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Age-based stock assessments are sometimes rejected by review panels due to large retrospective patterns. When this occurs, data-limited approaches are often used to set catch advice, under the assumption that these simpler methods will not be impacted by the problems causing retrospective patterns in the age-based assessment. This assumption has never been formally evaluated. Closed-loop simulations were conducted where a known source of error caused a retrospective pattern in an agebased assessment. Twelve data-limited methods, an ensemble of a subset of these methods, and a statistical catch-at-age model with retrospective adjustment were all evaluated to examine their ability to prevent overfishing and rebuild overfished stocks. Overall, none of the methods evaluated performed best across the scenarios. A number of methods performed consistently poorly, resulting in frequent and intense overfishing and low stock sizes. The retrospective adjusted statistical catch-at-age assessment performed better than a number of the alternatives explored. Thus, using a data-limited approach to set catch advice will not necessarily result in better performance than relying on the age-based assessment with a retrospective adjustment. Key words: closed-loop simulation, data-limited methods, management advice, retrospective analysis, Introduction In the US, age-based, integrated, fisheries stock assessment models are frequently used to estimate annual stock abundance (biomass), fishing mortality rates, and management reference points (Maunder and Punt 2013). [...]

The Northwest Atlantic continental shelf is a large ecosystem undergoing rapid environmental changes, which are expected to modify the productivity of natural marine resources. Current management of most fished species assumes stationary production relationships or time-invariant recruitment rates. With linear state-space models, we examined the evidence of dynamic productivity for 25 stocks of the Northeast US shelf. We expanded the suite of options available within the state-space approach to produce robust estimates. Fifteen of the stocks exhibited time-varying productivity or changes in their maximum reproductive rate. Few productivity time series are related across the whole region, though adjacent stocks of the same species exhibited similar trends. Some links to region-wide environmental variables were observed. We demonstrate that fish recruitment can often be better predicted over a short-term horizon by accounting for dynamic productivity, which could be valuable for fisheries management. Improving predictions by incorporating environmental covariates or covariance among the stocks must be considered case by case and with caution, as their relationships may change over time. Le plateau continental de l'Atlantique Nord-Ouest est un vaste ecosysteme subissant des changements environnementaux rapides. Ces derniers sont suspectes de modifier la productivite des ressources marines naturelles. Cependant, la gestion actuelle des especes de poissons est basee sur des relations de productivite constantes ou des taux de recrutement constants. A l'aide de modeles lineaires a espace d'etat, la pertinence d'une productivite dynamique est etudiee pour 25 stocks de poissons du plateau Nord-Est des USA. Des estimations robustes ont ete produites en developpant l'approche espace-etat. Quinze des stocks etudies presentent une productivite, ou taux maximum de reproduction, variant dans le temps. Au sein de cet ecosysteme, la productivite des stocks varie rarement de facon semblable. Seuls les stocks d'une meme espece localises dans des zones adjacentes presentent des tendances similaires. Les variables environnementales regionales expliquent tres peu la variabilite temporelle. Nous demontrons que le recrutement est souvent mieux predit a court terme avec une productivite dynamique, ce qui peut etre valorisable pour la gestion des peches. Pour ameliorer la prediction, l'utilisation de covariables environnementales ou de la covariance entre les stocks doit se faire au cas par cas. Comme ces relations ne persistent pas toujours dans le temps, leur utilisation doit faire l'objet de precautions prealables., Introduction Productivity--the capacity of a fish population to increase in numbers and mass--is affected by variations in the recruitment rate, body growth, and survival success (Shelton et al. 2006). The [...]

Decadal-scale climate variability and change can cause trends in oceanographic conditions that impact demographic rates. Rebuilding scenarios, therefore, developed assuming constant demographic rates may not be realistic. Winter flounder (Pseudopleuronectes americanus) is an important commercial and recreational species that has declined in the southern portion of its range despite reduced exploitation. Laboratory and mesocosm studies suggest that stock productivity is reduced under warmer conditions and that rebuilding to historical levels may not be possible. Our goal was to examine the rebuilding potential of winter flounder in the face of regional warming. We integrated winter temperature into a population model to estimate environmentally driven stock-recruitment parameters and projected the stock into the future under different climate and fishing scenarios. The inclusion of winter temperature had minor impacts on the estimates of current abundance, but provided greater understanding of the drivers of recruitment. Projections that included the environment suggest that rebuilding the stock to historical levels is unlikely. The integration of both fishing and the environment has the potential to provide more realistic expectations of future stock status. La variability et les changements climatiques decennaux peuvent produire des tendances dans les conditions oceanographiques qui influencent les taux demographiques. Aussi, les scenarios de reconstitution elabores en presumant des taux demographiques constants pourraient ne pas etre realistes. La plie rouge (Pseudopleuronectes americanus), une espece importante pour la peche commerciale et sportive, est en baisse dans la partie sud de son aire de repartition, malgre une reduction de son exploitation. Des etudes en laboratoire et en mesocosme donnent a penser que la productivity du stock diminue dans des conditions plus chaudes et que le retablissement des niveaux historiques pourrait ne pas etre possible. Notre objectif consistait a examiner le potentiel de reconstitution du stock de plie rouge etant donne le rechauffement regional. Nous avons incorpore la temperature hivernale dans un modele de population afin d'estimer les parametres de recrutement au stock modules par des facteurs ambiants et avons etabli des projections du stock pour differents scenarios climatiques et de peche. L'integration de la temperature hivernale a des effets mineurs sur les estimations de l'abondance actuelle, mais permet une meilleure comprehension des facteurs qui modulent le recrutement. Les projections qui integrent les conditions ambiantes indiqueraient que le retablissement des niveaux historiques du stock est improbable. L'integration de la peche et des conditions ambiantes pourrait produire des previsions plus realistes de l'etat futur du stock. [Traduit par la Redaction], Introduction With the reauthorization of the Magnuson-Stevens Act, rebuilding plans were implemented in the United States to provide a legally binding time line to reduce overfishing (NOAA1996). For many species [...]

As the impacts of climate change become more severe throughout the global oceans, fisheries managers will be increasingly challenged to rebuild stocks exhibiting declining productivity. In such cases, detailed knowledge of species life history will be necessary to both restrict harvest and manage other environmental conditions, where possible, that impact survivorship. A current example of these challenges, the Southern New England/Mid‐Atlantic Bight winter flounder stock remains in a persistently depleted state due to a combination of past harvest and the effects of climate change mediated through increased predation. To explore the recovery capacity of a subpopulation of this stock, a life‐cycle model was fit to 29 year classes of stage‐specific winter flounder data from surveys conducted in Narragansett Bay, Rhode Island and used to project future subpopulation abundance. Supporting a prevailing hypothesis, the results indicated that environmental factors influencing juvenile mortality were largely responsible for inhibiting recovery. Furthermore, recovery of the subpopulation to past levels of abundance was determined to be unlikely even under optimistic future conditions resulting from aggressive management interventions. Taken together, the findings of this work pose important questions regarding the realism of assessing climate‐challenged populations against biological reference points set under past environmental regimes and the degree to which harvest restrictions to promote recovery of such stocks should be allowed to limit warm‐water fisheries thriving in a warming ocean. [ABSTRACT FROM AUTHOR]

Analysis of the life span of a malathion-resistant strain, a malathion-susceptible strain and two other strains of Cryptolestes ferrugineus, the rusty grain beetle, at 75% relative humidity and 30 degrees Celsius reveals that virgin, malathion-resistant adults possess a longer life span of 37 weeks than virgin, susceptible adults. The life span is a vital factor for these insects, whose reproductive period is long. The fitness of C. ferrugineus is not affected by the malathion resistance gene.

New World Orders: Violence, Sanction, and Authority in the Colonial Americas. Edited by John Smolenski and Thomas J. Humphrey. (Philadelphia, PA: University of Pennsylvania Press, 2005. Pp. vi, 362. Cloth, [...]

Marine biota are redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of data availability, and mismatch between data and real species distributions. To assess the extent of this challenge, we review the global status and accessibility of ongoing scientific bottom trawl surveys. In total, we gathered metadata for 283,925 samples from 95 surveys conducted regularly from 2001 to 2019. We identified that 59% of the metadata collected are not publicly available, highlighting that the availability of data is the most important challenge to assess species redistributions under global climate change. Given that the primary purpose of surveys is to provide independent data to inform stock assessment of commercially important populations, we further highlight that single surveys do not cover the full range of the main commercial demersal fish species. An average of 18 surveys is needed to cover at least 50% of species ranges, demonstrating the importance of combining multiple surveys to evaluate species range shifts. We assess the potential for combining surveys to track transboundary species redistributions and show that differences in sampling schemes and inconsistency in sampling can be overcome with spatio-temporal modeling to follow species density redistributions. In light of our global assessment, we establish a framework for improving the management and conservation of transboundary and migrating marine demersal species. We provide directions to improve data availability and encourage countries to share survey data, to assess species vulnerabilities, and to support management adaptation in a time of climate-driven ocean changes. [ABSTRACT FROM AUTHOR]

Marine ecosystems have been heavily impacted by fishing pressure, which can cause major changes in the structure of communities. Fishing directly removes biomass and causes secondary effects such as changing predatory and competitive interactions and altering energy pathways, all of which affect the functional groups and size distributions of marine ecosystems. We conducted a meta-analysis of eighteen trawl surveys from around the world to identify if there have been consistent changes in size-structure and life history groups across ecosystems. Declining biomass trends for larger fish and invertebrates were present in nine systems, all in the North Atlantic, while seven ecosystems did not exhibit consistent declining trends in larger organisms. Two systems had alternative patterns. Smaller taxa, across all ecosystems, had biomass trends with time that were typically flat or slightly increasing. Changes in the ratio of pelagic taxa to demersal taxa were variable across the surveys. Pelagic species were not uniformly increasing, but did show periods of increase in certain regions. In the western Atlantic, the pelagic-todemersal ratio increased across a number of surveys in the 1990s and declined in the mid 2000s. The trawl survey data suggest there have been considerable structural changes over time and region, but the patterns are not consistent across all ecosystems. [ABSTRACT FROM AUTHOR]