An Exploration of Factors that Relate to the Occurrence of Multiple Brooding in Rockfish (Sebastes spp.)

Anna Holder, CSUMB

 

Abstract: Despite the identification of multiple brooding in some rockfish species (Sebastes spp.) over 50 years ago, multiple brooding continues to be a complicated and poorly understood component of the reproductive biology of rockfishes. We sought to better understand the oceanographic factors that relate to the capacity of individual Sebastes species to produce multiple broods by evaluating how well this life history trait could be predicted by data that reflect the mean latitude, ocean temperature, dissolved oxygen levels, and mean length for each species. The data used were catch and associated physical oceanographic data from the Northwest Fisheries Science Center combined shelf/slope bottom trawl survey, commercial landings from the Pacific Fisheries Information Network (PacFIN), and a review of the literature regarding the ability of each species to produce (or not) multiple broods. We fit binomial generalized linear models to the probability of being described as a multiple brooder to 24 shelf rockfish species to determine whether and to what extent these factors influenced the probability of the species being a multiple brooding species. Preliminary results suggest that multiple brooding species are significantly more likely in lower latitudes and/or in warmer waters. Completion of this research will result in a more comprehensive understanding of the reproductive biology of shelf rockfish, could contribute to climate change vulnerability assessments, and should eventually lead to improvements in stock assessment models for rockfish populations.

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Bio: Anna is a CSUMB alumna and current graduate student in the Applied Marine and Watershed Science program. Between her degrees, she spent time as an Environmental Scientist for the California Department of Fish and Wildlife where she gained state and federal fisheries management experience. Her undergraduate research focused on the impacts of hypoxia on the respiration and hatching success of the commercially important market squid. Her Master’s research is focused on multiple brooding behaviors of commercially important rockfish (Sebastes spp). Upon completing her master’s degree, Anna plans to pursue a career that will allow her to utilize fisheries science, mathematics, and technology to contribute to and inform the sustainable management of marine resources.

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Developing a Remote Sensing Capability for the Observation and Monitoring of Bull Kelp (Nereocystis luetkeana) Populations Along the California Coastline

Meredith McPherson, UCSC

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Abstract: Two species of surface canopy forming kelp, giant (Macrocystis pyrifera) and bull (Nereocystis luetkeana), form the base of a productive ecosystem along the entire west coast of North America. Kelp forests are threatened worldwide by the impacts of climate change, overfishing, and the resulting ecological disruptions. The annual nature of bull kelp's life cycle make them sensitive to persistent, multi-annual stressors. Based on California Department of Fish and Wildlife (CDFW) aerial observations, unprecedented and large-scale reductions of bull kelp along the northern California coastline were observed between 2008 and 2014 (73 to 93%) and are thought to be caused by a series of environmental perturbations beginning in 2011. A quantitative comparison of several platforms was undertaken to determine the spectral and spatial requirements to accurately quantify bull kelp at the CDFW survey site Van Damme, CA between 2009 and 2014 by applying multiple endmember spectral mixing analysis (MESMA). MESMA determines the fractional coverage of components, such as water, cloud, land, giant kelp and/or bull kelp, based on pixel spectral similarity to one or more reference spectra, termed endmembers. The results of this study will expand scientists' and managers' understanding of bull kelp ecosystem dynamics beyond limited in situ monitoring programs and aerial coverage data, and has the potential to reduce monitoring costs and increase sampling efficiency.

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Bio: Meredith is a third year PhD student in the Kudela lab at UC Santa Cruz.  Meredith studies kelp in northern California using a variety of remote sensing technologies, and is interested in understanding the effects of oceanographic, ecological, and biogeochemical processes on radical changes in kelp biomass in Sonoma and Mendocino counties over the past decade.  Previously, she completed her BS and MS in Ocean, Earth, and Atmospheric Sciences at Old Dominion University (ODU). Her research at ODU focused on studying the effects of in situ water column optical properties on seagrasses in Florida Bay as an undergrad and developing a mechanistic model to predict the impact of environmental conditions on carbon uptake and isotope discrimination in Eelgrass (Zostera marina) as a masters student, both under Dr. Richard Zimmerman.

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