An empirical model of fleet dynamics in New England trawl fisheries

1999 ◽  
Vol 56 (2) ◽  
pp. 253-264 ◽  
Author(s):  
Daniel S Holland ◽  
Jon G Sutinen
Keyword(s):  
New England ◽  
Empirical Model ◽  
Ideal Free Distribution ◽  
Species Group ◽  
Fishing Effort ◽  
Past Behavior ◽  
The Individual ◽  
Choice Of Species ◽  
Fleet Dynamics ◽  
Trawl Fisheries

Regulations and changes in market and environmental conditions that change the profitability of one fishery or area will result in a redistribution of fishing effort among alternative fisheries or areas. The magnitude of this effort displacement will depend on the relative profitability of the alternatives for the individual fishers affected. When fishing areas and fishers are heterogeneous, simple aggregate effort models such as those based on ideal free distribution theory may provide inaccurate predictions. We present an empirical model of individual vessel fishery and location choice based on trip data for a group of over 400 large trawlers fishing in New England. The model uses lagged average revenue rates for different alternatives and the individual vessel's past behavior to predict choice of species group and fishing location on a trip-by-trip basis. This model is used to predict aggregate effort levels in different fisheries and areas over time.

scholarly journals Finding the accelerator and brake in an individual quota fishery: linking ecology, economics, and fleet dynamics of US West Coast trawl fisheries

2013 ◽  
Vol 71 (2) ◽  
pp. 308-319 ◽  
Author(s):  
Isaac C. Kaplan ◽  
Daniel S. Holland ◽  
Elizabeth A. Fulton
Keyword(s):  
West Coast ◽  
Fishery Management ◽  
Fishing Effort ◽  
Target Species ◽  
The Pacific ◽  
The Us ◽  
Fleet Dynamics ◽  
Us West ◽  
Trawl Fisheries ◽  
Management Council

Abstract Isaac C. Kaplan, Daniel S. Holland, and Elizabeth A. Fulton. 2014. Finding the accelerator and brake in an individual quota fishery: linking ecology, economics, and fleet dynamics of US West Coast trawl fisheries. – ICES Journal of Marine Science, 71: 308–319. In 2011, the Pacific Fisheries Management Council implemented an individual transferrable quota (ITQ) system for the US West Coast groundfish trawl fleet. Under the ITQ system, each vessel now receives transferrable annual allocations of quota for 29 groundfish species, including target and bycatch species. Here we develop an ecosystem and fleet dynamics model to identify which components of an ITQ system are likely to drive responses in effort, target species catch, bycatch, and overall profitability. In the absence of penalties for discarding over-quota fish, ITQs lead to large increases in fishing effort and bycatch. The penalties fishermen expect for exceeding quota have the largest effect on fleet behaviour, capping effort and total bycatch. Quota prices for target or bycatch species have lesser impacts on fishing dynamics, even up to bycatch quota prices of $50 kg−1. Ports that overlap less with bycatch species can increase effort under individual quotas, while other ports decrease effort. Relative to a prior management system, ITQs with penalties for exceeding quotas lead to increased target species landings and lower bycatch, but with strong variation among species. The model illustrates how alternative fishery management policies affect profitability, sustainability and the ecosystem.

scholarly journals Animal Models in the Evaluation of the Effectiveness of Phage Therapy for Infections Caused by Gram-Negative Bacteria from the ESKAPE Group and the Reliability of Its Use in Humans

2021 ◽  
Vol 9 (2) ◽  
pp. 206
Author(s):  
Martyna Cieślik ◽  
Natalia Bagińska ◽  
Andrzej Górski ◽  
Ewa Jończyk-Matysiak
Keyword(s):  
Animal Models ◽  
Phage Therapy ◽  
Animal Experiments ◽  
Species Group ◽  
Effectiveness Evaluation ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Enterobacter Species ◽  
The Individual

The authors emphasize how extremely important it is to highlight the role played by animal models in an attempt to determine possible phage interactions with the organism into which it was introduced as well as to determine the safety and effectiveness of phage therapy in vivo taking into account the individual conditions of a given organism and its physiology. Animal models in which phages are used make it possible, among other things, to evaluate the effective therapeutic dose and to choose the possible route of phage administration depending on the type of infection developed. These results cannot be applied in detail to the human body, but the knowledge gained from animal experiments is invaluable and very helpful. We would like to highlight how useful animal models may be for the possible effectiveness evaluation of phage therapy in the case of infections caused by gram-negative bacteria from the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species) group of pathogens. In this review, we focus specifically on the data from the last few years.

scholarly journals The relative weight of traditions, economics, and catch plans in New Zealand fleet dynamics

2009 ◽  
Vol 66 (2) ◽  
pp. 291-311 ◽  
Author(s):  
Paul Marchal ◽  
Philippe Lallemand ◽  
Kevin Stokes
Keyword(s):  
New Zealand ◽  
Relative Weight ◽  
Fishing Effort ◽  
Expected Profit ◽  
Nested Logit ◽  
Individual Transferable Quota ◽  
Management Regime ◽  
One Year ◽  
Fleet Dynamics ◽  
Statistical Area

We investigate the relative weights of catch plans, expected profit, and traditions in fishers’ decision-making for five New Zealand fleets subject to an individual transferable quota (ITQ) management regime. Métiers were defined for these fleets as a combination of gears, management units, and a targeting index (either target species or statistical area). A nested logit random utility model was used to model the métier allocation of fishing effort in relation to catch plans, expected profit, and past fishing allocations. This study showed that traditions and catch plans appeared to be important determinants of fishers’ behavior for these New Zealand fleets. The model developed in this study fitted the data generally well and was also able to predict, in most cases, future effort allocation both one month and one year ahead.

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.

Wood Characteristics of Abies Balsamea in the New England States Compared to Abies Alba from Sites in Europe with Decline Problems

IAWA Journal ◽  
1986 ◽  
Vol 7 (4) ◽  
pp. 375-387 ◽  
Author(s):  
W. C. Shortle ◽  
J. Bauch
Keyword(s):  
New England ◽  
Starch Content ◽  
Soluble Sugars ◽  
Abies Balsamea ◽  
Abies Alba ◽  
The United States ◽  
Growth Increment ◽  
Physiological Alterations ◽  
Transverse Area ◽  
The Individual

The increasing concern about the health conditions of forests in the United States and Europe 1ed to a comparative study of wood characteristics of Abies balsamea (L.) Mill. in the New England states, and Abies alba Mi1!. in the Federal Republic ofGermany. The advanced visible disease in Abies alba at several sites can be documented by means of many structural and physiological alterations. In diseased trees a suppression of the annual growth increment is obvious, and the individual transverse area of early and latewood cells decreases. The moisture content diminishes in the sapwood significantly and at the same time, wetwood deve10ps and expands into the sapwood. The element content per gram of wood does not significantly differ between healthy and diseased trees of the same stand. The content of soluble sugars increases in diseased trees, while the starch content is drastically reduced. However, parallel to the growth suppression the total amount per year of elements, soluble sugars and starch is significantly less in diseased trees than in healthy ones. In addition, accessory compounds appear to increase with the progress of disease. Cambial electrical resistance is strongly related to damage c1assification, and thereby to cambial growth.

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.

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.

scholarly journals Improving the interpretation of fishing effort and pressures in mixed fisheries using spatial overlap metrics

2019 ◽  
Vol 76 (4) ◽  
pp. 586-596 ◽  
Author(s):  
Pierre Bourdaud ◽  
Morgane Travers-Trolet ◽  
Youen Vermard ◽  
Paul Marchal
Keyword(s):  
Gadus Morhua ◽  
Ideal Free Distribution ◽  
Fishing Effort ◽  
Added Value ◽  
Spatial Overlap ◽  
Spatially Resolved ◽  
Red Mullet ◽  
Mullus Surmuletus ◽  
Management Advice ◽  
Species Specific

Managing mixed fisheries requires understanding fishers’ behaviour to allow predicting future fisheries distribution and impact on marine ecosystems. A new approach was developed to compare fine-scale fishing effort distribution of Eastern English Channel (EEC) bottom trawlers to the monthly and spatially resolved abundance distributions of commercial species. First, the added value of using species-specific spatial overlap metric to quantify effective fishing effort and improve the relationship between fishing effort and fishing mortality was assessed. Second, based on the Ideal Free Distribution (IFD) theory, the species-specific weights given by fishers to different species were estimated by maximizing the overlap between target species assemblage and effort distributions in October. At a seasonal scale, our results emphasized the importance of cuttlefish (Sepia officinalis) and red mullet (Mullus surmuletus) for the global distribution of EEC bottom trawlers. In October, cuttlefish and red mullet were clearly more determining fishers’ location choice than historically harvested species and also than the overall expected revenue. This is likely due to external constraints such as low cod (Gadus morhua) quota, causing IFD assumptions violated. This study evidenced the importance of getting good insights into spatiotemporal distributions of stocks and fleets to understand fishers’ behaviour and improve mixed fisheries management advice.

Spatial evidence for information exchange and competition in the Gulf of St. Lawrence snow crab (Chionoecetes opilio) fishery

2006 ◽  
Vol 63 (2) ◽  
pp. 254-267 ◽  
Author(s):  
Darren M Gillis ◽  
Elmer Wade ◽  
Douglas P Swain
Keyword(s):  
Information Exchange ◽  
Personal Information ◽  
Spatial Scales ◽  
Ideal Free Distribution ◽  
Public Information ◽  
Fishing Effort ◽  
Spatial And Temporal Variation ◽  
Snow Crab ◽  
Chionoecetes Opilio ◽  
Crab Abundance

Throughout the 1990s, the Gulf of St. Lawrence snow crab (Chionoecetes opilio) harvest provided an example of effective co-management in a developing fishery. The Department of Fisheries and Oceans Canada (DFO) and the snow crab fleet (the fleet) shared information that coordinated management and exploitation throughout the season. A preseason survey by DFO provided resource distributions prior to the fishery's opening. In-season monitoring allowed managers to track spatial and temporal variation in crab availability. This level of detail allowed the application of the ideal free distribution as a management and conservation tool. However, proper justification for its application requires the demonstration of information exchange and competitive effects. The spatial distribution of effort suggests that both of these are present. Fishing effort was influenced by public information and potential information exchange within the fleet. Reduced aggregation at smaller spatial scales suggests competition in trap placement. Thus, increasing fleet size may have a disproportionately small impact on fishing mortality because of limitations in information exchange and the lack of personal information in the new vessels. However, the nonlinear relationship between crab abundance and catch rates suggests that managers should avoid policies that increase fishing effort during times of low crab abundance.

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