A new approach for estimating stock status from length frequency data

Froese, Rainer; Winker, Henning; Coro, Gianpaolo; Demirel, Nazlı; Tsikliras, Athanassios C.; Dimarchopoulou, Donna; Scarcella, Giuseppe; Probst, Wolfgang; Dureuil, Manuel; Pauly, Daniel

doi:10.1093/icesjms/fsy078

Cited by 140 publications

(233 citation statements)

References 34 publications

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“…Here, the values considered were simply the market price per kilogram of the fish in question, which tended to sharply increase with size. Also, relative biomass (B/B 0 ) was estimated using a new set of equations, based on Beverton and Holt (1966), and derived by Froese et al (2018). This method allows estimating B/B 0 under different levels of fishing mortality and L c values, using the same parameters as for yield-per-recruit analyses, i.e., von Bertalanffy growth parameters (L inf , K), natural mortality (M) and a and b from length-weight relationships (Froese et al, 2018).…”

Section: Methods and Data Sourcesmentioning

confidence: 99%

“…Relative yield-per-recruit (Y ′ /R), as estimated by Equation (4), also can be expressed by (Froese et al, 2018) 6 | Ratio of U/R vs. Y/R (i.e., U/Y, in Yuan) for 14 species in China's coastal seas, with the corresponding L c (in cm). Given that CPUE can be seen as proportional to biomass, dividing Equation 12by F/M gives…”

Section: The Estimation Of Relative Biomassmentioning

confidence: 99%

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Yield-per-Recruit, Utility-per-Recruit, and Relative Biomass of 21 Exploited Fish Species in China's Coastal Seas

Zhai

Pauly

2019

Front. Mar. Sci.

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Based on growth and related fishery parameters, three approaches, yield-per-recruit (Y/R), utility-per-recruit (U/R) analyses, and relative biomass (B/B 0) analyses were applied to 21 economically important, trawl-caught species in China's coastal seas to estimate their relative yield, economic value and biomass under different schedules of fishing mortality and mean length at first capture. The results show that all species suffer from overfishing, given the high average fishing mortality (F ∼ 1 year −1) and small mesh size (∼1 cm) used by trawlers. Long-term Y/R would double and U/R (expressed as price per landed weight) would increase 5-fold if mesh size were increased to about 10 cm. Comparing Y/R and U/R showed that the benefits of higher prices for larger individuals were detectable only if larger mesh sizes are used, so that individuals are caught only after they have been able to grow. The Y/R analyses also allowed estimating the biomass of the 21 assessed populations relative to their unexploited biomass, i.e., B/B 0. Species-specific B/B 0 values ranged from 0.01 to 0.58, with a mean of 0.16 (±0.03), i.e., much lower than the 50% reduction corresponding to Maximum Sustainable Yield (i.e., B/B MSY = 1, or B/B 0 = 0.5). This confirms the many authors who reported systematic overfishing along China's coastlines, and suggests that rebuilding stocks should be the foremost goal of fisheries management in China.

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Section: Methods and Data Sourcesmentioning

confidence: 99%

Section: The Estimation Of Relative Biomassmentioning

confidence: 99%

Yield-per-Recruit, Utility-per-Recruit, and Relative Biomass of 21 Exploited Fish Species in China's Coastal Seas

Zhai

Pauly

2019

Front. Mar. Sci.

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“…Additionally, indicator 3 shows that the percentage of mega spawners is currently 5%, when it should be greater than 30%. Therefore, recruitment overfishing and growth overfishing are occurring with the stock (Froese, 2004;Froese et al, 2018;Froese et al, 2012). Agreeing with Castillo et al (2018), there seems to be high fishing pressure…”

Section: Discussionmentioning

confidence: 96%

Assessment of a small-scale fishery: Lane Snapper (Lutjanus synagris) using a length metric method

Castillo

Fujiwara

2020

Preprint

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Small-scale fisheries are hard to assess because of the limited availability of data.Therefore, a method requiring easy-to-obtain catch-data is important for the assessment and management of small-scale fisheries. The objectives of this study were to assess the effect of fishing gear selectivity on a length-based metric method proposed by Froese by estimating three indicators using catch-data from Lane Snapper (Lutjanus synagris) collected in Honduras. These indicators are (1) the percentage of mature individuals in the catch, (2) the percentage of fish within the range of estimated optimal lengths to be captured and (3) the percentage of fish larger than the optimal length. These indicators determine the level of overfishing. The indicators were estimated separately for catchdata corresponding to gillnets, and each indicator was estimated with and without selectivity correction. Selectivity and mesh sizes of the fishing gear had a major impact in the estimation of indicators 1 and 2. As for indicator 3, it consistently showed a high level of exploitation. The three estimated indicators suggested that the Lane Snapper fishery in Honduras, is experiencing overfishing. Overall, the method proposed by Froese appears to be promising for the assessment of small-scale fisheries, but it should be used cautiously.

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“…Where data are available or can be collected to discern insights into receptor status and trends (e.g. [53,54]), assessments will be better able to qualify the risk additions to the cumulative effects load posed to receptors and hence on the resilience of the connected system.…”

Section: A Candidate Approach To Cumulative Effects Assessmentmentioning

confidence: 99%

Structuring cumulative effects assessments to support regional and local marine management and planning obligations

et al. 2018

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Cumulative effects assessments are a legal requirement in many jurisdictions and are key to informing marine policy. However, practice does not yet deliver fit-for-purpose assessments relative to sustainable development and environmental protection obligations. The complexity of cumulative effect questions, which are embedded in complex social-ecological systems, makes multiple, methodologically diverse assessments a necessity. Using the expansion of marine renewable energy developments in European Union waters as a case study, this paper explores how social-ecological systems thinking and cumulative effects assessment theory can combine to structure CEAs that better support the management and regulation of maritime activities at regional scales. A general perspective for cumulative effects assessment is proposed to remove ambiguity of intent and to orient assessments towards a common objective. Candidate principles for practice are presented for consideration. These principles are integrated into a stepped assessment approach that seeks to improve cumulative effects assessments of localised activities relative to the information needs of decision-makers implementing the ecosystem approach. Highlights• Understanding and managing cumulative effects is fundamental to sustainable development and requires regional coherence between assessments oriented towards resolving a common issue.

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A new approach for estimating stock status from length frequency data

Cited by 140 publications

References 34 publications

Yield-per-Recruit, Utility-per-Recruit, and Relative Biomass of 21 Exploited Fish Species in China's Coastal Seas

Yield-per-Recruit, Utility-per-Recruit, and Relative Biomass of 21 Exploited Fish Species in China's Coastal Seas

Assessment of a small-scale fishery: Lane Snapper (Lutjanus synagris) using a length metric method

Structuring cumulative effects assessments to support regional and local marine management and planning obligations

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