025 050 0.75 1.00 1.25 



AREA IN KILOMETERS 2 



40 



20 



20 

 (£ 



io 



•-20 



io 



20 



AMJJASONDJFMAMJ 

 1957 1958 



I 2 3 4 5 6 7 8 

 STATIONS 



Figure 2. — a. Hypsograph (area and depth) of White 

 Creek, Del. b. Monthly average and range of surface 

 water temperature, c. Overall average and range of 

 salinity at survey locations. MHW is mean high water; 

 MLW is mean low water. 



Individual collections were sorted, species 

 identified and counted, and fork lengths 

 recorded. Common and scientific names fol- 

 lowed American Fisheries Society (1960). At 

 times, many of the smaller anchovies, killi- 

 fishes, and silversides (up to about 10 mm.) 

 passed through the meshes of both nets, and, 

 therefore, their numbers were not recorded 

 in summary tables; however, notes on their 

 occurrences were included. 



We tabulated the collections by date, time, 

 gear, surface water temperature, salinity, 

 number of Atlantic menhaden, and combined 

 numbers of all other species (append, table 1). 

 Frequency of sampling varied; hence, avail- 

 ability is expressed in units of catch per 

 seine haul. We made some comparisons be- 

 tween the catches of the different nets, but 

 made no adjustment for variation in net ef- 

 ficiency. 



SPECIES COMPOSITION AND 

 SEASONAL OCCURRENCE 



Fifty-eight species, representing 48 genera 

 of 32 families, were collected (table 1). The 

 catch, by species and size ranges, is sum- 

 marized for each station, by month, in ap- 

 pendix table Z, A summary of the total monthly 

 catch by species is included as table 2. 



Various authors (Greeley, 1939; Warfel and 

 Merriman, 1944; Pearcy and Richards, 1962) 

 have classified fishes in seine collections ac- 

 cording to the particular biotope considered. 

 Any system of classification is arbitrary, be- 

 cause detailed information on reproduction and 

 subsequent movements of young is limited or 

 absent for many species. Our classification is 

 similar to that of Pearcy and Richards (1962) 

 and based generally on the seasonal relative 

 abundance of larvae and juveniles. Some dif- 

 ferences of details of their system and ours 

 inevitably occur because of differences in fish 

 fauna, physiography, and hydrography of the 

 streams considered. 



The following groupings are useful in de- 

 scribing the variation both in number and 

 availability of species in White Creek: 



I. Nonmigratory 



1. Brackish water resident species. -- 

 Those which are hatched in the creek 

 and may reside there throughout life: 

 sheepshead minnow (Cyprinodon 

 variegatus ), mummichog ( Fundulus 

 heteroclitus ). striped killifish (F. 

 majalis ), rainwater killifish ( Lucania 

 parva ), fourspine stickleback (Apeltes 

 quadracus ), tidewater silverside 

 ( Menidia beryllina ), and Atlantic silver- 

 side (M. menidia ). 



2. Fresh - water species.-- These were in- 

 frequently collected and derived from 



