Landing,consumption, and DNA barcoding of commercial seabream (Perciformes: Sparidae) in Kuwait

1. To our knowledge, this is the first inclusive assessment of the status of Sparidae fisheries in the territorial waters of Kuwait, integrating information on catch trends, consumer preferences, recreational fishing behaviour, and molecular based identification of fish species by DNA barcoding
2. Fisheries landing data were obtained from the official fisheries bulletin released by the Kuwait Central Statistical Bureau. Surveys were conducted to assess consumer preferences on seabream species, landed seabream species, and the behaviour of recreational anglers towards seabream species. DNA barcodes were generated to authenticate commercial seabream using the mitochondrial cytochrome c oxidase subunit I (COXI) gene and then compared with GenBank sequence entries; these sequences were then used to construct a neighbour-joining (NJ) phylogenetic tree.
3. Yellowfin seabream Acanthopagrus latus was the prime and most favoured commercial seabream species (45%), followed by Sparidentex hasta, which was the top-rated secondary, unassessed seabream species. Approximately 54% of households conduct recreational fishing more than twice a month, and most (77%) primarily target S. hasta and Ac. latus. Consumer demand for secondary seabreams, which were not assessed and are listed in the bulletin under the category ‘others’, was evident.
4. The NJ phylogenetic tree revealed that Arabian Gulf seabreams, including those of Kuwait, are genetically different from their counterparts inhabiting neighbouring waters.
5. The data presented here highlight the urgency to modify the existing fisheries list using accurate identification tools, such as DNA barcoding, for the sustainable and conservation-oriented management of local fisheries, which are in decline.

     

Forest conversion adversely affects native Macrobrachium shrimp assemblages in tropical Malaysian streams

1. Commodity-driven forest conversion represents one of the most severe threats to freshwater biodiversity in Southeast Asia, notably causing population declines and the extinction of freshwater fish species.
2. Although a variety of freshwater taxa are likely to be adversely affected by forest conversion, little is known about the impact on ecologically and economically important invertebrates such as decapod crustaceans.
3. This study evaluated the impact of forest conversion and land-use change on freshwater Macrobrachium shrimp species, using species richness, abundance, and environmental data collected from 20 streams across southern Peninsular Malaysia. Streams were located in three types of landscape: forest; oil palm plantation; and mixed land use, comprising young secondary forest, small-scale plantations, patches of open and sparsely vegetated areas, and agricultural fields and clearings.
4. Generalized linear models showed that even incomplete change from forest habitats to mixed land use and oil palm plantation resulted in significantly lower Macrobrachium native species richness and higher non-native species abundance. Native species richness was positively correlated with canopy cover, leaf litter, substrate size, and dissolved oxygen, and was negatively correlated with water temperature and conductivity. Native species richness was also negatively correlated with non-native species abundance, with non-native species abundance increasing along the human disturbance gradient.
5. These results highlight the need for riparian habitat protection to conserve native Macrobrachium and limit the spread of non-native species. A management priority should be to maintain or restore optimum instream habitat conditions for shrimps, which would also benefit fish and other benthic macroinvertebrates. Suitable riparian management requires substantial support and funding from multiple stakeholders, but it can be aligned with other catchment-based strategies to optimize the use of limited resources available for freshwater biodiversity conservation.

     

Resilient recreational fisheries or prone to collapse? A decade of research on the science and management of recreational fisheries

Are recreational fisheries resilient to harvest or prone to collapse? This paper reviews research published since that question was posed by Post et al. (2002, Fisheries 27 , 6–17). A number of patterns and processes have been identified that suggest understanding the risk of collapse requires knowledge of the fishing effort response, degree of depensation in the fishery and the life history of the harvested species. Processes involving the behaviour of fish, behaviour of anglers and management responses to declining quality can all impact the degree of resilience of recreational fisheries and their risk of collapse. The spatial context of an individual fishery can be important as they are often embedded in lake districts and joined by mobile anglers so their local dynamics are not independent from other fisheries. Typical regulations that restrict the behaviour of individual anglers in open‐access fisheries can provide some resilience but cannot prevent collapse if the fishing effort is too high. Many uncertainties remain related to the occurrence and intensity of the key processes and therefore adopting an adaptive experimental management approach might be the most useful approach to minimise the risk of collapse in recreational fisheries.     

Aquatic macroinvertebrates from littoral vegetated lakes in arid Patagonia: The influence of fish introduction on community structure

1. Wetlands in arid regions are characterized by their great heterogeneity, often including endemic species that contribute to regional aquatic biodiversity. In the Patagonian steppe, most lakes are naturally fishless and sustain a rich aquatic biodiversity, including endemics; however, many of these lakes have been stocked with Oncorhynchus mykiss (rainbow trout) during recent decades. The introduction of predatory fish into aquatic ecosystems naturally devoid of these organisms can produce profound alterations in the structure of the original communities and in the configuration of their biotic assemblages.
2. Aquatic invertebrates play important roles in both the structure and functioning of freshwater ecosystems, including their contribution to global biodiversity and their cascading effects across ecosystem boundaries.
3. The aim of this study was to assess the effect of introduced non-native fish on the pleustonic macroinvertebrate assemblage. Samples were taken from 10 shallow Patagonian lakes (five fishless and five stocked with fish) in two consecutive warm periods.
4. Lakes with fish had higher conductivity and phosphate values. Higher inter-annual differences were also observed in lakes with fish for phytoplanktonic chlorophyll a, nitrate, phosphate, conductivity, and water temperature.
5. The community structure (relative abundance of different taxa, species composition, and diversity index) was affected by the presence of rainbow trout, with the differences mainly driven by the relative abundance of Ostracoda, Hyalella, Chironomidae, and Haliplus species.
6. This approach can be used to assess the required conservation actions in shallow Patagonian steppe lakes, which have been listed as priority areas for waterbird conservation. Specifically, this study provides a baseline for monitoring future trends of the macroinvertebrate communities and for evaluating conservation and management efforts over time.

     

Exploring environmental predictors of aquatic macrophytes in water‐dependent Natura 2000 sites of high conservation value: Results from a long‐term study of macrophytes in Greek lakes

1. Aquatic macrophytes play a key role in lake dynamics, but human activities and eutrophication have resulted in macrophyte loss in many lakes throughout Europe. In this study, the relationships between aquatic macrophytes and gradients of environmental factors were explored using an extensive set of data collected from 13 lakes of the Greek mainland that are part of the European network Natura 2000.
2. The main objectives were to assess the importance of key abiotic predictors and estimate possible environmental thresholds of macrophyte richness, diversity, and abundance using boosted regression trees (BRTs), as well as to explore further the distribution of dominant macrophyte taxa along environmental gradients.
3. The results reveal conductivity as a significant predictor of macrophyte total cover and diversity. In addition, orthophosphate and nitrate nitrogen appear to play an important role for several macrophyte species and assemblages, reflecting a major effect of eutrophication on the distribution of taxa. The majority of macrophyte assemblages were found in waters characterized by high nutrient content, although their distribution extends along a wide range of phosphorus and nitrogen concentration. In contrast, charophyte species show the optimum of their distribution in clear, oligotrophic waters.
4. This integrated study can be used for ranking environmental factors that influence macrophyte distribution in the lakes of Greece and for identifying taxa or macrophyte assemblages that can be used as effective indicators of changes in the abiotic environment. In addition, the results can contribute to the conservation of freshwater habitats in the protected areas studied. In particular, measures that aim to improve water quality are expected also to restore oligotrophic habitats that are characterized by benthic charophyte vegetation. Overall, the links between macrophyte assemblages and abiotic factors are critically important in improving freshwater biodiversity management and environmental policies in east Mediterranean lakes.

     

Hobbyists acting simultaneously as anglers and aquarists: Novel pathways for non-native fish and impacts on native fish

1. Human translocations of non-native aquatic species are a global conservation challenge. Aquarists and anglers are two hobbyist groups whose practices are particularly likely to translocate non-native aquatic species, especially fish.
2. This article aims to stipulate a change of perspective among these hobbyists, who – by acting simultaneously as anglers and aquarists – establish novel pathways for non-native fish.
3. This study showed that: (i) 51 of 226 respondents to a questionnaire act simultaneously as anglers and aquarists; (ii) 53 of 237 non-native fish species in the European Union are used for both angling and aquarium hobbies; and (iii) hobbyists write online reports on the catch and exchange of a particularly invasive fish, the round goby (Neogobius melanostomus).
4. This combination of knowledge on how hobbyists use non-native fish and the ecological impacts of round goby demonstrates how the impact of an invasive species can be influenced by the combined behaviours of anglers and aquarists.
5. We suggest that future research in aquatic conservation should move beyond considering the commercial aquarium trade and angling as separate pathways for translocating non-native fish, and instead consider these hobbyist groups as interconnected.

     

Explaining recreational angling catch rates of Eurasian perch,Perca fluviatilis: the role of natural and fishing‐related environmental factors

Angling catch records are frequently used to reveal fish population developments. It is therefore important to understand the determinants of angling catches. This study focused on angler‐related, biotic and abiotic factors influencing catchability of Eurasian perch, Perca fluviatilis L. A multi‐lake (21 lakes) study based on angling diaries collected in Mecklenburg‐Vorpommern, Germany (2006/2007), found that angler‐related factors such as fishing experience, species preference and bait/lure type had a large impact on perch catch rates. Additionally, environmental conditions (nutritional status and water transparency) affected either the size or the number of perch caught by anglers. Catch rates varied seasonally, which was confirmed by an experimental fishery on a gravel pit (2008). This portion of the study showed that altered food availabilities in the course of the year caused food limitation in perch, which in turn facilitated high catch rates and female‐biased exploitation in autumn. It is concluded that both angler‐related and abiotic factors interact affecting perch catch rates and size of perch captured in recreational angling.     

Evidence of fish spillover from freshwater protected areas in lakes of eastern Ontario

1. Research has identified numerous conservation benefits attributed to the use of marine protected areas (MPAs), yet comparatively less is known about the effectiveness of freshwater protected areas (FPAs).
2. This study assessed multiple long‐standing (>70 years active) intra‐lake FPAs in three lakes in eastern Ontario, Canada, to evaluate their potential conservation benefits. These FPAs were intended initially to protect exploited populations of largemouth bass (Micropterus salmoides (Lacépède, 1802)), but since their establishment no empirical data have been collected to evaluate the effectiveness of FPAs for protecting bass or the broader fish community.
3. A comparative biological census of fish species abundance, biomass and species richness was conducted using snorkelling surveys within FPAs, along the bordering transition zones, and in more distant non‐protected areas of the lake that had similar habitats to the FPAs.
4. In general, the FPAs yielded benefits that were most obvious (in terms of abundance and biomass) for the focal protected species (i.e. largemouth bass) as well as several shiner species. Largemouth bass and shiner abundance and biomass were highest in the FPA, lowest in the distant non‐protected areas, and intermediate in the transition zone. Species richness was also highest in the FPAs in two of the three lakes.
5. Collectively, these results support the use of FPAs as a viable and effective conservation strategy that extends beyond simply limiting the exploitation of a target species. Beyond the benefits afforded to fish within the FPA, evidence of spillover in adjacent areas was also observed, which is promising. Additional research is needed on the effectiveness of FPAs in a variety of regions and water‐body types facing various threats in an effort to understand when, where and how to best use FPAs to benefit aquatic biodiversity.

     

On the brink – investigating biodiversity in endangered crater lakes of the Amber Mountains National Park (Madagascar)

相似文献   

Environmental determinants of perch (Perca fluviatilis) growth in gravel pit lakes and the relative performance of simple versus complex ecological predictors

Growth of fish is an important contributor to individual fitness as well as fish production. Explaining and predicting growth variation across populations is thus important from fundamental and applied perspectives, which requires knowledge about the ecological factors involved in shaping growth. To that end, we estimated environment-dependent von Bertalanffy growth models for 13 gravel pit lake populations of Eurasian perch (Perca fluviatilis) from north-western Germany. To identify the main drivers of perch growth, we evaluated the performance of 16 different biotic or abiotic lake variables in explaining growth variation among lakes. In addition, we compared growth predictions from the best-performing model incorporating “complex” variables that require intensive sampling effort, with a model using only “simple”, easily measurable lake variables (e.g. shoreline development factor). The derivation of a simple model aimed at future applications in typically data-poor inland fisheries, predicting expected growth potential from easily measurable lake variables. A model combining metabolic biomass of predators, maximum depth and shoreline development factor performed best in predicting perch growth variation across gravel pits. All three parameters in this model were positively related to perch growth. The best-performing simple model consisted only of the shoreline development factor. Length-at-age predictions from both models were largely identical, highlighting the utility of shoreline development factor in approximating growth potential of perch in gravel pits similar to our study lakes. Our results can be used to inform fisheries management and restoration efforts at existing or newly excavated gravel pit lakes.     

Indicator taxa for the conservation of pond invertebrate diversity

• 1. Ponds are a valuable resource for the conservation of freshwater biodiversity, but are often extremely numerous in a given area, making assessment of the conservation value of individual sites potentially time consuming.
• 2. The use of indicator taxa, the species richness of which is representative of total site species richness, may provide one way to improve the efficiency of survey work. However, such indicators are poorly developed for freshwater systems.
• 3. A data set was used describing the occurrence of macroinvertebrate taxa in ponds in Oxfordshire, UK, to assess the extent to which variation in the species richness of selected taxa most consistently represented variation in all other taxa.
• 4. Coenagriidae (Odonata) and Limnephilidae (Trichoptera) reflected the variation in species richness of other taxa most consistently, with Coenagriidae showing the best overall performance as an indicator taxon.
• 5. For both suggested indicator taxa, selection of sites based solely on the presence of at least one species of indicator would represent over 95% of all species recorded across all sites.
• 6. Further investigation in different geographical regions is necessary to establish whether these relationships are consistent over a wider area.

Copyright © 2003 John Wiley & Sons, Ltd.     

Macrophytes promote aquatic insect conservation in artificial ponds

1. Farmland ponds promote regional aquatic biodiversity; however, optimally managing these ponds requires knowledge on how the biodiversity differs between ponds across catchments with different land uses.
2. This study investigated the response of macrophytes, both those in the pond and on the bank, as well as dragonfly and water beetle species richness, diversity and composition in artificial ponds, to numerous environmental variables in catchments dominated by three land uses: protected areas (as reference sites), sugarcane‐dominated and forestry‐dominated landscapes, across two seasons.
3. There was a strong association between insect species richness and vegetation cover, particularly sedges (Cyperus spp.) in spring and bulrushes (Typha capensis) in summer. There was also a positive response between insect species richness and sedges up to 70% cover, and bulrushes up to 40% cover, after which there was a decrease. Furthermore, the protected area ponds contained more rare and specialist insect species. Pond size was not a major variable for biodiversity overall.
4. Although there was generally little congruence in composition among the three taxa, dragonflies were a good surrogate for water beetles and floating macrophytes.
5. Well‐vegetated ponds, both in the water and along the margin, are the most suited to promoting biodiversity, as long as the vegetation is not too dense, and not dominated by one plant species.
6. Artificial ponds in production landscapes have great potential for conserving aquatic species, irrespective of land use, as long as there is management for macrophyte density and heterogeneity.

     

Surveys of recreational anglers reveal knowledge gaps and positive attitudes towards manta ray conservation in Florida

1. South Florida has a significant number of recreational anglers, and some shore-based fishing sites overlap with habitat for juvenile manta rays. Although manta rays are prohibited from harvest in Florida, they are frequently seen foul-hooked or entangled in fishing line.
2. Recreational anglers (n = 198) were surveyed at piers and inlet jetties in Palm Beach County, Florida, USA to assess their knowledge of and actions and attitudes towards manta rays.
3. Analysis of the responses revealed that while most anglers could identify a manta ray (66.7%) and expressed no interest in casting at (93.4%) or catching a manta ray (95.5%), they lacked knowledge about threats to mantas, as well as their conservation and protected status. Surveyed anglers overwhelmingly supported manta ray conservation (82.3%) and environmental protection (98.0%).
4. Results indicate pier and inlet anglers are not using tackle strong enough to land a large ray to remove fishing gear, therefore it is recommended that outreach focuses on preventing recreational fishery interactions with manta rays, encouraging use of environmentally friendly tackle, and fostering engagement with anglers as citizen scientists.
5. These results can inform the design of outreach materials aimed at closing knowledge gaps and encouraging best practices. Positive attitudes towards the environment and existing neutral behaviours towards manta rays indicate an opportunity to shift the behaviour of shore-based anglers in this area in support of manta ray conservation.

     

Catching sharks: recreational saltwater angler behaviours and attitudes regarding shark encounters and conservation

相似文献   

Relationships between breeding waterbird abundance,diversity, and clear water status after the restoration of two shallow nutrient‐rich Danish lakes

1. Breeding waterbird communities have suffered globally from the effects of anthropogenic changes in water quality (especially nutrient enrichment) in recent decades, but few studies have demonstrated the positive effects of restorative actions.
2. Annual breeding waterbird surveys in the period 1977–2005 at two restored southern Danish lake basins (combining nutrient load reduction and biomanipulation) showed an up to five‐fold increase in abundance, and considerable changes in species richness and diversity, following restoration to clear water status in both lakes.
3. Parallel surveys at a third lake, which retained clear water quality throughout, offering a form of natural ‘control', showed no such changes over the same time period.
4. Consistent relationships between breeding waterbird abundance, species richness, and diversity with measures of water clarity (Secchi disc depth, chlorophyll a, and suspended matter) suggest that water clarity mainly drives the relationship; inverse relationships between these measures and total nitrogen and phosphorus were less consistent than for water clarity.
5. The results suggest that an improvement in water clarity plays a key role in restoring breeding waterbird communities and suggest that breeding waterbirds can be indicators of the success of lake restoration projects, but more studies are needed to confirm their wider utility under a variety of conditions.

     

Assessment of a terrestrial protected area for the conservation of freshwater biodiversity

1. Freshwater ecosystems are essential to human well-being and most have high biodiversity. However, this biodiversity has been suffering severe declines owing to the expansion of human activities. Protected areas (PAs) are essential for biodiversity conservation and have proved to be successful in stopping species extirpation if managed properly. Unfortunately, they are usually focused on terrestrial biodiversity, leaving freshwater ecosystems aside.
2. The main goal of this study was to determine the influence of a PA (Montesinho Natural Park (MNP), Portugal) on freshwater biodiversity. Aquatic macroinvertebrates and fishes were surveyed, and biodiversity (richness, abundance, Shannon-Wiener diversity, and Pielou's evenness) and water quality (IASPT) indices were calculated inside, at the periphery and outside the MNP.
3. Results showed that the PA does not affect positively either water quality or the two faunal groups monitored. Macroinvertebrate communities were not influenced by the PA; however, the abundance of pearl mussel Margaritifera margaritifera was significantly higher and size was significantly lower inside the MNP. The richness and abundance of fish communities were significantly higher outside the MNP, except for trout Salmo trutta abundance which was higher inside the MNP.
4. Given these results, the MNP does not guarantee the safeguard of overall aquatic biodiversity and habitats and we propose an extension of MNP to downstream areas in order to increase the number of species (mostly cyprinids) under legal protection. This work demonstrates that terrestrial PA planning and management should also consider aquatic biodiversity to achieve successful conservation.

     

Spatial patterns of recreational exploitation in eastern Australian ROFAs: implications for zonal management

Effective management of recreational fisheries requires information on fine‐scale spatial patterns of recreational exploitation. Such information is particularly important for specially designated regions such as recreational‐only fishing areas (ROFAs). Using data acquired through progressive counts and interview‐based surveys, this study quantitatively compared recreational effort, harvest‐per‐unit‐effort (HPUE) and species composition among zonal habitats in three representative estuarine ROFAs in eastern Australia. The zones compared were as follows: (1) entrance channels; (2) lake areas; (3) artificial reefs; (4) tributary creeks; (5) rivers; and (6) canals. In most cases, effort was concentrated in the lake zones, which had the greatest access to fisheries resources. The lake and channel zones were associated with some of the highest HPUEs for key taxa [Acanthopagrus spp. (hybrid complex of Acanthopagrus butcheri (Munro) × Acanthopagrus australis (Owen)), Platycephalus fuscus (Cuvier), Sillago ciliata (Cuvier) and Girella tricuspidata (Quoy & Gaimard)] and a greater number of highly sought‐after species. Drawing on specific examples from these findings, this paper concludes by illustrating how spatial information on exploitation gained from this type of research can be used to meet the fundamental goals of recreational fisheries management at fine spatial scales.     

The commercialization and use of exotic baits in recreational fisheries in the north‐western Mediterranean: Environmental and management implications

相似文献   

From a research study to a conservation partnership: Developing approaches to restoring common scoter populations

• 1. Like many sea‐duck populations, the British breeding population of common scoters Melanitta nigra has declined markedly. In 2009, a study was established to measure factors affecting lake use by breeding scoters, to inform conservation measures. That study, published in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) in 2016, showed that lakes used by scoters had relatively more shallow water and large invertebrates. Furthermore, lakes with abundant large invertebrates had relatively few brown trout Salmo trutta. These results probably reflect the importance of foraging habitat (shallow water), prey abundance (large invertebrates), and competition for prey (trout abundance) in influencing scoter lake use.
• 2. To develop this study, additional research, and scoter conservation measures, we formed a long‐term partnership, comprising nature conservation non‐governmental organizations, statutory agencies, fisheries managers and the regional hydropower company. The partnership meets regularly to coordinate and review research and develop conservation measures, building on the earlier lake‐use study.
• 3. At key scoter lakes managed for hydropower, the partnership negotiated a revised water level management regime, favouring shallow water availability in the breeding season. This regime was informed by additional research, showing the value of certain islands for nesting scoters, and water level requirements to maintain these as islands.
• 4. In a different key scoter area — an extensive near‐natural peatland where recreational angling takes place — the partnership established a trial of increased brown trout angling, with increased fish removal, to determine whether this would increase invertebrate prey abundance and benefit breeding scoters. Both conservation interventions are currently being evaluated by detailed monitoring.
• 5. Overall, the earlier study published in AQC, was important in strengthening and informing our researcher–practitioner partnership, as we collaborated within an adaptive management framework to reverse scoter declines. Long‐term interdisciplinary partnerships are likely to have an important role to play in general, for the successful conservation of aquatic biodiversity.

     

Environmental determinants of fish community structure in gravel pit lakes

Gravel pit lakes are increasingly common, and there is an urgent need to better understand the functioning of these artificial and disconnected ecosystems. However, our knowledge of the environmental determinants of fish community structure within these types of lakes remains poor. In this study, we quantified the taxonomic diversity, fish species and life‐stage composition in 17 gravel pit lakes sampled in 2012 and 2013 located in south‐west France to determine the potential role of environmental variables (i.e. lake morphology, productivity, water quality and human‐use intensity) as drivers of fish community structure and composition. Our results demonstrated that fish community structure significantly differed between gravel pit lakes, and we notably found that lakes managed for angling hosted higher levels of taxonomic diversity. We also found that young and large lakes supported higher native species biomass and were dominated by native European perch (Perca fluviatilis). Older, smaller and more productive lakes, located closer to the main urban area, supported a higher biomass of non‐native species such as largemouth bass (Micropterus salmoides). Native and non‐native sport fishing species such as northern pike (Esox lucius), pikeperch (Sander lucioperca), common carp (Cyprinus carpio) and cyprinid prey species were positively associated with fishery management effort, suggesting that management practices play also a critical role in shaping fish species composition. Overall, our study demonstrated that fish community composition followed a predictable shift along environmental gradients associated with the maturation of gravel pit lakes and the associated human practices.