Aquatic Sciences Meeting, Albuquerque 2001

CS14 Fish and Fisheries: Environmental Quality and Ecology

Date: Thursday, February 15, 2001, Time: 2:00:00 PM

Location: Sandia/Santa Ana

Blumenshine, S, C, Arkansas State University, State University, AR, USA, sblumens@navajo.astate.edu

Hambright, K, D, Israel Oceanographic & Limnological Research, Yigal Alon Kinneret Limnological Laboratory , Tiberias, Israel, kdh@ocean.org.il

Shapiro, J, , Israel Dept. of Fisheries, Tiberias, Israel,

FILTER FEEDING FISHES: A LINK BETWEEN WATER QUALITY AND FISHERIES MANAGEMENT?

Seasonal plankton consumption by the filter-feeding planktivore Sarotherodon galilaeus was examined experimentally by monitoring changes during 24h in plankton assemblages in 5m3 mesocosms containing varying densities of fish. Taxon-specific grazing rates ranged from 0-17mg/gfish/d, with mean daily total specific consumption of 1.6%. During the spring bloom of the dinoflagellate Peridinium gatunense, Sarotherodon consumed mostly (94%) netphytoplankton (=20µm). During the summer and fall, net- and nanophytoplankton accounted for 54 and 42%, respectively, of the diet of Sarotherodon. Bioenergetics modeling indicated that consumption rates were near maximum in spring (90%Cmax), while consumption was reduced in summer-fall (59%Cmax). Sarotherodon obtains sufficient energy through filter-feeding year-round though most growth (60%) occurs during the spring Peridinium bloom. Despite efficient feeding on Peridinium and nanophytoplankton by Sarotherodon, instantaneous plankton mortality estimates due to ingestion were two orders of magnitude smaller than maximum potential plankton growth rates. Thus the potential for the Sarotherodon population in Lake Kinneret to positively affect water quality through algal suppression is low.

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Aquatic Sciences Meeting, Albuquerque 2001

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