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 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.

scholarly journals Consequences of bias in age estimation on assessment of the northern stock of European hake (Merluccius merluccius) and on management advice

2007 ◽  
Vol 64 (5) ◽  
pp. 981-988 ◽  
Author(s):  
Michel Bertignac ◽  
Hélène de Pontual
Keyword(s):  
Age Estimation ◽  
Growth Parameters ◽  
Reference Points ◽  
Fishing Mortality ◽  
Merluccius Merluccius ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Management Advice ◽  
The Impact ◽  
European Hake

Abstract Bertignac, M., and de Pontual, H. 2007. Consequences of bias in age estimation on assessment of the northern stock of European hake (Merluccius merluccius) and on management advice. – ICES Journal of Marine Science, 64: 981–988. The results of a pilot tagging study on hake (Merluccius merluccius), conducted in the northern part of the Bay of Biscay in 2002, indicate that growth rates for this stock may be currently underestimated because of biased estimates of age. The impact that such a bias may have on the stock dynamics and the trends of the key population parameters, recruitment, spawning-stock biomass (SSB), and mortality are investigated. Assuming new growth parameters, a new age–length key is derived and used to produce and catch-at-age data and abundance indices, which are then used to assess the stock. Bias in estimating age affects the absolute levels of fishing mortality and stock biomass estimates, and also impacts the trend in SSB. However, trends in fishing mortality and recruitment are comparable, and the stock status with respect to precautionary reference points is broadly the same. As expected, the simulation also shows that the stock may be more reactive to changes in fishing levels, which affect medium-term forecasts. Long-term sustainable yields may also be impacted.

scholarly journals Implementing the precautionary approach into fisheries management: Making the case for probability-based harvest control rules

2020 ◽  
Author(s):  
Tobias K. Mildenberger ◽  
Casper W. Berg ◽  
Alexandros Kokkalis ◽  
Adrian R. Hordyk ◽  
Chantel Wetzel ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Management Strategies ◽  
Reference Points ◽  
Production Model ◽  
Scientific Uncertainty ◽  
Precautionary Approach ◽  
Control Rules ◽  
Stock Biomass ◽  
Harvest Control Rules

AbstractThe precautionary approach to fisheries management advocates for risk-averse management strategies that include biological reference points as well as decision rules and account for scientific uncertainty. In this regard, two approaches have been recommended: (i) harvest control rules (HCRs) with threshold reference points to safeguard against low stock biomass, and (ii) the P* method, a ‘probability-based HCR’ that reduces the catch limit as a function of scientific uncertainty (i.e. process, model, and observation uncertainty). This study compares the effectiveness of these precautionary approaches in recovering over-exploited fish stocks with various life-history traits and under a wide range of levels of scientific uncertainty. We use management strategy evaluation based on a stochastic, age-based operating model with quarterly time steps and a stochastic surplus production model. The results show that the most effective HCR includes both a biomass threshold as well as the P* method, and leads to high and stable long-term yield with a decreased risk of low stock biomass. For highly dynamics stocks, management strategies that aim for higher biomass targets than the traditionally used BMSY result in higher long-term yield. This study makes the case for probability-based HCRs by demonstrating their benefit over deterministic HCRs and provides a list of recommendations regarding their definition and implementation.

scholarly journals Spatial reference points for groundfish

2016 ◽  
Vol 73 (10) ◽  
pp. 2468-2478 ◽  
Author(s):  
Emilie Reuchlin-Hugenholtz ◽  
Nancy L. Shackell ◽  
Jeffrey A. Hutchings ◽  
Keyword(s):  
Fisheries Management ◽  
High Density ◽  
Reference Points ◽  
Spatial Reference ◽  
Individual Fitness ◽  
Fitness Consequences ◽  
Positive Individual ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Density Dependent Habitat Selection

Abstract According to density-dependent habitat selection theory, areas of high density can be indicative of high population productivity and have positive individual fitness consequences. Here, we explore six groundfish populations on the Scotian Shelf, Canada, where a decline in areas of high density beyond a certain threshold is associated with disproportionately large declines in Spawning Stock Biomass (SSB). This is evidenced by empirical, concave, positive relationships between high-density areas (HDAs) and SSB. We introduce a methodology to estimate the threshold below which SSB declines increasingly faster per unit of HDA decline. The spatial threshold among these six stocks was remarkably consistent; when stocks lose 70–80% of HDAs, disproportionately large SSB declines are likely to occur. We propose that spatial thresholds could serve as spatial reference points to complement existing SSB limit reference points (LRPs). For some stocks we identify spatial thresholds which correspond to SSB levels that exceed those associated with the designated SSB LRP, suggesting that a review of these SSB LRPs warrants merit. For other stocks, spatial reference points can be used in concert with SSB reference points, strengthening efforts to incorporate a precautionary approach to fisheries management. Our results warrant further research into the general application of HDA as spatial limit and target reference points for fisheries management in addition to other population status indicators within a broad recovery framework.

scholarly journals A two-stage biomass model to assess the English Channel cuttlefish (Sepia officinalis L.) stock

2014 ◽  
Vol 71 (9) ◽  
pp. 2457-2468 ◽  
Author(s):  
Michaël Gras ◽  
Beatriz A. Roel ◽  
Franck Coppin ◽  
Eric Foucher ◽  
Jean-Paul Robin
Keyword(s):  
Reference Points ◽  
Sea Surface ◽  
Sepia Officinalis ◽  
Sustainable Utilization ◽  
English Channel ◽  
Two Stage ◽  
Stock Biomass ◽  
Exploitation Rate ◽  
Spawning Stock ◽  
Age Structured

Abstract The English Channel cuttlefish (Sepia officinalis) is the most abundant cephalopod resource in the Northeast Atlantic and one of the three most valuable resources for English Channel fishers. Depletion methods and age-structured models have been used to assess the stock, though they have shown limitations related to the model assumptions and data demand. A two-stage biomass model is, therefore, proposed here using, as input data, four abundance indices derived from survey and commercial trawl data collected by Ifremer and Cefas. The model suggests great interannual variability in abundance during the 17 years of the period considered and a decreasing trend in recent years. Model results suggest that recruitment strength is independent of spawning–stock biomass, but appears to be influenced by environmental conditions such as sea surface temperature at the start of the life cycle. Trends in exploitation rate do not reveal evidence of overexploitation. Reference points are proposed and suggestions for management of the sustainable utilization of cuttlefish in the English Channel are advanced.

An Alternative Perspective on Recruitment Overfishing and Biological Reference Points

1987 ◽  
Vol 44 (4) ◽  
pp. 913-918 ◽  
Author(s):  
M. P. Sissenwine ◽  
J. G. Shepherd
Keyword(s):  
Fisheries Management ◽  
Reference Point ◽  
Reference Points ◽  
Fishing Mortality ◽  
Alternative Perspective ◽  
Conventional Models ◽  
Definition Of ◽  
Yield Per Recruit ◽  
Spawning Biomass

Biological reference points are used to guide fisheries management decisions. The reference points most often used are expressed in terms of fishing mortality rate (F). Fmsy relates to the maximization of sustainable yield. In principle, it is a most useful reference point, but in practice it is difficult to estimate. Fmax and F0.1 relate to certain levels of yield per recruit and are easily estimated, but they ignore conservation of the resource. Recruitment overfishing has usually been understood to occur when a population has been fished down to a point where recruitment is substantially reduced or fails. It has not been used as a basis for a biological reference point because the definition is vague and cannot be readily related to fishing mortality. Levels of spawning biomass below which recruitment seems to be reduced have been used, but their determination from available data is usually difficult and controversial. We propose an alternative definition of recruitment overfishing in terms of the level of fishing pressure that reduces the spawning biomass of a year class over its lifetime below the spawning biomass of its parents on average. Conventional models and types of data can be used to determine this level of F, denoted as Frep, which clearly relates to the replacement of spawning biomass and thus to sustainability of a population and yield in the long term.

scholarly journals Ecosystem-based reference points under varying plankton productivity states and fisheries management strategies

2019 ◽  
Vol 76 (7) ◽  
pp. 2045-2059 ◽  
Author(s):  
Chuanbo Guo ◽  
Caihong Fu ◽  
Robyn E Forrest ◽  
Norm Olsen ◽  
Huizhu Liu ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Management Strategies ◽  
Reference Points ◽  
Productivity Change ◽  
Pacific Herring ◽  
Fishing Mortality ◽  
Pacific Cod ◽  
Sustainable Fisheries ◽  
Ecosystem Effects ◽  
Plankton Biomass

Abstract In the context of ecosystem-based fisheries management, which should consider changing and uncertain environmental conditions, the development of ecosystem-based biological reference points (EBRPs) to account for important multi-species (MS) interactions, fishery operations, and climate change, is of paramount importance for sustainable fisheries management. However, EBRPs under varying plankton productivity states and fisheries management strategies are seldom developed, and the ecosystem effects of these changes are still largely unknown. In this study, ecosystem-based FMSY (fishing mortality rate at MSY) values were estimated within an end-to-end ecosystem model (OSMOSE) for three focused fish species (Pacific Herring, Clupea pallasii; Pacific Cod, Gadus macrocephalus; Lingcod, Ophiodon elongatus) under three plankton productivity states of differing plankton biomass at high, current, and low levels. In addition, ecosystem effects were compared across different plankton productivity and fisheries management strategies with the latter consisting of two fishery scenarios (i.e. single-species-focused (SS) and MS-focused), various fishing mortality rates, and two harvest policies (with and without harvest control rules, HCRs). Main findings of this study include: (i) plankton productivity change affected the values of ecosystem-based FMSY, which increased as plankton productivity states changed from low to high plankton biomass; (ii) ecosystem-based FMSY for Pacific Herring and Pacific Cod stocks increased when fishery scenarios shifted from SS-focused to MS-focused; (iii) fisheries management incorporating HCR yielded more stable system catch and system biomass; and (iv) high plankton biomass combined with fisheries management using HCR could maintain stable ecosystem production and sustainable fisheries. Based on our findings, we highlight possible adaptive fisheries management strategies in the face of future climate and ocean changes. Overall, EBRPs complement SS stock assessments by incorporating key ecological processes and ecosystem properties, thus providing supporting evidence for better incorporation of ecosystem considerations into scientific advice for sustainable fisheries management.

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 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.

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