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Full-Text Articles in Life Sciences

Spatiotemporal Trends And Drivers Of Fish Condition In Chesapeake Bay, Robert J. Latour, James Gartland, Christopher F. Bonzek Sep 2017

Spatiotemporal Trends And Drivers Of Fish Condition In Chesapeake Bay, Robert J. Latour, James Gartland, Christopher F. Bonzek

VIMS Articles

Measures of condition in fishes are often used to assess the general well-being of fish populations since condition reflects the biotic and abiotic factors experienced by individuals over moderate time scales. Fish condition can also be used as an indicator of ecosystem suitability in the context of ecosystem-based management. From an ecosystem perspective, evaluation of fish condition is best described over multiple spatiotemporal scales and in a multi-species context. This study analyzed 14 yr (2002-2015) of fisheries-independent trawl survey data to evaluate trends in condition for 16 demersal fishes inhabiting Chesapeake Bay, the largest estuary in the USA. Seasonal and …


Tracking Decadal Changes In Striped Bass Recruitment: A Calibration Study Of Seine Surveys In Chesapeake Bay, Mary C. Fabrizio, Troy D. Tuckey, Olivia M. Philips, Brian K. Gallagher Mar 2017

Tracking Decadal Changes In Striped Bass Recruitment: A Calibration Study Of Seine Surveys In Chesapeake Bay, Mary C. Fabrizio, Troy D. Tuckey, Olivia M. Philips, Brian K. Gallagher

Reports

In this study we estimated calibration factors necessary to maintain the long‐term integrity of the juvenile striped bass surveys in the Chesapeake Bay region. These surveys provide annual indices of recruitment (estimated as juvenile fish abundance in summer) and are used by fisheries managers in Virginia and Maryland to inform adjustments of annual harvest limits for striped bass from the commercial and recreational fisheries in Chesapeake Bay. During the multi‐decadal history of the survey, a potentially influential change occurred: VIMS deployed a net (the VA net) with a mesh material that differed from the standard net that MD DNR continued …


Beyond Zar: The Use And Abuse Of Classification Statistics For Otolith Chemistry, C. M. Jones, M. Palmers, J. J. Schaffler Jan 2017

Beyond Zar: The Use And Abuse Of Classification Statistics For Otolith Chemistry, C. M. Jones, M. Palmers, J. J. Schaffler

OES Faculty Publications

Classification method performance was evaluated using otolith chemistry of juvenile Atlantic menhaden Brevoortia tyrannus when assumptions of data normality were met and were violated. Four methods were tested [linear discriminant function analysis (LDFA), quadratic discriminant function analysis (QDFA), random forest (RF) and artificial neural networks (ANN)] using computer simulation to determine their performance when variable-group means ranged from small to large and their performance under conditions of typical skewness to double the amount of skewness typically observed. Using the kappa index, the parametric methods performed best after applying appropriate data transformation, gaining 2% better performance with LDFA performing slightly better …