气候变化对东海北部外海越冬场渔业群落格局的影响

为探讨东海北部外海越冬场渔业多样性和群落格局对气候变化的响应,采用中国14家渔业公司底拖网渔业生产和科学调查获得的26种渔业数据,结合东海月平均海表温度,应用经验正交函数分解(EOF)和主成分方法(PCA)分析了海洋表面温度和渔业群落的年际变化特征,并通过线性回归和广义相加模型(GAM)解析群落结构变化和海表温度的关系.结果表明:20世纪70年代到2011年海表温度在1982/1983年出现冷水期(20世纪70年代—1982年)向暖水期(1983—2011年)的跃变.冷水期内为增温趋势,暖水期内1998年之前为增温,1998年之后为降温趋势.群落结构变化特征显示:多样性波动在较大程度上受到马面鲀的影响,20世纪80年代末和90年代初马面鲀成为绝对优势鱼种,多样性处于较低水平.不含马面鲀时,多样性指数在增温期(1972—1998)随时间显著增加,在降温期(1999—2011)则同步下降,表明海表温度会影响渔业群落的多样性水平.主成分分析第一因子(PC1)和第二因子(PC2)的方差解释率为32.4%,PC1表现为长周期的年代际变化模式,可能与气候变化相关;PC2则为短周期的年际变化模式,与厄尔尼诺和拉尼娜现象发生的时间相对应.线性拟合和GAM分析结果显示,PC1与冬季海表温度EOF主模态(win EOF1)的线性关系达到极显著水平,win EOF1和sum EOF2(夏季海表温度EOF第二模态)联合效应对PC1的方差解释率达到88.9%,win EOF1对PC2也有显著的非线性影响,表明群落格局的年代际和年际变化特征受到气候和海洋水文结构的影响.     

典型气候事件对浙江近海底层鱼类时空分布的影响

气候变化对海洋生态系统产生多方面的影响,作为海洋生物中的主体,鱼类对气候变化的响应机制研究是探索典型气候事件对海洋生态系统影响的关键。根据2013-2022年浙江近海底拖网渔业资源调查数据,结合尼诺指数(Ocean Nino Index, ONI)、海表温度 (Sea Surface Temperature, SST)、海表温度距平 (Sea Surface Temperature Anomaly, SSTA)、叶绿素a浓度(Chlorophyll a, Chl-a)等海洋环境数据,采用小波函数、相关性分析等探究典型气候事件厄尔尼诺、拉尼娜对浙江近海底层鱼类生物量及其时空分布的影响。结果表明,浙江近海底层鱼类生物量与SST及Chl-a呈极显著正相关(P ＜ 0.01)。厄尔尼诺与拉尼娜发生时期春、秋季生物量均小于正常年份,正常年份及拉尼娜事件期间春季生物量具有显著性差异(P ＜ 0.05);正常年份及厄尔尼诺事件期间秋季生物量具有极显著性差异(P ＜ 0.01)。对ONI与海洋环境因子指数进行交叉小波发现,浙江近海SST、Chl-a对于典型气候事件均存在不同的频域同步及相关性:ONI与SST在时间局部存在2-3.9个月频域同步,SST滞后ONI3个月;ONI与 Chl-a存在1.7-3个月频域同步,Chl-a与ONI呈正相关;ONI与生物量存在3-3.6个月频域同步,生物量滞后于ONI3个月;ONI与SSTA在研究期间不存在明显的频域同步。春季,相较于正常年份,厄尔尼诺期间鱼类整体分布偏北;秋季厄尔尼诺发生期间鱼类整体向南移动,拉尼娜期间则向北移动。厄尔尼诺及拉尼娜事件不仅对鱼类群落在纬度上的分布产生影响,还会对鱼类向近岸洄游的快慢产生影响。两种典型气候事件通过影响浙江近海SST等环境进而对浙江近海底层鱼类时空分布产生影响。     

基于GLBM模型的中国大陆阿根廷滑柔鱼鱿钓渔业CPUE标准化

西南大西洋阿根廷滑柔鱼既是西南大西洋生态系统中的重要种类,也是鱿钓渔业的重要捕捞对像.单位捕捞努力量渔获量(CPUE)是表示渔业资源状况及其丰度的常用指标.根据2000-2010年中国大陆鱿钓船在西南大西洋的生产统计数据和海洋卫星遥感获得的海洋环境数据(表温,表温水平梯度,海面高度,叶绿素浓度),利用基于贝叶斯的广义线性模型(GLBM),分未加入固定交互选项、加入固定交互选项和加入随机交互选项3种情况对中国大陆西南大西洋阿根廷滑柔鱼鱿钓渔业的CPUE进行标准化.根据偏差信息准则(DIC)值最小来确定最佳贝叶斯模型.结果表明,包含纬度、海表温度、表温水平梯度、海面高度、月×纬度、月×经度及年×纬度变量且加入随机交互项的GLBM模型为最适.标准化后的CPUE较名义CPUE小,年间变化平缓.与广义线性模型(GLM)和广义加性模型(GAM)标准化的CPUE比较,GLBM模型更能反映其资源丰度的真实水平.研究认为,2001-2010年间经GLBM模型标准化后的CPUE呈现逐年下降的趋势.     

吕泗渔场沿岸海域春夏季鱼类生态类群

根据2010年春夏季吕泗渔场沿岸海域2个航次渔业资源调查资料,对该海域鱼类的种类组成和生态类群结构进行分析,并与我国不同纬度海域进行比较.结果表明:春季(5月)出现鱼类21种,生态类群以暖温种(9种)为主,分别占该季节鱼类总尾数和总质量的45.2%和72.9%;优势种主要由暖温性的小黄鱼、焦氏舌鳎和半滑舌鳎组成.夏季(9月)出现鱼类28种;暖水种(21种)大量出现,分别占该季鱼类总尾数和总质量的75.2%和71.7%,棘头梅童鱼、凤鲚等成为优势种.方差分析表明,两个季节吕泗渔场温度和盐度均差异明显,导致鱼类物种更替,呈现出暖温种、沿岸种和近海种逐渐减少,而暖水种和河口种逐渐增加的趋势.     

环境因子对黄海南部春季帆张网小黄鱼和黄鮟鱇渔获分布的影响

帆张网渔业是黄海南部重要的渔业捕捞方式之一.本文根据2006-2009年春季黄海南部帆张网的渔获数据,利用广义线性模型(GLM)和广义加性模型(GAM)定量研究了年份、位置、水深和海水表层温度(SST)对小黄鱼和黄鮟鱇渔获量分布的影响.结果表明:GAM模型较GLM模型可以更好地解释小黄鱼和黄鮟鱇单位捕捞努力量渔获量(CPUE)时空分布与环境因子之间的关系.小黄鱼和黄鮟鱇CPUE呈显著负相关,小黄鱼CPUE呈现由北向南沿纬度方向逐渐减小的趋势,尤其在长江口周围较小;黄鮟鱇CPUE在长江口附近也较小.SST对小黄鱼和黄鮟鱇CPUE的影响显著,小黄鱼和黄鮟鱇适宜表温范围分别为9～11℃和9～14℃.     

环境因子对东海区帆式张网主要渔获物渔获量影响

帆式张网渔业是东海区重要的渔业捕捞方式之一．利用广义加性模型(GAMs)定量研究了海表水温、渔场水深、渔场位置和潮汐(农历日期)等环境因子对东海区帆式张网主要渔获物渔获量变动的影响．结果表明,海表水温和渔场水深是影响带鱼、小黄鱼和鲳鱼单位努力渔获量(CPUE)的主要因子,且各因子的影响程度不尽相同,多呈非线性相关关系．从模型的拟合结果来看,海表水温对带鱼的影响最大,其次是水深,渔场位置和潮汐的影响很小．渔场水深对小黄鱼的影响最大,海表水温、渔场位置和潮汐的影响比较接近．渔场水深和海表水温是影响鲳鱼单位努力渔获量的主要环境因子,影响程度比较接近．     

基于GAM模型的阿拉伯海鲐鱼渔场分布与环境关系

基于2016-2017年中国印度洋围拖网生产数据以及同期的海表温度、叶绿素、表层海流和海面高度数据,采用广义加性模型(Generalized Additive Model,GAM)建立了围网单位捕捞努力量渔获量(catch per unit effort,CPUE)对海洋环境的非线性响应模型,分析了阿拉伯海鲐鱼(Scomber australasicus)渔场分布与海洋环境关系.结果表明:空间因子和环境因子对阿拉伯海鲐鱼渔场有显著影响,GAM模型的方差解释率为30.1%;印度洋季风对鲐鱼CPUE影响大,鲐鱼CPUE在印度洋东北季风高,在夏季季风低;全年阿拉伯海鲐鱼围网渔场主要分布在60°E、13°N-15°N斜向椭圆区域;模型表明,鲐鱼渔场适宜海表温度为26~28℃,叶绿素浓度0.2~0.5 mg·m^-3,海面高度0.2~ 0.4 m;影响鲐鱼渔场的因子按重要性依次为海面高度、经纬度、海表温度和叶绿素浓度.     

东南太平洋智利竹筴鱼资源和渔场的时空变化

根据2005-2008年我国在东南太平洋的智利竹筴鱼大型拖网渔捞日志资料,结合卫星遥感反演的海表温度数据,分析了智利竹筴鱼渔场的年际和季节变化规律以及CPUE与SST的关系。结果表明: 2005和2006年智利竹筴鱼中心渔场的季节变化规律较为类似,而2007年和2008年的春季(9-11月)中心渔场发生了较大的变动;西部海域也存在一定的渔场分布。2005-2008年作业渔场的最适宜SST为13-15℃,随着月份的增加最适温度随之增加,2007、2008年的秋季最适海表温度同2005、2006年相比较有降低的趋势。2005-2007年月平均CPUE与产量重心对应的SST呈显著负相关关系(P<0.05)。     

海州湾蟹类群落种类组成及其多样性

本研究根据2011年3月、5月、7月、9月和12月在海州湾海域进行的渔业资源底拖网调查数据,采用Margalef种类丰富度指数(D)、Shannon-Wiener多样性指数(H′)和Pielou均匀度指数(J′)等分析了该海域蟹类群落种类组成及其多样性的时空变化。结果表明,本次调查共捕获蟹类34种,隶属于18科27属,其中玉蟹科种数最多,有3属4种。从适温属性来看,主要以暖水种(16种)和暖温种(15种)为主,冷温种3种。蟹类群落各多样性指数的月际间变化较大,其中物种丰富度指数(D)3月最高,12月最低;多样性指数(H′)和均匀度指数(J′)均在7月最高,12月最低。多样性指数的空间分布呈现一定的月变化:在3月、5月、7月均表现为北高南低;9月为中部低,南、北部海域较高;12月均呈南高北低的趋势。蟹类单位网次渔获尾数空间分布格局呈现明显的月变化;平均单位网次渔获尾数呈现一定的月变化,总体上表现为3月、5月、12月高于7月和9月。Pearson相关分析结果表明,在5月,多样性指数(H′)和均匀度指数(J′)与底层水温呈显著负相关,与底层盐度呈极显著正相关,多样性指数还与水深呈显著正相关;12月均匀度指数与底层水温和水深均呈极显著负相关,与底层盐度呈显著负相关;在3月、7月和9月,各多样性指数与底层水温、底层盐度及水深均无显著相关性。海州湾蟹类种类组成及多样性的时空变化主要与海州湾地处温带海域、水温等海洋环境因子的季节变化以及优势种的数量分布有关。     

东海海樽类优势种的数量变化

本文根据1997-2000年东海23°30′-33°N、118°30′-128°E海域4个季节海洋调查资料,用生态特征指标和聚集强度测度等分析方法,分析了东海海樽类优势种的数量变化和生态适应。结果表明:东海海樽类优势种有双尾纽鳃樽东方亚种(Thaliademocraticaorientalis)、小齿海樽(Doliolumdenticulatum)、Doliolumsp.、软拟海樽(Dolioettagegenbauri)等4种。双尾纽鳃樽东方亚种和软拟海樽适温适盐范围较小,属于狭温狭盐性暖水种;Doliolumsp.和小齿海樽属于广温广盐性的暖水种。狭温狭盐性的暖水种往往具有较高的丰度、聚集强度和较低的出现频率,广温广盐性的暖水种则与之相反。冬夏季是两类不同优势种交替的季节。双尾纽鳃樽东方亚种、小齿海樽数量与水文环境因子线性关系不显著,Doliolumsp.丰度与底层温度呈正相关(F=4.17,P=0.042),软拟海樽与底层温度呈极显著的正相关(F=18.3,P<0.0001)。春季海樽类优势种在东海南部的高丰度区与黑潮表层水对陆架的入侵在时间和空间上基本一致。双尾纽鳃樽东方亚种是冬、春、夏3季黑潮暖流指示种,软拟海樽仅是春、夏季黑潮暖流指示种     

Quantifying the impact of environmental variables upon catch per unit effort of the blue shark Prionace glauca in the western English Channel

The effect of environmental variables on blue shark Prionace glauca catch per unit effort (CPUE) in a recreational fishery in the western English Channel, between June and September 1998–2011, was quantified using generalized additive models (GAMs). Sea surface temperature (SST) explained 1·4% of GAM deviance, and highest CPUE occurred at 16·7° C, reflecting the optimal thermal preferences of this species. Surface chlorophyll a concentration (CHL) significantly affected CPUE and caused 27·5% of GAM deviance. Additionally, increasing CHL led to rising CPUE, probably due to higher productivity supporting greater prey biomass. The density of shelf‐sea tidal mixing fronts explained 5% of GAM deviance, but was non‐significant, with increasing front density negatively affecting CPUE. Time‐lagged frontal density significantly affected CPUE, however, causing 12·6% of the deviance in a second GAM and displayed a positive correlation. This outcome suggested a delay between the evolution of frontal features and the subsequent accumulation of productivity and attraction of higher trophic level predators, such as P. glauca.     

The impact of the 1997–1999 warm-SST and low-productivity episode on fisheries in the southwestern Gulf of Mexico

Satellite-derived time-series of sea surface temperature (SST), chlorophyll a, and net primary productivity showed a period of warm SST and low productivity during 1997 and 1999 in the southwestern Gulf of Mexico followed by a period of colder than average SST (2000–2001). This shift between the warm and cold oceanic conditions might have caused significant changes in the structure of the ecosystem that is shown by changes in primary productivity and fishery landings between those periods. Handling editor: L. Naselli-Flores     

Spatio‐temporal dynamics in the location of the fishing grounds and catch per unit effort (CPUE) for Chilean jack mackerel (Trachurus murphyi Nichols, 1920) from Chinese trawl fleets on the high seas of the Southeast Pacific Ocean, 2001–2010

The decadal spatio‐temporal distribution of the fishing effort and catch per unit effort (CPUE) for Chilean jack mackerel, Trachurus murphyi, stock are poorly understood. Data from the Chinese jack mackerel fleet was used to describe the location of the fishing effort and the relationship between standardized CPUE and sea surface temperatures (SST) during the period 2001–2010. A significant change in the spatio‐temporal distribution of fishing effort and standardized CPUE was observed for jack mackerel during the study period. From January to March, the average CPUE was generally <15 tonnes (t) per net, except for 2007–2009. CPUE increased significantly during the autumn‐winter (April to August), then gradually decreased in the spring and early summer (September to December). Average standardized CPUE in 2001–2005 was 23.3 t per net, but decreased to 19.7 t per net in 2006–2010. The change in the gravity center location of CPUE between months was similar during the primary fishing period (autumn to winter) in 2001–2006. After 2006, the pattern began to differ in July–October, which resulted in fishers spending more time to search for aggregations. A seasonal change was observed in the range of SSTs associated with high CPUE. Generally, the optimal SST range was from 13.0–15.0°C in autumn, 12.0–14.0°C in winter, 13–16°C in spring, and 15–19°C before 2006. However, a 1–2°C decrease in the optimal range in recent years was associated with a shift in the fishing grounds location to the southern area. In 2009, the optimal SST range was lower than in all other years. Taken together, the results suggest that a more thorough understanding of the seasonal or decadal relationship between SST and location of the fishing grounds is critical to improving the efficiency of the fishery and its management.     

Translocation of marbled African lungfish,Protopterus aethiopicus (Telostei: Protopteridae), and its fishery in Lake Baringo,Kenya

The translocation of the marbled African lungfish Protopterus aethiopicus into Lake Baringo created a new fishery for the local community, who capture them primarily in a bottom-set long line fishery. Its introduction, development and current fishery status in the lake are documented. Annual catch data were obtained from the District Fisheries Office, while catch and effort data of the long line fishery were recorded at one active fish-landing site between February and October 2001. Lungfish comprise a significant component of commercial landings, sometimes exceeding catches of the Baringo tilapia Oreochromis niloticus baringoensis as the most landed species by weight. Daily catch rates and effort varied considerably, ranging from 5.51–15.18kg day^?1 and from 50–590 baited hooks day^?1, respectively. Daily catch per fisher ranged from 0–35.72kg, while the overall mean catch per unit effort (CPUE) was only 0.003kg per hook-hour. This study provides the only baseline CPUE data for a lungfish long line fishery that the authors are aware of, for comparison with future studies in this or other lakes where lungfish are similarly exploited. Recommendations for improved management and the maintenance of a viable lungfish long line fishery in Lake Baringo are presented.     

Inter-annual variability in the breeding performance of seabirds in relation to oceanographic anomalies that affect the Crozet and the Kerguelen sectors of the Southern Ocean

Global warming is expected to increase the frequency and intensity of inter-annual variation in Sea-Surface Temperatures (SST) associated with a latitudinal shift of frontal structures in the Southern Ocean. However, the long-term consequences of these major climatic events on the biotic environment remain poorly understood. We studied the effect of SST anomalies in the southern Indian Ocean on the breeding success of eight seabird species, and found these temperature anomalies to have different effects depending on the foraging habitat of the species. The breeding success of four seabird species foraging mainly south of the Polar Front in Antarctic waters was significantly depressed by warm SST occurring mainly in winter and spring, prior to breeding. Conversely, warm SST anomalies were associated with a higher breeding success for species foraging mainly north of the Polar Front, while no significant effect was found for two species that forage on the Kerguelen plateau. These different responses to changes in the SST were also observed for two closely related species (sooty albatross Phoebetria fusca and light-mantled sooty albatross P. palpebrata ) breeding at Kerguelen. These observations highlight the importance of multi-species long-term monitoring programs for understanding the ecological consequences of environmental variability. Our results suggest that the predicted southward shift of the Polar Front caused by oceanic warming could lead to an important decrease in the breeding performance of top predator seabirds depending on the location and changes of their foraging habitat in relation the Polar Front.     

Catch Composition on Red Shrimps’ (Aristaeomorpha foliacea and Aristeus antennatus) Grounds in the Eastern Ionian Sea

In the present study, the catch composition and the catch per unit effort (CPUE) by weight and numbers in red shrimps’ (Aristaeomorpha foliacea and Aristeus antennatus) grounds was examined in the southern part of the eastern Ionian Sea, in order to collect important information for the Greek waters, where no deep-water fishery exists. In the depth stratum 500–700 m, the catch of the commercial species represented a high proportion (>70%) of the total catch. Red shrimps and several other commercial species were found in important quantities. The present results suggest the possibility of developing a deep-water fishery in Greece. In such a case, attention should be paid because of the high vulnerability of A. foliacea – the main deep-water fishing resource in the area – to the fishing pressure.     

Ocean temperature and density dependence as key drivers of the population dynamics of an intertidal crab at the Brazilian oceanic islands

Understanding how climatic and density-dependent processes affect demography is crucial for predicting population responses to climate change. For marine invertebrates with complex life cycle such as decapod crustaceans, increasing temperatures might affect survival and development of early pelagic stages, whereas high density can increase competition and thus reduce growth and fecundity of older life stages. In this study, we investigate the effects of warm ocean events, body size and density on the population dynamics of the intertidal Sally lightfoot crab (Grapsus grapsus) at the Brazilian oceanic islands. Firstly, we assessed the trends of marine heatwaves (MHW) and positive temperature anomalies (ΔSST+) at the equatorial St Peter and St Paul (SPSP) Archipelago and Rocas Atoll and the subtropical Trindade Island. We then jointly analyzed short-term count, capture-recapture and fecundity data, and long-term population monitoring data (2003–2019) using an integrated population model. Warm ocean events have become more frequent and intense only at the equatorial islands. Increasing MHW frequency positively influenced recruitment in the high-density SPSP population, while MHW intensity and ΔSST+ frequency had negative impacts. Conversely, no climatic effects were observed for the low-density Rocas population, which has the largest crabs. Despite a lack of warming in Trindade, this subtropical population with intermediate density and body size was negatively affected by ΔSST+. Our findings revealed population-specific responses to climate change when accounting for local life history and ecology. Thus, environmental and density-dependent effects should be broadly considered in future conservation studies regarding ocean warming impacts on marine invertebrate populations.     

Multi‐decadal range changes vs. thermal adaptation for north east Atlantic oceanic copepods in the face of climate change

Populations may potentially respond to climate change in various ways including moving to new areas or alternatively staying where they are and adapting as conditions shift. Traditional laboratory and mesocosm experiments last days to weeks and thus only give a limited picture of thermal adaptation, whereas ocean warming occurring over decades allows the potential for selection of new strains better adapted to warmer conditions. Evidence for adaptation in natural systems is equivocal. We used a 50‐year time series comprising of 117 056 samples in the NE Atlantic, to quantify the abundance and distribution of two particularly important and abundant members of the ocean plankton (copepods of the genus Calanus) that play a key trophic role for fisheries. Abundance of C. finmarchicus, a cold‐water species, and C. helgolandicus, a warm‐water species, were negatively and positively related to sea surface temperature (SST) respectively. However, the abundance vs. SST relationships for neither species changed over time in a manner consistent with thermal adaptation. Accompanying the lack of evidence for thermal adaptation there has been an unabated range contraction for C. finmarchicus and range expansion for C. helgolandicus. Our evidence suggests that thermal adaptation has not mitigated the impacts of ocean warming for dramatic range changes of these key species and points to continued dramatic climate induced changes in the biology of the oceans.     

Change and stasis in marine hybrid zones in response to climate warming

Aim We test the prediction that hybrid zones between warm‐ and cold‐adapted species will move towards the territory formerly occupied by the cold‐adapted species in response to a warming climate. We use multiple tests of this prediction to distinguish amongst potential mechanistic hypotheses of responses to climate change. Location We sampled 97 locations on the Atlantic coast of Spain and France and the English Channel that span three hybrid zones formed between two species of marine mussels (Mytilus galloprovincialis and M. edulis). Methods Mussels were sampled in 2005–07 and analysed at a nuclear gene (Glu‐5′) that is diagnostically differentiated between the subject species. Results were compared to those of studies made in the same region over the past two decades. Historical change in sea surface temperature (SST) was analysed using National Oceanic and Atmospheric Administration (NOAA) Optimum Interpolation Daily SST. Species distribution models (random forest and maximum entropy) of the current distribution of mussels were constructed and validated by hindcasting the historical distributions of these species. Validated models were used in combination with forecasts of SST to predict changes in mussel distribution to 2050 and 2100. Results We show that over the past two decades two of the hybrid zones in France have not changed in either position or shape. The third hybrid zone, however, has shifted in the predicted direction, c. 100 km eastward into the warming English Channel. Species distribution modelling strongly implicates changes in winter cold SST as driving this change in the position of one of the hybrid zones. Forecasts of future SST indicate that rapid changes in distribution will occur over the next century. Main conclusions Hybrid zones can be used to conduct repeated tests of ecological responses to climate change and can be valuable in sorting among prospective mechanistic hypotheses that underlie that change. Winter temperatures, but not seasonal high temperature, appear to control the distribution of both species. Species distribution modelling indicates that the collapse of these hybrid zones is imminent, with the rapid expansion of the subtropical species in response to continuing SST warming.