Assessing the Status of the Cod (Gadus morhua) Stock in NAFO Subdivision 3Ps in 2019
Notice bibliographique
Résumé
The status of the Atlantic Cod (Gadus morhua) stock in the Northwest Atlantic Fisheries Organization (NAFO) Subdivision 3Ps was assessed during a Fisheries and Oceans Canada (DFO) Regional Peer Review Process meeting held November 19–22, 2019. Total landings for the 2018–19 management year (April 1–March 31) were 4,742 t or 79% of the Total Allowable Catch (TAC). Survey abundance and biomass estimates from the DFO research vessel (RV) spring survey were below average during 2016 to 2019. Sentinel gillnet catch rates have been very low and stable since 1999. Sentinel line-trawl catch rates have been below average for the past eight years and the 2018 catch rate was the lowest in the time-series. A new integrated state space model resulting from the 2019 3Ps Cod Framework was used to assess the status of the stock and estimate fishing mortality. A new biomass limit reference point (LRP) was determined for the stock based on the relationship between spawning stock biomass (SSB) and recruitment estimated from the model. The LRP is 66,000 t of SSB. Using the new assessment model, SSB at January 1, 2020, is estimated to be 16 kt (12 kt–21 kt). The stock is in the Critical Zone (24% of Blim [18–32%]) as defined by the DFO Precautionary Approach (PA) Framework. The probability of being below Blim is >99.9%. The estimated fishing mortality rate (ages 5–8) has ranged between 0.12 and 0.21 since 2010 and in 2019 was 0.21 (0.15–0.30), with an assumed catch of 4,453 t. Natural mortality was estimated to be 0.49 (0.41–0.58) (ages 5–8) in 2019. Values during the last four years are the highest in the time series. Recruitment (age 2) estimates have been below the long-term average since the mid-1990’s. Projection of the stock to 2022 was conducted assuming fishery removals to be within +/-30% of current levels, assuming a catch of 4,453 t for 2019, and with no catch. Under these scenarios, there is a probability >99% that the stock will remain below Blim between 2020 and the beginning of 2022. The probability of stock growth to 2022 from 2019 is less than 1% or less across catch scenarios (+/-30% of current levels) and is 16% when there are no removals. Natural mortality plays an important role in projections for this stock. If natural mortality rates are appreciably different from those used, projected outcomes will differ from values reported above. Bottom temperatures in 3Ps remain above normal, and the spring bloom continues to be reduced in magnitude. Zooplankton biomass in 3Ps was near normal in 2017 and 2018 after four years of low production, with an increased proportion of smaller species. Data were unavailable from 2019. Ongoing warming trends, together with an increased dominance of warm water fishes, indicate that this ecosystem continues to experience structural changes. Reduced growth and condition indicate that cod productivity in 3Ps is reduced.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».