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LARVAL FISH DIVERSITY IN SUISAN MARSH, CALIFORNIA: ARE INTERMEDIATE FLOWS THE BEST?
Citation:
Meng, L AND S. A. Matern. LARVAL FISH DIVERSITY IN SUISAN MARSH, CALIFORNIA: ARE INTERMEDIATE FLOWS THE BEST? Presented at Southern New England Chapter of the American Fisheries Society, Old Lyne, CT, June 14, 2000.
Description:
We sampled larval fish in Suisun Marsh, in the San Francisco Bay estuary from February to June 1995-1999. We used principal components analysis (PCA) and canonical correspondence analysis (CCA) on 13 taxonomic groups making up 99.7% of the catch and several environmental variables. Both analyses identified a distinct group of warm-water species that included delta smelt Hypomesus transpacificus, clupeids, striped bass Morone saxatilis, inland silversides Menidia beryllina and gobies. Sculpins, Sacramento suckers Catastomus occidentalis, longfm smelt Spirinchus thaleichthys, threespine sticklebacks Gasterosteus aculeatus, and splittail Pogonichthys macrolepidotus made up a group generally preferring cooler water and higher outflows. Gobies and sculpins dominated catches making up 51 and 40% of the total. Catch composition was similar in most sloughs, except Cordelia in the western marsh. Cordelia had higher diversity, more marine species, and most of the longfin smelt, threespine sticklebacks and northern anchovies Engralis mordax. The CCA showed temperature, salinity and riverine outflow to be the most important physical factors determining larval catches. Larval fish diversity was highest when freshwater flows into the estuary were intermediate and may be related to positioning the mixing zone in the Suisun Bay area in spring. Larvae of special status species were captured by the survey. Longfin smelt were captured mostly in February and March in the western end of the marsh, whereas delta smelt catches were later and distributed throughout the marsh. Delta smelt catches overlapped with wakasagi smelt Hypomesus nipponensis catches temporally and spatially and suggest potential for hybridiztion. Larval splittail catches were confined mostly to 1995 when high flows peaked during their spawning season in March and April. Larval catches were similar at all tidal stages, except for 1995 and 1997 when they were notably greater on high tide.