Variation in the Competitive Abilities of Fishermen and its Influence on the Spatial Distribution of the British Columbia Salmon Troll Fleet

1990 ◽  
Vol 47 (6) ◽  
pp. 1116-1121 ◽  
Author(s):  
M. V. Abrahams ◽  
M. C. Healey
Keyword(s):  
British Columbia ◽  
Ideal Free Distribution ◽  
Fishing Effort ◽  
Catch Rate ◽  
Fish Distribution ◽  
Fish Stocks ◽  
Fishing Vessels ◽  
Catch Rates ◽  
Ideal Free ◽  
The Ideal

We estimated the catch rates of individual fishing vessels within the British Columbia salmon troll fleet from the data of a 7-yr log book program. Catch rates varied considerably among vessels. A portion of the variation could be attributed to environmental variation. However, there were also significant differences in competitive ability among vessels. The top ranked vessels had a catch rate 3.6 times that of the lowest ranked vessels. Top ranked vessels distributed their fishing effort among more fishing areas than bottom ranked vessels, but were also more successful at catching fish when fishing in the same areas as bottom ranked vessels. This information, through an application of the ideal free distribution theory, can be used to develop a model that will describe the expected relationship between vessel distribution, vessel catch rate, and fish distribution, potentially allowing vessel distributions to be used as a tool for assessing fish stocks.

Implications of interference among fishing vessels and the ideal free distribution to the interpretation of CPUE

1998 ◽  
Vol 55 (1) ◽  
pp. 37-46 ◽  
Author(s):  
D M Gillis ◽  
R M Peterman
Keyword(s):  
Ideal Free Distribution ◽  
Fishing Effort ◽  
Catch Per Unit Effort ◽  
Free Distribution ◽  
Fishing Vessels ◽  
Factor Interactions ◽  
The Relationship ◽  
Index Of Abundance ◽  
Ideal Free ◽  
The Ideal

Despite recognized biases, catch per unit effort (CPUE) statistics remain widely used for the estimation of fish abundance. Previous workers have shown that CPUE can be a misleading index of abundance due to fish behavior, the nominal effort units used, and increases through time in efficiency of fishing (catchability). We examine the theoretical implications of a different factor, interactions among fishing vessels, for the relationship between abundance and CPUE. Our model simulates a fishery that occurs in several adjacent fishing grounds. The spatial distribution of catch and effort is based on a simplification of the Baranov catch equation, the relationship between fishing efficiency and local fishing effort (interference), and the assumptions of the ideal free distribution. Our results indicate that (i) even low levels of interference among fishing vessels can cause a breakdown in the correlation between CPUE and local abundance and (ii) the influence of interference on this relationship is dependent on the correlation of abundances among adjacent areas. Our model suggests an alternative index of abundance, based on the proportion of fishing effort on a ground, that would be appropriate for cases where interference occurs among fishing gear.

Movement Dynamics in a Fishery: Application of the Ideal Free Distribution to Spatial Allocation of Effort

1993 ◽  
Vol 50 (2) ◽  
pp. 323-333 ◽  
Author(s):  
Darren M. Gillis ◽  
Randall M. Peterman ◽  
Albert V. Tyler
Keyword(s):  
Spatial Distribution ◽  
Ideal Free Distribution ◽  
Fishing Effort ◽  
Catch Per Unit Effort ◽  
Exploitation Competition ◽  
Spatial Allocation ◽  
Free Distribution ◽  
Fishing Vessels ◽  
Ideal Free ◽  
The Ideal

Many traditional analyses of fisheries data assume that there is a negligible effect of alternative fish stocks on the spatial distribution of fishing effort and that the amount of local effort does not influence catchability. There is growing evidence that contradicts these assumptions. Because of the potential biases that these erroneous assumptions may cause in the interpretation of catch-per-unit-effort (CPUE) statistics, it is important to determine the factors governing the spatial distribution of effort in a fishery. We used data on the Hecate Strait, British Columbia, Canada, trawl fishery to test hypotheses about spatial allocation of effort and interaction among fishing vessels. The ideal free distribution of Fretwell and Lucas (1970. Acta Biotheor. 19: 16–36) was the foundation for deriving these tests. We found evidence for competition among vessels, although we could not distinguish whether the mechanism was interference or exploitation competition. As well, CPUE was generally equalized among the areas fished, as predicted by the ideal free distribution, because of movement of boats among areas. Thus, area-specific CPUE would not be a reliable index of relative abundance of fish in different areas; relative fishing effort may be better.

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.

Foraging behaviour in tadpoles of the bronze frogRana temporalis: Experimental evidence for the ideal free distribution

2004 ◽  
Vol 29 (2) ◽  
pp. 201-207 ◽  
Author(s):  
Dheeraj K. Veeranagoudar ◽  
Bhagyashri A. Shanbhag ◽  
Srinivas K. Saidapur
Keyword(s):  
Experimental Evidence ◽  
Foraging Behaviour ◽  
Ideal Free Distribution ◽  
Free Distribution ◽  
Ideal Free ◽  
The Ideal

Aggregation and the `Ideal Free' Distribution

10.2307/4456 ◽  
1983 ◽  
Vol 52 (3) ◽  
pp. 821 ◽  
Author(s):  
William J. Sutherland
Keyword(s):  
Ideal Free Distribution ◽  
Free Distribution ◽  
Ideal Free ◽  
The Ideal

Fishing the line: catch and effort distribution around the seasonal haddock (Melanogrammus aeglefinus) spawning closure on the Scotian Shelf

2013 ◽  
Vol 70 (7) ◽  
pp. 973-981 ◽  
Author(s):  
A. van der Lee ◽  
D.M. Gillis ◽  
P. Comeau ◽  
P. Hurley
Keyword(s):  
Ideal Free Distribution ◽  
Fishing Effort ◽  
Additive Models ◽  
Catch Rate ◽  
Melanogrammus Aeglefinus ◽  
Boundary Line ◽  
The West ◽  
Fishing The Line ◽  
The Impact ◽  
Effort Distribution

Permanent and seasonal area closures are a common regulatory strategy in multispecies fisheries; however, few studies have closely examined seasonal closures. We examined the impact of the Browns Bank spawning closure on the spatial distribution of fishing effort and how the fleet utilized a “fishing the line” strategy. Generalized estimating equations were used to examine changes in effort distribution when the closure was and was not in effect. Effort displaced from the bank concentrated primarily within two areas up to 30 km from the closure boundary, one along the east boundary line and one along the west. Trends in catch rate (as value) with distance from the line were further examined using generalized additive models during the closed period, with results differing between regions. In the east, areas of greater catch rate could be identified and typically corresponded to areas of greater effort, while in the west region, no trends in catch rates were often observed, potentially indicating vessel distributions that correspond to the ideal free distribution. Implementation of a seasonal area closure on Browns Bank resulted in concentrations of vessels near the closure boundary, suggestive of a fishing the line strategy, with specific catch rate trends depending on vessel spatial distributions and target species.

scholarly journals Lack of recreational fishing compliance may compromise effectiveness of Rockfish Conservation Areas in British Columbia

2018 ◽  
Author(s):  
Dana Haggarty ◽  
Steve J.D. Martell ◽  
Jonathan B. Shurin
Keyword(s):  
British Columbia ◽  
Protected Areas ◽  
Marine Protected Areas ◽  
Fishing Effort ◽  
Area Ratio ◽  
Recreational Fishing ◽  
Conservation Areas ◽  
Fish Stocks ◽  
Ecological Recovery ◽  
Recovery Education

Compliance with spatial fishing regulations (e.g., marine protected areas, fishing closures) is one of the most important, yet rarely measured, determinants of ecological recovery. We used aerial observations of recreational fishing events from creel surveys before, during, and after 77 Rockfish Conservation Areas (RCAs) were established in British Columbia, Canada. There was no evidence of a change in fishing effort in 83% of the RCAs, and effort in five RCAs increased after establishment. Fishing effort in open areas adjacent to the RCAs declined with time and was higher than effort in the RCAs in all 3 years. Next, we used compliance data for 105 RCAs around Vancouver Island to model the drivers of compliance. Compliance was related to the level of fishing effort around the RCA, the size and perimeter-to-area ratio of RCAs, proximity to fishing lodges, and the level of enforcement. Noncompliance in RCAs may be hampering their effectiveness and impeding rockfish recovery. Education and enforcement efforts to reduce fishing effort inside protected areas are critical to the recovery of depleted fish stocks.

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