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 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.

Detecting and correcting underreported catches in fish stock assessment: trial of a new method

2010 ◽  
Vol 67 (8) ◽  
pp. 1247-1261 ◽  
Author(s):  
Nicolas Bousquet ◽  
Noel Cadigan ◽  
Thierry Duchesne ◽  
Louis-Paul Rivest
Keyword(s):  
Gadus Morhua ◽  
Stock Assessment ◽  
Population Analysis ◽  
Assessment Model ◽  
Fish Stock ◽  
Stock Biomass ◽  
Stock Assessments ◽  
Spawning Stock ◽  
Age Structured ◽  
Fish Stock Assessment

Landings from fisheries are often underreported, that is, the true landings are greater than those reported. Despite this bias, reported landings are widely used in fish stock assessments, and this might lead to overoptimistic exploitation strategies. We construct a statistical stock assessment model that accounts for underreported landings using the theory of censoring with sequential population analysis (SPA). The new model is developed and implemented specifically for the cod stock ( Gadus morhua ) from the southern Gulf of St. Lawrence (Canada). This stock is known to have unreported overfishing during 1985–1992. We show in simulations that for this stock, the new censored model can correctly detect the problematic landings. These corrections are nearly insensitive to subjective boundaries placed on real catches and robust to modifications imposed in the simulation of landings. However, when surveys are too noisy, the new SPA for censored catches can result in increased uncertainty in parameters used for management such as spawning stock biomass and age-structured stock size.

Estimating uncertainty of data limited stock assessments

2016 ◽  
Vol 74 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Alexandros Kokkalis ◽  
Anne Maria Eikeset ◽  
Uffe H. Thygesen ◽  
Petur Steingrund ◽  
Ken H. Andersen
Keyword(s):  
Stock Assessment ◽  
Assessment Method ◽  
Fish Stocks ◽  
Stock Status ◽  
North East ◽  
The North ◽  
Stock Biomass ◽  
Uncertainty Estimates ◽  
Stock Assessments ◽  
Spawning Stock

Many methods exist to assess the fishing status of data-limited stocks; however, little is known about the accuracy or the uncertainty of such assessments. Here we evaluate a new size-based data-limited stock assessment method by applying it to well-assessed, data-rich fish stocks treated as data-limited. Particular emphasis is put on providing uncertainty estimates of the data-limited assessment. We assess four cod stocks in the North-East Atlantic and compare our estimates of stock status (F/Fmsy) with the official assessments. The estimated stock status of all four cod stocks followed the established stock assessments remarkably well and the official assessments fell well within the uncertainty bounds. The estimation of spawning stock biomass followed the same trends as the official assessment, but not the same levels. We conclude that the data-limited assessment method can be used for stock assessment and that the uncertainty estimates are reliable. Further work is needed to quantify the spawning biomass of the stock.

A reanalysis of North Sea plaice spawning-stock biomass using the annual egg production method

2009 ◽  
Vol 66 (9) ◽  
pp. 1999-2011 ◽  
Author(s):  
Cindy J. G. van Damme ◽  
Loes J. Bolle ◽  
Clive J. Fox ◽  
Petter Fossum ◽  
Gerd Kraus ◽  
...  
Keyword(s):  
North Sea ◽  
Egg Production ◽  
Stock Assessment ◽  
Population Analysis ◽  
Spatial Dynamics ◽  
Production Method ◽  
Southern Bight ◽  
The North ◽  
Stock Biomass ◽  
Spawning Stock

Abstract van Damme, C. J. G., Bolle, L. J., Fox, C. J., Fossum, P., Kraus, G., Munk, P., Rohlf, N., Witthames, P. R., and Dickey-Collas, M. 2009. A reanalysis of North Sea plaice spawning-stock biomass using the annual egg production method. – ICES Journal of Marine Science, 66: 1999–2011. Uncertainty about the quality of current virtual population analysis-based stock assessment for North Sea plaice (Pleuronectes platessa) has led to various abundance indices. We compared biomass estimates from the annual egg production (AEP) method with current stock assessments based on catch-at-age to validate the current and historical perception of exploitation. The AEP method was also used to investigate the dynamics of the spatial components of plaice in the North Sea. We corrected for fecundity down-regulation and changes in sex ratio. Estimates from both methods were similar in trend and absolute biomass. On the Dogger Bank, there was a dramatic decline in biomass from 1948 and 1950 to 2004, and in the Southern Bight, the stock appeared to increase from 1987 and 1988 to 2004, although not reaching the historically high levels of 1948 or 1950. The timing of spawning of North Sea plaice does not appear to have changed throughout the period of high exploitation. We conclude that the AEP method is a useful way to hindcast the spatial dynamics of heavily exploited flatfish stocks.

Comparison of the performance of age-structured models with few survey indices

2018 ◽  
Vol 75 (6) ◽  
pp. 2016-2024
Author(s):  
Hiroshi Okamura ◽  
Yuuho Yamashita ◽  
Momoko Ichinokawa ◽  
Shota Nishijima
Keyword(s):  
Stock Assessment ◽  
Population Analysis ◽  
Assessment Model ◽  
Sufficient Information ◽  
Abundance Estimates ◽  
Virtual Population ◽  
Stock Biomass ◽  
Abundance Indices ◽  
Spawning Stock ◽  
Age Structured

Abstract Age-structured models have played an important role in fisheries stock assessment. Although virtual population analysis (VPA) was once the most widely used stock assessment model for when catch-at-age information is available, (hierarchical) statistical catch-at-age analysis (SCAA) is about to take that position. However, the estimation performance of different age-structured models has not been evaluated sufficiently, especially in cases where there are few available abundance indices. We examined the performance of VPA and SCAA using simulation data in which only the abundance indices of spawning stock biomass and recruitment were available. The simulation demonstrated that VPA with the ridge penalty selected by minimizing retrospective bias provided near-unbiased abundance estimates without catch-at-age error and moderately biased estimates with catch-at-age error, whereas SCAA with random-walk selectivity suffered from problems in estimating parameters and population states. Without sufficient information on abundance trends, naïvely using SCAA with many random effects should be done cautiously, and comparing results from various age-structured models via simulation tests will be informative in selecting an appropriate stock assessment model.

scholarly journals Development of a stock–recruit model for simulating stock dynamics for uncertain situations: the example of Northeast Atlantic mackerel (Scomber scombrus)

2011 ◽  
Vol 68 (5) ◽  
pp. 848-859 ◽  
Author(s):  
E. John Simmonds ◽  
Andrew Campbell ◽  
Dankert Skagen ◽  
Beatriz A. Roel ◽  
Ciaran Kelly
Keyword(s):  
Stock Assessment ◽  
Management Plan ◽  
Maximum Sustainable Yield ◽  
Fish Stock ◽  
Northeast Atlantic ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Functional Forms

Abstract Simmonds, E. J., Campbell, A., Skagen, D., Roel, B. A., and Kelly, C. 2011. Development of a stock–recruit model for simulating stock dynamics for uncertain situations: the example of Northeast Atlantic mackerel (Scomber scombrus). – ICES Journal of Marine Science, 68: 848–859. The assumption of a relationship between recruitment and a spawning stock is the cornerstone of the precautionary approach and may constrain the use of a maximum sustainable yield (MSY) target for fisheries management, because the failure to include such a relationship suggests that providing a measure of stock protection is unnecessary. The implications of fitting different functional forms and stochastic distributions to stock-and-recruit data are investigated. The importance of these considerations is shown by taking a practical example from management: the management plan for Northeast Atlantic mackerel (Scomber scombrus), a fish stock with an average annual catch of 600 000 t. The historical range of spawning-stock biomass is narrow, and historical data from a stock assessment explain only a small proportion of the recruitment variability. We investigate how best to reflect the uncertainty in the stock–recruit relationship. Selecting a single model based on simple statistical criteria can have major consequences for advice and is problematic. Selecting a distribution of models with derived probabilities gives a more complete perception of uncertainty in dynamics. Differences in functional form, distribution of deviations, and variability of coefficients are allowed. The approach appropriately incorporates uncertainty in the stock–recruit relationship for FMSY estimation.

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.

scholarly journals Seabird diets as bioindicators of Atlantic herring recruitment and stock size: a new tool for ecosystem-based fisheries management

2018 ◽  
Vol 75 (8) ◽  
pp. 1215-1229 ◽  
Author(s):  
Lauren C. Scopel ◽  
Antony W. Diamond ◽  
Stephen W. Kress ◽  
Adrian R. Hards ◽  
Paula Shannon
Keyword(s):  
Fishery Management ◽  
Gulf Of Maine ◽  
Clupea Harengus ◽  
Data Series ◽  
Atlantic Herring ◽  
Stock Biomass ◽  
Stock Assessments ◽  
Spawning Stock ◽  
Fishery Data ◽  
Ecosystem Based Fisheries Management

Ecosystem-based fishery management requires understanding of relationships between exploited fish and their predators, such as seabirds. We used exploratory regression analyses to model relationships between Atlantic herring (Clupea harengus) in the diet of seabird chicks at nine nesting colonies in the Gulf of Maine and four types of fishery- and survey-derived herring data. We found several strong relationships, which suggests spatial structuring in herring stocks and likely patterns of herring movements before they recruit into the fishery. Some types of herring data seldom used in stock assessments — notably acoustic surveys, fixed-gear landings, and mass-at-age (i.e., weight-at-age) — correlated as strongly with seabird data as more commonly used series, such as mobile-gear landings and modeled spawning stock biomass. Seabird chick diets collected at specific locations thus offer a promising means to assess the size, distribution, and abundance of juvenile herring across a broad area prior to recruitment, which is a major source of uncertainty in fisheries. Common terns (Sterna hirundo) showed the most potential as a bioindicator, correlating well and showing consistent spatial patterns with 11 of 13 fishery data series.

How precautionary is the policy governing the Ross Sea Antarctic toothfish (Dissostichus mawsoni) fishery?

2013 ◽  
Vol 26 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Peter A. Abrams
Keyword(s):  
Food Web ◽  
Ross Sea ◽  
Antarctic Toothfish ◽  
Dissostichus Mawsoni ◽  
Population Forecasts ◽  
Accurate Picture ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Population Sizes ◽  
Future Population

AbstractThis article reviews the adequacy of data and models currently being used to estimate the present and future population sizes of the Antarctic toothfish (Dissostichus mawsoniNorman) in the Ross Sea regional ecosystem. The current tagging programme is unlikely to provide an accurate picture of total population size, and estimates of both the pre-exploitation spawning stock biomass and the ratio of current to pre-exploitation biomass are unreliable. Many parameters necessary for estimating future population growth or decline have not been measured, and the current objective of a 50% reduction in biomass relative to unexploited biomass may easily fail to prevent a much larger reduction from taking place. The need to guess values of important parameters makes it impossible to set bounds on the potential errors of population forecasts. Current scientific knowledge is far from what is needed to predict the likely effects of food-web responses to harvesting of toothfish in the Ross Sea, or to predict the feedback effects of those food-web changes on toothfish populations.

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.

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