• Tim Lee

    Tim Lee
    Univ. of California, Berkeley
    Studied fish eggs and larvae samples.

    This summer, I had the great opportunity to work with the Resource Assessment and Conservation Engineering (RACE) Division of the Alaska Fisheries Science Center (AFSC). The RACE Division is composed of individuals from myriad areas of expertise including but not limited to oceanography, fisheries biology, genetics, and pathobiology.

    I worked with scientists from the Recruitment Process Program, specifically with the Early Life History (ELH) and Taxonomy Group . The ELH group conducts research on life history and distribution of larval fish in the Gulf of Alaska and Bering Sea (GOA, BS) to determine what affects their survival to recruitment and fluctuations of populations.

    Studying larval fish is particularly vital because it helps determine spawning areas and adult populations. Furthermore, larval fish play an essential role as diet components for many organisms, thereby helping to characterize marine ecosystems over time.

    Carefully studying every sample of fish eggs and larvae collected is essential to determine where and which species occur in particular regions of the GOA and BS. My primary step was to become familiar with identifying fish eggs and larvae to the lowest possible taxa, using "Laboratory Guide to Early Life History Stages of Northeast Pacific Fishes" (Matarese et al. 1989).

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    Some of the samples I studied.


    Identification of fish eggs and larvae can be especially challenging since for fish at early stages, many diagnostic characteristics overlap between different taxa. With the use of a stereo dissecting microscope, Laboratory Guide, and assistance from ELH scientists, I learned to distinguish larvae using meristic (e.g. fin-ray counts) and morphological (e.g. standard length, vertebrae count) and pigmentation characteristics.

    The samples I worked with were collected from a Fisheries-Oceanography Experiment (FOX) Cruise conducted by the NOAA ship Miller Freeman during the summer of 1987 in the northwestern Gulf of Alaska. This extensive cruise, which ranged from Unimak Pass to Kodiak Island (total of 148 stations), allowed me to become familiar with eggs and larvae commonly found within this region. From these samples, I was able to compare the distribution and abundance of the most widely distributed taxa (walleye pollock, flathead sole, arrowtooth flounder) to samples collected from this region with more recent cruises, observing changes within a 20 year span.

    To study life history, I looked at length ranges for each taxa of interest. I used "Atlas and Abundance and Distribution Patterns of Ichthyoplankton from Northeast Pacific Ocean" (Matarese et al. 2003), to analyze length distributions of each taxa on a seasonal basis. I also retrieved data for each station and taxa from IchBase, which consists of data from Fisheries Oceanography Coordinated Investigations (FOCI) cruises throughout the GOA and BS from 1970s to present.

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    A larval flatfish in one of the samples I studied.



    Using these data, I created maps using ArcGIS to show abundance and distribution of taxa of interest. This allowed me to observe and compare abundances between geographic regions and the location of spawning grounds. Using bathymetry and other oceanographic data, I was able to consider of environmental factors that might potentially affect the abundance and distribution of early life stages.

    The experience of working with larval fishes has prompted new options of environmental science emphasis I might pursue as a career. I thank Susanne McDermott, Morgan Busby, (RACE Division), and other members of Early Life History Group for providing this wonderful experience.