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Record W7133276437

Assessment of 2J3KL capelin in 2020

2022· other· en· W7133276437 on OpenAlexaboutno aff
Fisheries and Oceans Canada, Pêches et Océans Canada

Bibliographic record

VenueFederal Open Science Repository of Canada / Le Dépôt fédéral de science ouverte du Canada · 2022
Typeother
Languageen
Field
Topic
Canadian institutionsnot available
Fundersnot available
KeywordsCapelinEcosystemZooplanktonBiomass (ecology)HerringAbundance (ecology)Marine ecosystem
DOInot available

Abstract

fetched live from OpenAlex

Due to COVID-19 limitations, the spring acoustic survey was not conducted in 2020. However, Capelin larval indices, fall bottom trawl survey data, the Capelin forecast model, commercial landings and samples, and other ecosystem and environmental variables were used in the assessment. Based on all available evidence, Capelin abundance remains very low and this stock is experiencing reduced productivity. Under current ecosystem conditions and exploitation levels, no sustained growth has been observed for 30 years, and prospects remain poor. Capelin is an integral component of the ecosystem on the Newfoundland and Labrador Shelf. Continued low abundance is inhibiting the production and/or recovery potential of other finfish (e.g., Northern cod). The Newfoundland and Labrador climate experiences important fluctuations at decadal time scales, with potential impacts on ecosystem productivity. The Capelin collapse in 1990-91 and the recent declines (2015-17) were associated with cold periods, while the modest increases between the mid-2000s to mid-2010s were observed in generally warm periods. A modest increase in Capelin was observed (2013-15) in the warmer-than-average 2000s. This increase, however, was short-lived and followed by a colder period and return to low levels of Capelin. Since 2018, a warming trend has been observed. Higher nitrate inventories since approximately 2015 have resulted in improved primary (chlorophyll) and secondary (zooplankton biomass) production indices over the past four to five years. Ongoing changes in zooplankton seasonality and community structure (fewer large, energy-rich calanoids and more small copepods) may impact Capelin recovery. Increased summer and fall zooplankton biomass since 2016 may have contributed to the recent improvement of the fall adult Capelin condition index. However, Capelin larval productivity has remained low since 2014 despite an increase in abundance of a preferred prey (Pseudocalanus) over the same period. Ecosystem conditions in the Newfoundland Shelf and Northern Grand Bank (Northwest Atlantic Fisheries Organization [NAFO] Divs. 2J3KL) remain indicative of overall limited productivity of the fish community, with the total Research Vessel (RV) biomass index still much lower than prior to the collapse in the early-1990s. While there has been some recovery since this collapse, declines were observed after the mid-2010s. The current total RV biomass index remains below the early-2010s level, but with some positive signals in 2020. The increase in groundfish biomass observed from the mid-2000s to the mid-2010s appears stalled. These increases have been associated with bottom-up processes, including an improved prey field. Groundfish declines observed in recent years are associated with simultaneous reductions in Capelin and shrimp availability. Estimates of consumption by fishes and the occurrence of Capelin in cod and Greenland Halibut stomachs indicate low Capelin availability in 2020, with levels comparable to the 2017-19 period. The estimate of the spring acoustic biomass index from the forecast model for 2021 is near the average of the post-collapse period. The projection for 2021 is approximately 24% of the post-collapse high (forecast model estimate for 2015) and approximately 6% of the spring acoustic biomass index values observed in the late-1980s (1985-90). There is a 65% probability that the spring 2021 index will be about the same as 2020, and a 32% probability of an increase. The preliminary 2022 projection suggests a decline in the biomass index from 2021. There have been seven consecutive low larval abundance years (2014-20) including all of the year-classes available to the fishery in 2021. The commercial fishery landed 89% of the Total Allowable Catch (TAC) for Divs. 2J3KL in 2020 (16,114 tonnes). Overall, current removals from all predation are large compared to the fishery. Delays in beach spawning have persisted since 1991 and are associated with low larval productivity and smaller year classes. The large size of age-1 Capelin during the fall of 2020 suggests a high proportion of age-2 fish will be maturing in 2021. Due to the high rate of post-spawning mortality, this is expected to result in low numbers of age-3 Capelin in 2022. Low larval production has resulted in impaired recruitment for this stock. Late spawning, early maturation, and changes in feeding conditions for Capelin in Divs. 2J3KL are associated with low Capelin productivity during the last five years and poor prospects for 2021 and 2022. Given this stock’s continued low levels, significant ecological role, and poor prospects – including record low larval production in four of the last five years – it is advised that removals from all sources be kept at the lowest possible level.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame machine prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.

metaresearch head score (Codex)0.001
metaresearch head score (Gemma)0.002
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: Observational
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.166
Threshold uncertainty score0.330

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0010.002
Meta-epidemiology (narrow)0.0010.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0020.001
Science and technology studies0.0000.000
Scholarly communication0.0010.001
Open science0.0010.001
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0070.001

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.008
GPT teacher head0.253
Teacher spread0.246 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designObservational
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations0
Published2022
Admission routes1
Has abstractyes

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