The past,present and future use of drifting fish aggregating devices (FADs) in the Indian Ocean

The use of drifting fish aggregating devices (FADs) has become the dominant practice in tropical tuna purse seine fishing. However, just as FADs can increase fishing efficiency, their use has been associated with several negative ecosystem impacts, and moves are being made to manage the use of FADs. In the evaluation of potential management options it is important to consider how fishers will respond to the introduction of control measures, which first requires an understanding of fishery and fleet dynamics. This paper addresses this need by characterising the past and present use of FADs in the Indian Ocean tropical tuna purse seine fishery. The paper describes historical trends in fishing practices, summarises spatiotemporal patterns in the use of FADs and establishes and attributes variation in FAD fishing strategies within the fleet. It also provides an overview of current FAD management policies in the Indian Ocean and examines the observed effects of existing measures on the behaviour of the purse seine fleet. Using this comprehensive understanding, the potential impact on the purse seine fleet of a number of plausible FAD management options are discussed and inferences are drawn for the future sustainability of tropical tuna purse seine fishing in the Indian Ocean.     

Application of a vessel monitoring system to advance sustainable fisheries management—Benefits received in Taiwan

Vessel monitoring systems (VMS) are considered important instruments for fisheries monitoring, control and surveillance (MCS) to reverse the current depressed state of the world’s fisheries, and have been mandated worldwide by fishery management agencies. The essential function of the system is to provide near-real time vessel position; the potential applications could, however, be more than that. This study explores the additional benefits, with practical examples, that Taiwan has received from implementing the system: in improving the quantity and quality of logbooks recovered, obtaining access to fishery-independent fishing effort estimates and prompt catch/effort reporting, enabling the possibility of regional management and understanding of both fleet dynamics and vessel behavior, and increasing efficiency of vessel safety protection. For other distant-water fishing nations, Taiwan’s experiences serve to demonstrate how the application of VMS technology can advance sustainable fisheries management.     

Second-guessing uncertainty: Scenario planning for management of the Indian Ocean tuna purse seine fishery

An important task of natural resource management is deciding amongst alternative policy options, including how interventions will affect the dynamics of resource exploitation. Yet predicting the behaviour of natural resource users in complex, changeable systems presents a significant challenge for managers. Scenario planning, which involves thinking creatively about how a socio-ecological system might develop under a set of possible futures, was used to explore uncertainties in the future of the Indian Ocean tuna purse seine fishery. This exercise stimulated thinking on how key social, economic and environmental conditions that influence fleet behaviour may change in the future, and how these changes might affect the dynamics of fishing effort. Three storylines were explored: an increase in marine protection, growing consumer preference for sustainable seafood, and depletion of tuna stocks. Comparing across several possible future scenarios, a number of critical aspects of fleet behaviour were identified that should be important considerations for fishery managers, but which are currently poorly understood. These included a switch in fishing practices, reallocation of effort in space, investment in new vessels and exit from the fishery. Recommendations for future management interventions in the Indian Ocean were offered, along with suggestions for research needed to reduce management uncertainty.     

Fishermen responses on marine protected areas in the Baltic cod fishery

Much of the research that concerns the impacts of management measures in the eastern Baltic cod fishery has focused on fish stock rather than understanding fishermen's attitudes towards regulations. Hence, there is little information available on fishermen's responses although they are the ones whom the regulations affect most profoundly. This study analyses the views of fishermen towards management measures with an emphasis on fishing closures (marine protected areas, MPAs). Swedish log-book data from 1996 to 2005 were used to describe MPA induced fishing effort displacements. Fishermen argued that MPAs have been inefficient in conservation of cod stock. The enlargement of Bornholm MPA in 2005 caused substantial effort displacement towards areas dominated by smaller sized fish. This contributed to the increased discarding of juvenile cod. Enlarged MPAs also intensified competition between different fleet segments and reallocated fishing areas. To reduce fishing mortality, fishermen suggested days-at-sea (effort) regulation and an effective landings control system for all fleets that exploit cod stocks in the Baltic Sea Main Basin. These measures would better motivate fishermen for mutual rule compliance, which is a prerequisite for a sustainable cod fishery.     

Impacts of Kelvin wave forcing in the Peru Humboldt Current system: Scenarios of spatial reorganizations from physics to fishers

Because climate change challenges the sustainability of important fish populations and the fisheries they support, we need to understand how large scale climatic forcing affects the functioning of marine ecosystems. In the Humboldt Current system (HCS), a main driver of climatic variability is coastally-trapped Kelvin waves (KWs), themselves originating as oceanic equatorial KWs. Here we (i) describe the spatial reorganizations of living organisms in the Humboldt coastal system as affected by oceanic KWs forcing, (ii) quantify the strength of the interactions between the physical and biological component dynamics of the system, (iii) formulate hypotheses on the processes which drive the redistributions of the organisms, and (iv) build scenarios of space occupation in the HCS under varying KW forcing. To address these questions we explore, through bivariate lagged correlations and multivariate statistics, the relationships between time series of oceanic KW amplitude (TAO mooring data and model-resolved baroclinic modes) and coastal Peruvian oceanographic data (SST, coastal upwelled waters extent), anchoveta spatial distribution (mean distance to the coast, spatial concentration of the biomass, mean depth of the schools), and fishing fleet statistics (trip duration, searching duration, number of fishing sets and catch per trip, features of the foraging trajectory as observed by satellite vessel monitoring system). Data sets span all or part of January 1983 to September 2006. The results show that the effects of oceanic KW forcing are significant in all the components of the coastal ecosystem, from oceanography to the behaviour of the top predators – fishers. This result provides evidence for a bottom-up transfer of the behaviours and spatial stucturing through the ecosystem. We propose that contrasting scenarios develop during the passage of upwelling versus downwelling KWs. From a predictive point of view, we show that KW amplitudes observed in the mid-Pacific can be used to forecast which system state will dominate the HCS over the next 2–6 months. Such predictions should be integrated in the Peruvian adaptive fishery management.     

Harvesting harders Liza richardsoni in the Benguela upwelling region

Harders were fished commercially in the Western Cape even prior to the settlement of Dutch colonialists in 1652. The principal means of exploitation has remained the beach seine, but gill (drift and set) nets and purse-seines have also been used. Yields have increased from about 37 000 fish in 1652 to mostly between 5,5 and 9,1 million fish in recent years. Population biology and ecology of the resource are largely unknown, but the existing information about stock identity and structure, distribution, feeding, growth, reproduction and seasonal availability is synthesized. Provisional data are presented on mesh selectivity of gill nets for harders. Management of the resource has been aimed at protecting juveniles, monitoring catches, limiting and phasing out of large-scale purse-seine fishing, limitation of excessive participation in the fishery, enforcement of human presence during fishing operations, and encouragement to diversify fishing effort. Despite the limited scientific knowledge of the resource, appropriate management action and such fortunate resource characteristics as seasonal fluctuation in availability, natural distribution over much of the coastline and a failure of the species to shoal along with other commercially exploited pelagic species have resulted in harvests remaining within the production capacity of the stock and in prevention of growth overfishing.     

The artisanal fishery of Cynoscion guatucupa in Argentina: Exploring the possible causes of the collapse in Bahía Blanca estuary

Cynoscion guatucupa Cuvier 1829 is a migratory pelagic fish species, which has a wide geographical distribution. It is the most important fishing resource for local communities in Bahía Blanca estuary and has been captured by artisanal fishermen since the 1900s. The industrial fleet has been fishing this species in the coastal area of Buenos Aires province since the 1950s, and, since 1970, landings have increased sharply. Between 2000 and 2004, the artisanal fishery in the estuarine waters of Bahía Blanca collapsed. Variations in total landings of the artisanal fleet might have arisen from the environmental variables within the estuary, fishing activity in the surrounding sea region, local pressure within the estuary and/or several other variables. Our results suggest that neither oceanographic parameters nor local pressure seem to have influenced the artisanal fishery of C. guatucupa in the estuarine region. Instead, this fishery seems to have been partially influenced by the increasing fishing pressure exerted by the industrial fishing fleet operating in open waters around the estuary. This study emphasizes the need to take into account fisheries data from both the estuarine environment and the surrounding sea region, particularly when designing management plans for the sustainable use of migrating fish resources.     

Using fine‐scale catch predictions to examine spatial variation in growth and catchability of Panulirus cygnus along the west coast of Australia

Puerulus settlement has been monitored throughout the western rock lobster Panulirus cygnus fishery for nearly 40 years. These data, in combination with indices of effort and water temperature, were used to produce recruitment‐catch relationships for each 1° transect of latitude in the coastal part of this fishery from Kalbarri to Cape Leeuwin, as well as at the offshore Abrolhos Islands (total of eight transects). The fine spatial scales of these models provided estimates of certain life history traits that are known to affect lobster catches between adjacent fishing ports. This catch modelling showed that the proportions of 3‐ and 4‐year‐old post‐settlement lobsters contributing to the catches varied markedly from the southern to northern transects, suggesting that juvenile lobsters grow substantially faster in the warmer northern and offshore waters of this fishery. These proportions provide accurate estimates of juvenile growth rates, which are vital in the construction of location‐specific growth algorithms required by the age‐structured models used in the management of this fishery. Model estimates of density‐dependent mortality were greater in the more densely populated centre of the fishery and markedly lower at the northern and southern limits of this species distribution. Annual increases in fishing efficiency were also found to be lowest at the northern and southern extremes of the fishery and greatest in the centre of the fishery, where technology advances and increased fleet mobility have enabled the fleet to increase efficiency by 1–3% each year. Catchability (q) was found to be most influenced by water temperatures in the cooler southern transects, whereas at the Abrolhos Islands, changes in water temperature produced almost no discernable change in q. The catch modelling was also used to quantify the impact of management changes introduced in the 1993/94 fishing season. Increased protection of female lobsters and an 18% pot reduction resulted in a 3–4% permanent reduction in the catch rates of lobsters throughout most of the coastal fishery, whereas at the offshore Abrolhos Islands, catch rates increased by c. 20%, presumably owing to a reduction in the level of pot saturation.     

大西洋大眼金枪鱼渔业概况

大西洋大眼金枪鱼（Ｔｈｕｎｎｕｓ ｏｂｅｓｕｓ）是高经济价值鱼种,其分布几乎覆盖整个大西洋水域。研究大西洋大眼金枪鱼的渔业对于我国远洋渔业意义重大。所以在此对其渔业及资源状况进行研究。根据三种主要渔业（延绳钓、围网和竿钓）的渔获量,可看出大眼金枪鱼渔业的发展概况。为了分析资源状况,文中使用了Ｗａｌｔｉｒｓ ａｎｄ Ｈｉｌｂｏｒｎ（１９７６）产量模型。其结果是９９．６千公吨的最大持续产量和１１４．７     

History,effort distribution and landings in an artisanal bottom longline fishery: An empirical study from the North Atlantic Ocean

Commercial fishing data were used to reconstruct historical spatio-temporal patterns of fishing effort and landings in the bottom longline fishery of the Azores. Key events during an important 15-year period were charted, through fisher interviews together with GIS analysis. While effort distribution varied over time, the prevailing pattern was a shift in focus from eastern to western areas and from shelf/slope to offshore banks and seamounts in response to policy measures (e.g. banning bottom longline inside 3 NM, public aids for modernization of the fleet) and reduced fishing yields. Areas 12–50 NM from shore represented the most vital fishing grounds in terms of fishing effort and production. Declining landings of the major demersal species, in recent years, indicate that present catch levels are not sustainable and further measures need to be taken in order to sustain fisheries resources. Knowledge of fleet behavior and the distribution of fishing effort, particularly in patchy environments, provide valuable insights into the impacts of past management decisions and help predict the outcome of new policies both in this region and elsewhere.     

Spatial management of small-scale fisheries on the west coast of Baja California Sur, Mexico

To understand small-scale fisheries in Mexico, the spatial and temporal distribution of the landed catch of several species was analyzed, including abalone, clams, snails, octopus, squids, lobsters, shrimps, blue crabs, sharks, rays and finfish along the 349 km of the Gulf of Ulloa coast. Data reported by fishers from 1998 to 2009 on catch volume and value per group of species and per fishing locality, together with the number of landing events, were used to define fishing zones and the relative importance of each fishery. Finfish turned out the primary fishery in the region, but the other fisheries showed relevant spatial changes that should be considered when establishing management goals and fishing regulations according to resource availability, fleet efficiency, processing capacity, commercialization of fishing products and profit distribution.     

Performance of a northwestern Mediterranean bottom trawl fleet: How the integration of landings and VMS data can contribute to the implementation of ecosystem-based fisheries management

The European Union has established a framework to achieve or maintain good environmental status in the marine environment by 2020. The Marine Strategy Framework Directive requires the application of the ecosystem approach to the management of human activities, covering all sectors having an impact on the marine environment. However, fisheries in the Mediterranean are far from a systematic implementation of an ecosystem-based fisheries management (EBFM). Aiming to address this issue, this study explores the potential of the relationship between daily yield by vessel (landings and income by species) and vessel position (known via vessel monitoring system) as a tool for fleet management. This approach is possible due to the current dynamics of Mediterranean fleets, with vessels returning daily to the harbour where landings are registered as weight and income by vessel. Moreover, vessels of >15 m total length have been compulsory monitored by VMS since 2005. A bottom trawl fleet that operates in the northwestern Mediterranean was chosen to develop this approach. Different groups of trawlers were identified, which could be linked to the strategies displayed by the fishermen that were mainly driven by the target species dynamics. Accurate knowledge of the fishing targets driving the fleet dynamics and of the fishing strategies at the vessel level (i.e. fishing ground habitat where the fishing pressure is exerted and corresponding landings) are shown to be a feasible tool for fleet management.     

基于北斗卫星船位监控系统数据的南海双拖渔船作业特征研究

船位监控系统（vessel monitoring system,VMS）数据在渔船作业特征挖掘分析方面已有较多应用。本文以粤渔10000/10011双拖渔船2017年8月16日—9月16日的VMS数据为例,详细分析了该双拖渔船的作业状态,研究了航次和网次提取方法,并对捕捞强度的空间分布进行了分析。研究结果表明,粤渔10000/10011有4个航速区间,分别为<1.0 m/s、1.0~1.8 m/s、1.8~2.9 m/s和>2.9 m/s,对应渔船的抛锚和慢速、夜间拖网航速、白天拖网航速和巡航状态;2017年8月16日—9月16日期间,粤渔10000/10011共进行了5个航次19个网次的拖网作业,其捕捞强度空间分布呈现近岸海域高离岸海域低的特征,且夜间拖网主要在离岸海域,白天拖网会转移到水深相对浅的近岸海域。     

Discrete choice modelling of fisheries with nuanced spatial information

Temporary marine area closures or more permanent Marine Protected Areas are being proposed as potential options in ecosystem-based marine spatial management. These policy options are known to displace fishing effort. In this paper, EU Vessel Monitoring System (VMS) data is combined with other site and vessel information and used to model the fishing site choice decision of Irish demersal otter trawlers. Uniquely, the fishing ground options used in the analysis reflect the actual seabed contours trawled by the fleet. The fishing site choice model, based on this natural site definition is compared to an alternative destination choice model where the fleet decision is specified using a grid based site definition as employed in previous work. It is argued that the natural site specification is a more realistic specification of the fisher site choice decision. Using the preferred natural fishing site choice model, a policy scenario involving the hypothetical closure of one of the fishing ground options is then simulated to examine the possible redistribution of fishing effort.     

Allocation of effort in artisanal fisheries: The importance of migration and temporary fishing camps

In order to avoid conflicts when spatially explicit rules are implemented, it is critical to understand the spatial distribution of fishing effort, the migration patterns of fishermen and the use of temporary fishing camps. The migration of fishermen is a process shaped by historical patterns of resource availability, in addition to economic and political factors. We present an example in which a temporary fishing camp used for extraction of benthic resources (Loco: Concholepas concholepas) changed into a permanent one during the study period. Throughout the study period fishing effort (trips) was closely related to the productivity of the different fishing grounds, with more trips directed to the most productive areas. The conversion from a temporary to a permanent fishing camp did not improve the efficiency of the loco fishery, but did allow better access to alternative resources (surf clams) on nearby fishing grounds. The succession from simple shelters to a permanent ‘caleta’ is a common situation along the Chilean coast, motivated originally by resource availability and more recently by the creation of the TURF system. In particular the TURF system converts temporary (resource driven) movements of fishermen into rigid stationary caletas, which creates a number of problems. Temporary fishing camps are common when fishing grounds are far from the base port, but they require specific administrative tools in order to achieve sustainable fisheries management.     

Interdecadal variability of anchoveta abundance and overcapacity of the fishery in Peru

Paleontological and historical stock abundance estimates indicate that pelagic fish populations inhabiting upwelling ecosystems undergo large interdecadal variations in abundance with amplitudes equal to, if not larger than, the interannual variability. The interdecadal variability is characterized by periods of high and low abundance, termed “pseudo-cycles”, because of their irregular periodicity. Fisheries targeting small pelagic fish suffer from overall overcapitalization, like many other fisheries, but also from an additional overcapitalization problem: a phase displacement between rapid fish population decreases and a slower disinvestment which follows. This lag produces economic hardship.Here we document the fish:fishery relationship for the Peruvian anchoveta. Anchoveta pseudo-cycles of 20 to >100 years are observed, with the present stock abundance most likely located near upper part of the cycle. Fleet overcapacity expressed as the proportion of unused present capacity is estimated at 72% and processing overcapacity at 89%. A simple bio-economic model demonstrates the risks associated with the pseudo-periodicity in fish stock abundance in conjunction with fishery investment, open access, and overcapacity: a timing bomb for the fishing sector. The lag between disinvestment and decrease in fish abundance is quantified. A reduction of the fishing and processing capacity and measures to decrease the investment lag are recommended to limit the social, economical and political tensions that will result from the expected decrease in stock abundance. Finally, some management options to reduce these risks are discussed.     

Norway's experience with ITQs

This paper discusses the development of ITQs in Norway. Even if some would deny that anything such exists, fisheries management in Norway has some unmistakable characteristics of an ITQ system. Both boatowners and policy makers have discovered the attractions of transferable quotas, the former as a means to increase their private profits, the latter as a vehicle to reduce fleet overcapacity. The slow evolution of transferability is mainly the result of ideological opposition and opposition to structural changes, the latter involving falling number of fishermen, changes in location of the fishing industry, and changed composition of the fishing fleet. The development of this system in the purse seine fleet and the fleet fishing for cod and similar species is traced. Then the concept of resource rent is discussed, as well as how it has become capitalized in quota values, which show up as a rise in value of long term assets of the fishing industry.     

中西太平洋金枪鱼围网渔场聚类及其原因分析

本文根据1995-2010年我国中西太平洋金枪鱼围网生产统计数据,按年和月不同时间空间分辨率对金枪鱼围网渔场进行聚类分析,划定不同渔场类型;同时结合海表温度（SST）及Niño3.4区指数,探讨其渔场类型形成的原因。研究表明,在月为时间尺度下气候异常事件（El Niño和La Niña事件）发生频次与渔场聚类结果类别相关联,在1-12月发生气候异常事件频数分布可划分为以下几个阶段:1-3月、4-6、7-9月、10-12月,与月时间尺度下金枪鱼围网中心渔场4种聚类结果的时间范围具有一致性。通过渔场重心聚类结果和El Niño和La Niña事件分类统计对比发现,在年时间尺度下,气候异常事件的类型与聚类结果相关联,聚类结果同一类别包含的年份发生的气候异常事件具有一致性,即在同一类别下1995年、1997年为强El Niño年;1998年、2007、年、2009年为正常年份;2010年为强La Niña年;1999年、2000年、2001年为La Niña年;1996年、2008年为La Niña年;2002年、2004年为El Niño年。研究认为,中心渔场的年际聚类变化与El Niño、La Niña事件的发生分布具有很强的相关性,因此可以利用El Niño、La Niña指标来预测渔场的年间和月份间的变化。     

The relationship of anchovy and sardine to water masses in the Peruvian Humboldt Current System from 1983 to 2005

The Humboldt Current System (HCS) is dominated by two pelagic species; Peruvian anchovy or anchoveta (Engraulis ringens) and sardine (Sardinops sagax). Using data from 43 acoustic surveys conducted from 1983 through 2005 by the Peruvian Marine Institute (IMARPE), we examined the distribution of these two species relative to water masses. We tested the hypothesis that anchovy was found more frequently in upwelled cold coastal water (CCW) and mixed waters (MCW) than in other water types and that sardine was more associated with more offshore oceanic surface subtropical water (SSW). Surface temperature, salinity, latitude, season and distance to the coast data were used to define water masses. Results using generalized additive models (GAM), modelling sardine and anchovy presence–absence as a function of year, water body, bottom depth and latitude, showed that anchovy were primarily found in CCW and MCS, while sardine were more ubiquitous relative to water masses with some predilection for SSW. These results were supported by various indexes of anchovy and sardine distribution versus water mass as well as temporal and location variables.     

鱼类自然死亡率的估算及其影响因子的探讨

为探讨鱼类自然死亡率参数,文中讨论了1种通过资源量和渔获量数据估算鱼类自然死亡率(M)的方法。蒙特卡罗模拟分析显示当资源量的白色噪音,即变异系数(CV)水平小于大约10％时自然死亡率的估计值基本上是准确的;捕捞死亡率的变化对自然死亡率估计的影响不大。文中构造了长寿命自然死亡率小和短寿命自然死亡率大的2个鱼类种群,模拟结果表明这种方法更适用于寿命短而自然死亡率大的种群。另外该方法在黄海鲲鱼(Engraulis japonicus)渔业数据上的应用同样得到了良好的结果。