Anthropogenic influences on population sizes, age and growth of naturalized rainbow trout, <i>Oncorhynchus mykiss</i>, in Kenya
Notice bibliographique
Résumé
Abstract Riverine fishery in Kenya has witnessed profound changes since the 1950s, especially after independence (in 1963) when watersheds on the south‐eastern slopes of Mt Kenya were opened up for settlement. In particular, rainbow trout populations have declined essentially resulting from anthropogenic changes through over‐exploitation and/or degraded habitats. While there still are self‐sustaining rainbow trout populations in this stream among others they are in decline an indication that changes that have occurred on the watershed have altered their sizes, age and growth. The study was carried out in the Sagana, a third‐order stream, which rises at about 4000 m altitude on the south‐eastern slope of Mt Kenya, to obtain and document information on population sizes, age and growth of rainbow trout populations and to relate them with those recorded in the 1950s when trout streams were pristine (with little human influence). Stations were fished bi‐monthly from 1996 to 1998 and later for 6 months in 2002. Information on age and growth was obtained by use of annual marks, tagging fish of known age, and by validating their age using captive fish of known age. The minimum mean back‐calculated length at age for age one rainbow trout was 13.09 cm in upstream station and 15.10 cm for downstream stations. However, there was no significant difference in mean back‐calculated lengths at age for all years between fish in upstream and downstream stations ( t ‐test, t = −0.01, P = 0.99). Although female fish showed higher mean annual back‐calculated length increments than males, there was no significant difference in mean back‐calculated lengths at age between sexes ( t ‐test, t = −0.27, P = 0.80). The rate of growth in length was rapid for 1‐year‐old fish and declined in the second and third years. This study observed that most of the fish were small with only a few reaching more than 2 years of age because of overfishing. There are good reasons for optimism about the future of trout populations in this stream but concerted efforts are required to rehabilitate them. If trout populations are to increase, a management strategy is required to reduce fishing pressure and to maintain stream fishery against competing needs for resources in the catchments.
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 distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 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) | 0,000 | 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 tête enseignante, 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 ».