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Changing distribution and abundance of small pelagic fishes may drive changes in predator distributions, affecting predator availability to fisheries and surveys. However, small pelagics are difficult to survey directly, so we developed a novel method of assessing the aggregate abundance of 21 small pelagic forage taxa via predator stomach contents. We used stomach contents collected from 22 piscivore species captured by multiple bottom trawl surveys within a vector autoregressive spatio-temporal model to assess trends of small pelagics on the Northeast US shelf. The goal was to develop a spatial "forage index" to inform survey and (or) fishery availability in the western North Atlantic bluefish (Pomatomus saltatrix) stock assessment. This spatially resolved index compared favorably with more traditional design-based survey biomass indices for forage species well sampled by surveys. However, our stomach content-based index better represented smaller unmanaged forage species that surveys are not designed to capture. The stomach-based forage index helped explain bluefish availability to the recreational fishery for stock assessment and provided insight into pelagic forage trends throughout the regional ecosystem. [ABSTRACT FROM AUTHOR]

Ecosystem approaches to fisheries management are being explored worldwide, but few evaluations of multispecies harvest control rules (HCRs) exist. Our goal was to perform a simulation test of a suite of HCRs using an age-structured predator–prey model to represent the dynamics of a small pelagic fish, Atlantic menhaden (Brevoortia tyrannus), and its predator, striped bass (Morone saxatilis). We evaluated a suite of static and dynamic single and multispecies HCRs to estimate effects on stock performance metrics. No single HCR achieved ecosystem management objectives for both stocks given their current reference points, but HCRs that involved the "40–10 rule" for striped bass performed well across all predator performance metrics. The most influential factor determining performance of striped bass HCRs was striped bass fishing mortality, and relatively few HCRs achieved target SSB for Atlantic menhaden. Our study indicated that some HCRs recommended for forage fish management may not be effective in systems with generalist predators, and that ecosystem management objectives might be achievable by simultaneously adopting HCRs for both predator and prey stocks that complement one another. [ABSTRACT FROM AUTHOR]

The abundance of alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis) has declined throughout their range, and there are increasing concerns about their conservation status. Because of their diadromous life history, variability in rates of survival in fresh water can affect overall recruitment. The objective of our study was to assess how river temperature and flow influence young of the year (YOY) river herring recruitment in the Northeast US. Observations of adult and juvenile fish in five rivers were used to construct spawner-YOY recruits models; these rivers were chosen because of the length of the time series (> 15 years) and the paired observations of spawners and juveniles. An environmentally explicit stock-recruitment model explained a substantial fraction (41% to 80%) of the variance in YOY abundance, depending on river system. Our approach allowed for a preliminary discussion of potential mechanisms, which need to be further substantiated by focused field and laboratory studies. Early summer river flow and river temperature had the greatest influence, indicating the importance of conditions in nursery habitats. In certain systems, spring or fall conditions were also important determinants of survival, suggesting additional effects of the environment on spawning of adults and juvenile egress from freshwater nursery habitats. L'abondance des gaspareaux (Alosa pseudoharengus) et des aloses d'ete (Alosa aestivalis) a diminue dans toute leur aire de repartition, et leur situation de conservation est l'objet d'inquietudes croissantes. En raison du cycle biologique diadrome de ces poissons, la variabilite de leurs taux de survie en eau douce peut avoir une incidence sur leur recrutement global. L'objectif de l'etude consistait a evaluer l'influence de la temperature et du debit des rivieres sur le recrutement d'aloses de l'annee (YOY) dans le nord-est des Etats-Unis. Des observations sur des poissons adultes et juveniles dans cinq rivieres ont ete utilisees pour batir des modeles geniteurs-jeunes de l'annee YOY recrutes; ces rivieres ont ete choisies en raison de la disponibilite de longues series chronologiques (> 15 ans) et d'observations appariees de geniteurs et juveniles. Un modele stock-recrutement integrant explicitement les conditions du milieu explique une fraction importante (de 41% a 80%, selon reseau hydrographique) de la variance de l'abondance des YOY. Notre approche permet une discussion preliminaire des mecanismes potentiels, qui devront etre etoffes davantage par des etudes de terrain et de laboratoire ciblees. Les debits et la temperature des rivieres au debut de l'ete exercaient la plus grande influence, indiquant l'importance des conditions des habitats d'elevage. Dans certains reseaux, les conditions estivales ou automnales etaient egalement d'importants determinants de la survie, donnant a penser que d'autres facteurs du milieu influencent le frai des adultes et le depart des juveniles des habitats d'elevage en eau douce. [Traduit par la Redaction], Introduction Alewives (Alosa pseudoharengus) and blueback herring (Alosa aestivalis), collectively known as 'river herring', are native to the east coast of North America. Alewives range from Labrador and Newfoundland to [...]