and 1%, respectively, and the values in brackets are standard deviations.

).

5.2.2. Developmental Stage Heterogeneity Test

In the “Twelfth Five-Year Plan” period, the NQP to enable MEHQ was still in the initial stage. During this period, NQP mainly provided basic support for MEHQ through technological innovation and infrastructure upgrading. Although the impact coefficient is relatively low, only 0.122, it has shown its positive role in promoting MEHQ. The results of the heterogeneity test at this stage show that NQP plays an important role in promoting the transformation of the marine economy from a traditional model to MEHQ model.

Entering the “13th Five-Year Plan” period, the role of NQP enabling MEHQ has further emerged. With the increase in the urbanization rate and the expansion of the urban population, the marine economy has ushered in new opportunities for development. At this stage, NQP is more reflected in the industrial upgrading and the cultivation of emerging industries, which has injected new vitality into the marine economy. Heterogeneity test results show that the impact coefficient has significantly increased compared with the “Twelfth Five-Year” period, indicating that the role of NQP in promoting MEHQ is increasing.

In the “14th Five-Year Plan” period, the effect of NQP enabling MEHQ is more significant. With the development of new urbanization showing new characteristics and trends, the marine economy is also facing the requirements of higher quality and more sustainable development. At this stage, NQP not only continues to play a driving role in technological innovation and industrial upgrading but also pays more attention to the coordination and symbiosis with the marine ecological environment, and promotes the development of the marine economy in the direction of green, low-carbon, and circular. Heterogeneity test results show that the impact coefficient has risen to 0.700, which fully proves the key role of NQP in promoting MEHQ. At the same time, the interaction between NQP and other factors is also closer, which jointly promotes MEHQ to a higher level and higher quality (see

Table 5. Regression results by time period.

Variable	MEHQ
	The 12th Five-Year Plan Period	The 13th Five-Year Plan Period	The 14th Five-Year Plan Period
NQP	0.221 ** (0.036)	0.536 *** (0.056)	0.768 *** (0.053)
POP	−0.005 (0.006)	0.006 (0.005)	0.022 *** (0.006)
TI	−0.008 *** (0.005)	0.002 (0.001)	−0.023 *** (0.0043)
GOV	0.006 * (0.008)	−0.008 (0.005)	0.022 ** (0.008)
ENT	−0.053 *** (0.022)	−0.036 ** (0.022)	0.036 *** (0.008)
CUL	−0.002 (0.006)	−0.002 (0.004)	0.003 (0.008)
_cons	0.633 *** (0.224)	0.563 ** (0.160)	−0.486 *** (0.061)
N	221	221	221
R2_a	0.538	0.790	0.925
City FE	Yes	Yes	Yes
Year FE	Yes	Yes	Yes

Note: *, **, and *** are significant at the level of 10%, 5%, and 1%, respectively, and the values in brackets are standard deviations.

).

5.2.3. Structural Heterogeneity Test

When studying the impact of the structural heterogeneity of NQP on MEHQ, this paper deeply discusses the contribution of new technology, new business forms, and the new economy to MEHQ. As shown in

Table 6. Grouped regression results based on different structures.

Variable	MEHQ
	New Technology	New Formats	New Economy
NQP	1.0005 *** (0.155)	1.025 *** (0.063)	1.036 *** (0.136)
POP	−0.003 ** (0.003)	0.004 ** (0.003)	0.006 *** (0.003)
TI	−0.022 *** (0.002)	−0.003 (0.002)	0.004 (0.000)
GOV	0.010 *** (0.004)	0.021 *** (0.005)	−0.003 *** (0.000)
ENT	0.061 *** (0.004)	−0.0432 *** (0.008)	0.031 ** (0.021)
CUL	0.006 (0.005)	0.005 *** (0.003)	−0.002 (0.002)
_cons	−0.352 *** (0.033)	0.432 *** (0.121)	0.122 (0.131)
N	221	221	221
R2_a	0.609	0.903	0.823
City FE	Yes	Yes	Yes
Year FE	Yes	Yes	Yes

Note: ** and *** are significant at the level of 5% and 1%, respectively, and the values in brackets are standard deviations.

, the dimension of new technology shows that the heterogeneity of NQP reflects the diversity of workers’ skill levels, knowledge structure, and innovation ability. This diversification not only provides abundant labor resources for MEHQ but also promotes the upgrading of urban industrial structure and the transformation of the economic development mode.

At the same time, with the continuous development of NQP, new business forms also show a diversified trend. The development of traditional industries mainly relies on material resources, while the development of NQP makes non-material resources such as knowledge, information, and technology become an important part of the industrial structure. This change has injected new impetus into MEHQ and promoted the transformation of the urban economy to the direction of knowledge intensive and technology intensive.

In addition, the heterogeneity of the new economy also plays a key role in MEHQ. With the progress of science and technology, new production materials such as intelligent equipment and digital tools continue to emerge, significantly improving production efficiency and quality. The application of these new means of production has promoted the upgrading of traditional industries and provided a convenient and efficient way for MEHQ.

5.3. Robustness Test

This paper carries out the following rigorous robustness tests (

Table 7. Robust regression results.

Variable	Replace the Core Explanatory Variables	Replace the Explained Variable	Tailing Treatment	Instrumental Variable Method
NQP	0.022 *** (0.002)	0.621 *** (0.0327)	0.563 *** (0.023)	0.641 *** (0.014)
POP	0.008 *** (0.003)	0.006 *** (0.001)	0.008 *** (0.003)	0.005 ** (0.002)
TI	−0.002 (0.003)	−0.002 (0.131)	−0.002 (0.005)	−0.023 *** (0.006)
GOV	0.002 (0.006)	0.005 (0.001)	0.005 (0.005)	0.008 *** (0.005)
ENT	−0.025 *** (0.005)	−0.053 *** (0.006)	−0.027 *** (0.009)	0.056 *** (0.005)
CUL	−0.005 (0.002)	−0.006 ** (0.002)	−0.005 (0.006)	0.010 *** (0.005)
_cons	0.369 *** (0.352)	0.427 *** (0.202)	0.248 *** (0.303)	−0.219 *** (0.086)
N	221	221	221	221
R2_a	0.866	0.835	0.856	0.831
City FE	Yes	Yes	Yes	Yes
Year FE	Yes	Yes	Yes	Yes

Note: ** and *** are significant at the level of 5% and 1%, respectively, and the values in brackets are standard deviations.

): First, the replacement of core explanatory variables is adopted, and the entropy–TOPsis method is used to re-assign NQP, so as to construct a new comprehensive index of NQP development. Secondly, considering the possible lag effect of the influence of NQP on MEHQ, MEHQ with a lag of one stage is used as the explained variable test to investigate the dynamic relationship between them more comprehensively. Third, in order to eliminate the possible interference of the outliers in the samples to the regression analysis, all variables were treated at the 1% level by double-tailed reduction, and on this basis, the regression analysis was conducted again. Finally, in order to prevent the occurrence of endogeneity problems, the instrumental variable method is used to test endogeneity. Specifically, the IV-2SLS regression is carried out by selecting one phase lag of NQP as the instrumental variable, because there is a strong correlation between one phase lag of NQP and the current period of NQP, and it will not directly affect MEHQ, thus meeting the strict exogenous conditions for the selection of instrumental variables. After the above robustness test, it is found that the impact of NQP on MEHQ is still consistent with the baseline regression results, which further enhances the reliability and robustness of the conclusions in this paper.

5.4. Mechanism Test

In order to deeply explore whether the innovation of marine science and technology, the upgrading of marine industrial structure, and the allocation of marine resource factors have a profound impact on MEHQ as the media of NQP, this paper makes a systematic and rigorous discussion on the basis of fully referring to the theoretical analysis above. As can be seen from

Table 8. Mediation mechanism test results.

Model	(1)	(2)	(3)	(4)
Variable	HSTI	HIND	HFE	HNU
NQP	1.236 *** (0.065)	0.635 *** (0.062)	0.7786 *** (0.088)	0.219 *** (0.060)
HSTI				0.106 *** (0.026)
IND				0.026 * (0.015)
APF				0.236 *** (0.034)
POP	−0.002 (0.006)	−0.005 (0.001)	−0.005 (0.005)	0.006 *** (0.001)
TI	0.003 (0.001)	−0.007 (0.006)	0.006 (0.006)	−0.003 (0.005)
GOV	−0.002 (0.003)	−0.007 (0.003)	0.013 *** (0.008)	0.001 (0.006)
ENT	0.054 *** (0.035)	0.056 *** (0.062)	−0.157 *** (0.015)	−0.055 *** (0.008)
CUL	−0.0086 (0.005)	−0.006 (0.008)	−0.022 *** (0.008)	−0.006 (0.005)
_cons	−0.768 *** (0.296)	1.186 *** (0.268)	0.893 *** (0.186)	0.356 *** (0.038)
N	221	221	221	221
R2_a	0.775	0.639	0.882	0.879
City FE	Yes	Yes	Yes	Yes
Year FE	Yes	Yes	Yes	Yes

Note: * and *** are significant at the level of 10% and 1%, respectively, and the values in brackets are standard deviations.

, NQP has a positive and significant impact on marine science and technology innovation, marine industrial structure upgrading, and marine resource factor allocation, all of which are verified at the significance level of 1%, with regression coefficients of 1.236, 0.635, and 0.786, respectively. In the mediation effect analysis of a specific path, path 1 reveals the mechanism of “NQP promotes MEHQ through technological innovation”, and its intermediary effect value is 0.226, indicating that technological innovation plays an important role in promoting MEHQ. Path 2 shows the effect of “NQP promotes MEHQ through the upgrading of marine industrial structure”, and the effect value is 0.069, indicating that the upgrading of marine industrial structure plays a positive intermediary role in the process of enabling MEHQ by NQP. Path 3 reflects the effect of “NQP promotes MEHQ with the help of allocation of marine resource factors”, with an intermediary effect value of 0.135, highlighting the important position of allocation of marine resource factors in promoting MEHQ. By summarizing the mediation effects of the above three specific paths, the overall mediation effect is 0.213. Furthermore, after the introduction of three intermediary variables, the regression coefficient of NQP on MEHQ drops to 0.113, indicating that the direct effect of NQP is less than the sum of the three intermediary effects. In terms of the comparison of the intermediary effect, the proportion of marine science and technology innovation, marine industrial structure optimization, and marine resource allocation in the overall intermediary effect is 15%, 20%, and 31%, respectively, showing the distribution law of “path 3 > path 2 > path 1”. In summary, hypothesis 3 is supported by empirical evidence.

5.5. Space Spillover Effect

NQP, as the key driving force of social and economic development, has a direct impact on the inner structure and economic layout of cities, and its spatial spillover effect also has a non-negligible impact on the promotion of MEHQ. Therefore, this study adopts the global autocorrelation test method to deeply analyze the spatial correlation between NQP and MEHQ. According to the test analysis, the results show that the Moran index of NQP and MEHQ in the study area is significantly positive. However, there are obvious differences between the two in the process of dynamic change, which fully indicates that there is a significant spatial correlation between them. Therefore, the spatial Durbin model (SDM) is used to further study the spatial spillover effects of the two.

After statistical analysis, using the LM test, LR test, and Wald test, the SDM model is unanimously confirmed as the most suitable model, and the possibility of model degradation into the spatial autocorrelation model (SAR) or spatial error model (SEM) is excluded. In addition, the results of the Hausman test are significant at the 1% significance level, further supporting the decision to choose a fixed-effect model. Therefore, the spatial weight matrix based on geographical distance and the spatial Durbin model based on fixed effects are adopted to deeply explore the spatial impact of NQP on MEHQ, and the relevant effects are analyzed in detail (Figure 1). For every 1% increase in the development level of NQP, the MEHQ level increases by about 0.526%. Furthermore, the improvement of NQP also led to an increase of about 0.152% in MEHQ in neighboring cities. This is mainly due to the fact that NQP is often accompanied by technological innovation, management innovation, and other innovative activities. The dissemination and diffusion of these innovative activities between cities provides a steady stream of innovation power for MEHQ. By learning from and absorbing the development experience and technological achievements of advanced cities, late-developing cities can better achieve leapfrog development and promote the continuous deepening of MEHQ. NQP emphasizes the concept of sustainable development, such as green development and circular development, and its spatial spillover effect helps promote cooperation and exchanges between cities in resource conservation and environmental protection. Therefore, if hypothesis 4 is verified, sufficient attention should be paid to the possible positive spatial spillover effect of NQP.

6. Conclusions and Suggestion

6.1. Conclusions

This study conducted an in-depth analysis and discussion on the NQP data of 17 coastal cities in China’s Bohai Rim region from 2010 to 2022 and empirically tested the internal relationship between NQP and MEHQ and its mechanism by using multiple econometric models. The following conclusions are drawn:

(1)

In this specific historical stage, NQP has played a crucial role in promoting MEHQ. It not only significantly promoted the upgrading of the marine economy, but also became a key force in promoting the development, transformation, and upgrading of the urban marine economy.

(2)

The impact of NQP on MEHQ is not only significant but also dynamic and different. This effect is obviously different in different regions, different stages of development, and different components of the NQP.

(3)

NQP effectively promotes MEHQ through the three core paths of promoting marine science and technology innovation, optimizing marine industrial structure, and improving the allocation of marine resource factors. The implementation of these paths has provided a solid foundation for the sustainable and healthy development of the marine economy.

(4)

The development of NQP in coastal cities around the Bohai Sea shows a strong spatial autocorrelation. This kind of autocorrelation has a positive spatial spillover effect on MEHQ in the surrounding areas. This effect shows a certain diffusion characteristic in the spatial distribution, which has a positive impact on a wider area.

6.2. Suggestions

(1)

To further enhance the core competitiveness and innovation capacity of MEHQ, it is essential to increase investment in marine science and technology innovation, particularly in key technological areas and emerging industries. This involves not only financial investment but also support in terms of talent, technology, and other critical aspects. Simultaneously, it is necessary to establish and improve the marine science and technology innovation system; strengthen collaboration among industry, academia, research institutions, and application sectors; and promote the transformation and practical application of scientific and technological achievements. Through these measures, sustained technical support can be provided for MEHQ.

(2)

To optimize the marine industrial structure, efforts should focus on promoting traditional marine industries as well as fostering the development and growth of emerging marine industries. This necessitates optimizing resource allocation and adjusting the industrial structure reasonably through policy guidance and market mechanisms. By implementing these measures, the overall efficiency and competitiveness of the marine economy can be significantly improved.

(3)

Regional cooperation and coordinated development must be strengthened by fully leveraging the spatial autocorrelation and spatial spillover effects of coastal cities around the Bohai Sea. This will facilitate resource sharing, complementary advantages, and coordinated development among regions. Through the establishment and improvement of regional cooperation mechanisms, the diffusion and application of high-quality productivity can be promoted across a broader region, injecting new momentum into MEHQ.

(4)

The government should develop and refine relevant policies and measures to provide robust policy guarantees and support for the advancement of high-quality marine productivity. This includes enhancing financial investment, offering tax incentives, and supporting talent introduction and training programs. Such comprehensive policy support aims to create an optimal policy environment and market environment for MEHQ. Only through such systematic efforts can the sustainable and healthy development of high-quality marine productivity be ensured.

6.3. Discussion

Reviewing previous studies, we find that although there have been many discussions on NQP and MEHQ, most studies focus on a single dimension or specific field, while this study comprehensively and deeply analyzes the multidimensional impact of NQP on MEHQ through multiple econometric models. The results of this study are consistent with the consensus of previous studies that emphasize the role of NQP in promoting MEHQ, but we provide more abundant and detailed empirical evidence on specific impact paths and effect differences.

From a theoretical perspective, this study not only validates the important role of NQP in MEHQ, but also reveals the multidimensional and dynamic mechanism of its action, providing a new perspective for understanding the relationship between NQP and MEHQ. From the practical point of view, our research provides specific strategic suggestions for MEHQ in coastal cities around the Bohai Sea and even wider areas, which has important reference value.

The study also has some limitations. First, the scope of our study is mainly focused on coastal cities in the Bohai Rim region and may not be fully representative of the national or global situation. Second, although we have considered multiple influencing factors, there are many influencing factors for MEHQ, and there may be other variables not included in the model. In the future, we can further expand the scope of the study to include samples and data from more regions, while exploring more factors that may affect MEHQ to provide a more comprehensive and in-depth analysis. In addition, with the continuous emergence of new technologies and new business forms, the connotation and extension of NQP will continue to expand, and future studies can further focus on the impact of these emerging fields on MEHQ.