scholarly journals On the spillover effect and optimal size of marine reserves for sustainable fishing yields

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9798
Author(s):  
Nao Takashina
Keyword(s):  
Numerical Simulations ◽  
Migration Rate ◽  
Marine Reserves ◽  
Marine Reserve ◽  
Practical Importance ◽  
Spillover Effect ◽  
Optimal Size ◽  
Fishing Mortality ◽  
Optimal Reserve ◽  
Reserve Size

Marine reserves are an essential component of modern fishery management. Marine reserves, which represent a management tradeoff between harvesting and conservation, are fundamental to maintenance of fisheries. Finding optimal reserve sizes that improve fishing yields is not only of theoretical interest, but also of practical importance to facilitate decision making. Also, since the migratory behavior of some species influences the spillover effect of a marine reserve, this is a key consideration when assessing performance of marine reserves. The relationship between optimal reserve size and migration rate/mode has not been well studied, but it is fundamental to management success. Here, I investigate optimal reserve size and its management outcome with different levels of spillover via a simple two-patch mathematical model. In this model, one patch is open to fishing, and the other is closed. The two-patch model is aggregated by single-population dynamics when the migration rate is sufficiently larger than the growth rate of a target species. At this limit, I show that an optimal reserve size exists when pre-reserve fishing occurs at fishing mortality larger than fMSY, the fishing mortality at the maximum sustainable yield (MSY). Also, the fishing yield at an optimal reserve size becomes as large as MSY at the limit. Numerical simulations at various migration rates between the two patches suggest that the maximum harvest under management with a marine reserve is achieved at this limit. This contrasts with the conservation benefit which is maximized at an intermediate migration rate. Numerical simulations show that the above-mentioned condition for an optimal reserve size to exist derived from the aggregated model is necessary when the migration rate is not sufficiently large, and that a moderate migration rate is further necessary for an optimal reserve size to exist. However, high fishing mortality reduces this requirement.

scholarly journals On the spillover effect and optimal size of marine reserves for sustainable fishing yields

2019 ◽  
Author(s):  
Nao Takashina
Keyword(s):  
Numerical Simulations ◽  
Migration Rate ◽  
Marine Reserves ◽  
Marine Reserve ◽  
Practical Importance ◽  
Spillover Effect ◽  
Optimal Size ◽  
Fishing Mortality ◽  
Optimal Reserve ◽  
Reserve Size

AbstractMarine reserves are an essential component of modern fishery management. Marine reserves, which represent a management tradeoff between harvesting and conservation, are fundamental to maintenance of fisheries. Finding optimal reserve sizes that improve fishing yields is not only of theoretical interest, but also of practical importance to facilitate decision making. Also, since the migratory behavior of some species influences the spillover effect of a marine reserve, this is a key consideration when assessing performance of marine reserves. The relationship between optimal reserve size and migration rate/mode has not been well studied, but it is fundamental to management success. Here, I investigate optimal reserve size and its management outcome with different levels of spillover via a simple two-patch mathematical model. In this model, one patch is open to fishing, and the other is closed. The two-patch model is aggregated by single-population dynamics when the migration rate is sufficiently larger than the growth rate of a target species. At this limit, I show that an optimal reserve size exists when pre-reserve fishing occurs at fishing mortality larger than fMSY, the fishing mortality at the maximum sustainable yield (MSY). Also, the fishing yield at an optimal reserve size becomes as large as MSY at the limit. Numerical simulations at various migration rates between the two patches suggest that the maximum harvest under management with a marine reserve is achieved at this limit. This contrasts with the conservation benefit which is maximized at an intermediate migration rate. Numerical simulations show that the above-mentioned condition derived from the aggregated model is necessary when the migration rate is not sufficiently large, and that a moderate migration rate is further necessary for an optimal reserve size to exist. However, high fishing mortality reduces this requirement.

Marine reserves for Caribbean spiny lobster: empirical evaluation and theoretical metapopulation recruitment dynamics

2001 ◽  
Vol 52 (8) ◽  
pp. 1589 ◽  
Author(s):  
Romuald N. Lipcius ◽  
William T. Stockhausen ◽  
David B. Eggleston
Keyword(s):  
Habitat Quality ◽  
Marine Reserves ◽  
Spiny Lobster ◽  
Empirical Evaluation ◽  
Circulation Model ◽  
Transport Processes ◽  
Adult Density ◽  
Fishing Mortality ◽  
Before And After ◽  
Optimal Reserve

Field data on spiny-lobster abundance, habitat quality, and hydrodynamic transport patterns for a reserve (ECLSP) and three exploited sites (CI, EI, LSI) were used to assess reserve success in reducing fishing mortality and increasing theoretical metapopulation recruitment. Fishing mortality was estimated empirically by quantification of lobster density at ECLSP and the three exploited sites before and after the start of the fishing season in two years. Fishing mortality was estimated to be 47–98% lower at the reserve. Using a circulation model , we theoretically assessed effectiveness of ECLSP and nominal reserves at the exploited sites in augmenting recruitment through redistribution of larvae to all sites. Larvae discharged from ECLSP and EI recruited throughout Exuma Sound, whereas those from LSI and CI recruited only to CI and LSI. Hence, only reserves at EI and ECLSP would be suitable for metapopulation recruitment. In selecting an optimal reserve for metapopulation recruitment, use of information on habitat quality or adult density did not yield a higher probability of success than did determining the reserve location by chance. The only successful strategy was one that used information on transport processes. Designation of effective marine reserves therefore requires careful attention to metapopulation dynamics and recruitment processes.

Incorporating behavioural variation in individual-based simulation models of marine reserve effectiveness

2012 ◽  
Vol 39 (3) ◽  
pp. 282-294 ◽  
Author(s):  
RUSSELL C. BABCOCK ◽  
DANIEL P. EGLI ◽  
COLIN G. ATTWOOD
Keyword(s):  
Census Data ◽  
Marine Reserves ◽  
Marine Reserve ◽  
Simulation Models ◽  
Marine Species ◽  
Fish Populations ◽  
Range Of Movement ◽  
Mobile Species ◽  
Individual Based Simulation ◽  
Optimal Reserve

SUMMARYEffective spatial management of marine species requires informed planning, as well as ongoing assessment. For mobile species such as fish, knowledge of the scale and variation in movement is central to key planning decisions, such as the size and shape of marine reserves and the interpretation of the response of protected populations. For example, populations of species that require large areas of habitat may not show increases in abundance inside small reserves, but calculating optimal reserve size is complicated by individual variations in behaviour. Fish movements can be used to quantitatively inform marine reserve planning and assessment. An individual based numerical simulation model including acoustic telemetry and census data was used to simulate changes in populations of snapper Pagrus auratus in north-eastern New Zealand. Four behavioural categories and offshore migration were used to represent the observed variability in movement. Age-structures of modelled fish populations in fully exploited areas, marine reserves and virgin populations differed substantially. However, the population structure within reserves resembled a fully fished population more closely than an unfished population. Due to the range of movement types shown by snapper, fish were not ‘locked up’ by reserves, and fish with centres of activity based in reserves were predicted to have a relatively high chance of being caught outside these reserves. Furthermore, the model showed that the response of fish populations within marine reserves was dependent on levels of exploitation in fished areas. For snapper in coastal reef areas, reserves c. 40 km2 or more may be required to achieve abundances > 50% of the unfished stock. On balance, while marine reserves with sizes similar to Leigh and Tawharanui (c. 5 km2) can achieve significant levels of protection for snapper, they are too small to fully protect resident reserve snapper populations.

Determination of Optimal Reserve between Two Machines in Series with the Repair Time has Change of Distribution after the Truncation Point

GIS Business ◽  
2019 ◽  
Vol 14 (6) ◽  
pp. 577-585
Author(s):  
T. Vivekanandan ◽  
S. Sachithanantham
Keyword(s):  
Real Life ◽  
Random Variable ◽  
Repair Time ◽  
Inventory Level ◽  
Optimal Size ◽  
Truncation Point ◽  
In Series ◽  
Optimal Reserve ◽  
Optimal Inventory Level ◽  
Two Machines

In inventory control, suitable models for various real life systems are constructed with the objective of determining the optimal inventory level.  A new type of inventory model using the so-called change of distribution property is analyzed in this paper. There are two machines M1 and M2  in series and the output of M1 is the input of M2. Hence a reserve inventory between M1 and M2 is to be maintained. The method of obtaining the optimal size of reserve inventory, assuming cost of excess inventory, cost of shortage and when the rate of consumption of M2  is a constant, has already been attempted.  In this paper, it is assumed that the repair time of M1  is a random variable and the distribution of the same undergoes a change of distribution  after the truncation point X0 , which is taken to be a random variable.  The optimal size of the reserve inventory is obtained under the above said  assumption . Numerical illustrations are also provided.

Modelling the effects of reserve size and fishing mortality for Caribbean queen conchStrombus gigas

2012 ◽  
Vol 22 (6) ◽  
pp. 721-730 ◽  
Author(s):  
Jennifer Hernandez-Lamb ◽  
Anthony Dibello ◽  
Shelley Lewis ◽  
Gail Mackin ◽  
Kevin Kirby ◽  
...  
Keyword(s):  
Fishing Mortality ◽  
Reserve Size

scholarly journals Spillover from marine reserves and the replenishment of fished stocks

2009 ◽  
Vol 36 (4) ◽  
pp. 268-276 ◽  
Author(s):  
BENJAMIN S. HALPERN ◽  
SARAH E. LESTER ◽  
JULIE B. KELLNER
Keyword(s):  
Empirical Evidence ◽  
Empirical Data ◽  
Marine Reserves ◽  
Marine Reserve ◽  
Population Models ◽  
The Other ◽  
Marine Resources ◽  
Common Phenomenon ◽  
Small Scales ◽  
Effective Conservation

SUMMARYNo-take marine reserves are widely recognized as an effective conservation tool for protecting marine resources. Despite considerable empirical evidence that abundance and biomass of fished species increase within marine reserve boundaries, the potential for reserves to provide fisheries and conservation benefits to adjacent waters remains heavily debated. This paper uses statistical and population models to evaluate published empirical data on adult spillover from marine reserves and shows that spillover is a common phenomenon for species that respond positively to reserve protection, but at relatively small scales, detectable on average up to 800 m from reserve boundaries. At these small scales, local fisheries around reserves were likely unsustainable in 12 of 14 cases without the reserve, and spillover partially or fully offsets losses in catch due to reserve closure in the other two cases. For reserves to play a role in sustaining and replenishing larger-scale fished stocks, networks of reserves may be necessary, but as few exist this is difficult to evaluate. The results suggest reserves can simultaneously meet conservation objectives and benefit local fisheries adjacent to their boundaries.

Are the scientific foundations of temperate marine reserves too warm and hard?

2012 ◽  
Vol 39 (3) ◽  
pp. 199-203 ◽  
Author(s):  
A.J. CAVEEN ◽  
C.J. SWEETING ◽  
T.J. WILLIS ◽  
N.V.C. POLUNIN
Keyword(s):  
Scientific Literature ◽  
Research Effort ◽  
Marine Reserves ◽  
Marine Reserve ◽  
Relative Lack ◽  
Empirical Basis ◽  
High Profile ◽  
Warm Temperate

SUMMARYThe scientific literature (including some of the most high-profile papers) on the ecological and fisheries effects of permanent no-take marine reserves is dominated by examples from hard tropical and warm temperate ecosystems. It appears to have been tacitly assumed that inference from these studies can directly inform expectations of marine reserve effects in cooler temperate and cold temperate waters. Trends in peer-reviewed studies indicate that the empirical basis for this assumption is tenuous because of a relative lack of research effort in cooler seas, and differences between tropical and temperate regions in ecology, seasonality, the nature of fisheries and prevailing governance regimes.

scholarly journals A connectivity portfolio effect stabilizes marine reserve performance

2020 ◽  
Vol 117 (41) ◽  
pp. 25595-25600
Author(s):  
Hugo B. Harrison ◽  
Michael Bode ◽  
David H. Williamson ◽  
Michael L. Berumen ◽  
Geoffrey P. Jones
Keyword(s):  
Marine Reserves ◽  
Marine Reserve ◽  
Management Strategies ◽  
Temporal Stability ◽  
Parentage Analysis ◽  
Larval Supply ◽  
Dispersal Patterns ◽  
Temporal Fluctuations ◽  
Local Populations ◽  
Portfolio Effect

Well-managed and enforced no-take marine reserves generate important larval subsidies to neighboring habitats and thereby contribute to the long-term sustainability of fisheries. However, larval dispersal patterns are variable, which leads to temporal fluctuations in the contribution of a single reserve to the replenishment of local populations. Identifying management strategies that mitigate the uncertainty in larval supply will help ensure the stability of recruitment dynamics and minimize the volatility in fishery catches. Here, we use genetic parentage analysis to show extreme variability in both the dispersal patterns and recruitment contribution of four individual marine reserves across six discrete recruitment cohorts for coral grouper (Plectropomus maculatus) on the Great Barrier Reef. Together, however, the asynchronous contributions from multiple reserves create temporal stability in recruitment via a connectivity portfolio effect. This dampening effect reduces the variability in larval supply from individual reserves by a factor of 1.8, which effectively halves the uncertainty in the recruitment contribution of individual reserves. Thus, not only does the network of four marine reserves generate valuable larval subsidies to neighboring habitats, the aggregate effect of individual reserves mitigates temporal fluctuations in dispersal patterns and the replenishment of local populations. Our results indicate that small networks of marine reserves yield previously unrecognized stabilizing benefits that ensure a consistent larval supply to replenish exploited fish stocks.

Influence of marine reserve size and boundary length on the initial response of exploited reef fishes in the Florida Keys National Marine Sanctuary, USA

2007 ◽  
Vol 23 (S1) ◽  
pp. 55-65 ◽  
Author(s):  
Aaron Bartholomew ◽  
James A. Bohnsack ◽  
Steven G. Smith ◽  
Jerald S. Ault ◽  
Douglas E. Harper ◽  
...  
Keyword(s):  
Marine Reserve ◽  
Florida Keys ◽  
Initial Response ◽  
Reef Fishes ◽  
Boundary Length ◽  
Reserve Size

The role of dispersal and demography in determining the efficacy of marine reserves

2005 ◽  
Vol 62 (4) ◽  
pp. 863-871 ◽  
Author(s):  
Leah R Gerber ◽  
Selina S Heppell ◽  
Ford Ballantyne ◽  
Enric Sala
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Transition Probabilities ◽  
Marine Reserves ◽  
Marine Reserve ◽  
Adult Mortality ◽  
Current Theory ◽  
Transition Matrices ◽  
Surrounding Matrix ◽  
Matrix Habitat

Marine reserves are rapidly becoming an important tool for protection and recovery of depleted marine populations. However, the relative value of reserves to particular species is strongly dependent on its life history and behavior. We present a general conceptual framework for considering dispersal in simple demographic models. This framework includes transition matrices that consist of two age-structured models connected by transition probabilities for general migration, ontogenetic shifts, and recruitment in both a reserve and an unprotected area. We show that life history characteristics and perturbation analysis can be used to predict changes in growth rate due to a decrease in adult mortality resulting from a marine reserve for different levels and types of dispersal. Reserves enhanced growth rate for all species irrespective of net dispersal between the reserve and surrounding matrix habitat, but the efficacy of reserves relative to catch reduction depended significantly on the magnitude and sign of net dispersal across the reserve boundary. Patterns of reserve efficacy across different dispersal types were strongly species specific. Given the paucity of spatially explicit data for many marine systems and species, this simple approach represents a first step in applying life history information to advance current theory and provide practical considerations for marine reserve management.

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