scholarly journals Interactions between fish and fisher's spatial distribution and behaviour: an empirical study of the anchovy (Engraulis ringens) fishery of Peru

2004 ◽  
Vol 61 (7) ◽  
pp. 1127-1136 ◽  
Author(s):  
Sophie Bertrand ◽  
Erich Díaz ◽  
Miguel Ñiquen
Keyword(s):  
Spatial Scale ◽  
Spatial Dynamics ◽  
Fishing Ground ◽  
Fish Stock ◽  
Commercial Fishing ◽  
Spatial Concentration ◽  
Time Period ◽  
Engraulis Ringens ◽  
Spatio Temporal ◽  
Potential Interactions

Abstract Fishing data provide, with wide spatio-temporal coverage, inexpensive information about exploited species, but a precondition for their interpretation is a good comprehension of fish and fisher spatial dynamics and interactions. In Peru, anchovy (Engraulis ringens) is exploited by an industrial fleet of about 800 purse-seiners operating all along the coast. Using simultaneous acoustic survey and commercial fishing data for the 1998–2001 time period, we present a preliminary, exploratory, and empirical approach to identify the nature of potential interactions between Peruvian anchovy and fisher behaviour. We show that (i) Peruvian anchovy exhibited a composite spatial strategy for the study period, i.e. a change in biomass was associated with both change in geographical extension and density; (ii) fishing behaviour significantly varied within and among vessels in terms of travel duration, searching duration, and number of fishing sets; and (iii) interactions between fish and fisher behaviours differed according to the spatial scale. At a fish stock scale (the scale of fishing ground selection for fishers), fishing was more efficient with low biomass and high spatial concentration (low stock range and high biomass); at a local fish spatial scale (the scale of searching for a school inside the fishing ground), fishing performance was favoured by high mean local abundances and low spatial concentration (the way fish is distributed inside its stock range); finally, at the school scale (the scale of the fishing set), both high abundance and high spatial concentration were favourable to fishing success.

The importance of scale for fishing impact estimations

2009 ◽  
Vol 66 (5) ◽  
pp. 829-835 ◽  
Author(s):  
G. J. Piet ◽  
F. J. Quirijns
Keyword(s):  
Life History ◽  
Spatial Scale ◽  
Bottom Trawl ◽  
Spatial Processes ◽  
Temporal Scales ◽  
Fishing Impact ◽  
Trawl Fishery ◽  
Time Period ◽  
Spatio Temporal ◽  
The Impact

The impact of a bottom trawl fishery on fish or benthos is often determined by multiplying the frequency of the passing of the trawl by a factor for the effect (i.e., % mortality) of the singular passing of the gear. As fishing intensity in an area is not homogeneously distributed, it is necessary to determine the proportions of the area that are fished with different trawling frequencies, as these subareas together contribute to the overall species’ mortality. In this study, we show that the perceived proportion of the area fished with a specific trawling frequency depends upon the spatial and temporal scale used. A smaller spatial scale results in an increased perceived patchiness of the fishing intensity, while a longer time period does the opposite. The implication is that to determine the fishing-induced mortality of a particular species, the trawling frequency needs to be determined at those spatio-temporal scales that are appropriate considering the species’ spatial processes (e.g., dispersion) or temporal processes described by life history characteristics.

scholarly journals Spatial and Temporal Variability of Parasite Communities: Implications for Fish Stock Identification

Fishes ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 71
Author(s):  
Juan F. Espínola-Novelo ◽  
Marcelo E. Oliva
Keyword(s):  
Spatial Scale ◽  
Temporal Variability ◽  
Temporal Scale ◽  
Fish Stock ◽  
Spatial And Temporal Variability ◽  
Stock Identification ◽  
Parasite Communities ◽  
Principal Coordinates ◽  
Ca 50 ◽  
Engraulis Ringens

The spatial and temporal variability of parasite communities have received little attention when used as biological tags for identifying fish stocks. This study evaluated the potential spatial and temporal variability of the parasite communities affecting three marine fish species collected between 1993 and 2017. To avoid the potential effect of host age in parasite communities, individuals of similar ages were selected: 1123 Engraulis ringens (12–24 months old), 1904 Trachurus murphyi (24–36 months old), and 630 Merluccius gayi (36–48 months old). Most taxa show differences in the prevalence at the spatial and temporal scales, but the prevalence of some larval endoparasites remains constant at the temporal scale. At the spatial scale, an analysis of similarity (ANOSIM) showed differences in the parasite communities of three species; a canonical analysis of principal coordinates (CAP) showed low values of correct allocations (CA; ≈50%) and values of allocation due to chance (AdC) were lower than the CA. At the temporal scale, an ANOSIM showed differences between the three species. A CAP showed low values of CA (≈50–60%) and the AdC was always lower than CA. Samples at the spatial scale were well allocated to their localities or nearby localities, suggesting a spatial stability. Samples from different years were not well discriminated, suggesting temporal variability. Therefore, in studies regarding parasites as a tool for stock identification, temporal variability must be taken into account.

scholarly journals Detecting Tourism Typologies of Regional Destinations Based on Their Spatio-Temporal and Socioeconomic Performance: A Correlation-Based Complex Network Approach for the Case of Greece

2021 ◽  
Vol 2 (1) ◽  
pp. 113-139
Author(s):  
Dimitrios Tsiotas ◽  
Thomas Krabokoukis ◽  
Serafeim Polyzos
Keyword(s):  
Network Analysis ◽  
Complex Network ◽  
Community Detection ◽  
Optimization Algorithm ◽  
Spatial Dimension ◽  
Economic Dimension ◽  
Complex Network Analysis ◽  
Time Period ◽  
Time Patterns ◽  
Spatio Temporal

Within the context that tourism-seasonality is a composite phenomenon described by temporal, geographical, and socio-economic aspects, this article develops a multilevel method for studying time patterns of tourism-seasonality in conjunction with its spatial dimension and socio-economic dimension. The study aims to classify the temporal patterns of seasonality into regional groups and to configure distinguishable seasonal profiles facilitating tourism policy and development. The study applies a multilevel pattern recognition approach incorporating time-series assessment, correlation, and complex network analysis based on community detection with the use of the modularity optimization algorithm, on data of overnight-stays recorded for the time-period 1998–2018. The analysis reveals four groups of seasonality, which are described by distinct seasonal, geographical, and socio-economic profiles. Overall, the analysis supports multidisciplinary and synthetic research in the modeling of tourism research and promotes complex network analysis in the study of socio-economic systems, by providing insights into the physical conceptualization that the community detection based on the modularity optimization algorithm can enjoy to the real-world applications.

scholarly journals Spatial and spatio-temporal analysis of Salmonella infection in dairy herds in England and Wales

2008 ◽  
Vol 137 (6) ◽  
pp. 847-857 ◽  
Author(s):  
S. E. FENTON ◽  
H. E. CLOUGH ◽  
P. J. DIGGLE ◽  
S. J. EVANS ◽  
H. C. DAVISON ◽  
...  
Keyword(s):  
Transition Probabilities ◽  
Spatial Clustering ◽  
Markov Chain Model ◽  
Temporal Analysis ◽  
Dairy Herds ◽  
Chain Model ◽  
Time Period ◽  
Spatio Temporal ◽  
Using Data ◽  
Residual Deviance

SUMMARYUsing data from a cohort study conducted by the Veterinary Laboratories Agency (VLA), evidence of spatial clustering at distances up to 30 km was found for S. Agama and S. Dublin (P values of 0·001) and borderline evidence was found for spatial clustering of S. Typhimurium (P=0·077). The evolution of infection status of study farms over time was modelled using a Markov Chain model with transition probabilities describing changes in status at each of four visits, allowing for the effect of sampling visit. The degree of geographical clustering of infection, having allowed for temporal effects, was assessed by comparing the residual deviance from a model including a measure of recent neighbourhood infection levels with one excluding this variable. The number of cases arising within a defined distance and time period of an index case was higher than expected. This provides evidence for spatial and spatio-temporal clustering, which suggests either a contagious process (e.g. through direct or indirect farm-to-farm transmission) or geographically localized environmental and/or farm factors which increase the risk of infection. The results emphasize the different epidemiology of the three Salmonella serovars investigated.

Necessary Components of Economic Surplus in Fisheries Economics

1980 ◽  
Vol 37 (5) ◽  
pp. 858-870 ◽  
Author(s):  
Lee G. Anderson
Keyword(s):  
Consumer Surplus ◽  
Fish Stock ◽  
Commercial Fishing ◽  
Fishing Industry ◽  
Fisheries Economics ◽  
Economic Surplus ◽  
Detailed Model ◽  
Maximum Economic Yield ◽  
Worker Satisfaction ◽  
Different Levels

There are four main types of economic surpluses that can be achieved when exploiting a fishery. They are rent to the productive nature of the fish stock, normal factor rents to inputs, consumer surplus, and what is called here, worker satisfaction bonus, WSB. The latter refers to nonmonetary benefits individuals can obtain from participating in commercial fishing and, to be complete, in other occupations as well. It is discussed frequently, but has never received any formal treatment in the literature. In this paper the logic behind WSB in the fishing industry is discussed and its implications on policy is shown. A detailed model is developed which can show how all of the components of economic surplus relate to one another and how they will vary at different levels of output.Key words: fisheries economics, economic surplus, worker satisfaction bonus, maximum economic yield

scholarly journals Spatially mismatched trophic dynamics: cyclically outbreaking geometrids and their larval parasitoids

2010 ◽  
Vol 6 (4) ◽  
pp. 566-569 ◽  
Author(s):  
Snorre B. Hagen ◽  
Jane U. Jepsen ◽  
Tino Schott ◽  
Rolf A. Ims
Keyword(s):  
Trophic Interactions ◽  
Travelling Waves ◽  
Methodological Approach ◽  
Spatial Dynamics ◽  
Population Cycles ◽  
Trophic Levels ◽  
Trophic Dynamics ◽  
Spatial Mismatch ◽  
Larval Parasitoids ◽  
Spatio Temporal

For trophic interactions to generate population cycles and complex spatio-temporal patterns, like travelling waves, the spatial dynamics must be matched across trophic levels. Here, we propose a spatial methodological approach for detecting such spatial match–mismatch and apply it to geometrid moths and their larval parasitoids in northern Norway, where outbreak cycles and travelling waves occur. We found clear evidence of spatial mismatch, suggesting that the spatially patterned moth cycles in this system are probably ruled by trophic interactions involving other agents than larval parasitoids.

scholarly journals Environmental effects on recreational squid jigging fishery catches

2012 ◽  
Vol 69 (10) ◽  
pp. 1823-1830 ◽  
Author(s):  
Miguel Cabanellas-Reboredo ◽  
Josep Alós ◽  
Miquel Palmer ◽  
Beatriz Morales-Nin
Keyword(s):  
Environmental Effects ◽  
Environmental Variables ◽  
Seasonal Pattern ◽  
Night Time ◽  
Sea Temperature ◽  
Time Period ◽  
Movement Characteristic ◽  
Alternative Hypotheses ◽  
Specific Vulnerability ◽  
Spatio Temporal

Abstract Cabanellas-Reboredo, M., Alós, J., Palmer, M., and Morales-Nin, B. 2012. Environmental effects on recreational squid jigging fishery catches. – ICES Journal of Marine Science, 69: 1823–1830. Experimental fishing sessions simulating the operating procedures of the recreational fishery for the European squid that operates at inshore Palma Bay (Balearic Islands, Spain) were conducted to investigate the effects of environmental variables on squid catches. The catch per unit of effort (cpue) of recreational-like jigging sessions showed a seasonal pattern (higher cpue during colder months). Two alternative hypotheses can explain such a pattern. First, squid could migrate inshore during colder months to seek spatio-temporal windows within which the sea temperature maximize spawning success. Second, the timing of the seasonal reproductive peak and the growth rate of any given cohort would result in a higher percentage of squid whose body size is greater than the gear-specific vulnerability threshold during the colder months. The combination of environmental variables that maximized cpue was a low sea surface temperature, a low windspeed, low atmospheric pressure, and days close to the new moon. A specific period of the day, narrowly around sunset, favoured the catches. Within this narrow period, the sunlight is still sufficient to allow the recreational fishing lures to be effective, and the squid have already shifted to a more active pattern of movement characteristic of the night-time period.

Measuring Spatial Concentration: The Use of Threshold Profiles

2003 ◽  
Vol 30 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Ron Johnston ◽  
David Voas
Keyword(s):  
Spatial Pattern ◽  
Spatial Scale ◽  
Concentration Profile ◽  
Gini Coefficient ◽  
Reference Group ◽  
Public Policies ◽  
Spatial Concentration ◽  
England And Wales ◽  
Alternative Approach ◽  
Single Number

The measurement of spatial pattern is often undertaken using one of a number of single-number indices, such as the Gini coefficient, which may not illuminate certain aspects of the pattern involved—especially the degree to which the members of the reference group are spatially concentrated. We suggest an alternative approach based on a concentration profile which shows the degree to which a group is spatially concentrated according to a range of thresholds. This is illustrated with data on male unemployment in England and Wales in 1991, which also shows the importance of spatial scale to the study of concentrations and, potentially, to the formulation of spatially focused public policies.

SPATIO-TEMPORAL PATTERNS IN A CHOLERA TRANSMISSION MODEL

2015 ◽  
Vol 23 (03) ◽  
pp. 471-484 ◽  
Author(s):  
A. K. MISRA ◽  
MILAN TIWARI ◽  
ANUPAMA SHARMA
Keyword(s):  
Spatial Patterns ◽  
Dimensional Space ◽  
Spatial Dynamics ◽  
Transmission Model ◽  
Cholera Epidemic ◽  
Temporal System ◽  
Spatially Extended ◽  
Variable Population ◽  
Spatio Temporal ◽  
Variable Population Size

Cholera has been a public health threat for centuries. Unlike the biological characteristics, relatively less effort has been paid to comprehend the spatial dynamics of this disease. Therefore, in this paper, we have proposed a cholera epidemic model for variable population size and studied the spatial patterns in two-dimensional space. First, we have performed the equilibrium and local stability analysis of steady states obtained for temporal system. Afterwards, the local and global stability behavior of the endemic steady state in a spatially extended setting has been investigated. The numerical simulations have been done to investigate the spatial patterns. They show that dynamics of the cholera epidemic varies with time and space.

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