scholarly journals Decline of the Manila clams stock in the northern Adriatic lagoons

2017 ◽  
Vol 58 (1) ◽  
pp. 89-104 ◽  
Author(s):  
Massimo Ponti ◽  
Marco Abbiati ◽  
Victor Ugo Ceccherelli ◽  
Elena Gamba ◽  
Alessandro Ragazzoni ◽  
...  
Keyword(s):  
Sustainable Management ◽  
Wild Population ◽  
Coastal Lagoons ◽  
Ruditapes Philippinarum ◽  
Wild Populations ◽  
Commercial Activity ◽  
Northern Adriatic ◽  
Larval Recruitment ◽  
Summer Heat ◽  
Good Accordance

The Manila clam, Ruditapes philippinarum, introduced in the Venice lagoons in 1983 and rapidly spread to the nearby coastal lagoons represents one of the most important commercially-exploited resources of this area. Abundance, size-class and biomass distribution of the wild population living in the Pialassa Baiona lagoon were assessed and related to the hydrological and sediment characteristics. Despite the lagoon being affected by eutrophication, chemical and thermal pollution, the clams were harvested by about thirty professional fishermen until 2003. The commercially available stock was estimated at 36.8 10 3 kg in July 2002, 29.3 10 3 kg in April 2003, and 10.3 10 3 kg in October 2003. Stock estimations and observed mortality were in good accordance with the fishermen data. The decline of the available stock could be due to both overfishing and the extraordinary summer heat wave occurred in 2003, which may have reduced larval recruitment and increased the mortality. Overall, the juvenile recruitment appeared insufficient to annually restore the natural stock. Although the national and regional high relevance of clams market, local harvesting of wild populations appeared marginal and inadequate to support a remunerative commercial activity, due to the variability and unpredictability of the annual yield and the lack of a sustainable management based on a production chain’s approach.

scholarly journals Genomic approach for conservation and the sustainable management of endangered species of the Amazon

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0240002
Author(s):  
Paola Fazzi-Gomes ◽  
Jonas Aguiar ◽  
Gleyce Fonseca Cabral ◽  
Diego Marques ◽  
Helber Palheta ◽  
...  
Keyword(s):  
Genetic Information ◽  
Sustainable Management ◽  
Taxonomic Status ◽  
Accurate Information ◽  
Wild Populations ◽  
Genetic Management ◽  
Current Management ◽  
Arapaima Gigas ◽  
Genomic Approach ◽  
Multiplex System

A broad panel of potentially amplifiable microsatellite loci and a multiplex system were developed for the Amazonian symbol fish species Arapaima gigas, which is currently in high danger of extinction due to the disorderly fishing exploitation. Several factors have contributed to the increase of this threat, among which we highlight the lack of genetic information about the structure and taxonomic status of the species, as well as the lack of accurate tools for evaluation of the effectivity of current management programs. Based on Arapaima gigas’ whole genome, available at the NCBI database (ID: 12404), a total of 95,098 unique perfect microsatellites were identified, including their proposed primers. From this panel, a multiplex system containing 12 tetranucleotide microsatellite markers was validated. These tools are valuable for research in as many areas as bioinformatics, ecology, genetics, evolution and comparative studies, since they are able to provide more accurate information for fishing management, conservation of wild populations and genetic management of aquaculture.

scholarly journals Stable producer–scrounger dynamics in wild birds: sociability and learning speed covary with scrounging behaviour

2017 ◽  
Vol 284 (1852) ◽  
pp. 20162872 ◽  
Author(s):  
L. M. Aplin ◽  
J. Morand-Ferron
Keyword(s):  
Multiple Scales ◽  
Wild Population ◽  
Bimodal Distribution ◽  
Wild Populations ◽  
Extensive Game ◽  
Learning Speed ◽  
The Social ◽  
Game Theoretic ◽  
Foraging Task ◽  
Broad Scale

There has been extensive game-theoretic modelling of conditions leading to equilibria of producer–scrounger dichotomies in groups. However there is a surprising paucity of experimental evidence in wild populations. Here, we examine producer–scrounger games in five subpopulations of birds feeding at a socially learnt foraging task. Over four weeks, a bimodal distribution of producers and scroungers emerged in all areas, with pronounced and consistent individual tactic specialization persisting over 3 years. Tactics were unrelated to exploratory personality, but correlated with latency to contact and learn the foraging task, with the late arrivers and slower learners more likely to adopt the scrounging role. Additionally, the social environment was also important: at the broad scale, larger subpopulations with a higher social density contained proportionally more scroungers, while within subpopulations scroungers tended to be central in the social network and be observed in larger foraging flocks. This study thus provides a rare example of a stable, dimorphic distribution of producer–scrounger tactics in a wild population. It further gives support across multiple scales for a major prediction of social foraging theory; that the frequency of scroungers increases with group size.

Agronomic value and morphophysiological diversity of non-Ladino Italian white clover wild populations compared with variety germplasm

2012 ◽  
Vol 63 (4) ◽  
pp. 377 ◽  
Author(s):  
P. Annicchiarico
Keyword(s):  
Seed Yield ◽  
White Clover ◽  
Competitive Ability ◽  
Wild Population ◽  
Total Yield ◽  
Reproductive Traits ◽  
Northern Italy ◽  
Forage Yield ◽  
High Yield ◽  
Wild Populations

Non-Ladino Italian white clover wild populations are widespread in hill and mountain areas of the Alps and northern Apennines. The agronomic value of these populations is unknown. This study was based on results of four experiments and had the following objectives: (i) comparing 11 small-leaved or medium-leaved wild populations from these areas with eight medium-leaved or large-leaved varieties of different origin and one wild population from Sardinia, for forage yield in a mown association with cocksfoot, forage yield under sheep grazing, seed yield, forage quality, and 14 vegetative or reproductive traits; (ii) investigating the relationships among traits; (iii) assessing the association of individual trait expression with the environments of origin of the wild populations. Clover competitive ability was greater in large-leaved material, tended to imply higher total yield of the association, and was unrelated to clover yield under grazing. Most wild populations from northern Italy were acyanogenic, several exhibited high yield under grazing and high seed yield, and one medium-leaved wild population outperformed any medium-leaved variety for forage and seed yield traits. Higher altitude of collecting site of these populations was related to lower forage yield and smaller size of some traits. Pasture collecting habitat implied greater adaptation to grazing than woodland, greater competitive ability than wasteland, and several morphophysiological differences relative to populations collected from wasteland or meadow. The Sardinian wild population displayed low seed yield and high cyanogenic potential, whereas the Ladino variety Giga was top-performing for forage yield in association and seed yield. Several vegetative and reproductive traits showed covariation. The generated results can drive the exploitation of non-Ladino genetic resources from northern Italy.

scholarly journals Introduction, dispersal and naturalization of the Manila clam Ruditapes philippinarum in British estuaries, 1980–2010

2015 ◽  
Vol 95 (6) ◽  
pp. 1163-1172 ◽  
Author(s):  
John Humphreys ◽  
Matthew R. C. Harris ◽  
Roger J. H. Herbert ◽  
Paul Farrell ◽  
Antony Jensen ◽  
...  
Keyword(s):  
Ecosystem Function ◽  
Coastal Waters ◽  
Significant Risk ◽  
Ruditapes Philippinarum ◽  
Manila Clam ◽  
Sea Surface ◽  
Wild Populations ◽  
Field Surveys ◽  
History Of ◽  
The Government

The introduction of the Manila clam into British coastal waters in the 1980s was contested by conservation agencies. While recognizing the value of the clam for aquaculture, the government decided that it posed no invasive risk, as British sea temperatures would prevent naturalization. This proved incorrect. Here we establish the pattern of introduction and spread of the species over the first 30 years of its presence in Britain. We report archival research on the sequence of licensed introductions and examine their relationship in time and space to the appearance of wild populations as revealed in the literature and by field surveys. By 2010 the species had naturalized in at least 11 estuaries in southern England. These included estuaries with no history of licensed introduction. In these cases activities such as storage of catch before market or deliberate unlicensed introduction represent the probable mechanisms of dispersal. In any event naturalization is not an inevitable consequence of introduction and the chances of establishment over the period in question were finely balanced. Consequently in Britain the species is not currently aggressively invasive and appears not to present significant risk to indigenous diversity or ecosystem function. However it is likely to gradually continue its spread should sea surface temperatures rise as predicted.

scholarly journals AN IMPLICIT COVER PROBLEM IN WILD POPULATION STUDY

2010 ◽  
Vol 02 (01) ◽  
pp. 21-31 ◽  
Author(s):  
MARY V. ASHLEY ◽  
TANYA Y. BERGER-WOLF ◽  
WANPRACHA CHAOVALITWONGSE ◽  
BHASKAR DASGUPTA ◽  
ASHFAQ KHOKHAR ◽  
...  
Keyword(s):  
Optimization Problem ◽  
Wild Population ◽  
Combinatorial Optimization Problem ◽  
Set Cover ◽  
Not Given ◽  
Wild Populations ◽  
Feedback Arc Set ◽  
Hitting Set ◽  
Cover Problem ◽  
Hitting Set Problem

In an implicit combinatorial optimization problem, the constraints are not enumerated explicitly but rather stated implicitly through equations, other constraints or auxiliary algorithms. An important subclass of such problems is the implicit set cover (or, equivalently, hitting set) problem in which the sets are not given explicitly but rather defined implicitly. For example, the well-known minimum feedback arc set problem is such a problem. In this paper, we consider such a cover problem that arises in the study of wild populations in biology in which the sets are defined implicitly via the Mendelian constraints and prove approximability results for this problem.

Impact of Perkinsus olseni infection on a wild population of Manila clam Ruditapes philippinarum in Ariake Bay, Japan

2018 ◽  
Vol 153 ◽  
pp. 134-144 ◽  
Author(s):  
Tsukasa Waki ◽  
Miki Takahashi ◽  
Tatsuya Eki ◽  
Masato Hiasa ◽  
Kousuke Umeda ◽  
...  
Keyword(s):  
Wild Population ◽  
Ruditapes Philippinarum ◽  
Manila Clam ◽  
Ariake Bay

scholarly journals Genetic impact of gadoid culture on wild fish populations: predictions, lessons from salmonids, and possibilities for minimizing adverse effects

2006 ◽  
Vol 63 (2) ◽  
pp. 198-208 ◽  
Author(s):  
Dorte Bekkevold ◽  
Michael M. Hansen ◽  
Einar E. Nielsen
Keyword(s):  
Life History Traits ◽  
Wild Population ◽  
General Trend ◽  
Fish Populations ◽  
Gene Pools ◽  
Wild Populations ◽  
Genetic Studies ◽  
Hatchery Fish ◽  
Genetic Impact ◽  
Up Scaling

Abstract Little is known about the effects of ranched gadoids escaping into wild populations, and plans for substantial up-scaling of gadoid mariculture raise concerns about detrimental effects on local gene pools. Genetic studies from salmonid populations subjected to intentional or unintentional releases of hatchery-produced fish suggest that wild gene pools are affected by introgression, but that the genetic impact can be minor relative to expectations from the often substantial numbers of released hatchery fish. However, even if resilience to introgression is a general trend, wild population fitness is still predicted to be jeopardized by releases. In this paper, we review theoretical genetic effects of escapes of cultivated individuals and the empirical evidence for introgression effects, which are based mainly on salmonid studies. Based on knowledge of gadoid population structure and life history traits, we make predictions for effects of gadoid mariculture on wild populations and discuss approaches for monitoring and minimizing introgression effects.

scholarly journals The decline and impending extinction of the South China tiger

Oryx ◽  
1997 ◽  
Vol 31 (4) ◽  
pp. 243-252 ◽  
Author(s):  
Ronald Tilson ◽  
Kathy Traylor-Holzer ◽  
Qiu Ming Jiang
Keyword(s):  
Field Study ◽  
South China ◽  
Reproductive Output ◽  
Wild Population ◽  
Local People ◽  
Conservation Priorities ◽  
Panthera Tigris ◽  
Captive Population ◽  
Wild Populations ◽  
The South

The South China tiger Panthera tigris amoyensis is the rarest of the five living tiger subspecies, the most critically threatened and the closest to extinction. No wild South China tigers have been seen by officials for 25 years and one was last brought into captivity 27 years ago. The 19 reserves listed by the Chinese Ministry of Forestry within the presumed range of the tiger are spatially fragmented and most are too small to support viable tiger populations. Over the last 40 years wild populations have declined from thousands to a scattered few. Despite its plight and occasional anecdotal reports of sightings by local people, no intensive field study has been conducted on this tiger subspecies and its habitat. The captive population of about 50 tigers, derived from six wild-caught founders, is genetically impoverished with low reproductive output. Given the size and fragmentation of potential tiger habitat, saving what remains of the captive population may be the only option left to prevent extinction of this tiger subspecies, and even this option is becoming increasingly less probable. This precarious dilemma demands that conservation priorities be re-evaluated and action taken immediately to decide if recovery of the wild population will be possible.

scholarly journals The conservation status of the Chinese alligator

Oryx ◽  
1999 ◽  
Vol 33 (2) ◽  
pp. 152-159 ◽  
Author(s):  
John Thorbjarnarson ◽  
Wang Xiaoming
Keyword(s):  
Captive Breeding ◽  
Wild Population ◽  
Conservation Status ◽  
Population Decline ◽  
Anhui Province ◽  
Reserve Design ◽  
Wild Populations ◽  
Current Conservation ◽  
Term Survival ◽  
Chinese Alligator

AbstractThe Chinese alligator Alligator sinensis is one of the world's most endangered reptiles. At one time widespread throughout much of the lower Yangzi River basin, the remaining wild individuals are now restricted to a small area in southern Anhui Province and perhaps in adjacent Zhejiang Province. Population estimates conducted in the 1980s suggested that only 500–735 wild individuals remained at that time. Current figures suggest that the wild population is c. 400 individuals and continues to decline. The principal factor contributing to historic population decline has been habitat loss, but deliberate killing of alligators and the heavy use of pesticides have also had significant negative effects. The current conservation programme in Anhui Province is based on captive breeding and the establishment of a reserve for small groups of wild alligators. However, the inferred recent decline in the size of the wild population suggests that the reserve design is inadequate for the long-term survival of alligators. Programmes to survey the status of the remaining wild populations and evaluate the feasibility of establishing new wild populations by reintroducing captive-bred animals are currently being developed.

scholarly journals Influence of Seascape on Coastal Lagoon Fisheries: the Role of Habitat Mosaic in the Venice Lagoon

2021 ◽  
Author(s):  
Luca Scapin ◽  
Matteo Zucchetta ◽  
Fabio Pranovi ◽  
Piero Franzoi
Keyword(s):  
Water Quality ◽  
Coastal Lagoons ◽  
Spatial Scales ◽  
Venice Lagoon ◽  
Habitat Characteristics ◽  
Artisanal Fishery ◽  
Sediment Grain Size ◽  
Northern Adriatic ◽  
Broad Scale

AbstractFisheries are a staple human activity supported by coastal lagoons. Together with water quality and trophic status, lagoon morphology is acknowledged as one of the main ecological drivers of fishery yields; however, the role of lagoon seascape structure is still poorly understood. This paper investigates how morphological variables, habitat distribution and seascape diversity and complexity affect yields of artisanal fishery performed with fyke nets in the Venice Lagoon (northern Adriatic Sea, Italy). Two spatial scales were considered in the analysis, with water quality parameters (temperature, salinity, dissolved oxygen, turbidity, water residence times, N, P and chlorophyll-a concentrations) being measured at a fine, fyke-net scale and morphological (average bottom elevation and sediment grain size) and habitat features (habitat proportion, diversity and complexity) being measured at a broader, seascape scale. Generalised linear mixed models were employed to model 8 years of nekton and green crab catches, disentangling the role of broad-scale morphology and seascape from that of fine-scale water quality. Broad-scale variables clearly influenced fishery target species. Among them, lagoon residents were associated with specific morphological and habitat characteristics, while marine migrants showed a stronger link with overall habitat diversity and complexity. This evidence emphasises how artisanal fishery in the Venice Lagoon relies on the conservation of morphological and habitat heterogeneity. Moreover, it highlights how habitat restoration performed at the seascape level should also be taken into account, in addition to controlling hydrology and water quality, when managing fishery resources in coastal lagoons.

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