FISHERY BULLETIN: VOL. 78. NO. 4 



other factors may also affect the distribution of 

 blacksmith. For example, kelp and high relief 

 rocks may serve as orientation points or shelter for 

 fish in the water column (Limbaugh 1955; Quast 

 1968a, b, c; Ebeling and Bray 1976; Hobson and 

 Chess 1976). 



In this paper, I first examine the distribution of 

 blacksmith in relation to water currents over a 

 reef that is subjected to occasional reversals in 

 current flow to see if they consistently gather at 

 the incurrent end. Since foraging is the major 

 activity of blacksmith while assembled in these 

 midwater aggregations, I then determine if plank- 

 ton is more abundant at the incurrent end. Finally, 

 by examining caged and free-living individuals, 

 I see whether blacksmith that forage at the in- 

 current end consume more prey. 



METHODS 



Study Site 



Naples Reef is a large rocky outcrop (275 x 

 80 m) located 24 km west of Santa Barbara and 1.6 

 km offshore (Figure 1). The substratum is a series 

 of uplifted sandstone rills and ridges that parallel 



the coast. Depths across the reef average 8-10 m, 

 although some prominences come to within 5 m of 

 the surface. A sandy bottom 16-20 m deep sur- 

 rounds the reef, with rocky outcrops inshore and 

 cobbles offshore. The assemblage of plant and 

 animal life on and around the reef is among the 

 richest along the Santa Barbara coast. Giant kelp, 

 Macrocystis pyrifera, is always present on the reef, 

 although kelp densities fluctuated considerably 

 throughout the study period. The species composi- 

 tion and abundance of fishes at Naples Reef are 

 listed in Ebeling et al. (1980). 



Naples Reef is well suited to study the effects of 

 water currents on the distribution of fish. The reef 

 is almost always swept by measurable longshore 

 currents. Although usually these come from the 

 east, occasionally they come from the west. A shift 

 in the distribution of fish when the currents 

 reverse would provide strong evidence that water 

 currents affect the fish's distribution. 



Surveys 



In December 1975, 1 initiated biweekly counts of 

 all fish in the water column at four sites on the reef 

 (Figure 1). At each site, I fixed a line from a 



Figure l. — Contour map of Naples Reef, southern California. Heavy lines indicate locations of midwater transects: 30 m (to cross 

 mark) and 60 m (to end) from the starting points ( circles). Letters indicate incurrent and excurrent locations where zooplankton were 

 sampled: A locations — when current flowed from the east; B locations — when current flowed from the west. Midwater cages were 

 located at the A locations. The shaded portion indicates the rocky substratum, while the surrounding open area represents ssmd. The 

 dashed line indicates the margin of the kelp bed. Depths are in meters. 



830 



