FISHERY BULLETIN: VOL. 74, NO. 3 



be treated in depth later (Hobson and Chess in 

 prep.), when these data can be reconsidered along 

 with the data on organisms simultaneously acces- 

 sible on the sea floor and other substrata, as well as 

 in the water column above habitats different from 

 those described here. 



TERMINOLOGY 



In this report, the term zooplankton encom- 

 passes all the varied small organisms we collected 

 with a plankton net during day and night, and 

 (most important to this study) which proved to 

 include the major foods of a well-defined assem- 

 blage of fishes. All the organisms that we consider 

 within this definition belong to groups included in 

 most general accounts of the zooplankton (e.g., 

 Newell and Newell 1963; Wickstead 1965). 



Nevertheless, some planktologists would ex- 

 clude from zooplankton forms like large caridean 

 shrimps that irregularly enter the water column at 

 night. But among crustaceans such distinctions 

 fail to establish where, along the continua of size, 

 mobility, and time spent in the water column, 

 forms like large carideans are apart from those 

 minute calanoid copepods that are zooplankters by 

 any definition. A number of terms defining certain 

 ecological categories among zooplankton have 

 been proposed (e.g., holoplankton, meroplankton, 

 tychoplankton, etc.), but while such terms are 

 useful in certain contexts, we have seen none that 

 define categories meaningful to the concepts 

 developed in this paper (see Discussion). 



STUDY AREA 



The study area is 25 to 75 m off the western shore 



of Big Fisherman's Cove (Figure 1). Most of the 

 area is open water about 5 to 15 m deep over a 

 sandy sea floor largely overgrown by the brown 

 alga Dicfyopteris zonariodes (most of which is 

 anchored to tubes of the polychaete Chaetopterus 

 variopedatus (Figure 2)). From the seaward edge 

 of the study area, the bottom falls sharply to the 

 greater depths (more than 30 m) that lie at the 

 center of the cove. Shoreward, and at the mouth of 

 the cove, lies a forest of giant kelp, Macrocystis 

 pyrifera. This large brown alga grows to the 

 water's surface from a rocky bottom that slopes up 

 to the shoreline from depths of about 8 m (Figure 

 3). Water temperatures during the study ranged 

 from lows around 12°C in spring, to highs around 

 20°C in late summer. 



FISHES STUDIED 



The fishes studied are those that, during either 

 day or night, swim in the water column and feed 

 principally on zooplankters. They are: 



Family Scorpaenidae: scorpionfishes 

 Olive rockfish, Sebastes serranoides (Eigen- 



mann and Eigenmann) 

 Kelp rockfish, S. atrovirens (Jordan and 

 Gilbert) 

 Family Pomadasyidae: grunts 

 Salema, Xenistius californiensis (Stein- 

 dachner) 

 Family Sciaenidae: drums 



Queenfish, Seriphus politus Ayres 

 Family Embiotocidae: surfperches 

 Walleye surfperch, Hyperprosopon argen- 



teum Gibbons 

 Kelp perch, Brachyistius frenatus Gill 



.^-T. 



Figure l.-Big Fisherman's Cove, 

 Santa Catalina Island. The study site 

 lies near the opposite shore, between 

 the buoy and the headland. 



568 



