scholarly journals CONFOUNDING EFFECTS OF THE EXPORT OF PRODUCTION AND THE DISPLACEMENT OF FISHING EFFORT FROM MARINE RESERVES

2004 ◽  
Vol 14 (4) ◽  
pp. 1248-1256 ◽  
Author(s):  
Benjamin S. Halpern ◽  
Steven D. Gaines ◽  
Robert R. Warner
Keyword(s):  
Marine Reserves ◽  
Fishing Effort

How useful is the ratio of fish density outside versus inside no-take marine reserves as a metric for fishery management control rules?

2011 ◽  
Vol 68 (2) ◽  
pp. 343-359 ◽  
Author(s):  
Elizabeth A. Babcock ◽  
Alec D. MacCall
Keyword(s):  
Fishery Management ◽  
Spatial Scales ◽  
Marine Reserves ◽  
Density Ratio ◽  
Relative Weight ◽  
Fishing Effort ◽  
Management Control ◽  
Fish Density ◽  
Control Rules ◽  
Stock Depletion

A management strategy evaluation (based on five species in the California, USA, nearshore fishery) of control rules that reduce relative fishing effort as a function of the ratio of fish density outside versus inside no-take marine reserves (as a measure of depletion) showed that although the control rules allowed effort to increase at first, in the long term, they were effective at maintaining spawning stock biomass and yield for all simulated species, including depleted ones. Scenarios with fish movement, illegal fishing in the reserve, or post-dispersal density dependence in recruitment required higher density ratio targets, such as 60% of mature fish or 80% of all fish, to avoid stock depletion. The effort allowed by multispecies density-ratio control rules depended on the relative weight given to more or less depleted species. High variability in recruitment or in monitoring data caused the allowable effort to fluctuate. Density-ratio control rules have the advantages that they require no historical data, they can be used at local spatial scales, and they adjust to changing environmental conditions.

scholarly journals Evaluating marine reserves as a management policy in the central-southern anchovy (Engraulis ringens) fishery of Chile

2021 ◽  
Vol 49 (2) ◽  
pp. 212-226
Author(s):  
Juan Pablo Díaz Vega ◽  
Yarela Flores Arévalo
Keyword(s):  
Marine Reserves ◽  
Marine Reserve ◽  
Fishing Effort ◽  
Management Policy ◽  
Decision Variable ◽  
Southern Chile ◽  
Artisanal Fishing ◽  
Fishing Activity ◽  
Engraulis Ringens ◽  
The Impact

The anchovy (Engraulis ringens) fishery in central-southern Chile, like many fisheries worldwide, is overexploitation mainly due to poor and short-term management by fishing authorities and communities. This study proposes and evaluates marine reserves as a possible tool to apply since there is a current marine reserve law in Chile. The study's methodology is the simulation of a bioeconomic model that includes two areas: one is the protected, and the other is the artisanal fishing, in which the protected area transfers biomass to the artisanal fishing area. The reserve is incorporated as a decision variable in the management of this resource. It is determined as a percentage of protection of the total fish population related to fishing effort, which quantifies and evaluates the impact of protecting a stock of parental fish on the fishery's sustainability. Biomass data used is from 2000-2006, during which the anchovy fishery was fully exploited. The carrying capacity and intrinsic growth rate are estimated, and biomass is projected at different protection and effort levels. Results show that if a marine reserve with a protection level of 30% had been applied as a management policy in the anchovy fishery of central-southern Chile in the early 2000s, the fishing activity would be in a state of full exploitation rather than overexploitation as it is today. This model's fundamental contribution is that it makes possible fishery evaluation with real data from the same fishing activity.

ON THE OPTIMAL SIZE AND NUMBER OF RESERVES IN A MULTI-SITE FISHERY MODEL

2015 ◽  
Vol 23 (01) ◽  
pp. 31-47 ◽  
Author(s):  
ALI MOUSSAOUI ◽  
MERYEM BENSENANE ◽  
PIERRE AUGER ◽  
ALASSANE BAH
Keyword(s):  
Marine Reserves ◽  
Fishing Effort ◽  
Optimal Number ◽  
Reduced Model ◽  
Fish Stock ◽  
Optimal Size ◽  
Fleet Size ◽  
Fish Catch ◽  
Total Fish ◽  
Fishery Model

This paper addresses the problem of the optimal size and number of marine reserves to achieve maximum value in commercial fisheries. A simplified network planning situation is analyzed to optimize the size and number of marine reserves. We consider a general 2L-patch model of harvesting population dynamics with continuous time. Fish movements between the sites, as well as vessel displacements between the fishing sites, are assumed to take place at a faster time scale than the variation of the stock and the change of the fleet size. We take advantage of these two time scales to derive a reduced model governing the dynamics of the total fish stock and the total fishing effort. This reduced model is used to determine the optimal size and number of a marine reserves in order to maximize the catch at equilibrium. We show that the optimal number that maximizes the total fish catch at equilibrium depend intricately on the size of the reserve: A small number of reserves is optimal when the size of the reserve is higher and inverse.

scholarly journals The blue paradox: Preemptive overfishing in marine reserves

2018 ◽  
Vol 116 (12) ◽  
pp. 5319-5325 ◽  
Author(s):  
Grant R. McDermott ◽  
Kyle C. Meng ◽  
Gavin G. McDonald ◽  
Christopher J. Costello
Keyword(s):  
Large Scale ◽  
Marine Reserves ◽  
Marine Reserve ◽  
Fishing Effort ◽  
Resource Extraction ◽  
Fishing Activity ◽  
Conservation Policies ◽  
Starting Point ◽  
Resolution Dataset ◽  
General Conservation

Most large-scale conservation policies are anticipated or announced in advance. This risks the possibility of preemptive resource extraction before the conservation intervention goes into force. We use a high-resolution dataset of satellite-based fishing activity to show that anticipation of an impending no-take marine reserve undermines the policy by triggering an unintended race-to-fish. We study one of the world’s largest marine reserves, the Phoenix Islands Protected Area (PIPA), and find that fishers more than doubled their fishing effort once this area was earmarked for eventual protected status. The additional fishing effort resulted in an impoverished starting point for PIPA equivalent to 1.5 y of banned fishing. Extrapolating this behavior globally, we estimate that if other marine reserve announcements were to trigger similar preemptive fishing, this could temporarily increase the share of overextracted fisheries from 65% to 72%. Our findings have implications for general conservation efforts as well as the methods that scientists use to monitor and evaluate policy efficacy.

scholarly journals Evaluation of the effectiveness of marine reserves for transient spawning aggregations in data-limited situations

2013 ◽  
Vol 71 (3) ◽  
pp. 435-449 ◽  
Author(s):  
Arnaud Grüss ◽  
David M. Kaplan ◽  
Jan Robinson
Keyword(s):  
Marine Reserves ◽  
Fishing Effort ◽  
Spawning Aggregation ◽  
Management Options ◽  
Spawning Site ◽  
Spawning Aggregations ◽  
Stock Biomass ◽  
Fish Spawning ◽  
Spawning Stock ◽  
Effort Reduction

Abstract Many coral reef fish species form predictable, transient spawning aggregations. Many aggregations are overfished, making them a target for spatial management. Here, we develop a per-recruit model to evaluate the performance of no-take marine reserves protecting transient spawning aggregations. The model consists of only 14 demographic and exploitation-related parameters. We applied the model to a protogynous grouper and a gonochoristic rabbitfish from Seychelles and tested six scenarios regarding the extent of protected areas, the level of fish spawning-site fidelity, and fishing effort redistribution post reserve implementation. Spawning aggregation reserves improve spawning-stock biomass-per-recruit and reduce the sex ratio bias in protogynous populations for all scenarios examined. However, these benefits are often small and vary among the different scenarios and as a function of sexual ontogeny. In all scenarios, increases in yield-per-recruit do not occur or are negligible. The long-term yield increases due to spawning aggregation reserves may still occur, but only if spawning-stock biomass recovery results in a recruitment subsidy. Given these limited benefits, the value of no-take reserves must be weighed against those of other management options, such as fishing effort reduction and seasonal fishery closures. The latter is particularly appropriate when spawning and non-spawning areas overlap in space.

scholarly journals High-seas fish wars generate marine reserves

2016 ◽  
Vol 113 (14) ◽  
pp. 3767-3772 ◽  
Author(s):  
Guillermo E. Herrera ◽  
Holly V. Moeller ◽  
Michael G. Neubert
Keyword(s):  
Fishery Management ◽  
Marine Reserves ◽  
Fishing Effort ◽  
Economic Benefits ◽  
Theoretic Model ◽  
Fish Stocks ◽  
Stock Size ◽  
Game Theoretic ◽  
Game Theoretic Model ◽  
High Seas

The effective management of marine fisheries is an ongoing challenge at the intersection of biology, economics, and policy. One way in which fish stocks—and their habitats—can be protected is through the establishment of marine reserves, areas that are closed to fishing. Although the potential economic benefits of such reserves have been shown for single-owner fisheries, their implementation quickly becomes complicated when more than one noncooperating harvester is involved in fishery management, which is the case on the high seas. How do multiple self-interested actors distribute their fishing effort to maximize their individual economic gains in the presence of others? Here, we use a game theoretic model to compare the effort distributions of multiple noncooperating harvesters with the effort distributions in the benchmark sole owner and open access cases. In addition to comparing aggregate rent, stock size, and fishing effort, we focus on the occurrence, size, and location of marine reserves. We show that marine reserves are a component of many noncooperative Cournot–Nash equilibria. Furthermore, as the number of harvesters increases, (i) both total unfished area and the size of binding reserves (those that actually constrain behavior) may increase, although the latter eventually asymptotically decreases; (ii) total rents and stock size both decline; and (iii) aggregate effort used (i.e., employment) can either increase or decrease, perhaps nonmonotonically.

scholarly journals Spatial assessment of fishing effort around European marine reserves: Implications for successful fisheries management

2008 ◽  
Vol 56 (12) ◽  
pp. 2018-2026 ◽  
Author(s):  
Vanessa Stelzenmüller ◽  
Francesc Maynou ◽  
Guillaume Bernard ◽  
Gwenaël Cadiou ◽  
Matthew Camilleri ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Marine Reserves ◽  
Fishing Effort ◽  
Spatial Assessment

Effects of marine reserves on predator-prey interactions in central California kelp forests

2020 ◽  
Vol 655 ◽  
pp. 139-155
Author(s):  
DC Yates ◽  
SI Lonhart ◽  
SL Hamilton
Keyword(s):  
Species Interactions ◽  
Size Structure ◽  
Marine Reserves ◽  
Mortality Rates ◽  
Kelp Forests ◽  
Negative Effects ◽  
Central California ◽  
Invertebrate Predators ◽  
Predatory Fishes ◽  
Density And Biomass

Marine reserves are often designed to increase density, biomass, size structure, and biodiversity by prohibiting extractive activities. However, the recovery of predators following the establishment of marine reserves and the consequent cessation of fishing may have indirect negative effects on prey populations by increasing prey mortality. We coupled field surveys with empirical predation assays (i.e. tethering experiments) inside and outside of 3 no-take marine reserves in kelp forests along the central California coast to quantify the strength of interactions between predatory fishes and their crustacean prey. Results indicated elevated densities and biomass of invertebrate predators inside marine reserves compared to nearby fished sites, but no significant differences in prey densities. The increased abundance of predators inside marine reserves translated to a significant increase in mortality of 2 species of decapod crustaceans, the dock shrimp Pandalus danae and the cryptic kelp crab Pugettia richii, in tethering experiments. Shrimp mortality rates were 4.6 times greater, while crab mortality rates were 7 times greater inside reserves. For both prey species, the time to 50% mortality was negatively associated with the density and biomass of invertebrate predators (i.e. higher mortality rates where predators were more abundant). Video analyses indicated that macro-invertivore fishes arrived 2 times faster to tethering arrays at sites inside marine reserves and began attacking tethered prey more rapidly. The results indicate that marine reserves can have direct and indirect effects on predators and their prey, respectively, and highlight the importance of considering species interactions in making management decisions.

CRITICAL FACTORS OF WATER CONTENT FOR FISH STOCKS IN THE WATER RESERVOIRS OF KAZAKHSTAN

2017 ◽  
pp. 9-18
Author(s):  
Saule Zhangirovna Asylbekova ◽  
Kuanysh Baibulatovich Isbekov ◽  
Evgeniy Vyacheslavovich Kulikov
Keyword(s):  
Water Content ◽  
Water Level ◽  
Water Availability ◽  
Hydrological Regime ◽  
Fishing Effort ◽  
Water Reservoirs ◽  
The Caspian Sea ◽  
Annual Fish ◽  
Commercial Fish ◽  
Fish Stocks

The hydrological regime of water reservoirs in different years has a decisive impact on the abundance of commercial fish stocks and the quality of ichthyocenoses. In this connection in 2015-2016 there was conducted a retrospective analysis and ranking of hydrological regime impact on these factors. The paper gives evaluation of catches and fish stocks under different scenarios of water availability in the main fishing ponds of the Republic of Kazakhstan that give about 80% of the annual fish catch of the country (except the Caspian Sea). There were analyzed 2000 factors of hydrological regime (water level, annual discharge) and 1845 factors of fishing stocks (catches, abundance, fish biomass). The paper determines the critical characteristics of water availability for fish stocks. There have been proposed a number of administrative decisions and actions in case if water content would approach to the critical level. Among them: limitation of fish catches in the following year; widening zones restricted for fishing; intensification of safety measures of the fish young in residual ponds during arid periods; introduction of catch standards for a unit of fishing effort in low-water years, high-water years and years with normal water level in rivers.

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