one collection to the next. On several occasions it was 

 limited to a small pool at the seaward end of one (or of 

 each) groin and on others was a very long trough in excess 

 of 200 m in length. Because the groins (of timber pilings) 

 were well covered with encrusting invertebrates and 

 because the currents tended to scour out the areas at the 

 seaward ends of the groins, these man-made structures 

 acted as unnatural foci for the concentration of motile 

 animals. Despite this the presence of the groins affected 

 only the catch in the tidal pool, because at the times we 

 made the surf collections the tide had receded beyond 

 the groins. 



The minimum and maximum water temperatures ob- 

 served were: surf, 6.4° and 28.6°C; tidal pool, 3.7° and 

 26.8°C. The salinities in the surf ranged from 23.2 to 

 35.0%=; those in the tidal pool, from 25.8 to 33.4% . 

 (For data on temperature and salinity, see Tables 1 and 

 2.) The lowest salinities were recorded after heavy local 

 rains. Because the collections were made near the time of 

 predicted low water, the maximum diluting effect of the 

 groundwater was manifest. 



MATERIALS AND METHODS 

 Collecting and Handling Specimens and Data 



Collections were made by seine at approximately 

 biweekly intervals (from 11 October 1969 to 10 October 

 1971) in the surf and tidal pool (when present) near the 

 time of predicted low water. All except three of the 

 collections were made in the morning (0500-1130 EST). 

 The time required to make a collection varied from 5 to 

 40 min (x = 15.4) in the surf and from 1 to 25 min (x = 

 10.3) in the tidal pool. 



The surf was seined with a 19.8- by 1.8-m, 9-mm 

 stretch-mesh nylon bag seine with bag opening of 1.8 m 

 in diameter and length of 1.8 m. Initially, the tidal-pool 

 collections were made with the 19.8-m seine — later 

 (because of ease of handling) with a 7.1- by 1.6-m, 9-mm 

 stretch-mesh nylon bag seine with bag opening of 1.8 m 

 in diameter and length of 1.8 m. Except when beaching 

 and when collecting in the tidal pool was restricted to 

 small pools at the groins, the seines were pulled parallel 

 to the beach. 



In the surf, the seine was pulled approximately 185 m, 

 the distance between the groins. During almost all of the 

 first year, two hauls, each about one-half the distance 

 between the groins, were made — the first haul starting 

 opposite one groin, the second terminating opposite the 

 other. Later each surf collection was made with a single 

 tow. Generally, the seine was towed with the longshore 

 current which usually ran from northeast to southwest. 

 The distance seined and the number of hauls in the tidal 

 pool varied with the length and configuration of the pool, 

 but never exceeded 185 m. The use of seines of different 

 lengths did not affect the catch in the tidal pool because 

 even the smaller seine was long enough to reach across 

 the width of the pool. There were no duplicate or 

 reciprocal tows in either the surf or tidal pool, i.e., a 

 given area was seined only once per collecting trip. 



Assuming that the opening of the seine was 12 m (±2 m), 

 the area covered in a seine haul between the groins in the 

 surf was about 2,220 m 2 . Surf and tidal-pool catches 

 made on the same day were considered as different 

 collections and were handled separately. Air and water 

 temperatures, salinity, and turbidity were measured and 

 observations were made on the condition of the sea, 

 height of the breakers, wind velocity and direction, cloud 

 cover, character of the bottom, and depth of water seined. 



All material was measured and weighed after preserva- 

 tion. Standard length (SL), fork length (FL) — when 

 applicable, total length (TL), and weight (W) of each 

 fish were taken. Specimens were thoroughly blotted ex- 

 ternally and excess moisture was squeezed out of the gill 

 chambers of fishes before weighing. Similar techniques 

 were used for invertebrates except that carapace length 

 (CL) and width (CW) were measured on crabs. 



Data were coded for input on 80-column Hollerith code 

 punch cards. Four types of cards were used for each 

 collection: 1) location data card, 2) physical data card, 3) 

 species data card (number of specimens, total weight, 

 and length and weight ranges), and 4) specimen data 

 card (scientific name, sex if determined, lengths, weight, 

 and miscellaneous data as appropriate). Data were 

 analyzed on an IBM System 360/40 DOS computer. The 

 software used for the analyses of the data was the 

 Dynamic Computer Systems/Multi-purpose Information 

 Processor and the UCLA BMD, Biomedical Computer 

 Programs. 



In this study we define the seasons as follows: October, 

 November, December — Fall; January, February, 

 March — Winter; April, May, June — Spring; and July, 

 August, September — Summer. 



Selectivity of Collecting Method 



The method of collecting used in this study was highly 

 selective. The material that could be collected by seining 

 was determined by the characteristics of the net (length, 

 configuration, and mesh size), certain environmental 

 factors, and the speed at which the net could be pulled, 

 which is largely a reflection of environmental conditions. 

 In the surf the environmental factors with the greatest 

 effects were velocity of longshore current, condition and 

 height of sea, nature of bottom, temperature, and tur- 

 bidity; in the tidal pool those of greatest importance were 

 conditions prevailing at the previous flood tide and the 

 configuration of the pool itself which was a product of the 

 conditions existing at the time of formation. 



In the surf large individuals were not as readily 

 collected as smaller ones; however, at times of low water 

 temperatures the motility of larger animals was reduced 

 greatly, thereby decreasing their chances of escaping 

 capture. Individuals less than a certain critical size (a 

 function of mesh size) were not retained in the net unless 

 they became entrapped with other animals and debris in 

 the bag of the seine. 



The seine was usually pulled with the longshore 

 current because most frequently it was impossible to 

 make headway against it. Even though our hauls were for 



