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3t4 



7^8 ti II I "iL"ii'liL' 'ill 111' 111' liiitil' 111 



B. chrysuro 

 B. tyronnus 

 M mffnidio 



B chrysuro, M curemo 

 8 tyronnus, A mitchilli 

 M menidio 



JULY- SEPTEMBER, 1957 



B cfirysaro, M curema 



8 tyronnus 



F heteroclifus, M menkfia, H berylllna 



B. cbrysuro 

 8 tyronnus 

 F heteroclitus, Mberylltno 



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mini IIIIIIIIIIIIII 



7*8 



iimmmiiiiiiiiii 



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OCTOBER- DECEMBER, t957 



M curemo 

 A mitchilli 

 M menidio 



M curemo 



A mitchilli, 8 tyronnus 



M: menidio 



B. chrysuro, M. curemo 



8 tyronnus 



M menidio, F heteroclitus, Mberylllno 



M. curemo 

 B tyronnus 



C voriegotus, F heteroclitus, M menidio, 

 M.beeylliita 



l»2 



5t6 



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Ihlllllllllllllllll 



mill iiiiiiiiiiiir 



IIIIIIIIIIIIII mil 



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APRIL-JUNE, 1958 



8 tyronnus. M cepholus 

 r neferocnttjs, M. beryllina 



M curemo 



U cepttalus. 8 tyronnus, A. mfchllli 



F /teterodifus, Uberytlttto 



U curetito 



8 tyronnus 



r fteteroclttus, Mberylltno 



A. rostrate 

 hi curemo 

 6 tyronnus 

 F netefoctftus 



I 5 10 50 100 500 



TOTAL CATCH PER UNIT EFFORT 



DIADROMOUS ^^^ 

 INCIDENTAL '^KXiti 



SPRING-FALL " 



RESIDENT ;«««< 



Figure 5. — Total catch per seine haul, by 3-month intervals, of principal species groups occurring in White Creek, 

 Del., plotted on a logarithmic scale. Listed species made up about two-thirds of each group catch. Where two or 

 more species are included, listing is in the order of decreased availability. 



(catches of each two adjacent stations were 

 combined). A small number of species con- 

 stituted at least two-thirds of each group 

 total and varied between seasons and stations. 

 Several species, including the Atlantic men- 

 haden, sheepshead minnow, mummichog, and 

 tidewater silverside, demonstrated a seasonal 

 upstream preference. These contrasted with 

 a fairly uniform distribution of most other 

 species. Incidental species were regarded as 

 strays from outside the creek. Although at 

 times they occurred throughout the creek, 

 incidental species appeared mostly at down- 

 stream stations. 



Change of species composition within groups 

 generally was graded smoothly over the length 



of the creek; however, the lumping of species 

 by station groups in figure 5 suggests some 

 discontinuity. For example, the principal resi- 

 dent species shifted from silversides to killi- 

 fishes upstream during summer and fall. On the 

 other hand, there was an apparent irregularity 

 in the distribution of the mummichog, rainwater 

 killifish, and fourspine and threespine stickle- 

 backs (append, table Z). This irregularity oc- 

 curred at station 2 where, although salinities 

 corresponded to those of lower White Creek, a 

 small tributary entered the cove and habitat 

 characteristics were similar to those in upper 

 White Creek. 



Species predominating within certain groups 

 changed seasonally. The Atlantic silverside 



