Linking the dynamics of harvest effort to recruitment dynamics in a multistock, spatially structured fishery

2004 ◽  
Vol 61 (9) ◽  
pp. 1658-1670 ◽  
Author(s):  
Eric A Parkinson ◽  
John R Post ◽  
Sean P Cox
Keyword(s):  
Ideal Free Distribution ◽  
Distribution Model ◽  
Model Parameters ◽  
Empirical Relationships ◽  
Fish Size ◽  
Sport Fishery ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Angler Behavior ◽  
High Fish ◽  
Ideal Free

A freshwater sport fishery that targets hundreds of geographically isolated stocks is simulated by combining a model of angler behavior with a model of rainbow trout (Oncorhynchus mykiss) population dynamics. Ideal free distribution (IFD) theory, which suggests that angling quality will be similar on all lakes, is used to drive angler effort distribution. Model parameters are based on creel survey data from 53 lakes and empirical relationships between growth, survival, and density derived from whole-lake density manipulations on nine lakes over a period of 10 years. We compared angling quality, population density, fish size, and yield under unfished conditions, harvest rates that maximize sustained yields (MSY), and an IFD equilibrium driven by angler behavior. The IFD equilibrium rarely maximized yields. Stocks with high MSY angling quality are overexploited at the IFD equilibrium because anglers move to take advantage of exceptional angling opportunities. These stocks would often be viewed as more resistant to harvest pressure because they have higher stock productivities and habitat capacities. However, in our model, they are systematically overharvested because their high fish density attracts excessive angling pressure. Conversely, stocks with low MSY angling quality are underexploited because anglers move to take advantage of better angling quality on other lakes.

scholarly journals Swift Foxes and Ideal Free Distribution: Relative Influence of Vegetation and Rodent Prey Base on Swift Fox Survival, Density, and Home Range Size

ISRN Zoology ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Craig M. Thompson ◽  
Eric M. Gese
Keyword(s):  
Home Range ◽  
Landscape Heterogeneity ◽  
Ideal Free Distribution ◽  
Survival Rates ◽  
Home Range Size ◽  
Range Size ◽  
Distribution Model ◽  
Free Distribution ◽  
Swift Fox ◽  
Ideal Free

Swift foxes (Vulpes velox) are an endemic mesocarnivore of North America subject to resource and predation-based pressures. While swift fox demographics have been documented, there is little information on the importance of top-down versus bottom-up pressures or the effect of landscape heterogeneity. Using a consumable resource-based ideal free distribution model as a conceptual framework, we isolated the effects of resource-based habitat selection on fox population ecology. We hypothesized if swift fox ecology is predominantly resource dependant, distribution, survival, and space use would match predictions made under ideal free distribution theory. We monitored survival and home range use of 47 swift foxes in southeastern Colorado from 2001 to 2004. Annual home range size was 15.4 km2, and seasonal home range size was 10.1 km2. At the individual level, annual home range size was unrelated to survival. Estimates of fox density ranged from 0.03 to 0.18 foxes/km2. Seasonal survival rates were 0.73 and 1.0 and did not differ seasonally. Foxes conformed to the predictions of the ideal free distribution model during winter, indicating foxes are food stressed and their behavior governed by resource acquisition. During the rest of the year, behavior was not resource driven and was governed by security from intraguild predation.

Advancing the application of the ideal free distribution to spatial models of fishing effort: the isodar approach

2012 ◽  
Vol 69 (10) ◽  
pp. 1610-1620 ◽  
Author(s):  
D.M. Gillis ◽  
A. van der Lee
Keyword(s):  
Behavioral Ecology ◽  
Interference Competition ◽  
Ideal Free Distribution ◽  
Spatial Dynamics ◽  
Spatial Models ◽  
Fishing Effort ◽  
Model Parameters ◽  
Free Distribution ◽  
Ideal Free ◽  
The Ideal

The ideal free distribution (IFD) of behavioral ecology has been used in the study of the distribution of fishing effort since the 1990s. Concurrently, evolutionary perspectives on forager distributions have led to the development of theoretical curves of equal fitness, named isodars, to test IFD hypotheses. We develop isodars, based upon catch rates and unknown costs, to quantify regularity in the distribution of fishing effort among alternative areas. Our analyses indicate that these isodars provide significantly better predictions than a simple IFD without costs. Autocorrelation in the catch and effort data necessitates the use of generalized linear least squares when estimating model parameters. Differences in costs that are proportional to effort are more clearly identified in the model than nonlinear effects, which may arise from extreme interference competition. The isodar approach provides a new tool for examining the spatial dynamics of catch and effort data. It improves the accuracy of predictions and provides new parameters related to costs and vessel interactions that can be applied to rapidly identify situations where effort dynamics have changed.

An experimental investigation of a new ideal free distribution model

1996 ◽  
Vol 10 (1) ◽  
pp. 45-49 ◽  
Author(s):  
Tom Tregenza ◽  
Judith J. Shaw ◽  
David J. Thompson
Keyword(s):  
Experimental Investigation ◽  
Ideal Free Distribution ◽  
Distribution Model ◽  
Free Distribution ◽  
Ideal Free

Effects of food and oxygen availability on habitat selection by guppies in a laboratory environment

1986 ◽  
Vol 64 (1) ◽  
pp. 88-93 ◽  
Author(s):  
André J. Talbot ◽  
Donald L. Kramer
Keyword(s):  
Food Supply ◽  
Poecilia Reticulata ◽  
Ideal Free Distribution ◽  
Oxygen Availability ◽  
Distribution Model ◽  
Oxygen Effect ◽  
Potential Cost ◽  
Free Distribution ◽  
Ideal Free ◽  
The Ideal

Using the ideal free distribution model proposed in 1970 by S. D. Fretwell and H. L. Lucas, we investigated how local food and oxygen availability influenced the distribution of a group of guppies (Poecilia reticulata, Teleostei, Poeciliidae) among five habitats in a large tank. Our study differed from previous investigations of ideal free distributions in the larger number of habitats available, the presence of resource-free zones between habitats, the visual isolation of the different habitats, the availability of resources over an entire day rather than a short feeding period, and the systematic variation of a potential cost component (low oxygen). In our system, the ideal free distribution model was a poor predictor of fish distributions. Although the proportion of fish in a habitat was positively correlated with food supply, there were too few fish where the food supply was high and too many fish where the food supply was low to equalize average feeding rates in all habitats. The proportion of fish in a habitat was not affected by oxygen concentration, whether food was limited or superabundant. Large, stable differences in density occurred between habitats receiving identical treatments. Time spent by the fish in sampling alternative habitats and the ease with which some individuals could restrict the access of others to the habitats may have contributed to the failure of the ideal free distribution model. The effectiveness with which guppies use the surface film for respiration under hypoxic conditions may explain the lack of a dissolved oxygen effect. Our study demonstrates the need to understand conditions that promote or hinder the appearance of ideal free distributions before they can be used to predict the relationship between animal density and resource availability in nature.

Understanding gas bubble trauma in an era of hydropower expansion: how do fish compensate at depth?

2020 ◽  
Vol 77 (3) ◽  
pp. 556-563 ◽  
Author(s):  
Naomi K. Pleizier ◽  
Charlotte Nelson ◽  
Steven J. Cooke ◽  
Colin J. Brauner
Keyword(s):  
Bubble Growth ◽  
Gas Bubble ◽  
Hydroelectric Dams ◽  
Dissolved Gas ◽  
Empirical Relationships ◽  
Lethal Effects ◽  
Exposed Fish ◽  
Total Dissolved Gas ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
The Relationship

Hydrostatic pressure is known to protect fish from damage by total dissolved gas (TDG) supersaturation, but empirical relationships are lacking. In this study we demonstrate the relationship between depth, TDG, and gas bubble trauma (GBT). Hydroelectric dams generate TDG supersaturation that causes bubble growth in the tissues of aquatic animals, resulting in sublethal and lethal effects. We exposed fish to 100%, 115%, 120%, and 130% TDG at 16 and 63 cm of depth and recorded time to 50% loss of equilibrium and sublethal symptoms. Our linear model of the log-transformed time to 50% LOE (R2 = 0.94) was improved by including depth. Based on our model, a depth of 47 cm compensated for the effects of 4.1% (±1.3% SE) TDG supersaturation. Our experiment reveals that once the surface threshold for GBT from TDG supersaturation is known, depth protects rainbow trout (Oncorhynchus mykiss) from GBT by 9.7% TDG supersaturation per metre depth. Our results can be used to estimate the impacts of TDG on fish downstream of dams and to develop improved guidelines for TDG.

scholarly journals A Multivariate High-Order Markov Model for the Income Estimation of a Wind Farm

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 388
Author(s):  
Riccardo De Blasis ◽  
Giovanni Batista Masala ◽  
Filippo Petroni
Keyword(s):  
Markov Model ◽  
Electricity Market ◽  
Wind Farm ◽  
Central Italy ◽  
High Order ◽  
Distribution Model ◽  
Spot Price ◽  
Model Parameters ◽  
Price Series ◽  
Cross Correlations

The energy produced by a wind farm in a given location and its associated income depends both on the wind characteristics in that location—i.e., speed and direction—and the dynamics of the electricity spot price. Because of the evidence of cross-correlations between wind speed, direction and price series and their lagged series, we aim to assess the income of a hypothetical wind farm located in central Italy when all interactions are considered. To model these cross and auto-correlations efficiently, we apply a high-order multivariate Markov model which includes dependencies from each time series and from a certain level of past values. Besides this, we used the Raftery Mixture Transition Distribution model (MTD) to reduce the number of parameters to get a more parsimonious model. Using data from the MERRA-2 project and from the electricity market in Italy, we estimate the model parameters and validate them through a Monte Carlo simulation. The results show that the simulated income faithfully reproduces the empirical income and that the multivariate model also closely reproduces the cross-correlations between the variables. Therefore, the model can be used to predict the income generated by a wind farm.

scholarly journals No neighbour-induced increase in root growth of soybean and sunflower in mesh divider experiments after controlling for nutrient concentration and soil volume

AoB Plants ◽  
2021 ◽  
Author(s):  
Bin J W Chen ◽  
Li Huang ◽  
Heinjo J During ◽  
Xinyu Wang ◽  
Jiahe Wei ◽  
...  
Keyword(s):  
Root Growth ◽  
Nutrient Concentration ◽  
Ideal Free Distribution ◽  
Plant Performance ◽  
Root Competition ◽  
Individual Level ◽  
Key Factor ◽  
Promising Solution ◽  
Soil Volume ◽  
Ideal Free

Abstract Root competition is a key factor determining plant performance, community structure and ecosystem productivity. To adequately estimate the extent of root proliferation of plants in response to neighbours independently of nutrient availability, one should use a setup that can simultaneously control for both nutrient concentration and soil volume at plant individual level. With a mesh-divider design, which was suggested as a promising solution for this problem, we conducted two intraspecific root competition experiments one with soybean (Glycine max) and the other with sunflower (Helianthus annuus). We found no response of root growth or biomass allocation to intraspecific neighbours, i.e. an ‘ideal free distribution’ (IDF) norm, in soybean; and even a reduced growth as a negative response in sunflower. These responses are all inconsistent with the hypothesis that plants should produce more roots even at the expense of reduced fitness in response to neighbours, i.e. root over-proliferation. Our results suggest that neighbour-induced root over-proliferation is not a ubiquitous feature in plants. By integrating the findings with results from other soybean studies, we conclude that for some species this response could be a genotype-dependent response as a result of natural or artificial selection, or a context-dependent response so that plants can switch from root over-proliferation to IDF depending on the environment of competition. We also critically discuss whether the mesh-driver design is the ideal solution for root competition experiments.

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