Fishery Yields Research Articles

Assessing fishery and ecological consequences of alternate management options for multispecies fisheries

AbstractDemands for management advice on mixed and multispecies fisheries pose many challenges, further complicated by corresponding requests for advice on the environmental impacts of alternate management options. Here, we develop, and apply to North Sea fisheries, a method for collectively assessing the effects of, and interplay between, technical interactions, multispecies interactions, and the environmental effects of fishing. Ecological interactions involving 21 species are characterized with an ensemble of 188 plausible parameterizations of size-based multispecies models, and four fleets (beam trawl, otter trawl, industrial, and pelagic) characterized with catch composition data. We use the method to evaluate biomass and economic yields, alongside the risk of stock depletion and changes in the value of community indicators, for 10 000 alternate fishing scenarios (combinations of rates of fishing mortality F and fleet configuration) and present the risk vs. reward trade-offs. Technical and multispecies interactions linked to the beam and otter trawl fleets were predicted to have the strongest effects on fisheries yield and value, risk of stock collapse and fish community indicators. Increasing beam trawl effort led to greater increases in beam trawl yield when otter trawl effort was low. If otter trawl effort was high, increases in beam trawl effort led to reduced overall yield. Given the high value of demersal species, permutations of fleet effort leading to high total yield (generated primarily by pelagic species) were not the same as permutations leading to high catch values. A transition from F for 1990 to 2010 to FMSY, but without changes in fleet configuration, reduced risk of stock collapse without affecting long-term weight or value of yield. Our approach directly addresses the need for assessment methods that treat mixed and multispecies issues collectively, address uncertainty, and take account of trade-offs between weight and value of yield, state of stocks and state of the environment.

Global evidence of positive impacts of freshwater biodiversity on fishery yields.

AimAn often‐invoked benefit of high biodiversity is the provision of ecosystem services. However, evidence for this is largely based on data from small‐scale experimental studies of relationships between biodiversity and ecosystem function that may have little relevance to real‐world systems. Here, large‐scale biodiversity datasets are used to test the relationship between the yield of inland capture fisheries and species richness from 100 countries.LocationInland waters of Africa, Europe and parts of Asia.MethodsA multimodel inference approach was used to assess inland fishery yields at the country level against species richness, waterside human population, area, elevation and various climatic variables, to determine the relative importance of species richness to fisheries yields compared with other major large‐scale drivers. Secondly, the mean decadal variation in fishery yields at the country level for 1981–2010 was regressed against species richness to assess if greater diversity reduces the variability in yields over time.ResultsDespite a widespread reliance on targeting just a few species of fish, freshwater fish species richness is highly correlated with yield (R 2 = 0.55) and remains an important and statistically significant predictor of yield once other macroecological drivers are controlled for. Freshwater richness also has a significant negative relationship with variability of yield over time in Africa (R 2 = 0.16) but no effect in Europe.Main conclusionsThe management of inland waters should incorporate the protection of freshwater biodiversity, particularly in countries with the highest‐yielding inland fisheries as these also tend to have high freshwater biodiversity. As these results suggest a link between biodiversity and stable, high‐yielding fisheries, an important win–win outcome may be possible for food security and conservation of freshwater ecosystems. However, findings also highlight the urgent need for more data to fully understand and monitor the contribution of biodiversity to inland fisheries globally.

Early detection of reproduction deficits and the compensatory potential of enhancement stocking for vendace, Coregonus albula, fisheries in German lakes

AbstractEnhancement stocking is a widespread but rarely evaluated practice in German vendace, Coregonus albula L. fisheries, which is precautionarily carried out to buffer yield fluctuations. However, it is assumed that stocking of larval vendace can elevate year‐class strength only in the presence of substantial reproductive deficits, which so far cannot be detected prior to the spring time period when stocking is conducted by fisheries managers. Simple measures for the early quantification of natural reproduction were tested, and the efficiency of larval enhancement stocking in a lake with strong reproduction deficits was analysed. Analysis in four lakes over 3 years revealed a significant positive correlation between standardised catches of vendace larvae caught with pump‐driven illuminated traps in spring and the abundance of young‐of‐year (YoY) vendace in the following autumn, whereas standardised catches of spawners were insufficient to forecast YoY recruitment. In a lake with low natural vendace reproduction, stocked vendace contributed 73–100% of year‐class strength and fisheries yield. Accordingly, enhancement stocking can efficiently compensate for reproduction deficits, and the simple larvae sampling method may facilitate early detection of these deficits, which would allow fisheries managers to respond accordingly through larvae stocking.

Visualizing Trade‐Offs between Yield and Spawners per Recruit as an Aid to Decision Making

AbstractThere is a fundamental conflict between harvesting fish and conserving their biomass. Managers mediate this conflict with regulations that control fishery methods and amounts of harvest. In most recreational fisheries, aside from closed seasons, the precise control of fishing effort is difficult to achieve because fisher entry into a managed area is often unlimited and because effort can be influenced by both direct and indirect factors. Choosing the best fishing regulations is also complicated by a need to jointly regulate and accommodate the desires of different user groups who share the fishery. Regulations may need to account for (1) low‐consumptive uses of fish populations that occur from catch‐and‐release fishing by recreational anglers and/or (2) both tribal subsistence and commercial fishers. We applied a suite of graphical techniques to data on a shared fishery, that for Walleye Sander vitreus in Mille Lacs Lake, Minnesota, to examine the trade‐offs between fishery yield and spawner biomass on a per‐recruit basis across a range of harvest tactics, so that fisheries managers could simultaneously evaluate a variety of regulations. We also used Bluegill Lepomis macrochirus data from several Minnesota lakes to further evaluate the utility of our approach. Some regulations were uniformly better than others because they provided higher yield for a given spawning biomass, and higher spawning biomass for a given yield at equilibrium, under a range of plausible levels of fishing effort. For a given level of fishing effort, we were able to identify a frontier in the yield–biomass space whereby an increase in either the yield or the biomass could only be achieved by a reduction in the other. In the absence of density‐dependent changes to growth, maturity, or mortality, regulations that included a minimum length produced more optimal yield and spawner biomass than those that did not include a minimum length. We reduced the daunting task of choosing from dozens of regulations by considering just a few graphs that best demonstrated the trade‐offs offered by a suite of regulations.Received December 24, 2014; accepted August 21, 2015

Valuation of fishery among artisanal bait fishers use non-commercialized bait at the Mida Creek, Kenya

Humanistic valuation of resources is critical to understanding drivers to patterns and impacts, however, value of non-traded intertidal tropical bait, such as polychaetes and hermit crabs, used by artisanal fishers, is unknown. Bait harvested intertidal habitats and used for fishing at Mida Creek, were quantified, and variable and fixed cost incurred determined, income and profitability, were computed and compared. Fishers harvest and use 58 baits pieces, to land 2.4 kg of fish with an average earning of 3.8 $.d -1 . Bait values were similar among bait types and sites, but income (3.3 $), earning (4.1 $) and profitability (255%), were significantly higher for polychaete bait fishers. This was attributed to lower bait harvesting and fishing expenditure. Bait fishery is a labour intensive, and profitable enterprise, that is, however, comparable to semi-skilled wage livelihood options, in the region. Improvement in profits, may be achieved by increasing fishery yield, by adoption of alternative fishery and livelihoods.

Effects of spatial heterogeneity in growth and fishing effort on yield-per-recruit models: an application to the US Atlantic sea scallop fishery

AbstractConventional yield-per-recruit (Y/R) and spawning-stock biomass-per-recruit (SSB/R) models make no allowance for spatial heterogeneity in fishing mortality, natural mortality, or growth across the stock area, although variability in these processes can affect model results. For example, areas with higher growth and/or lower natural mortality rates should be fished at a lower rate to maximize Y/R; however, these areas may be especially attractive to fishers and are often fished harder. Here, Y/R and SSB/R models are developed that simultaneously account for spatial heterogeneity in growth and fishing effort. These models are applied to the US Atlantic sea scallop (Placopecten magellanicus) fishery. The spatial variability in growth uses depth-integrated models from the literature and variability in effort is based on, alternatively, uniform, observed, and relative-optimal spatial harvesting distributions. The observed effort patterns are derived from vessel monitoring system positions, and illustrate one application for these widely collected but underutilized spatial data. In this example, the distribution of observed fishing effort reduces Y/R compared with the relative-optimal, or the uniform effort distribution implicitly assumed by conventional Y/R analysis. SSB/R was in some cases considerably higher under the relative-optimal distribution of effort than when calculated using observed or uniform effort patterns. Such more realistic spatially integrated Y/R and SSB/R models can help to evaluate the impact of effort patterns on fishery yield and stock egg production. These models demonstrate that the spatial distribution of effort can be as important as the overall average fishing mortality when managing fisheries to optimize Y/R, SSB/R, and yield.

Stocking strategies for a pre-alpine whitefish population under temperature stress

Cold-water fish stocks are increasingly affected by steadily increasing water temperatures. The question arises whether stock management can be adapted to mitigate the consequences of this climatic change. Here, we estimate the effects of increasing water temperatures on fisheries yield and population dynamics of whitefish, a typical cold-water fish species. Using a process-based population model calibrated on an empirical long-term data set for the whitefish population (Coregonus lavaretus (L.) species complex) of the pre-alpine Lake Irrsee, Austria, we project density-dependent and temperature-dependent population growth and compare established stock enhancement strategies to alternative stocking strategies under the aspect of increasing water temperatures and cost neutrality. Additionally, we contrast the results obtained from the process-based model to the results from simple regression models and argue that the latter show qualitative inadequacies in projecting catch with rising temperatures. Our results indicate that increasing water temperatures reduce population biomass between 2.6% and 7.9% and catch by the fishery between 24% and 48%, depending on temperature scenario and natural mortality calculation. These reductions are caused by accelerated growth, smaller asymptotic size and lower annual survival of whitefish. Regarding stocking strategies under constant temperatures, we find that stocking mostly whitefish larvae, produces higher population biomass than stocking mostly one-summer-old whitefish, while catch remains almost constant. With increasing temperatures, stocking one-summer-old fish is more beneficial for the angling fishery. Adaption to climate change by changing stocking strategies cannot, however, prevent an overall reduction in catch and population size of this cold-water fish species.

The good, the bad and the ugly of marine reserves for fishery yields.

Marine reserves (MRs) are used worldwide as a means of conserving biodiversity and protecting depleted populations. Despite major investments in MRs, their environmental and social benefits have proven difficult to demonstrate and are still debated. Clear expectations of the possible outcomes of MR establishment are needed to guide and strengthen empirical assessments. Previous models show that reserve establishment in overcapitalized, quota-based fisheries can reduce both catch and population abundance, thereby negating fisheries and even conservation benefits. By using a stage-structured, spatially explicit stochastic model, we show that catches under quota-based fisheries that include a network of MRs can exceed maximum sustainable yield (MSY) under conventional quota management if reserves provide protection to old, large spawners that disproportionally contribute to recruitment outside the reserves. Modelling results predict that the net fishery benefit of MRs is lost when gains in fecundity of old, large individuals are small, is highest in the case of sedentary adults with high larval dispersal, and decreases with adult mobility. We also show that environmental variability may mask fishery benefits of reserve implementation and that MRs may buffer against collapse when sustainable catch quotas are exceeded owing to stock overestimation or systematic overfishing.

Flood pulse effects on multispecies fishery yields in the Lower Amazon.

Seasonally fluctuating water levels, known as ‘flood pulses’, control the productivity of large river fisheries, but the extent and mechanisms through which flood pulses affect fishery yields are poorly understood. To quantify and better understand flood pulse effects on fishery yields, this study applied regression techniques to a hydrological and fishery record (years 1993–2004) for 42 species of the Amazon River floodplains. Models based on indices of fishing effort, high waters and low waters explained most of the interannual variability in yields (R2=0.8). The results indicated that high and low waters in any given year affected fishery yields two and three years later through changes in fish biomass available for harvesting, contributing 18% of the explained variability in yields. Fishing effort appeared to amplify high and low water effects by changing in direct proportion to changes in fish biomass available for harvesting, contributing 62% of the explained variability in yields. Although high waters are generally expected to have greater relative influence on fishery yields than low waters, high and low waters exerted equal forcing on these Amazonian river-floodplain fishery yields. These findings highlight the complex dynamics of river-floodplain fisheries in relation to interannual variability in flood pulses.

ECONOMIC IMPACTS OF CHANGES IN AN ALASKA CRAB FISHERY FROM OCEAN ACIDIFICATION

A dynamic computable general equilibrium (CGE) model is linked to a bioeconomic model for the Bristol Bay red king crab (BBRKC) fishery to analyze regional economic impacts of ocean acidification (OA)-induced changes in fishery yields. Yield projections based on two alternative forms (linear versus nonlinear) of OA effects on the survival of juvenile BBRKC are compared to a baseline without OA effects. Results demonstrate considerable uncertainty in yields, and show that economic impacts are sensitive to the form of OA effects, and to changes in the world price of BBRKC (Q22, Q54, Q57, R13).

Patterns and ecological implications of historical marine phytoplankton change

There is growing evidence that average global phytoplankton concentrations have been changing over the past century, yet published trajectories of change are highly divergent. Here, we review and analyze 115 published phytoplankton trend estimates originating from a wide variety of sampling instruments to explore the underlying patterns and ecological implica- tions of phytoplankton change over the period of oceanographic measurement (1889 to 2010). We found that published estimates of phytoplankton change were much less variable when estimated over longer time series and consistent spatial scales and from the same sampling instruments. Average phytoplankton concentrations tended to increase over time in near-shore waters and over more recent time periods and declined in the open oceans and over longer time periods. Most published evidence suggests changes in temperature and nutrient supply rates as leading causes of these phytoplankton trends. In near-shore waters, altered coastal runoff and increased nutrient flux from land may primarily explain widespread increases in phytoplankton there. Conversely, in the open oceans, increasing surface temperatures are strengthening water column stratification, reducing nutrient flux from deeper waters and negatively influencing phytoplankton. Phytoplank- ton change is further affected by biological processes, such as changes in grazing regimes and nutrient cycling, but these effects are less well studied at large scales. The possible ecosystem consequences of observed phytoplankton changes include altered species composition and abun- dance across multiple trophic levels, effects on fisheries yield, and changing patterns of export production. We conclude that there is evidence for substantial changes in phytoplankton concen- tration over the past century, but the magnitude of these changes remains uncertain at a global scale; standardized long-term measurements of phytoplankton abundance over time can substan- tially reduce this uncertainty.

Predicting Consumer Biomass, Size-Structure, Production, Catch Potential, Responses to Fishing and Associated Uncertainties in the World's Marine Ecosystems.

Existing estimates of fish and consumer biomass in the world’s oceans are disparate. This creates uncertainty about the roles of fish and other consumers in biogeochemical cycles and ecosystem processes, the extent of human and environmental impacts and fishery potential. We develop and use a size-based macroecological model to assess the effects of parameter uncertainty on predicted consumer biomass, production and distribution. Resulting uncertainty is large (e.g. median global biomass 4.9 billion tonnes for consumers weighing 1 g to 1000 kg; 50% uncertainty intervals of 2 to 10.4 billion tonnes; 90% uncertainty intervals of 0.3 to 26.1 billion tonnes) and driven primarily by uncertainty in trophic transfer efficiency and its relationship with predator-prey body mass ratios. Even the upper uncertainty intervals for global predictions of consumer biomass demonstrate the remarkable scarcity of marine consumers, with less than one part in 30 million by volume of the global oceans comprising tissue of macroscopic animals. Thus the apparently high densities of marine life seen in surface and coastal waters and frequently visited abundance hotspots will likely give many in society a false impression of the abundance of marine animals. Unexploited baseline biomass predictions from the simple macroecological model were used to calibrate a more complex size- and trait-based model to estimate fisheries yield and impacts. Yields are highly dependent on baseline biomass and fisheries selectivity. Predicted global sustainable fisheries yield increases ≈4 fold when smaller individuals (< 20 cm from species of maximum mass < 1kg) are targeted in all oceans, but the predicted yields would rarely be accessible in practice and this fishing strategy leads to the collapse of larger species if fishing mortality rates on different size classes cannot be decoupled. Our analyses show that models with minimal parameter demands that are based on a few established ecological principles can support equitable analysis and comparison of diverse ecosystems. The analyses provide insights into the effects of parameter uncertainty on global biomass and production estimates, which have yet to be achieved with complex models, and will therefore help to highlight priorities for future research and data collection. However, the focus on simple model structures and global processes means that non-phytoplankton primary production and several groups, structures and processes of ecological and conservation interest are not represented. Consequently, our simple models become increasingly less useful than more complex alternatives when addressing questions about food web structure and function, biodiversity, resilience and human impacts at smaller scales and for areas closer to coasts.

Trade-offs in fishery yield between wetland conservation and land conversion on the Gulf of Mexico

Trade-offs in fishery yield between wetland conservation and land conversion on the Gulf of Mexico

Simulating bottom-up effects on predator productivity and consequences for the rebuilding timeline of a depleted population

Bottom-up control within ecosystems is characterized, in part, by predator populations exhibiting growth and recruitment changes in response to variability in prey density or production. Annual prey availability can vary more than 10-fold in marine ecosystems, with prey experiencing a dramatic increase or pulse in production within some years. To assess the bottom-up effects of such pulses on predator growth, production, and fisheries management, we developed an age-specific, predator–prey simulation model (parameterized for summer flounder, Paralichthys dentatus) based on simple hypothesized mechanisms for consumption, growth, and population dynamics. Pulses in each of the three modeled prey groups (small crustaceans, forage fish, larger fish prey) generated different magnitudes of change in predator weight-at-age (w), spawning stock biomass (S), fishery yield (Y), and recruitment (R), due to ontogenetic differences in growth potential and dietary composition across predator age classes. Increases in productivity of small forage fishes generated the greatest gains in predator w, S, Y, and R, relative to pulses of the other prey groups. Median increases in R following a prey pulse were minimal (<4%) except under high fishing rates that stimulated a stronger compensatory response in the population (8–11% increase in R), demonstrating the interactive role of top-down and bottom-up effects on predator productivity. Seasonal migration patterns determined the degree of spatiotemporal overlap of predators with the spatially constrained pulses in prey production. Prey pulses reduced the median time required for depleted populations to be rebuilt by 0–5% following declines in fishing pressure. Reductions in time to recovery were highly variable due to recruitment stochasticity, but stock recovery was more sensitive to the severity of harvest control measures than to availability of the non-limiting prey. Understanding the relative magnitudes of such bottom-up processes, particularly in the presence of varied fishing pressure can aid in developing ecosystem approaches to fisheries management that account for such ecological interactions more explicitly.

Linking integrity of coastal habitats and fisheries yield in the Mantalip Reef System

Reef systems comprised of adjacent mangroves, seagrass beds and coral reefs are common in the tropics. These multi-habitat systems exhibit enhanced productivity of coastal areas compared to single habitat systems. Yet in the Philippines, only few studies had been done demonstrating the importance of inter-habitat interactions in enhancing coastal productivity. This study investigates (1) the fisheries connectivity among component habitats of the Mantalip Reef System (Negros Oriental, Philippines), and (2) its implications to refining the current fisheries management scheme. As indicator of connectivity proxy, we inferred inter-habitat movement of fish through size-frequency distributions of families, focusing on species present in two or more of the habitats (mangroves, seagrass beds and coral reef). Fisheries yield was also determined through monitoring of catch landings. Although only 13.97% of all reef fishes were found to utilize multiple habitats, these included large-sized and commercially important taxa that comprised 52.68% of the demersal, reef-associated (vis-à-vis pelagic, open ocean) fish catch biomass. Juveniles were more abundant in the near-shore habitats (mangroves and seagrass), while more mature stages were more abundant in subtidal areas (seagrasses and reefs), demonstrating the critical importance of a multi-system continuum in the juvenile-adult life stages of these taxa. The estimated annual fisheries yield attributable to mangroves (18.88–37.36 mt) and seagrass beds (3.37 mt) increased substantially the total productivity of coral reefs in the system. Altogether, this study underlines the importance of maintaining the integrity and connectivity of adjacent coastal habitats to sustain fisheries demand in the Mantalip Reef System. Results of the study have guided the review of the municipal fisheries ordinance and MPA management plans. Information campaigns in the LGU have also been geared towards emphasizing the importance of their coastal habitats as an interconnected unit.

The panorama of artisanal fisheries of the Araguaia River, Brazil

Seasonal changes in composition and yield of artisanal fishery catches may occur due to natural fluctuations in hydrological regime, fishers, and gear used. In this context, the present study aimed to test the hypothesis that the hydrological cycle of the Araguaia River influences the activity of small-scale commercial fishing by examining the following predictions: fishery yield is influenced by the hydrological regime; the main species exploited through artisanal fishing can change with variations in hydrological regime; and there are differences between male and female fishers in both yield and main exploited species due to differences in the sites that they explore and the gear that they use. Results from the study demonstrated a significantly higher fishery yield during the low-water season, when the catch per unit effort (CPUE) was 24.8 kg/fisher/day, compared to an ebb season CPUE of 19.9 kg/fisher/day. The main species caught by artisanal fisheries was indeed influenced by the hydrological regime of the Araguaia River and the fisher’s gender, which was associated with differences in fishing locations and gear used. These findings suggest that both Araguaia River hydrology and fisher gender should be taken into consideration in developing management strategies for achieving sustainable yields. Of note, our results for fishery yields were 305 % higher than official Brazilian estimates for the entire Araguaia basin over the same period, which suggests underestimation in the official statistics.

Improving the Reliability of Fishery Predictions Under Climate Change

The increasing number of publications assessing impacts of climate change on marine ecosystems and fisheries attests to rising scientific and public interest. A selection of recent papers, dealing more with biological than social and economic aspects, is reviewed here, with particular attention to the reliability of projections of climate impacts on future fishery yields. The 2014 Intergovernmental Panel on Climate Change (IPCC) report expresses high confidence in projections that mid- and high-latitude fish catch potential will increase by 2050 and medium confidence that low-latitude catch potential will decline. These levels of confidence seem unwarranted, since many processes are either absent from or poorly represented in the models used, data are sparse and, unlike terrestrial crop projections, there are no controlled experiments. This review discusses methodological issues that affect our understanding of climate impacts, such as how to improve coupled models from physics to fish and how to strengthen confidence in analysis of time series.

Simple fishery and marine reserve models to study the sloss problem

Habitat fragmentation is generally believed to be detrimental to the persistence of natural populations. In nature management one therefore tends to prefer many small nature reserves over one single large having equal total area. The paper presents two tractable analytical models to examine whether this preference is warranted in a metapopulation framework with reserves (patches) by formulating the dependence of the density as well as the global catch on the number of reserves. Studying these models, we seek to compare the two different strategies: whether a single large reserve will (1) conserve more species and (2) maintains high yield in fisheries than several small or vice versa? Our results indicate that it is favourable to make several small reserves instead one single large reserve. Indeed, at equilibrium, the density as well as the global catch are bigger in the Several Small (SS) strategy than in the Single Large (SL) one. In addition, in the case of SS strategy, an intermediate reserve number exists which is optimal for catch at equilibrium. The results in this paper may provide important implications for nature conservation.

Inland capture fisheries: status and data issues

AbstractLakes, reservoirs and wetlands cover a total area of about 7.8 million km2 and provide a rich environment for inland capture fisheries. Production from the world's inland capture fisheries has grown steadily to over 11.6 million tonnes in 2012, with almost 95% of the catches from developing countries. The sector is composed primarily of small‐scale fishers and provides employment to approximately 61 million people, of which 50% are women. Inland capture fisheries yield is only 6.3% of the global reported fish production (capture fisheries and aquaculture). However, it is proposed that this is an underestimate and actual yield may be several times greater. The apparent low proportion of fish provided by inland capture fisheries globally does not reflect adequately the importance of inland capture fisheries in today's society. A lack of accurate information renders analysis of existing data sets difficult and makes decision‐making problematic. Is the sector in serious trouble because of the multiple uses of and threats to inland water ecosystems? Is the sector stable and increased production due only to better reporting? Or, is the sector growing?

北黄海獐子岛养殖海域营养水平与虾夷扇贝增殖渔获量评估

PDF HTML阅读 XML下载 导出引用 引用提醒 北黄海獐子岛养殖海域营养水平与虾夷扇贝增殖渔获量评估 DOI: 10.5846/stxb201304220767 作者: 作者单位: 中国科学院海洋研究所海洋生态与环境科学重点实验室,中国科学院海洋研究所海洋生态与环境科学重点实验室,中国科学院海洋研究所海洋生态与环境科学重点实验室,中国科学院海洋研究所海洋生态与环境科学重点实验室,中国科学院海洋研究所海洋生态与环境科学重点实验室,中国水产科学研究院黄海水产研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金创新研究群体科学基金(41121064);国家重点基础研究发展计划973项目课题(2011CB403602) Estimation of nutrient level and fishery yield of Patinopecten yessoensis in mariculture area near the Zhangzidao Island of the north Yellow Sea Author: Affiliation: Key Laboratory of Marine Ecology and Environmental Sciences,Institute of Oceanology,Chinese Academy of Sciences,Key Laboratory of Marine Ecology and Environmental Sciences,Institute of Oceanology,Chinese Academy of Sciences,Key Laboratory of Marine Ecology and Environmental Sciences,Institute of Oceanology,Chinese Academy of Sciences,Institute of Oceanology, Chinese Academy of Sciences,Institute of Oceanology, Chinese Academy of Sciences,Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:营养盐作为浮游植物生长的物质基础,对海洋生态系统的物质循环起着决定性作用。调查研究了獐子岛附近海域营养盐含量水平、空间分布及营养盐结构,并据此估算了现有营养水平可支持的潜在生物量,评估了该海域虾夷扇贝增殖渔获量。结果表明,獐子岛附近海域海水总体营养水平较低,底层水中的营养盐浓度是表层水的2-3倍,海水中的营养盐浓度基本高于浮游植物生长的最低阈值,且溶解无机氮与磷酸盐的比值(DIN/PO4-P)和硅酸盐与磷酸盐的比值(SiO3-Si/PO4-P)均 > 22,全海域为磷营养限制。根据磷限制因子及食物链能流转移理论估算,该海域1000 km2现有的营养水平可支持一个生长周期内虾夷扇贝增殖的动态理论生产量为3.8-6.1万t,如人为增加5%-20%的水体磷,则虾夷扇贝增殖产量可增加0.25-1.00万t。 Abstract:Nutrients as the material basis for phytoplankton growth, play a decisive role in energy flow and matter cycling in marine ecological systems. In this study, the concentrations, spatial distributions and nutrient structure in seawaters near the Zhangzidao Island were studied. Besides, the potential biomass and fishery yield of Patinopecten yessoensis which could be supported by the current nutrient level also were estimated. Results suggested that the concentrations of phosphate (PO4-P), dissolved inorganic nitrogen (DIN) and silicate (SiO3-Si) were in the ranges of 0-0.67, 0.77-9.91 and 1.62-18.77 μmol/L, with averages of 0.19, 4.50 and 7.00 μmol/L, respectively. Among them, DIN was mainly dominated by nitrate nitrogen (NO3-N) with concentrations of 0.04-6.82 μmol/L (average of 2.12 μmol/L), followed by ammonium nitrogen (NH4-N) with concentrations of 0.40-6.07 μmol/L (average of 1.95 μmol/L), and nitrite nitrogen (NO2-N) was lowest with concentrations of 0.05-2.10 μmol/L (average of 0.42 μmol/L). Nutrients in the surface waters displayed a decreasing trend from coastal water to the middle area. This distribution was attributed to the riverine inputs (e.g., the Yalu River), which carried a certain amount of nutrients to the north Yellow Sea (NYS). In contrast, nutrients in the bottom waters presented higher values at the middle area and were 2-3 times higher than those in the surface waters. These distribution models were mainly influenced by the Yellow Sea Cold Water Mass (YSCWM), biological activities and Yellow Sea Warm Current (YSWC). In summer, due to the weak vertical mixing, a stable cold water mass having a large number of organic particles entrenched at the bottom layer in the central part of the NYS. By September, organic particles began to decompose, accompanied by the nutrient release to the bottom waters. These released nutrients were difficult to diffuse to the upper layers due to strong thermocline and pycnocline. Consequently, the nutrient values in the bottom waters at the central part of the NYS were higher. Besides the above reasons, biological activities were also an important factor causing the higher nutrient concentrations in the bottom waters than that in the surface waters. Phytoplankton activities in the euphotic layer were frequent and needed to absorb a lot of nutrients to sustain growth and reproduction, resulting in the loss of nutrients in the surface waters. Moreover, the YSWC could carry waters with high temperature and low nutrients to the surface waters of the NYS, diluting the nutrient concentrations in the surface waters. Therefore, the nutrient concentrations in the surface waters were lower than that in the bottom waters. In addition, nutrient concentrations in waters of the study area were higher than the minimum threshold values for the phytoplankton growth, and DIN/PO4-P ratio (averages of 28.90) and SiO3-Si/PO4-P ratio (averages of 47.27) were > 22, suggesting that PO4-P was the limiting factor. Based on the current PO4-P concentration and energy flow theory of food chain, the potential enhancement field of Patinopecten yessoensis at a growth cycle in 1000 km2 sea area was estimated to be 3.8-6.1×104 t. If 5%-20% of PO4-P was added in this area, the yield of Patinopecten yessoensis would increase 0.25-1.00×104 t. 参考文献 相似文献 引证文献