Obsolete - AFSC/RACE/EcoFOCI - Fish diet analyses performed in support of FOCI assessment surveys and ecosystem observations in the Bering Sea and the Gulf of Alaska. 1990's - 2...

The data set focuses on the diets of young of the year Gadus chalcogrammus from the Eastern Gulf of Alaska and the South Eastern Bering Sea. Diet data is available in select years and locations for year one Gadus chalcogrammus and juvenile Mallotus villosus, Thaleichthys pacificus, Lepidopsetta polyxystra, Limanda aspera, Gadus chalcogrammus, Atheresthes stomias, Hippoglossoides elassodon and Atheresthes evermanni. Diet data currently in EcoDAAT are from 1993-2010. The early 1990’s ,except for 1993, are focused on transects extending of the Pribilof islands. From 2000-2010 sampling occurred in the Eastern Gulf of Alaska, except for 2008 when sampling occurred in the South Eastern Bering Sea. Currently there are 166 prey taxa or groups identified within the diets of all fish. The majority of identifications being: large copepod, small copepod, and euphausiid.

The diet data from the Pribiloff’s in the South Eastern Bering Sea (1994-99) focused on comparing diets of young of the year Gadus chalcogrammus in a frontal zone compared to those in nearshore and oceanic/shelf habitat. In subsequent years diet data focused on understanding spatial and temporal patterns in diet across the shelf of the Eastern Gulf of Alaska.

Supplemental Information - Data Parameters and Units - Descriptive Information about the Data Parameters and Units.

Relative fullness of the stomach is visually ranked on a scale of 0 to 5 as follows: 0 = empty; 1 = trace amount of food; 2 = 25% full; 3 = 50% full; 4 = 75% full; and 5 = 100% full.

The relative condition of the contents was determined on a scale of 0 to 4, ranging of the stomach was visually ranked on a scale of 0 to 5 as follows: 0 = empty; 1 = trace amount of food; 2 = 25% full; 3 = 50% full; 4 = 75% full; and 5 = 100% full.

The relative condition of the contents was determined on a scale of 0 to 4, ranging from totally digested to fresh prey.

Gut contents were identified only to major taxonomic category (order). Each taxon group was enumerated and weighed individually for every stomach. Prey taxon data for 2012 and beyond will be identified to lowest possible taxa, in most cases species and stage. Taxa with stages of variable size will be placed in standard size bins. This higher resolution data is meant to more closely parallel the zooplankton dataset.

Supplemental Information – Methods - Descriptive Information about the methods used.

Sample Collection and Processing

Age-O pollock were collected using several different gear types and fishing strategies. Hauls were made in midwater along a grid of stations set up along the Alaska Peninsula, but opportunistic midwater and near bottom tows were also made in order to identify acoustic sign and to sample inlets around Kodiak Island and The primary midwater gears used were an 18.6-m high-opening shrimp trawl and a 24.4-m anchovy trawl, which both contained 3-mm mesh liners (Wilson et aI., 1996). Tows were made throughout the water column in either an oblique or stepped oblique fashion at an average ship speed of 5.9 km/h. Near-bottom juveniles were sampled with a 37-m Nor'eastern bottom trawl fitted with a 5-mm mesh liner. Age-O fish were easily differentiated from older age classes by length distributions; a subsample (a minimum of 20) of these fish was placed in buffered 10% formalin or 90% ethanol. These fish were approximately 110-140 days old .

In the laboratory, age-O pollock were chosen from the frozen samples. Fish were measured to the nearest millimeter (standard length; SL) and weighed to the nearest 0.001 g, and the stomach (from the esophagus to pylorus) was excised. Relative fullness of the stomach was visually ranked on a scale of 0 to 5 as follows: 0 = empty; 1 = trace amount of food; 2 = 25% full; 3 = 50% full; 4 = 75% full; and 5 = 100% full. The entire stomach contents were then blotted on blotting paper to remove excess moisture and weighed to the nearest 0.001 g. The stomach contents were separated under a dissecting scope. The relative condition of the contents was determined on a scale of 0 to 4, ranging from totally digested to fresh prey. Gut contents were identified only to major taxonomic category (order). Each taxon group was weighed and enumerated for every stomach.

Supplemental Information – Instruments - Descriptive Information about the instruments and equipment used.

Supplemental Information - Sampling Scales and Rates - Descriptive Information about the sampling spatial and temporal scales and rates.

Supplemental Information - Error Analysis - Descriptive Information about the error analysis.

Supplemental Information - Provenance and Historical References -

Descriptive Information about the provenance, historical data, key information packaged elsewhere.

Merati, N., and R. D. Brodeur. 1996. Feeding habits and daily ration of juvenile walleye pollock, Theragra chalcogramma, in the western Gulf of Alaska. In Ecology of juvenile walleye pollock, Theragra chalcogramma (R. D. Brodeur, P. A. Livingston,

T. R. Loughlin, A. B. Hollowed, eds.), p. 65-79. NOAA Tech. Rep. NMFS 126.

Logerwell, E.A., J.T. Duffy-Anderson, M.T. Wilson and D. McKelvey (2010). The influence of pelagic habitat selection and interspecific competition on productivity of juvenile walleye pollock (Theragra chalcogramma) and capelin (Mallotus villosus) in the Gulf of Alaska. Fish. Oceanogr., 19(4), 262–278. (this one can also be used for trawling)

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Data are not processed automatically.

No archive is ready to handle this kind of data.

on and offsite backups

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