应用Catch-MSY模型评估印度洋蓝枪鱼资源

Catch-MSY模型可仅依靠渔获量数据进行渔业资源评估,在数据缺乏状况下能暂时替代标准资源评估模型。本研究以印度洋蓝枪鱼(Makaira nigricans)为例,根据有、无信息的内禀增长率r和环境容纳量K的先验分布,设立15组情景进行模型灵敏度分析、资源评估和预测。结果表明,参数r和K呈强烈的负相关,而最大可持续产量(Maximum Sustainable Yield,MSY)与参数r呈正相关;数据时间序列长度对评估结果影响有限,而模型对起止年渔获量较为敏感。资源状况评估表明,印度洋蓝枪鱼资源生物量状况良好,即B₂₀₁₅/B_MSY大于1;而开发状况除其中两种情景外,均为过度捕捞,即F₂₀₁₅/F_MSY大于1。资源预测表明,为使未来10年内B/B_MSY>1的概率超过50%,需将渔获量缩减至当前渔获量的90%(13.86 kt);考虑到该模型在数据缺乏状况下会更加保守,若将当前渔获量的100%～110%(15.40～16.94 kt)设为管理目标,则未来5年内B/B_MSY >1的概率超过50%。     

Using data-limited approaches to assess data-rich Indian Ocean bigeye tuna: Data quantity evaluation and critical information for management implications

The majority of fishery stocks in the world are data limited, which limits formal stock assessments. Identifying the impacts of input data on stock assessment is critical for improving stock assessment and developing precautionary management strategies. We compare catch advice obtained from applications of various datalimited methods(DLMs) with forecasted catch advice from existing data-rich stock assessment models for the Indian Ocean bigeye tuna(Thunnus obesus). Our goal was to evaluate the co...     

Is f0.1 an appropriate harvesting strategy for the Cape hakes?

Time-series of catch per unit effort (CPUE) for the Cape hake stocks demarcated by ICSEAF in the Benguela region show steady declines until the late 1970s, followed by slowly increasing trends once catch levels were reduced. Analysis of these data by means of a dynamic form of the production model is discussed briefly, and it is shown that sustainable-yield-determining parameters could not be estimated with any reasonable degree of precision prior to the data contrast provided by the change in CPUE trends in the late 1970s. In general, an f_0.1 harvesting strategy has been applied to allow recovery of these resources from their depleted levels of the late 1970s. Analysis indicates that, except for ICSEAF Division 1.6, these stocks have now reached their equilibrium biomass levels under such a strategy. The question thus arises whether f_0.1 is the appropriate long-term strategy, i.e. to what extent current catches (or catch level increments) should be "traded" for future CPUE improvements. This is examined by means of Clark's bioeconomic model, which indicates that strategies corresponding to a lower fishing effort than that for f_0.1 are economically more advantageous. The precision with which the shape of the surplus production function can be estimated is poor; the implications of this for the choice of an appropriate harvesting strategy are discussed briefly. It is suggested that, as an initial amended strategy for most of these stocks, catch levels should be pegged at their f_0.1 equilibrium levels once the corresponding biomass level is exceeded. However, for Division 1.6, a change from an f_0.1 to an f_0.2 strategy is proposed. The economic advantages of this strategy are illustrated     

基于Schaefer模型的东南太平洋茎柔鱼资源评估和管理

东南太平洋茎柔鱼(Dosidicus gigas)是世界范围内最重要的经济头足类之一,也是我国鱿钓渔船的重要捕捞对象。本文根据2003—2012年中国大陆的渔业数据和FAO统计的东南太平洋茎柔鱼产量数据,利用Schaefer模型,基于贝叶斯统计方法,分基准方案和敏感性分析方案对东南太平洋茎柔鱼资源进行评估,并对其管理策略做了风险分析。结果表明,年渔获量和CPUE数据为贝叶斯资源评估模型提供了足够多的信息。2003—2012年捕捞死亡率低于目标参考点F0.1,渔获量小于最大可持续产量,资源量大于目标参考点Bmsy,资源状况良好,未遭受过度捕捞。在基准方案下,最大可持续产量为142.9万吨,维持最大可持续产量的资源量为214.7万吨,此时的捕捞死亡率为0.682;在敏感性分析方案下,最大的可持续产量为152.5万吨,维持最大可持续产量的资源量为229.6万吨,此时的捕捞死亡率为0.691。决策分析和风险分析表明,当捕获率设定为0.3以下时,资源能够得到较好的养护,资源崩溃的可能性很低。将捕获率设定在0.3左右是最适的管理策略,此时的持续产量为99万吨左右。     

Selected fishery and population parameters of eight shore-angling species in the Tsitsikamma National Park no-take marine reserve

An eight-year research angling dataset collected between February 1998 and December 2005 in the Tsitsikamma National Park marine protected area (MPA), along the south-eastern Cape coast of South Africa, was examined to provide estimates of important fishery and population parameters for eight important shore-angling species. Five different estimates of natural mortality (M), and the coefficients of variation (CVs) of catch per unit effort (CPUE) and size measurements were calculated. There was no consistency in estimates of M between methods, highlighting the difficulty in obtaining reliable estimates of this parameter for per-recruit assessments. The CVs of CPUE measurements were generally higher than those for size measurements. Estimates obtained for the most abundant species, blacktail Diplodus capensis, with a mean CPUE of 0.252 fish h^–1, yielded the lowest CVs for CPUE (0.806) and size (0.130) measurements. Therefore, blacktail is considered the preferred indicator species for making comparisons with estimates obtained for shore-angling fish in exploited areas and other MPAs along the South African coastline. The large inter annual variations in mean CPUE and size for all species indicated that a minimum assessment period of four years is required to obtain reliable estimates.     

A voluntary reduction in the commercial catch of rock lobster (Jasus edwardsii) in a New Zealand fishery

We describe the development and application of a management procedure (decision rule) that resulted in a voluntary reduction in the commercial catch of spiny rock lobster (Jasus edwardsii) in the lower east coast of North Island of New Zealand. The management procedure was developed from an accepted assessment of the CRA 4 (Wellington‐Hawke's Bay) fishery, which used an integrated length‐based assessment model fitted to commercial fishery catch‐per‐unit‐effort (CPUE) biomass indices, commercial length‐frequency data, and tag‐recapture data. The assessment model had been Bayesian, and used the joint posterior distribution of parameters to predict the effect of 384 alternative harvest control rules on the future size of the CRA 4 stock. The harvest control rules all used CPUE as their input, and generated annual changes in catch, which were then simulated by the population dynamics of the operating model. Uncertainty was added to evaluations through observation error, added to the simulated CPUE observations, and stochastic serial auto‐correlation variation in recruitment. We describe how this management procedure was used to effect a voluntary reduction in catch to address the problem of a rapidly declining population.     

Setting quotas using provisional data: a case study from the South Australian abalone fisheries

Stock assessments of quota or effort managed fisheries in which the duration of the fishing season is 12 months are invariably delivered well into the subsequent fishing season. As a result, quotas are frequently based on year-old data. This delay is often unavoidable because it may take months to collect, collate and analyse data necessary to assess fishery performance. The South Australian fisheries for blacklip (Haliotis rubra Leach, 1814) and greenlip abalone (H. laevigata Donovan, 1808) have addressed this issue by using provisional data on current stock status to inform application of the harvest strategy decision rules that set the quota for the next year. The primary index of relative abundance for these fisheries is catch per unit effort (CPUE). Our study uses 25 years (1988–2012) of CPUE data to quantify the differences between the provisional and complete-season CPUE estimates at the spatial scales used to assess the fisheries. We demonstrate that, in most cases, there was a strong relationship between the provisional and complete-season CPUE estimates for both species, with little evidence of bias. As the provisional CPUE estimates were a reliable and accurate predictor of the complete-season CPUE estimates, this provides a high degree of confidence in using provisional CPUE estimates to set quotas, thereby overcoming the difficulty of basing decisions on aged data. These findings are likely to be applicable to other fisheries, particularly those where much of the annual catch is obtained (or effort expended) in a short time period at the commencement of the fishing season.     

增殖放流影响下东海北部海域三疣梭子蟹(Portunus trituberculatus)最大可持续产量评估

当渔业资源出现衰退时,加强资源增殖放流以养护渔业资源、提高渔业产量对于渔业资源可持续利用具有重要意义;与此同时,增殖放流的实施会对基于资源开发与管理的评估的结果产生影响。基于2001~2015年间东海北部海域三疣梭子蟹(Portunus trituberculatus)渔业数据,采用增殖剩余产量模型,对东海北部海域三疣梭子蟹的最大可持续产量(MSY)及取得MSY时所需捕捞努力量(E_MSY)和原存生物量(B_MSY)进行了评估,并与传统Schaefer模型评估结果进行了比较。结果表明,当年增殖放流量约在3×10⁶~95×10⁶尾之间时,三疣梭子蟹年产量逐渐增加, MSY在14.2×10⁴ t和14.6×10⁴ t之间, E_MSY基本在15×10⁴吨位左右。增殖放流量增加,其对应的MSY也越高,能承受的E_MSY也越高(从15×10⁴~15.4×10⁴吨位之间),相反B_MSY则减小(从188.4×10⁴ t降至186.6×10⁴ t)。与传统的Schaefer模型评估结果相比,增殖剩余产量模型由于考虑了增殖放流生物量的因素,得到了MSY和E_MSY有所增加,而B_MSY有所下降的结论。研究结果有望为该研究海域三疣梭子蟹可持续地捕捞、放流与管理提供科学依据。     

Quantifying commercial catch and effort of monkfish Lophius vomerinus and L. vaillanti off Namibia

Abundance and exploitation patterns of monkfish Lophius vomerinus and L. vaillanti were investigated for use as inputs into a stock assessment framework to be used for management of the Namibian monkfish resource. Total numbers of monkfish caught per size-class were estimated using industry records of tail products classified into six commercial categories. The proportions per category varied each year. Analysis of the commercial data suggests that large numbers of juvenile monkfish are harvested annually. Catch-per-unit-effort (cpue) data of vessels targeting monkfish and sole (the two species are combined in terms of Namibian fleet legislation) for the period 1991–1999 were analysed using two different methods to construct indices of abundance. Both indices, one standardized on vessel horsepower and the other standardized by means of a Generalized Linear Model, showed an increase in catch rate of monkfish from 1991 to 1994 and between 1996 and 1998, but a decline from 1994 to 1996 as well as during 1999. Conversion factors for landed or tail weight to whole weight for four different tail products of monkfish were estimated. Results obtained from the study suggest that the factor of 3.04 currently applied in Namibia to all tail-weight classes is not appropriate for the current fishery and needs to be amended. For management purposes it is also suggested that four different conversion factors, one for each monkfish tail product, be implemented.     

Feeding ecology of South African Argyrosomus japonicus (Pisces: Sciaenidae), with emphasis on the Eastern Cape surf zone

A Monte-Carlo simulation approach is used to investigate the relative robustness of the results of the Butterworth–Andrew (B ₁ = K and B ₁ estimated) dynamic production-model observation-error estimators to different "true" values of the ratio of initial biomass B ₁ to unexploited equilibrium biomass K. The simulations use an underlying operating model typical of that appropriate for stocks of Cape hake off southern Africa. The B ₁ = K variant of the estimator results in lower estimated expected discrepancies for a number of management quantities over a wide range of the value of the "true" ratio. In addition, it is less likely to provide severe overestimates of the f _0.1 total allowable catch (TAC). Not all management quantities are equally sensitive to the value of the "true" ratio. In particular, f _0.1) TACs can be severely overestimated, although the maximum sustainable yield (MSY) is relatively well determined over a wide range of values of the ratio. It is therefore recommended that harvesting strategies which do not permit TACs to be set in excess of the estimated MSY be preferred.     

基于贝叶斯状态空间产量模型的大西洋黄鳍金枪鱼资源评估

黄鳍金枪鱼(Thunnus albacares)是全球远洋渔业的重要目标鱼种,要实现有效的管理,对其进行科学的资源评估是必不可少的.本文以大西洋黄鳍金枪鱼为研究对象,根据国际大西洋金枪鱼养护委员会的渔获量和单位捕捞努力量渔获量数据,使用贝叶斯状态空间模型进行资源评估,并探讨不同剩余产量函数和单位捕捞努力量渔获量数据对评...     

Genetic variation and population structure in the New Zealand snapper

Fifteen proteins encoded by 23 gene loci were electrophoretically surveyed in two samples of snapper Chrysophrys auratus (Forster) from Wellington Harbour and the Hauraki Gulf. Between 17% and 26% of the loci examined were found to be polymorphic and the proportion of heterozygous loci per individual was 7.9% to 8.4%. Using Rogers’ genetic distance coefficient an overall similarity of 0.98 was calculated between the two samples.

Three polymorphic loci Est‐4, Gpi‐1, and Idh were examined in an additional 10 samples from around New Zealand. Two genetically distinct stocks were apparent: one along the west coast, the other along the east coast of the North Island. There was an indication of stock mixing at Ninety Mile Beach and in the Bay of Plenty and East Cape. The distribution of alleles at the Est‐4 locus revealed a third stock in Hawke Bay that is genetically more similar to the west coast than the east coast stock. Hydrological conditions in Hawke Bay are more similar to those of the west coast than to those of the north east coast of the North Island. Thus it is possible that Est‐4 alleles are selectively maintained in response to an environmental factor.     

黄渤海带鱼(Trichiurus lepturus)渔业生物学参考点估计研究

It is important to find a reliable method to estimate maximum sustainable yield(MSY) or total allowable catch(TAC) for fishery management, especially when the data availability is limited which is a case in China. A recently developed method(CMSY) is a data-poor method, which requires only catch data, resilience and exploitation history at the first and final years of the catch data. CMSY was used in this study to estimate the biological reference points for Largehead hairtail(Trichiurus lepturus, Temminck and Schlegel) in the Yellow Sea and Bohai Sea, based on the fishery data from China Fishery Statistical Year Books during 1986 to 2012. Additionally,Bayesian state-space Schaefer surplus production model(BSM) and the classical surplus production models(Schaefer and Fox) performed by software CEDA and ASPIC, were also projected in this study to compare with the performance of CMSY. The estimated MSYs from all models are about 19.7×104–27.0×104 t, while CMSY and BSM yielded more reasonable population parameter estimates(the intrinsic population growth rate and the carrying capacity). The biological reference points of B/BMSY smaller than 1.0, while F/FMSY higher than 1.0 revealed an over-exploitation of the fishery, indicating that more conservative management strategies are required for Largehead hairtail fishery.     

Can additional abundance indices improve harvest control rules for New Zealand rock lobster (Jasus edwardsii) fisheries?

Although New Zealand rock lobster (Jasus edwardsii) fisheries can be assessed with a sophisticated Bayesian length‐based model, these assessments are expensive and time consuming; they cannot be conducted for each area every year. Harvest control rules are increasingly important management tools in New Zealand rock lobster fisheries. Recent work has developed and evaluated procedures for rebuilding or maintaining lobster stocks based on criteria agreed by stakeholders. Most management procedures depend on a single abundance index, often catch per unit of effort (CPUE). When management procedures react slowly to changes in vulnerable biomass, allowable catches get out of phase with the stock, causing large oscillations in both catches and CPUE. Lags between data and management actions and “latent years” are features of rules that reduce responsiveness. This study explores ways to improve the responsiveness of harvest control rules by using additional data to predict changes in vulnerable biomass. Four data sets are examined: CPUE trends, pre‐recruit indices, puerulus settlement indices, and size frequencies. Only pre‐recruit indices, which were explored with a simple delay‐difference model based on parameter estimates from recent assessments, appeared to have immediate potential for use in improving management procedures.     

Stock assessment and management implications of horse mackerel (Trachurus japonicus) in Korean waters, based on the relationships between recruitment and the ocean environment

This study presents an example of horse mackerel (Trachurus japonicus) stock to demonstrate that marine environmental factors are important in stock assessment for the new Korean Total Allowable Catch (TAC)-based fisheries management system. The estimated survival rate (S) of horse mackerel ranged from 0.25 to 0.36. The instantaneous coefficient of natural mortality (M) was 0.48/year, and the age at first capture was 0.83 year. Annual biomass of horse mackerel in Korean waters was estimated by a biomass-based cohort analysis using annual catch in weight at age during 1965–1995. Yield-per-recruit and spawning biomass-per-recruit were estimated under various harvest strategies at F_max, F_0.1, F_30% and F_40%. A method for estimating acceptable biological catch (ABC) is proposed for dealing with the large differences in the quality and quantity of information and data available. Using recruitment of horse mackerel estimated from various spawner–recruitment relationship models combined with salinity, volume transport, and zooplankton biomass as environmental factors, the ABC under the best information available was estimated to range from 3100 to 3800 mt.     

应用贝叶斯方法对有效信息较少的渔业资源进行资源评估-以印度洋长鳍金枪鱼的资源评估为例

众所周知,对有效信息较少的渔业资源进行资源评估面临很大的挑战,而贝叶斯方法在数据数量较少、质量较差的情况下能利用其它种群高质量的数据或已知的先验信息提高资源评估结果的可靠性。由于印度洋长鳍金枪鱼的数据质量较差而数据量有限,长鳍金枪鱼的资源评估结果存在很大的不确定性,为此,本文以印度洋长鳍金枪鱼的资源评估为例,以调查贝叶斯方法在有效信息较少的资源评估中的优势。本文根据不同的先验假设与捕捞数据系列,共构建了8个贝叶斯动态产量模型,以评估长鳍金枪鱼资源。结果表明:(1)分析参数的后验分布能提高捕捞数据系列选择与参数假设的合理性; (2) 利用种群统计学方法为内禀增长率(r)构建有信息先验,能提高资源评估结果的可靠性。与传统方法相比,当基于贝叶斯框架时,能将已知的知识表示为先验信息并能分析参数的后验分布,从而在数据较少或数据质量较差的情况下,能利用各种信息提高参数估计的合理性与资源评估的可靠性。因此,对数据量较少或数据质量较差情况下的渔业资源评估而言,贝叶斯方法非常有效,如本文所示的印度洋长鳍金枪鱼的资源评估。     

Assessing the South African sardine resource: two stocks rather than one?

Sardine Sardinops sagax distributed off the west and south coasts of South Africa have traditionally been assumed to comprise a single well-mixed stock for assessment and management purposes. New research, however, lends weight to the possibility of two stocks in this region. A precautionary management approach thus needs to consider the impact of management decisions on the hypothesised two individual stocks as well as on the resource as a whole. As a first step in this process, Bayesian assessments of South African sardine are presented, which compare results for the traditional single-stock hypothesis with those that follow from a new two-mixing-stock hypothesis. Recruits from the west stock are assumed to move to and remain part of the south stock in annual pulses of varying size. This movement is estimated to be appreciable, and to take place from a substantially more productive west stock to the south stock. This immigration makes a greater contribution to the south-stock biomass than do years of above-average south-stock recruitment. Importantly, this two-mixing-stock hypothesis is shown to be consistent with the data available. Further alternative sardine stock-structure hypotheses suggested by the most recent data are discussed.     

Population dynamics and potential yield of three species of giant winkles in the Western Cape,South Africa

Of the southern African intertidal and shallow subtidal trochid and turbinid gastropods, Turbo sarmaticus, T. cidaris and Oxystele sinensis, are the most abundant large species, and therefore obvious targets for a winkle fishery. T. sarmaticus is harvested by recreational snorkel divers, and an application has been made for a permit to experimentally harvest the other two species commercially. This study involves four major aspects, namely morphometrics and flesh yield, shore-based abundance estimates, subtidal abundance estimates, and an estimate of the potential yield for each of the three species off the South-Western Cape, South Africa. Abundance and biomass of the winkles increased from west to east, highest densities being recorded in the low intertidal regions to 2 m depth. Low biomasses of the three species were recorded west of Cape Hangklip and are unlikely to support a fishery there. East of Cape Hangklip, invasion of rock lobsters Jasus lalandii has had a considerable impact on T. cidaris and O. sinensis populations. Consequently, a boat-based fishery with an estimated annual total allowable catch of 75.5 tons for T. cidaris, with a bycatch of 9.9 tons for O. sinensis, can only be considered in the easternmost fisheries-management area between Kleinbaai and Quoin Point. Because previous studies on the harvesting potential of T. sarmaticus off the Western Cape concluded that it was not commercially sustainable, a total allowable catch for that species was not considered. Management options deserving considerations before the commencement of a giant winkle fishery are discussed.     

利用基于环境因子的动态产量模型评估西南大西洋阿根廷滑柔鱼

西南大西洋阿根廷滑柔鱼,Illex argentinus,巴塔哥尼亚南部群体是重要的经济种类。海洋环境因子在柔鱼资源分布中起着重要的作用。本研究利用基于环境因子的动态产量模型评估2000-2010年的滑柔鱼的资源量。假设海洋环境因子（滑柔鱼产卵场最适宜海表温度占比）影响动态产量模型的参数K,DIC值表明在正态分布和均匀分布下均是基于环境因子的评估模型优于基本的动态产量模型。阿根廷滑柔鱼的最大可持续产量（MSY）在351600吨到685 100吨之间,资源生物量在1322400吨到1 803 000吨之间,其捕捞死亡系数均小于F_0.1和F_MSY,资源处在良好状态,没有遭受过度捕捞。本研究为应用环境因子在柔鱼类的资源评估与管理提中供了科学的参考方法。     

The sensitivity of long-term yield targets to changes in fishery age-selectivity

Maximum sustainable yield (MSY) has been adopted as the primary management goal by several inter-government fishery organisations, and in the United States it forms the cornerstone of federal fishery management policy. MSY became a strategic goal for the management of Europe's fisheries following the resolution of the World Summit on Sustainable Development in 2002 to restore or maintain fish stocks to MSY levels by 2015. Calculation of MSY requires information on the rate at which biomass increases through growth and reproduction and the rate at which it decreases through natural mortality and fishing. Population-selection, which measures the age-specific rates of fishing mortality, is a key component for the calculation of yield as a function of fishing mortality and MSY, yet selection rarely features in either management advice or sensitivity analyses. Effective management of selection can potentially lead to increases in long-term yield, but before taking action managers need to understand what long-term increases are possible. Using a hypothetical stock, equilibrium yield curves were calculated for three scenarios in which the shape of the population-selection curve varied. The results illustrate the potential extent of variation in MSY and the corresponding fishing mortality required to achieve it (F_MSY) that may result solely due to changes in population selectivity. They show that relatively subtle changes in selection can produce substantial differences in MSY and F_MSY. The results are discussed with specific reference to the development of long-term management targets and the mechanisms by which managers might try to influence population-selection.