Assessment of the west coast of Newfoundland (4R) herring stocks in 2021
Notice bibliographique
Résumé
Based on preliminary data, landings of herring from the west coast of Newfoundland (NAFO Division 4R) totaled 4,862 t in 2020 and 3,074 t in 2021, with an annual total allowable catch (TAC) of 20,000 t. The fishery experienced difficulties due to a high incidence of herring below the legal size. The proportion of spring-spawners in the landings increased from a time-series low of 1.6% in 2014 to 89.6% in 2021. The proportion of spring spawners in the summer and fall acoustic surveys also increased from an average of 7.3% for the 2009-2017 period to an average of 44.6% in 2020 (summer: 44.8%, fall: 40.6%) and 51.5% in 2021 (summer: 229 %, fall: 75.4%). Landings of spring-spawning herring in 2020 and 2021 were mainly composed of fish of the 2013 year-class (age 7-8), and to a lesser extent of fish of the 2017 year-class (age 3-4). The acoustic survey biomass estimates of spring-spawning herring in 2020 and 2021 were mainly composed of fish of the 2017 year-class (age 3-4). Landings of fall-spawning herring in 2020 and 2021 were mainly composed of fish aged 9 years and over. The acoustic survey biomass estimates of fall-spawning herring were dominated by the 2016 year-class in 2020 (age 4) and 2021 (age 5). The 2021 summer acoustic survey was dominated by fish aged 8 years and over. The mean fork length at which 50% of individuals were mature (L50) was respectively 24.5 cm and 25.4 cm for spring and fall spawners. These values are higher or near the current minimum size limit of 24.76 cm in the commercial fishery. The L50 of both spring- and fall-spawning stocks has varied around the long-term average since the 2000 year-class. Both spring- and fall-spawning herring stocks show a downward trend in mean length-at-age and weight-at-age since the beginning of the 1990s. Since 2014, the relative condition index of the two spawning stocks is below the series’ average. The condition of both herring spawning stocks is positively related to the abundance of large-bodied copepod species. The acoustic surveys estimated the highest biomass indices since the beginning of the survey in 2021 for spring spawners (122,145 t, 95% CI: ± 20,803 t) and in 2020 for fall spawners (226,005 t, 95% CI: ± 35,507 t). These values represent minimum estimates of the amount of fish available at the time of the survey. The ratio of the biomass fished over the highest biomass index estimated in the acoustic surveys was considered to be a proxy for the maximum exploitation rate. In 2020 and 2021, the maximum exploitation rate was respectively 1.1% (1.0-1.2%) and 2.4% (2.0-2.9%) for spring spawners, and 1.7% (1.4-2.0%) and 0.2% (0.1-0.2%) for fall spawners. If the 20,000 t TAC had been taken in 2020-2021, the maximum exploitation rates would have resulted in 4.5-15.6% (4.2-19.1%) for spring spawners and 1.2-6.8% (1.0-8.0%) for fall spawners. Available evidence up to 2021 (low exploitation rates, commercial and acoustic survey catch-at-age, age- and length-at-maturity) indicates that maintaining the TAC at status quo should not pose a significant short-term risk to herring stocks in 4R.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,002 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| 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 ».