Food habits of the alewife, Alosa pseudoharenous, were studied in Indiana waters of Lake Michigan at 10 m (32.8 ft.) stations o transects at Burns Ditch and Michigan City from June to October, 1970. Organisms in stomachs were expressed as percent of the total volume, percent frequency of occurrence, and percent composition.Food selectivity of the alewife was studies at the 10 m station on Michigan City transect. Plankton samples were taken concurrently with fish samples and percent composition of various food items in plankton and stomach samples were compared to elucidate selection with an electivity index.The occurrence of copepods and cladocerans in alewife stomachs from Burns Ditch and Michigan City transects was similar; however, Michigan City alewife stomachs had three more cladoceran species than Burns Ditch samples. Oligochaetes were not present in any Michigan City stomach samples, and Pontoporeia affinis was not found in any Burns Ditch samples. When comparing these two sample sites, the alewife food habit differences may be due to difference in substrate, water quality, and the influence of the Burns Ditch river mouth.Based upon frequency of occurrence and percent volume, zooplankton comprised the largest portions of food in adult alewife (140 mm [5.5 in.] and greater) alewife stomach samples taken from June to October in 10 m of water on Michigan City transect. Cladoceran occurrence and percent volume in alewife stomachs increased monthly from June to September and October. Cyclops bicuspidatus, the major food item contributing to copepod percent volume in alewife stomachs, generally declined from July to October.Alewife size, for fish ranging from 140-169 mm (5.5-6.6 inc.) and 170-189 m (6.7-7.4 in.) did not appear to influence percent volume and frequency of occurrence of major food items consumed. Food selectivity of the two size groups was also similar for planktonic food species examined.Alewives ranging from 140-189 mm selected positively for the female Cyclops bicuspidatus while copepodites were always negatively selected. During October, large cladocerans, Leptodora and Daphnia, were positively selected. Although Diaptomus spp. Were similar in size to the female Cyclops, it was always negatively selected. The alewife selection for Bosmina longirostris was strongly negative in June, July, and October, but ws near random in August and September. Since the B. longirostris density in August and September was relatively high, the near random E values may indicate random filter feeding by the alewife. Prey size, mobility, and density appear to be major influences on adult alewife food selection.
| Identifer | oai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:handle/180364 |
| Date | January 1971 |
| Creators | Rhodes, Raymond J., 1946- |
| Contributors | McComish, Thomas S. (Thomas Sherman), 1938- |
| Source Sets | Ball State University |
| Detected Language | English |
| Format | viii, 82 leaves : ill. ; 28 cm. |
| Source | Virtual Press |
Page generated in 0.0406 seconds