WENNER ET AL.: EXPLORATION FOR GOLDEN CRAB 



DISCUSSION 



Although the results of this study suggest that 

 G. fenneri has a wide bathymetric occurrence in 

 the South Atlantic Bight, the depth extremes for 

 the species probably extend beyond those encom- 

 passed by our sampling design. Records of Geryon 

 sp. and G. affinis (which were probably G. fen- 

 neri ) from the Gulf of Mexico indicate a depth 

 distribution of 365-1,455 m (Pequegnat 1970), 

 while Luckhurst (in press) reported golden crabs 

 from 786 to 1,462 m near Bermuda. 



Although a broad bathymetric range for the 

 species is likely, maximum abundance occurs be- 

 tween 367 and 549 m in our study area. This 

 depth range coincides with that reported by Stone 

 and Bailey (1980) for maximum trap catches of 

 G. quinqiiedens along the Scotian Shelf and ap- 

 proximates the limits (320-530 m) determined by 

 Wigley et al. (1975) by trawl and photographic 

 methods to be most productive for that species off 

 the northeastern United States. 



Information on sediment composition taken co- 

 incidentally with fishing activities suggests that 

 abundance of both G. fenneri and G. quinquedens 

 is influenced by sediment type at these optimum 

 depths. Our catches were highest on substrates 

 containing a mixture of silt-clay and fora- 

 miniferan shell. In contrast, no golden crab were 

 collected on rock and coral rubble bottom such as 

 was encountered in the 550-640 m stratum. Other 

 studies have described an association of G. quin- 

 quedens with soft substrates. Wigley et al. (1975) 

 noted that bottom sediments throughout the area 

 surveyed for red crab from offshore Maryland to 

 Corsair Canyon (Georges Bank) consisted of a 

 soft, olive-green, silt-clay mixture. If golden crabs 

 preferentially inhabit soft substrates, then their 

 zone of maximum abundance may be limited 

 within the South Atlantic Bight. Surveys by 

 Bullis and Rathjen (1959) indicated that green 

 mud occurred consistently at 270-450 m between 

 St. Augustine and Cape Canaveral, FL (30''N and 

 28°N). This same depth range from Savannah, 

 GA to St. Augustine was generally characterized 

 by Bullis and Rathjen (1959) as extremely irregu- 

 lar bottom with some smooth limestone or "slab" 

 rock present. Our study indicates, however, that 

 the bottom due east between Savannah and St. 

 Catherines Island, GA at 270-540 m consists of 

 mud and biogenic ooze. Further north from Cape 

 Fear, NC to Savannah, bottom topography be- 

 tween 270 and 450 m is highly variable with 

 rocky outcrops, sand and mud ooze present (Low 



and Ulrich 1983). Additional information on sedi- 

 ment type during future fishing efforts will be 

 necessary before any validation of sediment pref- 

 erence by golden crab can be made. 



The catch data for golden crab in our survey 

 compares favorably with catch rates reported by 

 Otwell et al. (1984) in the Gulf of Mexico. Al- 

 though their study was not intended to assess the 

 resource, they reported mean catch per trap val- 

 ues of 7.4-8.4 for the nested design fished between 

 210 and 340 fathoms. Information on catch rates 

 of red crab from trap surveys and the fishery is 

 perhaps more relevant to our study. Ganz and 

 Herrmann (1975) reported an overall unculled 

 mean catch per pot of 40-93 red crabs off southern 

 New England; their study used four types of dou- 

 ble parlor offshore lobster pots. An average catch 

 of 26.8 red crabs per trap (conical-top entry) was 

 reported in 360-540 m depths on the Scotian Shelf 

 by Stone and Bailey (1980). The only available 

 information on weight per trap was provided by 

 Gerrior (1981) who found seasonal catch rates 

 that ranged from a low of 8.4 kg in March to a 

 high of 11.1 kg per pot in June. Although com- 

 parison of catch per unit of effort between these 

 studies is questionable because trap type and 

 fishing duration, as well as physical features of 

 the sampling areas differ, catch per trap of golden 

 crab in depths of maximum abundance off South 

 Carolina and Georgia appears promising. 



Comparison of catches (no. /trap) between the 

 Fathoms Plus trap and the Florida trap clearly 

 indicate superiority of the latter for golden crab. 

 These two traps also differed in the size and 

 weight of individuals caught, with larger and 

 heavier golden crab occurring in the Fathoms 

 Plus trap. Advantages of the Fathoms Plus traps 

 for commercial fishing operations would include 

 their lighter weight, ease of handling, and stack- 

 able configuration which conserves deck space. 

 Differences observed between traps may be re- 

 lated to trap design which affects success of entry 

 and maximum catch (Miller 1980) or behavioral 

 interactions which affect probability of capture 

 (Richards et al. 1983). Although no studies have 

 been done to evaluate behavior of G. quinquedens 

 or G. fenneri in regard to traps, responses of the 

 spider crab, Hyas araneus, and the rock crab, 

 Cancer irroratus, to top and side entry traps were 

 reported by Miller (1980). He found success of 

 entry by C. irroratus was greater, escapement 

 was reduced, and fewer agonistic encounters oc- 

 curred in top entry traps. In a complementary 

 study, however. Cancer productus had highest 



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