From the start of the program in 1950 

 through 1960 the exploratory fishing vessels 

 completed the following units of field work: 

 R/V Oregon , 72 cruises and 3,174 fishing 

 stations; R/V Silver Bay , 27 cruises and 2,584 

 fishing stations; R/V Combat , 10 cruises and 

 530 fishing stations; and R/V Pelican , 3 cruises 

 and 79 fishing stations. The specific cruise 

 objectives varied from general trawl and 

 dredge reconnaissances of unknown and unex- 

 plored areas to detailed commercial evalua- 

 tions of shrimp, snapper, grouper, tuna, 

 scallops, clams, sardine-like schooling fishes, 

 other foodfish species, and industrial or scrap 

 fish. 



To accomplish these objectives a wide 

 variety of gear was used, principally com- 

 mercial type fishing equipment. Commonly 

 used were shrimp trawls (Bullis, 1951), fish 

 trawls (Captiva and Rivers, 1960), midwater 

 trawls (Thompson, 1959; Bullis, I960), scallop 

 and clam dredges (Bullis and Cummins, 1961; 

 Cummins, Rivers, and Struhsaker, 1962), 

 seines and lampara nets (Butler, 1961), long- 

 lines (Bullis, 1955; Captiva, 1955; Wathne, 

 1959), and handlines. Also, a large volume of 

 material was collected at night-light dip-netting 

 stations and lesser quantities at rotenone 

 stations on isolated reefs in the southern 

 Gulf of Mexico and in the western Caribbean. 



The 40-foot shrimp trawl was used as a 

 standard gear for bottom exploration. This 

 trawl was fished with 5-, 6-, and 7-foot doors 

 using a single warp and bridle. Generally a 

 tickler chain was attached. Mesh size in the 

 trawl body was 2-inch stretched, and the 

 codend was 1-3/4-inch stretched mesh of 

 42-thread cotton. Frequently 1/4-inch 

 stretched mesh was used to line the codend. 

 Underwater observations of the trawl reveal 

 that it spreads to cover an optimum path 

 some 25 feet wide, at speeds of 2 to 3 knots 

 (Bullis and Cummins, 1963). Door sizes and 

 changes in speed alter the opening width 

 within a range of +20 percent. Looped chain on 

 the footrope and one to three sponge floats on 

 the headrope were used in conformity with 

 industry practices. 



Advantages of using the 40-foot shrimp 

 trawl include dependability of performance, 

 ease of construction and repair, and reasonable 

 cost (less than $100 for materials). Early 

 comparisons with industry try-nets (12- to 

 18-foot stretched spread) and the larger com- 

 mercial trawls (65- to 120-foot stretched 

 spread openings) indicate that the 40-foot size 

 was minimum for obtaining a representative 

 sample of the species on shrimp grounds and 

 a reliable estimate of their densities. This type 

 of net, however, is obviously selective, and 

 gross faunal evaluations based on shrimp trawl 

 catches alone can be quite misleading. The 

 larger and more active species of fish and 

 the sedentary or partially burrowed inverte- 

 brates are usually not caught or are taken only 



rarely. Therefore, 5- to 8-foot scallop dredges 

 and 55- to 65-foot New England-style fish 

 trawls were also used in general reconnais- 

 sance surveys. 



The pattern of exploratory fishing stations 

 differs markedly from patterns dependent on 

 the use of preplanned grid stations. In general 

 terms, an exploratory survey of an area is ini- 

 tially undertaken as a series of trawl and 

 dredge drags that cover a preselected depth 

 range. Trawling transects on the Continental 

 Shelf are designed to include one or more 

 drags at every 5-fathom depth interval. Only 

 rarely can this be accomplished owing to 

 frequent trawling interruptions caused by rock 

 and ;oral bottoms that preclude all types of 

 normal trawling. Preliminary reconnaissance 

 on the Continental Slope involved drags at 

 intervals of 10 to 25 fathoms out to the 

 300-fathom contour. From 300 to 500 fathoms, 

 trawling stations are made at 50-fathom inter- 

 vals, and when lower shelf coverage is sched- 

 uled, 100-fathom intervals are fished. To date, 

 only a limited amount of trawling has been 

 conducted at depths greater than 1,000 fathoms. 

 The maximum depth we have fished during 

 explorations with a trawl is 2,080 fathoms. 

 As in shallow water transecting, the pattern 

 on the slope is frequently interrupted, chiefly 

 owing to sudden changes in slope configuration. 

 Trawling on slope angles greater than 45° has 

 been uniformly unproductive of large biological 

 samples. 



In addition to depth coverage, every effort is 

 made to sample all trawlable bottom types 

 within each depth stratum. Good samples can 

 be obtained on mud, sand, and shell and 

 gravel. On sponge and alcyonarian bottom the 

 trawl generally becomes overloaded, making 

 analysis of samples obtained from these 

 bottoms difficult. Bottom temperature tran- 

 sects are made in an effort to trawl through 

 the various temperature strata. Finally, ex- 

 ploratory coverage of the bottom is designed 

 also to examine the distribution and density 

 of bottom organisms in relation to temperature. 



When plotted on a cruise chart, the patterns 

 emerging from the explorations may tend to 

 indicate a rather haphazard fishing station plan. 

 Indications are, however, that the organisms 

 of interest in the studies tend to orient them- 

 selves to bottom type, water temperature, and 

 depth much more closely than to any arbitrary 

 grid system that can be laid out neatly on a 

 chart. 



A major goal of this program is a 4-season 

 coverage of all Continental Shelf and Slope 

 areas from Cape Hatteras to eastern Brazil. 

 We believe that the resulting data should show 

 distributional patterns of bottom fauna. To 

 facilitate this study, the total backlog of 

 species distributional data has been trans- 

 ferred to automatic data processing cards, and 

 preliminary faunal summaries are now being 

 prepared. 



