The term river herring collectively refers to alewife (Alosa pseudoharengus) and blueback herring (A. aestivalis), two anadromous fishes distributed along the east coast of North America. Historically, river herring spawning migrations supported important fisheries, and their spawning runs continue to be of cultural significance to many coastal communities. Recently, substantial declines in spawning run size prompted a petition to consider river herring for listing under the Endangered Species Act (ESA). The ESA status review process requires an evaluation of a species’ response to multiple stressors, including climate change. For anadromous species that utilize a range of habitats throughout their life cycle, the response to a changing global climate is inherently complex and likely varies regionally. River herring occupy marine habitat for most of their lives, and we demonstrate that their relative abundance in the ocean has been increasing in recent years. We project potential effects of ocean warming along the US Atlantic coast on river herring in two seasons (spring and fall), and two future periods (2020–2060 and 2060–2100) by linking species distribution models to projected temperature changes from global climate models. Our analyses indicate that climate change will likely result in reductions in total suitable habitat across the study region, which will alter the marine distribution of river herring. We also project that density will likely decrease for both species in fall, but may increase in spring. Finally, we demonstrate that river herring may have increased sensitivity to climate change under a low abundance scenario. This result could be an important consideration for resource managers when planning for climate change because establishing effective conservation efforts in the near term may improve population resiliency and provide lasting benefits to river herring populations.
-Fin spine ageing is the most common technique used to estimate age and growth parameters of large pelagic billfishes from the families Istiophoridae and Xiphiidae. The most suitable methods for processing and interpreting these calcified structures for age estimation have not been clearly defined. Methodological differences between unvalidated ageing studies are of particular concern for highly migratory species because multiple researchers in different regions of the world may conduct age estimates on the same species or stock. This review provides a critical overview of the methods used in previous fin spine ageing studies on billfishes and provides recommendations towards the development of a standardized protocol for estimating the age of striped marlin, Kajikia audax and white marlin, Kajikia albida. Three on-going fin spine ageing studies from Australia, Hawaii, and Florida are used to illustrate some of the considerations and difficulties encountered when developing an ageing protocol for highly migratory fish species. Particular areas of concern that may influence age and growth estimates included differences in fin spine selection, sectioning methods, criteria for identifying and measuring annuli, distinguishing false annuli, validation procedures, identification of the first annulus, and methods used to replace annuli lost due to vascularization of the fin spine core. Key words:Age determination / Sclerochronology / Growth / Population dynamics / Marlin / Tuna longline fisheries Résumé -Déterminer l'âge à partir des rayons épineux des nageoires est la technique la plus commune pour déter-miner l'âge et les paramètres de croissance des grands poissons pélagiques à rostre de la famille des Istiophoridés et Xiphiidés, marlins, voiliers et espadons. Les méthodes les plus adaptées pour interpréter et traiter ces pièces osseuses pour l'estimation de l'âge n'ont pas été clairement définies. Des différences méthodologiques entre des études nonvalides d'âge prêtent à conséquence pour ces grands migrateurs car de nombreux chercheurs de différentes régions du monde peuvent faire des déterminations d'âge d'une même espèce et d'un même stock. Cette synthèse présente une analyse critique des méthodes utilisées antérieurement dans les études sur la détermination de l'âge à partir des rayons des nageoires de marlins et elle fournit des recommandations afin de développer un protocole standard pour détermi-ner l'âge du marlin rayé, Kajikia audax (ex. Tetrapturus audax), et du marlin blanc, Kajikia albida (ex. Tetrapturus albidus). Trois études en cours, en Australie, Hawaï et Floride, sont utilisées pour illustrer certaines des considérations et difficultés rencontrées lors du développement d'un protocole pour déterminer l'âge des poissons grands migrateurs. Les points pouvant influencer l'estimation de l'âge et de la croissance comprennent, en particulier, les différences dans la sélection des rayons d'une nageoire, les méthodes de coupe fine, les critères d'identification et de mesure des annuli, la distinct...
The Carolingians regarded much of Italy as a military frontier following their overthrow of the Lombard kingdom in 776. Although there was little national Lombard resistance to Frankish rule, other factors — which will be noted later — forced the Franks to keep up their military establishment in Italy. In some ways this military establishment followed the pattern of Carolingian arrangements in other conquered territories, in other ways the Italian situation was quite unique. Since the Carolingian failure to solve the problem of Italian unity was in at least a degree due to the Carolingian failure to meet the challenge of the Italian military frontier, the study of this problem throws some interesting light on the turbulent conditions in northern and central Italy before and after its incorporation in the German Holy Roman Empire.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.