Historical and contemporary habitat use of sperm whales around the Galápagos Archipelago: Implications for conservation

1. Sperm whales have occupied the waters off the Galápagos Islands, Ecuador, for at least the past 200 years. During the 19^th century, they were the target of intensive whaling that severely depleted the population. In recent times, after commercial whaling ended, sperm whales in the region remain vulnerable to multiple threats, especially potential entanglement in fishing gear, which may hinder their ability to recover from the whaling era.
2. As a highly mobile, long-lived species, long-term analysis of the habitat use of sperm whales is necessary to establish effective conservation and management strategies. Here, contemporary (1985–2014) and historical (1830–1850) sperm whale habitat use off the Galápagos Islands was analysed and contrasted to the extent of the Galápagos Marine Reserve (GMR). Contemporary habitat use and its variability over time were modelled as a function of geographic, oceanographic, and topographic variables using generalized additive models.
3. The fine-scale habitat (<50 km) used by sperm whales was associated with topographic (i.e. depth and slope) and oceanographic characteristics (i.e. relative sea surface temperature and standard deviation of sea surface temperature), but these preferences varied over time.
4. While historical and contemporary data indicate that sperm whale habitat primarily occurred within the boundaries of the GMR, in recent years, whales were found up to 30.1% of the time outside the GMR, potentially overlapping with commercial fisheries operating in the area.
5. The dynamic nature of the relationship of this nomadic species with its habitat highlights the need of large-scale conservation efforts across the Eastern Tropical Pacific region, including the wide-scale enforcement of regulations requiring the use of Automatic Identification System in fishing vessels, the promotion of on-board fisheries observer programmes, the development of adaptive management strategies, and international collaboration to identify and mitigate threats.

     

Fishing impacts and the degradation or loss of habitat structure

The wider effects of fishing on marine ecosystems have become the focus of growing concern among scientists, fisheries managers and the fishing industry. The present review examines the role of habitat structure and habitat heterogeneity in marine ecosystems, and the effects of fishing (i.e. trawling and dredging) on these two components of habitat complexity. Three examples from New Zealand and Australia are considered, where available evidence suggests that fishing has been associated with the degradation or loss of habitat structure through the removal of large epibenthic organisms, with concomitant effects on fish species which occupy these habitats. With ever-increasing demands on fish-stocks and the need for sustainable use of fisheries resources, new approaches to fisheries management are needed. Fisheries management needs to address the sustainability of fish-stocks while minimizing the direct and indirect impacts of fishing on other components of the ecosystem. Two long-term management tools for mitigating degradation or loss of habitat structure while maintaining healthy sustainable fisheries which are increasingly considered by fisheries scientists and managers are: (1) protective habitat management, which involves the designation of protected marine and coastal areas which are afforded some level of protection from fishing; and (2) habitat restoration, whereby important habitat and ecological functions are restored following the loss of habitat and/or resources. Nevertheless, the protection of marine and coastal areas, and habitat restoration should not be seen as solutions replacing conventional management approaches, but need to be components of an integrated programme of coastal zone and fisheries management. A number of recent international fisheries agreements have specifically identified the need to provide for habitat protection and restoration to ensure long-term sustainability of fisheries. The protection and restoration of habitat are also common components of fisheries management programs under national fisheries law and policy.     

Crayfish in central and southern Ukraine with special focus on populations of indigenous crayfish Astacus pachypus (Rathke, 1837) and their conservation needs

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Exploring uncertainty in population viability analysis and its implications for the conservation of a freshwater fish

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Genetic connectivity and phylogeography of the night shark (Carcharhinus signatus) in the western Atlantic Ocean: Implications for conservation management

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Understanding fishing and conservation of the Pacific seahorse (Hippocampus ingens) in Sinaloa,Mexico, through local ecological knowledge

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Changes in the distributions of freshwater mussels (Unionoida: Hyriidae) in coastal south‐eastern Australia and implications for their conservation status

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A simple approach for assigning the conservation status of freshwater fish based on their natural variability – a case study from the Iberian Ecoregion

A simple, non‐lethal method for assigning conservation status is proposed based on three conservation classes (favourable, unfavourable/inadequate and unfavourable/bad) to fish species based on their natural population variability. To demonstrate this approach, conservation classes were allocated to three native fish species (brown trout Salmo trutta L., northern Iberian chub Squalius carolitertii (Doadrio), and northern straight‐mouth nase, Pseudochondrostoma duriense (Coelho) based on basic population variables (density and biomass) using a 9‐year dataset (2004–2012) from 15 different sampling sites in Spain. The classification of the population variables into conservation classes was made using previously described nonparametric methods and percentiles categorisation, and the current conservation status of the studied species was established. Temporal trend analyses showed that S. carolitertii experienced a progressive significant decrease during the study period, whereas both S. trutta and P. duriense exhibited weak increases in density. The study exemplifies the need to quantify the natural variability of fish resources to reveal their current conservation status and to determine whether short‐term and long‐term management actions are needed to rehabilitate native fish assemblages. The proposed approach could easily be employed by fisheries managers to monitor the conservational status of other native species.     

Fish conservation in freshwater and marine realms: status,threats and management

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A review of the Leon springs pupfish (Cyprinodon bovinus) long‐term conservation strategy and response to habitat restoration

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Basking site and water depth selection by gharial Gavialis gangeticus Gmelin 1789 (Crocodylia,Reptilia) in National Chambal Sanctuary,India and its implication for river conservation

• 1. The species diversity of inland waters is among the most threatened of all ecosystems and in many parts of the world it is in continuing and accelerating decline. Such decline could be restrained by acknowledging the scope of target species, so that all relevant stages in their life cycle are considered.
• 2. The gharial Gavialis gangeticus is a prominent riverine species of the Indus, Ganges, Brahmaputra and Mahanadi river systems that is becoming increasingly rare due to reduction in water flow and available nesting beaches, modification of river morphology and increased mortality in fishing nets. Despite these threats, scientific information on habitat selection by gharial is still inadequate, which hinders conservation measures.
• 3. This paper presents the population status, basking site selection and water depth preferences of different size‐classes of gharial based on a study conducted in the National Chambal Sanctuary, India.
• 4. Between 1992 and 2007 a 40% decline in the gharial population was observed in the National Chambal Sanctuary. The decline was prominent in the recruitment class (<120 cm), which primarily comes from the nests laid in the wild, and also in sub‐adults (>180 to 270 cm) comprising both wild and reintroduced gharial.
• 5. Along the Chambal River, gharial preferred sandy parts of the river banks and sand bars for basking and showed less preference for rocky river banks and rocky outcrops. Clay river banks were least preferred.
• 6. Juvenile gharials <120 cm and 120–180 cm preferred water depths 1–3 m and 2–3 m, respectively. Gharial >180 cm (including sub‐adults and adults) preferred water depths >4 m.
• 7. Increasing demands for sand for development activities, and water abstraction for irrigation and energy generation coupled with mortality in fishing nets, are likely to affect gharial and other aquatic species, and steps need to be taken to maintain the minimum river flow necessary to sustain ecosystem processes.

Copyright © 2009 John Wiley & Sons, Ltd.     

Age and growth rates of the critically endangered fish Garra ghorensis can inform their conservation management

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Assessment of genetic structure,habitat suitability and effectiveness of reserves for future conservation planning of the Euphrates soft‐shelled turtle Rafetus euphraticus (Daudin, 1802)

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Promoting connectivity between priority freshwater sites for conservation in intermittent hydrological systems

1. Systematic conservation planning in freshwater ecosystems faces multiple challenges because of the dynamic nature of rivers and their multiple dimensions of connectivity. In intermittent hydrological systems connectivity is functional when water is available, allowing the exchange of aquatic individuals between isolated freshwater ecosystems. Integrating these isolated systems in their hydrological context is essential when identifying priority areas for conservation, in order to try to minimize the propagation of threats into target water bodies (management units) from the surrounding landscape.
2. Here, the use of a systematic planning approach is demonstrated to identify a set of priority management units to preserve freshwater biodiversity in an arid system of fragmented water bodies immersed in a landscape subject to a range of impacts.
3. Twenty-six water-dependent taxa from 59 mountain rock pools (gueltas) of three southern Mauritanian mountains were used as a case study. A conservation planning tool (marxan ) was used to find priority conservation areas to integrate intermittent hydrological systems in their hydrological context, promote connectivity, and minimize the downstream propagation of threats. Three types of connectivity were analysed: (i) no connectivity, (ii) connectivity between gueltas, and (iii) connectivity between gueltas and sub-catchments.
4. Considering different types of longitudinal connectivity affects the number and spatial allocation of the priority gueltas selected, and the conservation status of the gueltas and their upstream areas. Incorporating connections between gueltas and upstream locations in the modelling resulted in the selection of gueltas in areas with a low human footprint and in the increased connectivity of the solutions.
5. The results obtained revealed important locations for local biodiversity conservation, and the method presented can be used when assessing the propagation of potential waterborne threats into isolated management units. The framework developed allows connectivity to be addressed in conservation planning. It can be replicated in regions with similar isolated habitats that connect through intermittent hydrological systems and can also be applied to lateral and vertical hydrological connectivity.

     

Taxonomic confusion and market mislabelling of threatened skates: important consequences for their conservation status

• 1. The iconic European common skate (Dipturus batis) has been described as the first clear case of a fish species brought to the brink of extinction by commercial fishing. Its listing was upgraded to Critically Endangered on the 2006 IUCN Red List of Threatened Species. According to FAO fishery statistics, France is responsible for 60.2% of the 502 tonnes reported as ‘D. batis’ in the 2005 world landings.
• 2. Noticeable phenotypic differences within the species and inconsistencies in published data on its sexual maturation required careful re‐examination of its taxonomy. Morphology, genetics, and life history reveal that two distinct species have been erroneously confused since the 1920s under the single scientific name D. batis. Here it is argued that they should be resurrected as two valid species. The common skate D. batis species‐complex is split into two nominal species, the blue skate (provisionally called D. cf. flossada) and the flapper skate (D. cf. intermedia) with maximum lengths of 143.2 cm and 228.8 cm respectively.
• 3. This taxonomic confusion puts into question all previously accumulated data based on D. batis. Its endangered status highlights the need for an extensive reassessment of population collapses with accurately identified species. In 2006/2007 an extensive survey (4110 skates, 14.081 tonnes by weight) was conducted in the main French ports of the D. batis species‐complex and relatives (D. oxyrinchus, D. nidarosiensis and Rostroraja alba) that are mixed together in landings under the names ‘D. batis’ and ‘D. oxyrinchus’.
• 4. The survey reveals that official fishery statistics mask species‐specific declines, due to the mislabelling of five species under only two landing names. Trends in landings since the 1960s and the life history of these species suggest a dramatic decline and collapse of the spawning stock, preventing the recovery of relict populations.
• 5. The risk of extinction of these depleted species may be higher than previously assessed and might be unavoidable without immediate and incisive conservation action. Copyright © 2009 John Wiley & Sons, Ltd.

     

The native South American crayfishes (Crustacea,Parastacidae): state of knowledge and conservation status

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The conservation of the endangered Mediterranean common dolphin (Delphinus delphis): Current knowledge and research priorities

1. Preservation of endangered species is now recognized as a relevant component of regional and global conservation actions achieved through the maintenance of the remaining populations in a favourable conservation status. The Mediterranean common dolphin (Delphinus delphis) is listed as an Endangered subpopulation in the International Union for Conservation of Nature Red List, with declining numbers in some of the areas where it has been studied for numerous years. Prey depletion, fisheries bycatch, pollution, health risks, and climate change are among the recognized threats that the species is facing in the region.
2. The existing national, regional, and international legislation pertinent to Mediterranean countries should aid greater science–policy–management integration and support innovative research and monitoring towards effective conservation. The challenges inherent in studying the pelagic D. delphis should not preclude the use of long-term, year-round, multiplatform surveys, side by side with the latest molecular tools, which aid our understanding of its populations' genetic diversity, resistance to diseases, and resilience in a semi-enclosed fast-changing sea.
3. Addressing the multiplicity of problems confronting the species requires collaborative effort at all levels to share and merge resources, data, and expertise more efficiently. In this review, we provide an overview of the current knowledge on the Mediterranean common dolphin, the main threats, and knowledge gaps that are priorities for addressing its conservation, while providing clear recommendations for effectively safeguarding the species and its habitat at both local and regional levels.

     

Habitat suitability analysis for lacustrine brown trout (Salmo trutta) in Lake Walchensee,Germany: implications for the conservation of an endangered flagship species

• 1. The lacustrine brown trout (Salmo trutta) is endangered and of high conservation importance. In the only spawning habitat of the population in the Bavarian Lake Walchensee, the River Obernach, a substantial decrease in spawning runs has been reported. In this study, the present ecological state of the spawning stream was analysed with the objective of identifying life‐stage specific limitations to successful recruitment attributable to deficiencies in (i) spawning migration, (ii) spawning habitat quality, and (iii) habitat quality for juveniles.
• 2. Structural stream analysis showed that discharge and several migration barriers — particularly near the river outlet into the lake — prevent successful spawning migrations at normal water levels. Migration barriers are probably the main limiting factor for reproduction of lacustrine brown trout, whereas structural variability of the Obernach meets the habitat requirements of both spawners and juveniles.
• 3. Spawning site quality was suitable for trout, as indicated by stream substratum texture and high exchange rates between free‐flowing water and the interstitial zone in physico‐chemical parameters (redox potential, dissolved oxygen, pH, temperature and conductivity).
• 4. Analyses of fish community structure revealed dominance of lithophilic species, in particular of riverine brown trout (Salmo trutta). Its density and intact demographic population structure suggest that spawning and juvenile habitat quality for salmonids is not limiting. Recapture of stocked lacustrine trout juveniles also indicates habitat suitability for the juvenile stage.
• 5. In conclusion, the results show that the methodology used in this study is suitable for the identification of life‐stage specific habitat deficiencies in lacustrine brown trout and other fish species. Availability of habitat data throughout the species' distribution range is a first crucial step for the development of an effective recovery plan. Copyright © 2009 John Wiley & Sons, Ltd.

     

鱼类关键生境研究进展

鱼类关键生境(EFH)是指鱼类产卵、繁殖、摄食或育成所必须依赖的水域或底质环境。该文对EFH的产生和由来、研究和应用、评估内容和识别方法等现状进行了全面回顾和总结,重点在介绍相关概念和进展,并针对我国海洋渔业科研和管理中过于强调区域重要性和种类经济价值、而忽略具体生境保护的现实,提出了相应的建议,以期为我国渔业的科学管理和及其可持续发展提供参考。