FISHERY BULLETIN: VOL. 81, NO 3 



MATERIALS AND METHODS 



Sampling was conducted at seven sites (Fig. 2) from 

 18 June to 16 July 1978 from the 32.6 m RV Dolphin. 

 White line recorder tracings and bottom obser- 

 vations made with a Hydro Products TC-125 SDA 3 

 low light level underwater television system in con- 

 junction with loran-C positions were used to produce 

 maps of each site. The camera was suspended from 

 the hydrographic wire (Fig. 3) and towed at low speed 

 (~0.5 m/s; 1.0 kn) across each potential study area. 

 The sponge-coral habitat was defined by the pres- 

 ence of attached invertebrate growth. In addition to 



"Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



the six sponge-coral habitat sites, an open-shelf (non- 

 reef) area was studied to compare the species com- 

 position and biomass of both communities. Following 

 habitat delineation, fishes were sampled by 10-min 

 day and night trawl tows with a % scale version of a 

 Yankee No. 36 trawl (Wilk and Silverman 1976) at a 

 speed of 6.5 km/h. The 16.5 m longfootrope and the 

 11.9 m headrope of the net are attached to a 19 mm 

 diameter ground cable by 12.7 mm diameter 11.6 

 m long leg lines. Each 17.7 m long ground cable at- 

 taches to a 226 kg wooden door. The footrope has 

 about 1,000 rubber discs (114 mm diameter) at- 

 tached to it which enable the net to bounce over small 

 bottom irregularities. Day tows were made from 1 h 

 after sunrise to 1 h before sunset, whereas night tows 

 were made from 1 h after sunset to 1 h before sunrise. 



FIGURE 2.— Reef sampling sites for the 1978 

 survey. OS = open-shelf study area. 



76* 



75° 



34 



J3' 



30 



re 



29 



28' 



27 



77" 



28 



27" 79' 



78° 



538 



