y- 



-\ 



25 nnn 



clumped together to resist tidal removal. 

 Larvae hatch and develop quickly in the 

 warm pools. Their ability to withstand a 

 wide range of salinities and temperatures 

 (Carpelan 1961) makes it possible for 

 killifish to inhabit the variable 

 environment of the salt marsh. The 

 species appears to depend on intertidal 

 marsh pools for reproduction. 



Figure 41. The California killifish 

 ( Fundulus parvipinnis ) spawns and 

 develops in salt-marsh pools. 

 Illustration by J. DeWald. 



"complex," composed of arrow gobies 

 ( Clevelandia ios) , shadow gobies (Quietula 

 y-cauda ) and cheekspot gobies ( Ilypnus 

 gilberti ) and staghorn sculpin 

 ( Leptocottus armatus ) were less numerous. 

 The most abundant eggs were those of the 

 croaker family ( Sciaenidae) , topsmelt 

 ( Atherinops affinis ) , and northern anchovy 

 ( Engraulis mordax ) , respectively. Other 

 egg types included the sanddabs 

 ( Citharichthys spp.), slough anchovy 

 (Anchoa delicatissima ) and Pacific sardine 

 ( Sardinops sagax caeruleus ) . In the 

 process of capturing eggs and larvae, many 

 adult and juvenile fish were collected. 

 The most abundant were topsmelt, followed 

 by California killifish, staghorn sculpin 

 and long jaw mudsucker. 



Larger channels at Tijuana Estuary, 

 also sampled by Nordby, supported larval 

 fish communities of similar species but in 

 different abundances than in the tidal 

 creeks. Topsmelt appeared to be the 

 dominant pelagic fish, while the benthic 

 species, mostly gobies, were numerous and 

 widely distributed. Densities of larvae 

 and eggs peaked in late winter to early 

 spring 1981. Densities of larvae (90% 

 gobies) were generally under 5/m , but 

 rose to a maximum of 65/m^ during one 

 reproductive pulse. The absence of 

 California killifish in the egg and larval 

 catches is explained by its use of marsh 

 pools for spawning (Fritz 1975). Eggs are 



In comparing Nordby' s data on tidal 

 creeks and channels with his nearshore 

 samples (Table 12), it becomes clear that 

 tidal creeks provide different habitats 

 for fish utilization. Tidal creeks were 

 less than 20J similar to channels in their 

 larval communities because Atherinids 

 (most likely topsmelt), the tidal creek 

 dominant, attaches its eggs to floating 

 mats of Enteromorpha and other algae. 

 After hatching, many of the larvae remain 

 among the thick algal mats. This close 

 association was documented by sampling 

 creek areas with and without such mats 

 (Nordby, in prep.). In contrast, gobies 

 dominated the channels, and their 

 distribution may depend on adult 

 preferences for burrowing habitats, e.g. 

 the substrate type, current speed and 

 water temperature found in larger 

 channels . 



Egg composition was more similar 

 between tidal creeks and channels, and 

 especially between channels and nearshore 

 habitats. While the presence of eggs in 

 an estuary indicates some spawning 

 function, similar egg catches nearshore 

 make it unclear where the spawning has 

 occurred. Nordby argues that the estuary 

 is used by transient species (e.g. 

 croakers, sanddabs, sardines) which come 

 in to spawn. While such species don't 

 depend on this habitat for reproduction, 

 they do exploit it. In addition, larvae 

 may encounter less predation in enclosed 

 waters. Nordby found that copepods and 

 chaetognaths were more abundant outside 

 the estuary, where they were often caught 

 in the process of eating fish larvae. 

 Hence, enclosed waters may provide a 

 refuge and contribute significantly to 

 coastal water fish production. 



70 



