scholarly journals Is a management framework based on spawning-stock biomass indicators sustainable? A viability approach

2007 ◽  
Vol 64 (4) ◽  
pp. 761-767 ◽  
Author(s):  
Michel De Lara ◽  
Luc Doyen ◽  
Thérèse Guilbaud ◽  
Marie-Joëlle Rochet
Keyword(s):  
Fisheries Management ◽  
Significant Contribution ◽  
Bay Of Biscay ◽  
Fishing Mortality ◽  
Precautionary Approach ◽  
Management Framework ◽  
Control Approach ◽  
Management Indicators ◽  
Stock Biomass ◽  
Spawning Stock

Abstract De Lara, M., Doyen, L., Guilbaud, Th., and Rochet, M-J. 2007. Is a management framework based on spawning-stock biomass indicators sustainable? A viability approach. – ICES Journal of Marine Science, 64: 761–767: 000–000. Fisheries management agencies have to drive resources on sustainable paths, i.e. within defined boundaries for an indefinite time. The viable-control approach is proposed as a relevant method to deal with sustainability. We analyse the ICES precautionary approach (PA) by means of the notion of viability domain, and provide a mathematical test for sustainability. It is found that the PA based on spawning-stock biomass (SSB) and fishing mortality (F) indicators is sustainable only when recruits make a significant contribution to SSB. In this case, advice based upon SSB, with an appropriate reference point, is sufficient to ensure sustainability. In all other cases, SSB is not a sufficient metric of stock productivity and must be complemented with other management indicators to ensure sustainability. The approach is illustrated with numerical applications to the northern hake and Bay of Biscay anchovy.

CCAMLR’s precautionary approach to management focusing on Ross Sea toothfish fishery

2015 ◽  
Vol 27 (4) ◽  
pp. 333-340 ◽  
Author(s):  
Stuart Hanchet ◽  
Keith Sainsbury ◽  
Doug Butterworth ◽  
Chris Darby ◽  
Viacheslav Bizikov ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Management System ◽  
Ross Sea ◽  
Stock Assessment ◽  
Precautionary Approach ◽  
Adaptive Feedback ◽  
Stock Biomass ◽  
Stock Assessments ◽  
Antarctic Marine ◽  
Spawning Stock

AbstractSeveral recent papers have criticized the scientific robustness of the fisheries management system used by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), including that for Ross Sea toothfish. Here we present a response from the wider CCAMLR community to address concerns and to correct some apparent misconceptions about how CCAMLR acts to promote conservation whilst allowing safe exploitation in all of its fisheries. A key aspect of CCAMLR’s approach is its adaptive feedback nature; regular monitoring and analysis allows for adjustments to be made, as necessary, to provide a robust management system despite the statistical uncertainties inherent in any single assessment. Within the Ross Sea, application of CCAMLR’s precautionary approach has allowed the toothfish fishery to develop in a steady fashion with an associated accumulation of data and greater scientific understanding. Regular stock assessments of the fishery have been carried out since 2005, and the 2013 stock assessment estimated current spawning stock biomass to be at 75% of the pre-exploitation level. There will always be additional uncertainties which need to be addressed, but where information is lacking the CCAMLR approach to management ensures exploitation rates are at a level commensurate with a precautionary approach.

scholarly journals An alternative reference point in the context of ecosystem-based fisheries management: maximum sustainable dead biomass

2015 ◽  
Vol 72 (8) ◽  
pp. 2257-2268 ◽  
Author(s):  
Hans-Joachim Rätz ◽  
John Casey ◽  
Steven J. Holmes ◽  
Josep Lloret ◽  
Hendrik Dörner ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Reference Points ◽  
Production Model ◽  
Fish Stock ◽  
Compensatory Mechanism ◽  
Fishing Mortality ◽  
Dead Biomass ◽  
Selection Pattern ◽  
Stock Biomass ◽  
Spawning Stock

Abstract Under the 2013 Reform of the European Union's Common Fisheries Policy (CFP), fisheries management aims to ensure that, within a reasonable time frame, the exploitation of marine biological resources restores and maintains populations of harvested stocks above levels that can produce the maximum sustainable yield (MSY). The CFP also calls for the implementation of an ecosystem-based approach to fisheries management (EBFM). In this paper, we present the concept of maximum sustainable dead biomass (MSDB) and its associated management reference points for fishing mortality and spawning-stock biomass as alternatives to those associated with MSY. The concept of MSDB is illustrated by a dynamic pool production model of a virtual fish stock which takes into account variations in natural mortality (M), fishing mortality (F), and exploitation pattern. Our approach implies a compensatory mechanism whereby survivors may benefit from compensatory density dependence and is implemented through progressive substitution of M with F for varying rates of total mortality (Z). We demonstrate that the reference points for fishing mortality and spawning-stock biomass associated with MSDB are less sensitive to increasing compensation of M with F than those associated with MSY and more sensitive to changes in selection pattern. MSDB-based reference points, which are consistent with maximum stock productivity, are also associated with lower fishing mortality rates and higher stock biomasses than their MSY-based counterparts. Given that selection pattern can be influenced through fishery input measures (e.g. technical gear measures, decisions on areas, and/or times of fishing), whereas variations of M in response to F are not controllable (indeed poorly understood), that the results of many fish stock assessments are imprecise, that maximum stock productivity corresponds to MSDB and that MSY-based reference points may best be considered as limits, we propose that MSDB-based reference points provide a more appropriate basis for management under an EBFM.

scholarly journals Can fisheries-induced evolution shift reference points for fisheries management?

2013 ◽  
Vol 70 (4) ◽  
pp. 707-721 ◽  
Author(s):  
Mikko Heino ◽  
Loїc Baulier ◽  
David S. Boukal ◽  
Bruno Ernande ◽  
Fiona D. Johnston ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Fish Population ◽  
Reference Points ◽  
Population Characteristics ◽  
Biological Processes ◽  
Fishing Mortality ◽  
Intended Meaning ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Induced Changes

Abstract Heino, M., Baulier, L., Boukal, D. S., Ernande, B., Johnston, F. D., Mollet, F. M., Pardoe, H., Therkildsen, N. O., Uusi-Heikkilä, S., Vainikka, A., Arlinghaus, R., Dankel, D. J., Dunlop, E. S., Eikeset, A. M., Enberg, K., Engelhard G. H., Jørgensen, C., Laugen, A. T., Matsumura, S., Nusslé, S., Urbach, D., Whitlock, R., Rijnsdorp, A. D., and Dieckmann, U. 2013. Can fisheries-induced evolution shift reference points for fisheries management? – ICES Journal of Marine Science, 70: 707–721. Biological reference points are important tools for fisheries management. Reference points are not static, but may change when a population's environment or the population itself changes. Fisheries-induced evolution is one mechanism that can alter population characteristics, leading to “shifting” reference points by modifying the underlying biological processes or by changing the perception of a fishery system. The former causes changes in “true” reference points, whereas the latter is caused by changes in the yardsticks used to quantify a system's status. Unaccounted shifts of either kind imply that reference points gradually lose their intended meaning. This can lead to increased precaution, which is safe, but potentially costly. Shifts can also occur in more perilous directions, such that actual risks are greater than anticipated. Our qualitative analysis suggests that all commonly used reference points are susceptible to shifting through fisheries-induced evolution, including the limit and “precautionary” reference points for spawning-stock biomass, Blim and Bpa, and the target reference point for fishing mortality, F0.1. Our findings call for increased awareness of fisheries-induced changes and highlight the value of always basing reference points on adequately updated information, to capture all changes in the biological processes that drive fish population dynamics.

scholarly journals Evaluating management strategies to implement the recovery plan for Iberian hake (Merluccius merluccius); the impact of censored catch information

2009 ◽  
Vol 67 (2) ◽  
pp. 258-269 ◽  
Author(s):  
Ernesto Jardim ◽  
Santiago Cerviño ◽  
Manuela Azevedo
Keyword(s):  
Management Strategies ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Fishing Mortality ◽  
Merluccius Merluccius ◽  
Total Allowable Catch ◽  
Recovery Plan ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The Impact

Abstract Jardim, E., Cerviño, S., and Azevedo, M. 2010. Evaluating management strategies to implement the recovery plan for Iberian hake (Merluccius merluccius); the impact of censored catch information. – ICES Journal of Marine Science, 67: 258–269. Iberian hake assessment revealed an increase in fishing mortality (F) despite enforcement of a recovery plan. Recent landings exceeded the total allowable catch and discarding rates were high. Alternative management strategies based on F control were evaluated with respect to the probability of recovering spawning-stock biomass (SSB), expected profits, and robustness to uncertainty on catch information and stock dynamics. Results showed that the use of censored catch data, i.e. excluding the Gulf of Cádiz or discards, may lead to inappropriate conclusions. Reducing fishing mortality was necessary for SSB to recover. An Fmax strategy with discard reduction showed the highest probability of rebuilding SSB and led the fishery to sustainable exploitation, with an expected %SPR of 30–40% in 2025, mean individual weight in the landings of 450 g in 2015, and yield increasing by >20%. Because of uncertainty in the estimates of maximum sustainable yield, management strategies based on FMSY were least robust, but all strategies were robust to alternative stock–recruit models.

scholarly journals Identifying juvenile and sub-adult movements to inform recovery strategies for a high value fishery—European bass (Dicentrarchus labrax)

2021 ◽  
Author(s):  
Thomas Stamp ◽  
David Clarke ◽  
Shaun Plenty ◽  
Tim Robbins ◽  
James E Stewart ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Spatial Ecology ◽  
Juvenile Fish ◽  
Dicentrarchus Labrax ◽  
Fork Length ◽  
Stock Biomass ◽  
Spawning Stock ◽  
High Site ◽  
Poor Recruitment ◽  
The Uk

Abstract The European bass (Dicentrarchus labrax) support high value commercial and recreational fisheries, however the Spawning Stock Biomass (SSB) of the northern Atlantic stock (ICES divisions 4.b–c, 7.a, and 7.d–h) has rapidly declined to an unsustainable level. The decline in SSB has been attributed to high fishing pressure combined with poor recruitment. By tracking juvenile fish their spatial ecology can be identified, and appropriate fisheries management policies designed to boost recruitment can be implemented. Using acoustic telemetry 146 sub-adult European bass (25.2–60 cm fork length) were tracked for up to 370 d across three sites in the southwest of the UK. Tagged fish were detected 2 724 548 times (Range: 166–106 393 detections per fish). Linear modelling estimated tagged fish were resident within 2.4–20.1 km of the site where they were first caught for 42.9–75.5% of the year. Some fish were however resident throughout summer and winter. Individual fish were also tracked moving up to 317 km to other coastal sites, 81% of which returned to their original capture site. Fisheries management should account for the high site fidelity displayed by juveniles and sub-adults of this species and coastal nursery sites should be considered essential habitat.

A length-based multispecies model for evaluating community responses to fishing

2006 ◽  
Vol 63 (6) ◽  
pp. 1344-1359 ◽  
Author(s):  
Stephen J Hall ◽  
Jeremy S Collie ◽  
Daniel E Duplisea ◽  
Simon Jennings ◽  
Mark Bravington ◽  
...  
Keyword(s):  
Fish Species ◽  
Single Species ◽  
Community Level ◽  
Fishing Mortality ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Multispecies Model ◽  
Species Declines ◽  
Ecosystem Based Fisheries Management ◽  
Biomass Spectra

Quantitative ecosystem indicators are needed to fulfill the mandate for ecosystem-based fisheries management. A variety of community metrics could potentially be used, but before reference levels for such indices can be established the sensitivity of candidate indices to fishing and other disturbances must be determined. One approach for obtaining such information is to test candidate indicators with models that mimic real ecosystems and can be manipulated experimentally. Here we construct a size-based multispecies model of a community of fish species that interact by predation. The model was parameterized for 21 fish species to obtain a predation-regulated community. Following an analysis of the sensitivity of the model to parameter uncertainty, we tested the sensitivity of community-level indicators to increasing levels of fishing mortality (F). Abundance and biomass spectra were sensitive to fishing mortality, with the slope decreasing with increasing F. Species diversity size spectra were also very sensitive to F, with diversity in the largest size classes declining rapidly. In contrast, k-dominance curves were less sensitive to fishing pressure. Importantly, however, although most community-level metrics showed clear trends in response to fishing, single-species declines in spawning stock biomass were the most sensitive indicators of fishing effects.

A fisheries management strategy robust to ignorance: rotational harvest in the presence of indirect fishing mortality

2000 ◽  
Vol 57 (12) ◽  
pp. 2357-2362 ◽  
Author(s):  
Ransom A Myers ◽  
Susanna D Fuller ◽  
Daniel G Kehler
Keyword(s):  
Management Strategy ◽  
Narrow Range ◽  
Fishing Mortality ◽  
Placopecten Magellanicus ◽  
Sea Scallop ◽  
Simple Theoretical Model ◽  
Stock Biomass ◽  
Wide Range ◽  
Spawning Stock ◽  
Harvest Strategy

We develop a simple theoretical model of yield and spawning stock biomass per recruit for the American sea scallop (Placopecten magellanicus), which appears to have high indirect fishing mortality when harvested with dredges, i.e., mortality caused by the act of fishing that does not result in landings. The age at and degree to which individuals are affected by the indirect mortality are unknown, and it does not appear possible to develop a robust harvest strategy with yearly harvests unless indirect fishing mortality is well quantified. We show that there could be substantial benefits to a rotational harvest strategy for sessile species with high indirect fishing mortality. First, the strategy appears to be robust to ignorance about indirect fishing mortality and results in equal or better yields than a yearly harvest across a wide range of indirect fishing mortalities. Second, under most conditions, a higher spawning stock biomass is maintained. Third, rotational management is more easily enforced, as it does not require specifying a narrow range of fishing mortality in order to maximize yield.

scholarly journals On the dynamics of Sardina pilchardus: orbits of stability and environmental forcing

2010 ◽  
Vol 67 (8) ◽  
pp. 1565-1573
Author(s):  
A. P. Solari ◽  
M. T. G. Santamaría ◽  
M. F. Borges ◽  
A. M. P. Santos ◽  
H. Mendes ◽  
...  
Keyword(s):  
Sea Surface ◽  
External Forcing ◽  
Fishing Mortality ◽  
Sardina Pilchardus ◽  
Environmental Forcing ◽  
Stock Biomass ◽  
External Variables ◽  
Multiresolution Decomposition ◽  
Spawning Stock ◽  
Upwelling Index

Abstract Solari, A. P., Santamaría, M. T. G., Borges, M. F., Santos, A. M. P., Mendes, H., Balguerías, E., Díaz Cordero, J. A., Castro, J. J., and Bas, C. 2010. On the dynamics of Sardina pilchardus: orbits of stability and environmental forcing. – ICES Journal of Marine Science, 67: 1565–1573. The dynamics of Sardina pilchardus in Iberian upwelling are examined. Spawning-stock biomass (SSB), recruitment (R), and production (R/SSB) data for the years 1978–2006 are analysed in relation to the upwelling index (UPW) and sea surface temperature (SST). The population oscillates in two relatively stable orbits (identified by multiresolution decomposition of the recruitment series) because the external forcing (UPW and SST) are the inverse of each other and the synchrony is lost between the two external variables, R and R/SSB as they shift towards steep, negative (depensatory) trends. Such mechanics may have induced recruitment failures and significant decreases in abundance of Iberian sardine. The relationships are assumed to validate a complex and dynamic continuum (multiple orbits of stability) and an alternative variable-carrying-capacity population model. Radial systems with two orbits of stability are proposed for the R/SSB and S/SSB (where S is the stock size) relationships. Results are discussed in relation to classical and alternative SR models to address stock rehabilitation and fishing mortality issues as the population shifts towards low recruitment and abundance, and critical factors to consider in developing exploitation strategies for systems with multiple orbits of stability are discussed.

scholarly journals Daily egg production of anchovy in European waters

2004 ◽  
Vol 61 (6) ◽  
pp. 944-958 ◽  
Author(s):  
Stylianos Somarakis ◽  
Isabel Palomera ◽  
Alberto Garcia ◽  
Luis Quintanilla ◽  
Constantin Koutsikopoulos ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Egg Production ◽  
Stock Assessment ◽  
Production Method ◽  
Bay Of Biscay ◽  
Spawning Habitat ◽  
Independent Information ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The Mediterranean

Abstract Since the late 1980s, the Daily Egg Production Method (DEPM) has been applied to several anchovy stocks in European waters. DEPM surveys in the Bay of Biscay were well standardized and focused on providing fisheries-independent information for stock assessment purposes. Those targeting Mediterranean stocks were largely experimental and often opportunistic, with the main aim of developing and testing the method, rather than providing estimates of spawning stock biomass (SSB) for stock assessment. Consequently, the DEPM has been applied once, twice, or a maximum of three times in certain Mediterranean areas with no among-area standardization. Different techniques for several aspects of the method have been used in the Mediterranean, and the parameters estimated vary greatly among stocks and year of application. Evidence is provided that variability in biological production among sub-basins and/or years, a characteristic of Mediterranean Sea, may directly affect anchovy egg production. The daily specific fecundity of anchovy stocks can vary greatly among years, areas, or seasons in response to changing environmental and trophic regimes. When the correlation between regression-derived estimates of daily egg production and associated estimates of daily specific fecundity for anchovy in the Mediterranean, the Bay of Biscay, and upwelling areas are compared, a significant isometric relationship emerges for the Mediterranean and the Bay of Biscay, implying density-dependent use of spawning habitat. In upwelling areas, estimates of daily egg production are relatively high for a narrow range of generally low daily specific fecundities. There is a strong linear relationship between anchovy SSB and spawning area in European waters that does not differ significantly between the Bay of Biscay and the Mediterranean Sea.

A Surplus Yield Model Incorporating Recruitment and Applied to a Stock of Atlantic Mackerel (Scomber scombrus)

1978 ◽  
Vol 35 (2) ◽  
pp. 229-234 ◽  
Author(s):  
Gilbert G. Walter
Keyword(s):  
Fisheries Management ◽  
Fishing Mortality ◽  
Yield Model ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Stock Biomass ◽  
Equilibrium Yield ◽  
Class Strength ◽  
Nonequilibrium Conditions

A modification of Schaefer's surplus yield model that takes into account variations in year-class strength is introduced. Expressions for long-term equilibrium yield under assumptions of both linear and density-dependent recruitment are derived and compared. Strategies for exploitation under nonequilibrium conditions are discussed and equations derived. The model is fitted to a stock of mackerel and projections for the stock biomass in 1980 under various levels of fishing mortality are made. Key words: mathematical model, fisheries management, stock biomass projections

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