共查询到20条相似文献，搜索用时 31 毫秒
1.
2.
B. Louise Chilvers 《水产资源保护:海洋与淡水生态系统》2021,31(8):2204-2216
- Individual specialization in the foraging behaviour of marine predators can affect the ecology, evolution, and ability of a population to respond to environmental variability and human impacts.
- Here, blood serum and whisker stable isotope values from New Zealand (NZ) sea lion pups (Phocarctos hookeri) are compared with their mother’s values to identify whether they can be used as proxies to identify their mother’s isotopic niche and foraging strategy.
- Female NZ sea lions have been identified, both through telemetry and stable isotope research of blood serum and whiskers, to have two distinct foraging ecotypes (mesopelagic or benthic), consistent across their adult life. Females who are mesopelagic foragers have higher overlap and a greater risk of harmful interactions with fisheries.
- Stable isotope analysis of adult females can be used to determine the proportion of the female population exposed to these detrimental interactions. However, the capture, restraint, and removal of a whisker or blood from an adult female NZ sea lion is an expensive, time-consuming, and invasive undertaking. Instead, by comparing the blood serum and whisker δ13C and δ15N values of 12 NZ sea lion mother-and-pup pairs, for whom the foraging behaviour of the female is known, the question as to whether a pup’s blood serum or whisker isotope value can be used as a proxy to identify female foraging ecotype was investigated.
- The δ13C and δ15N values for the blood serum and whiskers of pups and their mothers were correlated and differed significantly between foraging ecotypes. This research validates that pup blood serum and whisker stable isotope values from 1-month-old pups can be used as indicators of female isotopic niche and therefore foraging ecotype.
- This tool can be used across all NZ sea lion colonies to indicate female NZ sea lion foraging ecotypes. For the Auckland Islands, it could determine the proportion of breeding females exposed to negative interactions with fisheries, leading to a better understanding of the level of these effects and helping to implement appropriate management to mitigate impacts.
3.
- Understanding the ecological and evolutionary processes that occur during range shift or (re-)colonization is of critical importance for species whose ranges are changing due to human-induced climate change or species such as New Zealand sea lions where their established colonies are significantly declining due to human impacts.
- The mechanisms underlying colonization are poorly understood. Observations are required to determine the processes that change individual's behaviour associated with colonization, but such observations are rare.
- Here, the establishment of a new breeding colony of New Zealand sea lions, Phocarctos hookeri, as they recolonized mainland New Zealand, an area from which they had been absent for ~200 years was investigated.
- There are differences in breeding location behaviour and population connectivity between established and establishing colonies of New Zealand sea lions. The recolonizing population is more dispersed with breeding locations that change annually and have more connections with other populations compared with established colonies and populations.
- The establishment of a new colony and the greater numbers of resightings between colonies means that for species' management, considerably more public education, habitat management, and protection is needed to ensure the safe return of New Zealand sea lions back on to mainland New Zealand.
4.
1. Historical records show the area of Mar del Plata (38°05′ S/57°32′ W, Argentina) as inhabited by extensive seal colonies; the present study describes the evolution of their size and location from the 16th century to the present. 2. Southern sea lion (Otaria flavescens Shaw 1800), South American fur seal (Arctocephalus australis Zimmerman 1783) and southern elephant seal (Mirounga leonina Linnaeus 1758) colonies, which consisted of between 80 000 and 165 000 animals, were subject to no commercial harvest, and only small local catches were performed by transient aboriginal groups. 3. During the second half of the 19th century coastal zones were rapidly colonized by man and by the turn of the century, the pinniped rookeries finally disappeared. Such a dramatic decline was not only due to spatial competition with man, but also to the indirect effect of pinniped over-exploitation in other areas of the south-western Atlantic. 4. No seal colonies were recorded in Mar del Plata during the 20th century until the mid sixties, when small non-breeding groups of sea lions and fur seals established themselves in the area. 5. The seal rookeries' decline in Mar del Plata provides an interesting example of how human activity may severely affect the conservation of pinniped colonies, even with no direct action through massive catches. © 1998 John Wiley & Sons, Ltd. 相似文献
5.
Yonat Swimmer Randall Arauz John Wang Jenny Suter Michael Musyl Allan Bolaños Andrés López 《水产资源保护:海洋与淡水生态系统》2010,20(4):445-451
- 1. This study compared the catch rates of targeted dolphinfish or mahimahi (Coryphaena hippurus), and sea turtles and other fish bycatch in a shallow‐set Costa Rican longline fishery using 14/0 circle hooks with and without a 10° offset. The effect of hook offset on hooking location and injury in captured sea turtles, specifically if the hooking was external, in the mouth, or in the esophagus was also evaluated.
- 2. Results were compared from six trips totalling 33 876 hooks with squid (Dosidicus gigas) used as bait. In total, mahimahi catch‐per‐unit‐effort (CPUE, expressed as number caught per 1000 hooks) was similar between hook types (CPUE～52).
- 3. Olive ridley sea turtles (Lepidochelys olivacea) were caught on all 42 sets. In total, 640 olive ridley turtles were caught and released alive. There were no significant differences in the number of sea turtles caught between hooks with and without an offset (CPUE～19) nor between hook type and anatomical hooking location, suggesting similar levels of injury for turtles caught on each hook type.
- 4. These data suggest that a 10° offset on 14/0 circle hooks does not confer any selective advantages over hooks with no offset with respect to capture rates of mahimahi, sea turtles, sharks, or pelagic stingrays in a shallow set pelagic longline fishery. Copyright © 2010 John Wiley & Sons, Ltd.
6.
7.
- River fish diversity is threatened by anthropogenic environmental alteration to landscapes. The early life-history stages of fish play an important role in maintaining diversity and population recruitment and can be heavily influenced by landscape patterns. Information on temporal and spatial distribution patterns of fish eggs and larvae is also important for biodiversity conservation and management of fish resources.
- The Yangtze River possesses a high diversity of fishes, including many commercially important species. The economy along the lower reach of the river is well developed, and most of the area is experiencing high pressure from human impacts. This section of the Yangtze River connects with the largest freshwater lake in China at the upstream end and flows into the estuary at the downstream end. These two landscape features are likely to have a significant impact upon the spatial distributions of fish egg and larval assemblages.
- Environmental variables, fish eggs, and larval assemblages were sampled in three locations, at Hukou, Anqing, and Jingjiang, in the lower reach of the Yangtze River. The results suggest that the higher number of species and greater abundance in upstream sites reflect the critical function of connectivity of Poyang Lake with the river for fish recruitment in the lower Yangtze. The delayed bloom of larval fish, occurrence of estuarine species, and a lower species number and abundance of freshwater fish downstream reflect the influence of tidal intrusion from the estuary.
- This study highlights the value of maintaining natural river–lakes connectivity in the Yangtze River as a conservation measure. The connected river–lake system should be designated as a priority area for fish resource protection in the lower reach of the Yangtze River. We recommend further measures to break down barriers between the river and other lakes and to restore the natural lateral connectivity of the floodplain ecosystem.
8.
Estefania Isaza-Toro John Josephraj Selvaraj Alan Giraldo-Lopez Omar Olimpo y Ortíz-Ferrín 《水产资源保护:海洋与淡水生态系统》2021,31(11):3311-3318
- Fish aggregating devices (FADs) are floating objects that facilitate the aggregation of fish; those that aggregate pelagic species such as tunas are of particular interest for artisanal and industrial fisheries.
- Due to the increasing use of these devices worldwide, bodies responsible for the administration and management of fishery resources have proposed control and surveillance activities focused on the use of such devices. To achieve this, it is essential to have access to quality information, which is usually obtained through on-board observer programmes such as the Colombian Fisheries Observer Program.
- Based on the historical records of this programme, and for the first time, the spatial–temporal distribution of the FADs in the eastern tropical sector of the Eastern Pacific Ocean is presented, analysing 166 records of tuna fishing operations carried out between 2009 and 2015. Of the 2,328 sets identified in the records, 957 corresponded to sets on FADs, of which 80.56% were effective and caught 12,246 tons of tuna.
- The number of sets of FADs increased over time, representing approximately 86.9% of the sets recorded in 2015, compared to 4.8% of this type of set recorded in 2009, with the Eastern Tropical Pacific Marine Corridor being the area of greatest concentration of sets.
- Considering that the Eastern Tropical Pacific Marine Corridor was designed to promote the conservation and sustainable use of biological diversity in the Eastern Tropical Pacific, this study highlights the need to include as a research priority, the potential effect that aggregation devices may have on the biological connectivity processes present in the corridor, as well as on the dynamics of large pelagic fish populations of commercial interest.
- In terms of management of FADs, it is recommended that a precautionary approach be adopted and that regulations related to the maximum number of FADs per vessel be adjusted according to their Inter-American Tropical Tuna Commission class, in addition to assigning a maximum number of sets per vessel.
9.
Laura Prosdocimi Natalia S. Teryda Gabriela S. Navarro Raymond R. Carthy 《水产资源保护:海洋与淡水生态系统》2021,31(4):830-840
- Fisheries bycatch of non-target species in the commercial fleet is a major source of anthropogenic injury and mortality for sea turtles and marine megafauna.
- The Río de la Plata maritime front (RLPMF) and its adjacent international waters – comprising part of the Argentine and Uruguayan exclusive economic zones, is a highly important fishing ground in the south-western Atlantic Ocean as well as feeding and development grounds for sea turtles.
- This paper analyses the distribution of the bottom and pelagic trawling fishery within the RLPMF using information from Vessel Satellite Monitoring System. With this information, areas of highest trawling intensity were defined and further evaluated their overlap with sea turtle habitat-use areas from available sea turtle satellite tracking information.
- Results besides identifying high-susceptibility areas for sea turtle bycatch by the commercial trawler fleet along the RLPMF, provide predictive tools to identify vulnerable areas to interaction of sea turtles and the commercial fishing fleet.
- Implementation of bycatch mitigation measures, such as reduced fishing effort areas by the Argentine and Uruguayan fisheries management agencies has the potential to benefit the fisheries as well as marine megafauna. Furthermore, there is a need for additional research on the impact that this fleet can have on sea turtles present in the area.
10.
Chetan Rao Shawn Dsouza Trisha Gupta Muralidharan Manoharakrishnan Aaron Savio Lobo 《水产资源保护:海洋与淡水生态系统》2021,31(9):2402-2411
- The impacts of fisheries on several charismatic marine fauna have been a subject of global concern. Sea snakes share the same habitats as many commercially important fish species and often end up as fisheries bycatch.
- Previous studies of bycatch from India have been limited to individual reports of mortality, with little information on the regional community structure of sea snakes. This study was carried out along the Konkan coast, off the central west coast of India, between 2016 and 2018, to determine trends in the bycatch of sea snakes in coastal fisheries.
- In this study, 922 sea snakes were encountered in 916.57 gillnet haul hours and 449.16 trawlers haul hours of fishing, comprising largely of two species: beaked sea snake (Hydrophis schistosus) and spine-bellied sea snake (Hydrophis curtus) (83.05 and 16.94% respectively) which was in stark contrast to a similar study conducted in 2002–03, which recorded a dominance of H. curtus (84%) followed by H. schistosus (14%) in the same region. Both studies, however, indicated higher mortality in H. curtus than in H. schistosus in trawl nets.
- This study highlights the significant impact of non-selective fishing practices on regional assemblages of other marine organisms such as sea snakes from South Asia, which has been relatively understudied, and the potential consequences for local ecosystems.
11.
12.
- Group membership is a key attribute of animal societies and central to the study of social structure in several taxa. However, social structure analyses are sensitive to the way data are collected and associations defined.
- In this study, a time–space method was used to investigate the social structure of common bottlenose dolphins Tursiops truncatus observed and photographed across 7 years in the semi-enclosed Gulf of Corinth, Greece. Instead of adopting traditional group definitions, individuals were considered as being members of the same group if photographed within a specific time and space window. This approach can be applied post hoc across studies and can offer advantages under challenging sampling conditions (e.g. when dealing with groups spread over vast areas or when group membership is otherwise hard to assess).
- Dolphins were mostly found around coastal cage aquaculture facilities farming European sea bass Dicentrarchus labrax and gilthead seabream Sparus aurata.
- Dolphins formed clusters largely or entirely composed of individuals of the same sex, suggestive of sex-based homophily. Habitat partitioning was not detected: there was substantial spatial overlap among dolphin clusters, with all individuals using a relatively small area in the northern portion of the Gulf, where most of the productive fish farms were located. Associations between females were stronger than those between males, and daughters tended to stay in the group of their mothers.
- Sex-based social clustering may allow females and calves to limit interactions with potentially aggressive males, while individuals of both sexes benefit from prey concentrated around fish farms.
- Adaptation to foraging around farms can result in trade-offs between the costs and benefits of nourishment and social interaction. This may have both positive or negative effects on the animals that should be considered in the context of ensuring their favourable conservation status.
13.
Esteban Avigliano Ana Ibañez Nidia Fabré Roberta Callicó Fortunato Ana Méndez Jorge Pisonero Alejandra V. Volpedo 《水产资源保护:海洋与淡水生态系统》2021,31(4):789-801
- The white mullet, Mugil curema, is a widely distributed euryhaline species, the migratory behaviour of which is poorly understood. The objective of this work was to study the large-scale habitat use of this species for the first time. Several environments were considered, such as euryhaline and hypersaline lagoons, the sea, and a river, distributed in the Central Pacific (Mexico) and Atlantic (Gulf of Mexico, Caribbean Sea-Venezuela, and north-eastern Brazil).
- Otolith core-to-edge Sr/Ca ratios of 163 fish, determined by laser ablation inductively coupled plasma mass spectrometry, were used to study the salinity-habitat migration history of the fish. Fish from Mexico (Tamiahua Lagoon, n = 4; Alvarado Lagoon, n = 2), Venezuela (n = 1), and Brazil (n = 12) (11.1% of the total) showed high Sr/Ca values at early life stages and were classified as marine estuarine opportunists. Two specimens (from Alvarado Lagoon and Balsas River, Mexico) showed Sr/Ca values consistently below the high salinity guide value (salinity < 33.5). For the rest of the fish (87.1%), the Sr/Ca ratio suggested a displacement from the estuary towards the sea or hypersaline environments, and so these fish were classified as estuarine migrants.
- A change-point analysis identified six individuals with a single stable otolith Sr/Ca signature through ontogeny (three from Brazil, one from Venezuela, and two from Tamiahua Lagoon, Mexico), suggesting limited displacement between environments with different salinities. The rest of the individuals showed between two and 10 changes in stable Sr/Ca signatures (mean = 4.07 ± 1.85). The highest number of changes in Sr/Ca ratio (4.87 ± 1.1) was found in fish from Laguna Madre (Mexico) and the lowest was found in fish from Brazil (3.27 ± 1.70) (H = 19.8, p = 0.002).
- Otolith Sr/Ca time series suggest that the migratory estuarine pattern is the most common throughout the study area. This work highlights that the sustainable use of M. curema depends on the conservation of estuaries and the corridors between them and other environments such as lagoons, rivers, mangroves and the sea.
14.
小型中上层海洋鱼类是重要的渔业资源,目前其捕捞产量约占到全球海洋渔获量二分之一。小型中上层海洋鱼类具有生命周期短、生长速度快、分布不均匀、易受环境因素影响等生物学特点,近年来,一些小型中上层海洋鱼类渔获量出现下降趋势,为保证其资源的可持续利用,对其进行准确的资源评估研究和制定合理有效的管理策略显得尤为重要。以文献计量统计分析为基础,对20多年来应用于小型中上层海洋鱼类资源评估的模型方法以及所需数据类型进行归纳与回顾,同时对模型中重要的参数估计、不确定性来源进行总结。分析认为,由于缺乏完整、准确的生物学信息导致无法对小型中上层海洋鱼类使用传统的资源评估方法进行评估,因此,其资源评估研究仍处在发展阶段。建议今后研究中应开展以下工作:1)努力提高现有模型的评估精度,尽可能考虑更多影响因素; 2)要进行长期系统的渔业资源独立调查; 3)充分利用体长等易获得数据,开发体长结构模型和基于生态系统的评估模型,降低模型选择的局限性。 相似文献
15.
Javier Noe Serrano-López Katherin Soto-López Rosa Isabel Ochoa-Báez John O'Sullivan Felipe Galván-Magaña 《水产资源保护:海洋与淡水生态系统》2021,31(7):1624-1635
- Devil rays of the genus Mobula are subject to fishing exploitation worldwide and are considered vulnerable to overexploitation due to population reduction, which is evidenced by a decline in the number of catches of these animals.
- Limited biological knowledge on these species has forced the use of precautionary conservation measures in countries where intensive fishing occurs.
- This study aimed to describe biological data of interest for estimating the feasibility of the recovery of Mobula populations, emphasizing the reproductive activity of three endangered species of the genus Mobula (Mobula munkiana, Mobula thurstoni, and Mobula mobular) in the Gulf of California.
- Reproductive organs were collected during 7 years of commercial fishing (2001–2007), and data on population structure, sex ratio, gamete production, and the number of offspring per breeding period were obtained.
- Maturity stages were determined through histological analysis of the gonads for both sexes, and the size at maturity was estimated based on anatomical and histological characteristics of the specimens caught.
- Considering the wide global distribution of Mobula species, there is an urgent need to apply strict conservation measures, such as established fishery closures during the breeding season or the establishment of catch periods after specimens have reached sexual maturity, especially in the countries where these animals are caught.
16.
- In order to increase their catches, longliners targeting sharks in the Gulf of Gabes, Tunisia, have increased the number of hooks per basket and have included new bait types instead of mackerel (Scomber scombrus). This paper reports the effects of these changes on catch composition, catch rates, size distribution, life‐stage captures, and mortality at haulback.
- Data from 48 and 96 longline sets, carried out during the shark fishing seasons of 2007 and 2008, with two hooks per basket, and 2016 and 2017, with five hooks per basket, respectively, were examined to assess the effect of gear change. Moreover, the effects of bait types were inspected based on 33 fishing sets using whole mackerel, 19 using salema (Sarpa salpa) halves, and 27 using pieces of stingray (Dasyatis spp.), sampled during 2016 and 2017.
- The species composition indicated that longliners expand the vertical distribution of their hooks to operate from the surface to the bottom. The catches with both longline designs were dominated by sandbar shark (Carcharhinus plumbeus). Despite gear changes, the catch rate of C. plumbeus decreased by 42.21%, suggesting population decline. The size composition indicated a shift towards larger specimens, mainly adult females, which could jeopardize the shark population. Moreover, the mortality of the main species at haulback seems to be affected by the design of the longline.
- The bait used, mainly pieces of stingray, significantly increased the catch rate of sandbar shark, which suggests a greater attractiveness of the new bait; however, fish size and mortality rates at haulback were unchanged in response to bait variation.
- The fishery operates in shark nursery grounds, which exposes these fish (principally C. plumbeus) to considerable exploitation pressure. The new fishing practices intensified the pressure and thus the risk of a rapid depletion of populations. To preserve the shark species in the area, the use of new gear and attractive bait should be banned.
17.
Intensive fishing has not forced dietary change in the South American fur seal Arctophoca (=Arctocephalus) australis off Río de la Plata and adjoining areas 
下载免费PDF全文
下载免费PDF全文 Damián G. Vales Fabiana Saporiti Luis Cardona Larissa R. De Oliveira Roberta A. Dos Santos Eduardo R. Secchi Alex Aguilar Enrique A. Crespo 《水产资源保护:海洋与淡水生态系统》2014,24(6):745-759
18.
Hector M. Guzman Roberto Cipriani Angel J. Vega Jorge Manuel Morales‐Saldaa 《水产资源保护:海洋与淡水生态系统》2020,30(2):315-330
- In Panama, shark fisheries were initially developed in the 1980s and progressively increased in production in the 1990s mainly due to the high demand for shark fins and meat from the international Asian market. Since then, and despite the exploitation rate (average 3,514 t year–1) and endangered status of some species, shark fisheries have seldom been studied, and official statistics are general or incomplete and not suitable for the development of appropriate conservation and management strategies.
- To understand the dynamics of shark fisheries in Panama, field surveys were conducted between 2007 and 2009 at several landing ports of small‐scale and industrial fisheries, at fish processing plants and on‐board fishing vessels in Pacific Panama, where most of the fishing vessels of the country operate.
- In general, it was found that the artisanal and industrial fisheries of the Pacific coast of Panama regularly exploit at least 18 species of sharks, which are also being exploited by neighbouring countries in the eastern Pacific, suggesting the importance of coordinated conservation initiatives across the multiple jurisdictions. A large number of the individuals caught were immature, implying a certain level of impact on recruitment rates. This pattern was particularly evident in species such as Sphyrna lewini, for which immature individuals represented at least 99% and 63% of the total catch by small‐scale and industrial fisheries, respectively. Catch per unit of effort analyses showed that Carcharhinus and Sphyrna species were the most exploited (representing ~80% of the catches) by industrial fisheries in Panama between 2006 and 2009, suggesting that fishery management should provide special attention to these groups.
- It is expected that the information presented here provides a baseline to develop new regulations, including the implementation of annual quotas and fishing seasons and the protection of nursery areas, for the long‐term sustainability and conservation of sharks in Panama.
19.