Flume weir for quantitative collection of nekton from vegetated intertidal habitats

I descnbe a flume welr for long-term quant~tahve sampling of nekton from vegetated intert~dal marshes at high tide The flume weir design is a s~gnlflcant advance over prevlous methods because ~t samples a relatively large and precisely defined area (100 m2) without affecting the normal movement patterns of nekton into or out of the s a m p l ~n g area untd the moment a sample is required Sampling by flume weir 1s nelther destruchve of the vegetated habitat nor restncted to the marsh edge as are many other methods recently used to sample nekton in intertidal marshes The mean efficiency w t h which fish and crustaceans 2 30 mm In length were recovered from flume weirs was in the range 86 to 99 % From July 1988 to June 1990 20 species of fish and 4 species of crustaceans comprising a total of 47 353 individuals (15 to 540 mm in length) were collected In 271 flume welr samples taken from intert~dal marsh sites adjacent to Sapelo Island Georgia USA Adults and ~uveniles of small resident marsh species composed 82 3 '10 of the total ~n d i v ~d u a l s collected Juveniles of seasonal migrant species which use marshes as nurseries were also common The most abundant of these was the w h ~t e shrimp Penaeus setlferus which was present only from June to November, but composed 12 9 % of the total nekton collected Other common seasonal species were mullet Mug11 spp and spot Leiostornus xanthurus which represented 1 7 and 16 O/O of the total catch respectively By providing a means of monitonng nekton densities at sites where conventional gears are clearly Inappropriate, the flume weir may allow researchers to address long-standing questions linlung marsh production with coastal fishenes As a management tool the flume weir may be used by coastal land managers to asslgn a fishenes value to specific intertidal h a b ~t a t s as part of a process to evaluate marsh mltigatlon and restoration efforts