珠海桂山风电场水域渔业资源声学评估与空间分布

2019年10月24日至26日，使用便携式Simrad EY60科学探鱼仪对珠海桂山岛海上风电场水域的渔业资源进行了声学调查，研究了该水域的渔业资源组成、数量密度、资源量密度及其空间分布。本次调查共捕获游泳生物和底栖无脊椎动物72种，其中34种参与声学评估。扫海面积法估算的鱼类平均数量密度与资源量密度分别为1.09×10⁴尾/km²，227.48 kg/km²；声学方法估算的鱼类数量密度与资源量密度分别为5.97×10⁵尾/km²，15.13 t/km²。风电场水域鱼类聚集性分布明显，在风电场西北与东南外围水域密度较高，中间水域的密度较低。鱼类单体目标强度（TS）分布范围为-68~-41dB，其中-68~-58 dB的单体TS占主要部分（79.12%），对应鱼类的体长范围为3~8 cm；随着水深的增加，单体平均TS先减小后增大。本研究是桂山风电场水域渔业资源的首次声学调查，结果较准确地反映了风电场水域多种鱼类的资源量及其分布信息，可为科学评价海上风电场建成运营后对渔业资源的长期影响提供基础数据。     

南澳白沙湾海藻养殖区内外渔业资源声学评估

为初步了解南澳岛白沙湾海藻养殖区鱼类资源状况,利用便捷式分裂波束式Simrad EY60科学探鱼仪,于2015年4月28日、12月2日与2016年4月19日对该海域进行3次声学调查,结果显示,3次调查中藻区内、外鱼类资源丰度密度分别为3.45/1.38×105、0.63/1.45×105、3.67/2.98×105尾/n mile2。藻区内春季鱼类资源量显著高于冬季,资源丰度密度随季节变化显著;藻区外资源丰度密度变化较小且均匀;藻区内、外鱼类资源丰度密度最高值出现于2~6 m水层,6~8 m次之,表、底层最小,资源丰度密度受深度影响显著。在海藻养殖期间,藻区内鱼类资源丰度密度较藻区外大且年变化明显,表明海藻生物量对鱼类资源量及其分布变化具有一定影响。本次调查通过声学评估技术对海藻养殖区鱼类资源进行初步评价,为其具有改善水质环境、恢复渔业资源的作用提供理论依据。     

南海柘林湾—南澳岛海洋牧场渔业资源本底声学评估

为掌握南海柘林湾—南澳岛海洋牧场水域渔业资源本底情况,于2011年4月到2012年2月,使用Simrad EY60科学探鱼仪先后于不同月份对其进行了4次调查。调查显示2011年4月,21种评估鱼类总平均数量密度和平均资源量密度分别为2.68×10⁴ 个/km²和0.73 t/km²;2011年8月,38种评估鱼类总平均资源数量密度和平均资源量密度分别为6.49×10⁴ 个/km²和0.71 t/km²;2011年11月,33种评估鱼类总平均资源数量密度和平均资源量密度分别为4.14×10⁴ 个/km²和0.93 t/km²;2012年2月,15种评估鱼类总平均资源数量密度和平均资源量密度分别为1.45×10⁴ 个/km²和0.36 t/km²。结果表明,4个月资源量密度均不高;11月资源密度和资源量最高;2月资源密度和资源量最低,声学评估种类明显减少。4月积分值主要分布于4～8 m水层;8月积分值于4～14 m水层内分布比较均匀;11月积分值主要分布水层与4月相似,但10 m以深水体所占百分比高于4月;2月积分值主要分布于4～10 m水层,尤其是6~8 m水层。资源密度与水深之间无明显线性关系。各月份调查站点资源密度与SST无明显线性关系。各月份平均丰度密度与SST呈明显线性关系 (R²=0.997 4)。各月份平均资源量密度与SST呈一定线性关系 (R²=0.287 2)。研究证实声学方法在海洋牧场渔业资源评估过程中表现出良好的效果,推动了声学技术在海洋牧场渔业资源研究领域的发展,为今后我国深入开展海洋牧场渔业资源增殖效果评估研究提供了现实基础和科学依据。     

厦门西部海域春季游泳动物资源的调查研究

根据2015年3月厦门西部海域游泳动物资源调查资料,对该海域的游泳动物组成特征进行了初步探讨。结果显示,共捕获游泳动物98种,其中鱼类51种、虾类16种、蟹类23种、口足类5种、头足类3种。优势种类有日本蟳(Charybdis japonica)、脊尾白虾(Exopalaemon carinicauda)、凤鲚(Coilia mystus)、叫姑鱼(Johnius belengerii)和哈氏仿对虾(Parapenaeopsis hardwickii)等5种。各站位游泳动物Margalef丰富度指数(D)平均值为5.358,Shannon-Wiener多样性指数(H')平均值为2.365,Pielou均匀度指数(J')平均值为0.732,平均资源量为307.068 kgkm2。鱼类、虾类、蟹类、口足类、头足类的资源量分别为192.7、28.8、72.7、7.9、5.0 kg/km2。与历史资料比较,游泳动物的种类和资源量均明显下降,亟需加强渔业资源的管理与保护。     

红水河岩滩水库鱼类资源声学评估

为评估梯级开发下渔业资源变化情况,2015年9月采用分裂波束鱼探仪EY60(120 kHz,250 W)对红水河岩滩水库库区及上游江段鱼类资源进行声学调查,并结合渔获物统计和地理统计分析对鱼类时空分布进行分析,评估鱼类资源量。结果显示整个调查区域的鱼类资源密度为(0.53±2.11)尾·m~(-2)(±SD),从水坝上游至库区呈增长趋势,鱼类资源密度水平分布与水深无显著相关关系。垂直分布方面,鱼类主要分布在30 m以内水层;不同大小个体对水深有一定的选择性,小个体鱼类(10 cm)约86.2%分布在30 m水层之内;大个体(30 cm)有44.7%分布在40 m以下水层。基于鱼类分布GIS建模,估算调查区域鱼类资源量为6.57×10~7尾。     

大亚湾杨梅坑人工鱼礁水域生物资源量声学评估

杨梅坑人工鱼礁区位于深圳市东部大亚湾海域,2007年3月20日开始投礁,12月25日正式完成全部工程施工任务,建礁体积9.51万km3,礁区面积966 m×2 851 m.从2007年4月到2009年5月,使用科学鱼探仪(EY60型,120 kHz,Simrad)先后在不同季节对大亚湾杨梅坑生态调控区的礁区内和礁区外水域进行了6次声学调查,共获取有效声学航程122.54 n mile,以了解建礁后该水域生物分布和资源量密度变化情况.调查中设站点进行生物学拖网采样以辅助声学评估.利用Echoview声学处理软件对数据进行分析处理,结合历史资料记载的生态、资源特点以及本研究中拖网生物学数据,以0.5 n mile为间隔输出积分值,并对该海域的生物资源量密度和生物资源量进行评估.声学评估结果表明,第1航次春季调查礁区内和礁区外的平均生物资源量密度分别为41×103 kg/n mile2和28×103kg/n mile2,第3航次春季调查礁区内和礁区外的平均生物资源量密度分别为16×103 kg/nmile2和10×103 kg/n mile2,第4航次夏季调查礁区内和礁区外的平均生物资源量密度分别为65×103 kg/n mile2和3×103 kg/n mile2,第5航次秋季调查礁区内和礁区外水域的平均生物资源量密度分别为165×103 kg/n mile2和45×103 kg/n mile2.结果表明,礁区内水域的平均生物资源量密度高于礁区外水域,并且随着建礁时间的推移,礁区内水域的生物资源总量基本呈增长趋势,同时礁区内的声学评估种类也明显增加.根据拖网生物学数据,建礁后优势种中的优质经济鱼类种数增加明显,如黄斑蓝子鱼和日本金线鱼等,说明人工鱼礁的建设有效地改良了渔业资源结构.     

马鞍列岛海域渔业资源声学评估

为掌握马鞍列岛岛礁海域渔业资源时空分布特征及其与环境间的关系,于2016年12月、2017年3月与5月,使用BioSonics DT-X科学回声探测仪辅以拖网采样对该海域进行3次声学调查。调查结果显示,2016年12月、2017年3月与5月分别评估鱼类46、32、43种,3次声学调查评估鱼类平均丰度密度分别为2.7×104、1.98×104和1.45×104尾/km2,鱼类平均资源量密度分别为0.33、0.34和0.30 t/km2,海域内评估鱼类资源总量分别为132、141和126 t。结果显示,3次调查鱼类丰度密度逐渐递减,3月资源量密度和资源量最高,其次为12月和5月。海区底层资源密度最高,中层次之,表层最少,资源密度水平分布与水深之间无明显线性关系,底层资源丰度密度与底质中粉砂质含量呈显著正相关性(R20.75)。近礁区资源丰度密度远高于远礁区,近礁区各月资源丰度密度与温度、盐度无显著线性关系,与溶解氧之间呈一定线性关系(R2=0.72);远礁区各月资源丰度密度与温度呈显著线性关系(R2=0.91),与溶解氧间线性相关性较弱(R2=0.63),与盐度间无明显线性关系。研究证实声学方法在马鞍列岛岛礁海域渔业资源评估中具有良好的作用效果,为后续进一步开展岛礁海域以及人工鱼礁区渔业资源增殖效果评估研究提供了科学依据与现实基础。     

九龙江口秋季游泳生物种类组成及分布特征

根据2015年秋季对九龙江口开展的桁杆拖网船调查资料,研究分析了该海域游泳生物的种类组成、分布特征、群聚结构和多样性水平等。结果表明,2015年秋季调查海域渔获游泳生物共61种,其中鱼类种类最多,有42种;蟹类次之,有8种;虾类、口足类和头足类分别有6种、3种和2种。渔获数量平均密度指数为518 ind/h,渔获重量平均密度指数为10.29 kg/h。主要渔获优势种类为凤鲚(Coilia mystus)、哈氏仿对虾(Parapenaeopsis hardwickii)、日本蟳(Charybdis japonica)、中华管鞭虾(Solenocera crassicornis)等。游泳生物种类丰富度指数D分布范围为3.112~4.682,平均为3.921;种类多样性指数H'分布范围为1.814~2.674,平均为2.390;种类均匀度指数J'分布范围为0.606~0.921,平均为0.789,多样性指数处于中度水平。     

南海中部海域渔业资源时空分布和资源量的水声学评估

2014年3月~2015年2月对南海中部12°N~15°N、111°E~117°E海域进行了4次渔业资源声学调查,其中2014年3月~4月(春季)、11月~12月(秋季)和2015年1月~2月(冬季)利用"南锋"号船载双频分裂波束科学探鱼仪系统(Simrad EK60,38 k Hz、120 k Hz,挪威)进行探测,2014年7月~8月(夏季)利用便携式分裂波束科学探鱼仪(Simrad EY60,70 k Hz,挪威)进行探测。通过鱼类目标强度现场测定,使用回波积分法获得了调查海域内渔业资源的丰度密度空间分布的季节变动特征。结合夏季调查灯光罩网采样数据,分析了调查海域内评估对象种类组成并估算资源总量。结果表明,夏季共捕获鱼类18种,头足类2种,其中鸢乌贼(Sthenoteuthis oualaniensis)为主要渔获种类,声学评估其资源量为2.36×106t,约占评估对象资源总量的73.19%。调查海域内单体目标强度均呈单峰状分布,且主要分布于-56.5~-41.5 d B,4次调查该海域范围内目标强度小于-71.5 d B的单体均分布于100 m以浅水层,而目标强度大于-20.5 d B的单体则均分布于100 m以深水层。     

洋山深水港海域大型底栖动物初步研究

2003~2005年每年2月、5月和8月按《海洋监测规范》中大型底栖动物调查方法,分别对洋山深水港一期工程施工海域(30°30′~30°54′N、121°45′~122°30′E)20个取样点进行了大型底栖动物调查。根据调查结果,分析与讨论该海域底栖动物的种类组成、生物量、栖息密度和群落多样性的分布与变化。监测结果显示:一期工程施工期,底栖动物的种类数逐年减少,2003~2005年种类数分别为21种、17种和16种;底栖动物栖息密度逐年下降,2003年(31.10 ind/m2)>2004年(12.50 ind/m2)>2005年(11.00 ind/m2);底栖动物平均总生物量总体表现为逐年降低,2003年(4.26 g/m2)>2005年(2.18 g/m2)>2004年(0.62 g/m2),2004年生物量下降尤为显著,2005年生物量略有回升;生物多样性指数也逐年降低,2003~2005年分别为0.81、0.36和0.16。三年监测结果表明,洋山深水港一期工程海域施工期底栖动物种类数、总生物量、栖息密度以及多样性指数总体呈逐年下降趋势,群落结构趋于简单化,说明工程海域施工期对大型底栖动物产生了一定程度的影响。     

Larger biomass of targeted reef fish in no‐take marine reserves on the Great Barrier Reef,Australia

• 1. An expansion of no‐take marine reserve zones of Australia's 348 000 km² Great Barrier Reef (GBR) Marine Park from 4.6% to 33.4% of the park area is proposed in 2004. However, limited evidence currently exists that no‐take marine reserves on the GBR have increased abundance of reef fish targeted by fisheries. This study provides such evidence for inshore reefs of the GBR.
• 2. Underwater visual surveys were used to estimate the effect of no‐take reserves on abundance of species targeted by hook‐and‐line fisheries around the Palm, Whitsunday and Keppel Islands, spanning 600 km of the length of the GBR. The reserves had been zoned ‘no fishing’ for 14 yr.
• 3. Densities of Plectropomus spp. and Lutjanus carponotatus, both targeted by fisheries, were much higher in protected zones than fished zones in two of the three island groups. Plectropomus spp. were 3.6 and 2.3 times more abundant in protected than fished zones of the Palm and Whitsunday island groups. L. carponotatus were 2.3 and 2.2 times more abundant in protected zones than fished zones of the Whitsunday and Keppel island groups.
• 4. The biomasses of Plectropomus spp. and L. carponotatus were significantly greater (3.9 and 2.6 times respectively) in the protected zones than fished zones at all three island groups.
• 5. Legal minimum sizes of Plectropomus spp. and L. carponotatus are ?38 cm and 25 cm TL respectively. There were significantly higher densities and biomasses of Plectropomus spp. >35 cm TL (density: 3.8 times; biomass: 5.1 times) and L. carponotatus >25 cm TL (density: 4.2 times; biomass: 5.3 times) in protected zones than fished zones at all three island groups.
• 6. No significant difference in abundance between protected and fished zones was found for two species not captured by fisheries (Siganus doliatus and Chaetodon aureofasciatus), and there were no significant differences in benthic characteristics between protected and fished zones.
• 7. Results suggest that no‐take marine reserves have increased stock biomass of targeted fish species on inshore GBR reefs.

Copyright © 2004 John Wiley & Sons, Ltd.     

Coral reef fish communities in management systems with unregulated fishing and small fisheries closures compared with lightly fished reefs – Maldives vs. Kenya

• 1. This study presents a comparison of the benthic cover and fish communities in three widely different management systems: (1) a heavily utilized subsistence fishery (yields >5 Mg km^?2 yr^?1); (2) moderately sized and well enforced fisheries closures (～9% of the nearshore area) surrounded by heavy fishing; and (3) a more lightly used management system (yields <5 Mg km^?2 yr^?1).
• 2. The objective was to compare management systems of small to moderate‐sized closures surrounded by heavy use in Kenya with a large‐scale light‐use management system in the Maldives.
• 3. Gross level attributes of the fish community suggest that the Maldives reefs had higher numbers of individuals (30%) and species (15%) than the Kenyan closures.
• 4. Maldivian reefs had higher abundance of some carnivores such as emperors (Lethrinidae), jacks (Carangidae), triggerfish (Balistidae), and trumpetfishes (Aulostomidae). Half the biomass of fish in the Maldives was, however, composed of surgeonfish (Acanthuridae), which resulted in a higher abundance of herbivores/detritivores than found in Kenyan closures.
• 5. Apex predator species were not a large portion of the biomass (<10%) in any system and, if remote reefs of the Pacific are examples of undisturbed ecosystems, then neither management system has fully protected apex species.

Copyright © 2011 John Wiley & Sons, Ltd.     

Population density estimation of southern stingrays Dasyatis americana on a Caribbean atoll using distance sampling

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Multicriteria estimate of coral reef fishery sustainability

A holistic basis for achieving ecosystem‐based management is needed to counter the continuing degradation of coral reefs. The high variation in recovery rates of fish, corresponding to fisheries yields, and the ecological complexity of coral reefs have challenged efforts to estimate fisheries sustainability. Yet, estimating stable yields can be determined when biomass, recovery, changes in per area yields and ecological change are evaluated together. Long‐term rates of change in yields and fishable biomass‐yield ratios have been the key missing variables for most coral reef assessments. Calibrating a fishery yield model using independently collected fishable biomass and recovery data produced large confidence intervals driven by high variability in biomass recovery rates that precluded accurate or universal yields for coral reefs. To test the model's predictions, I present changes in Kenyan reef fisheries for >20 years. Here, exceeding yields above 6 tonnes km^?2 year^?1 when fishable biomass was ~20 tonnes/km² (~20% of unfished biomass) resulted in a >2.4% annual decline. Therefore, rates of decline fit the mean settings well and model predictions may therefore be used as a benchmark in reefs with mean recovery rates (i.e. r = 0.20–0.25). The mean model settings indicate a maximum sustained yield (MSY) of ~6 tonnes km^?2 year^?1 when fishable biomass was ~50 tonnes/km². Variable reported recovery rates indicate that high sustainable yields will depend greatly on maintaining these rates, which can be reduced if productivity declines and management of stocks and functional diversity are ineffective. A number of ecological state‐yield trade‐off occurs as abrupt ecological changes prior to biomass levels that produce MSY.     

Effects of extensive bottom cultivation of tropical oyster <Emphasis Type="Italic">Crassostrea belcheri</Emphasis> on benthic invertebrate community structure in Ban Don Bay,Suratthani Province,Southern Thailand

The diversity, distribution, and species richness of benthic invertebrates were examined under extensive bottom cultivation of the tropical oyster Crassostrea belcheri during the summer of 2015 at Ban Don Bay, Suratthani Province, Southern Thailand. Oyster farms that had been operating for 25 years were selected for the study, and four sampling sites were allocated along each transect as (i) at the center of the farm, (ii) inside the farm, (iii) at the farm boundary, and (iv) a reference site. Results indicated that a total of 23 families and 28 species of benthic invertebrate taxa were recorded from the four sampling sites, and the macrobenthic invertebrates inhabiting all study sites consisted mainly of gastropods (11 species), polychaetes (11 species), and bivalves (8 species). No significant differences in total density, diversity index, evenness index, and species richness index of benthic invertebrates were found among each sampling site (P?>?0.05). Significant differences in total nitrogen, nitrate, nitrite, total ammonia, sulfide, total phosphorus, organic matter, and grain sizes of sediment were found among each sampling site, but no significant differences in pH and total nitrogen were found. Among the independent variables analyzed, correlation analysis showed relationships between benthic diversity indices and abiotic variables. There were no clear patterns of differences in the detrimental environmental effects between sampling site locations, which indicated a minimal ecological impact of oyster cultivation.     

Changes in northern Tanzania coral reefs during a period of increased fisheries management and climatic disturbance

• 1. Surveys of coral reefs in northern Tanzania were conducted in 2004/5 with the aim of comparing them over an～8‐year period during a time of increased efforts at fisheries management and the 1998 El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) coral mortality event that caused 45% mortality in northern Tanzania and much of the Indian Ocean.
• 2. Changes associated with both management, its absence, and the ENSO were found but changes were generally small and ecological measures indicated stability or improvements over this period, particularly when compared with reports from much of the northern Indian Ocean.
• 3. Fisheries management in two areas increased the biomass of fish and benthic communities. A small fisheries closure (0.3 km²) displayed little change in the coral community but ecological conditions declined as measured by sea urchins and fish abundances. This change may be associated with its small size because similar changes were not measured in the large closure (28 km²).
• 4. The few sites without any increased management were still degraded and one site had experienced a population explosion of a pest sea urchin, Echinometra mathaei.
• 5. The lack of significant changes across this disturbance indicates that these reefs are moderately resilient to climate change and, therefore, a high priority for future conservation actions.

Copyright © 2009 John Wiley & Sons, Ltd.     

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