Obsolete - AFSC/RACE/EcoFOCI - Otolith measurements and analyses performed in support of FOCI assessment surveys and ecosystem observations in the Bering, Beaufort, and Chukchi Seas and the Gulf of Alaska. 1995 - Present

Otolith data are collected to measure age and growth of larval pollock. They are used to determine whether growth rate, hatch data and/or temperature influence fish size.

The otolith data sets were constructed to allow researchers to compare intra- and inter-annual comparisons in age and growth data of larval walleye pollock in the Gulf of Alaska. This data was collected in conjunction with physical oceanographic data such as temperature and salinity

Otolith age data is reported in days, not years. Haul date is reported in Julian days. Temperature and salinity data is available in 1 meter depth intervals.|Larval walleye pollock were collected from three areas of interest in the Gulf of Alaska: Shumagin Islands, Sutwik Island, and Shelikof Strait during the late larval surveys conducted from mid-May to early June. All stations were 10 km apart. Larvae were sampled using a 60-cm bongo frame equipped with 505-um mesh nets and codends. The nets were towed to a maximum depth of 100 m, or in shallow areas 10 m off bottom. A Sea-Bird Electronics SBE-19 SEACAT profiler CTD was attached on the wire above the bongo frame to acquire in situ environmental data. Larvae were quickly sorted from the net 2 codend and preserved in 95% ethanol for otolith analysis. The contents of the other codend were preserved in 1.8 % buffered formaldehyde for quantitative sorting of all larval fish species. All formaldehyde-preserved larvae were enumerated, and their SL measured (±0.1 mm) with a dissection microscope. Up to 50-100 larvae preserved in ethanol from each area/year were selected to represent the full size range of fish occurring in each study area of interest. The standard length of larvae used for otolith analysis was corrected for shrinkage according to Porter et al. (2001). Sagitta otoliths were dissected from the fish and mounted in clear nail polish for age reading at 1,0000X magnification using a Zeiss Axioskop compound microscope. Age and length data were used to calculate linear growth equations and hatch date distributions.

Dougherty, A., Bailey, K., Vance, T., and Cheng, W. 2012. Underlying causes of habitat-associated differences in size of age-0 walleye pollock (Theragra chalcogramma) in the Gulf of Alaska. Marine Biology, 159, 1733–1744.</gco:CharacterString>

There are no legal restrictions on access to the data. They reside in public domain and can be freely distributed.

Contact Point of Contact

User must read and fully comprehend the metadata prior to use. Applications or inferences derived from the data should be carefully considered for accuracy. Data will reside at the Alaska Fisheries Science Center.

Acknowledgement of NOAA/NMFS/AFSC, as the source from which these data were obtained in any publications and/or other representations of these, data is suggested.

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Data are stored in .csv files.

To best of current science

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Contains data that has been through the QA/QC process. Some sample have not been examined but are preserved and stored for future studies.

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Samples selected and analyzed for specific studies. Not all available samples have been analyzed.

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Data are not processed automatically.

No current archive handles these kinds of data.

local and offsite backups

Larval walleye pollock were collected from three areas of interest in the GOA: Shumagin Islands, Sutwik Island, and Shelikof Strait during the late larval surveys conducted within the last 2 weeks in May 2000 and 2001, but as late as early June in 2000 in Shelikof Strait (Fig. 1). Whenever possible, the same stations from 2000 to 2001 were selected for otolith analyses. All stations were 18.5 km apart. Larvae were sampled with a 60-cm bongo frame equipped with 505-lm mesh nets and codends. The nets were towed to a maximum depth of 100 m, or in shallow areas 10 m off bottom. A Sea-Bird Electronics1 SBE-19 SEACAT profiler CTD was attached on the wire above the bongo frame to acquire in situ environmental data. Larvae were quickly sorted from one of the codends and preserved in 95 % ethanol for otolith analysis. The contents of the other codend were preserved in 1.8 % buffered formaldehyde for quantitative sorting of all larvae. All formaldehyde-preserved larvae were removed, enumerated, and their SL measured (±0.1 mm) with a dissection microscope. Up to 50 larvae preserved in ethanol from each area/year were selected to represent the full size range of fish occurring in each area. The Standard Length of larvae used for otolith analysis was corrected for shrinkage according to Porter et al. (2001). Sagitta otoliths were dissected from the fish and mounted in clear nail polish for age reading at 1,0009 magnification using a Zeiss Axioskop compound microscope. Age and length data were used to calculate linear growth equations.|Annette - can you add this?|||Dougherty, A., Bailey, K., Vance, T., and Cheng, W. 2012. Underlying causes of habitat-associated differences in size of age-0 walleye pollock (Theragra chalcogramma) in the Gulf of Alaska. Marine Biology, 159, 1733–1744