OCCURRENCE OF YOUNG-OF-THE-YEAR KING, 

 SCOMBEROMORUS CAVALLA , AND SPANISH, 



5. MACULATUS, MACKERELS IN 



COMMERCIAL-TYPE SHRIMP TRAWLS ALONG 



THE ATLANTIC COAST OF 



THE SOUTHEAST UNITED STATES^ 



King mackerel, Scomberomorus cavalla, and 

 Spanish mackerel, S. maculatus , are migratory 

 scombrids that support large recreational and 

 commercial fisheries along the southeast coast of 

 the United States (Manooch 1979). Recent evi- 

 dence indicates that both species may be overex- 

 ploited in portions of their range, prompting the 

 South Atlantic Fishery Management Council to 

 impose catch limits and landing quotas^. Many 

 aspects of the biology and ecology of adult mack- 

 erels in this region have been studied (Manooch 

 et al. 1978; Collette and Russo 1984), and the 

 larval stages have also received attention (Fahay 

 1975; Collins and Stender 1987). However, little 

 is known concerning the distribution and occur- 

 rence of juvenile (young-of-the-year) mackerels 

 along the Atlantic coast of the southeastern 

 United States, nor does it seem to be widely 

 known that large numbers of these young fishes 

 may be included in the bycatch of a major fishery. 

 This report provides preliminary information on 

 both of these topics. 



Methods 



During 1980-82 and 1985-86 the Marine Re- 

 sources Monitoring and Assessment Program 

 (MARMAP) at the South Carolina Marine Re- 

 sources Research Institute conducted trawl sur- 

 veys of the nearshore fish fauna in the South At- 

 lantic Bight (Cape Hatteras, NC, to Cape 

 Canaveral, FL). Before 1986, trawl gear consisted 

 of two semiballoon shrimp trawls with an 18.3 m 

 footrope, a 12.2 m headrope, 4.1 cm stretch mesh 

 in the cod end, and 1.5 x 0.9 m doors towed at 2.5 

 knots (4.6 m/second). In 1986, paired "tongue" 

 trawls with a 22.9 m footrope, 4.1 cm mesh, and 

 3.0 X 1.0 m doors were towed at approximately 

 2.5 knots. Sampling strategy and length of tow 

 (20 minutes to 1 hour) varied between cruises. 

 Station depths were 3-18 m in 1980-81 and 3-9 

 m in subsequent years. In each sample, all mack- 



erels were identified to species and measured 

 (fork length), and number and total weight were 

 recorded for each species. We conducted two addi- 

 tional cruises in 1986 to test tongue trawl nets 

 equipped with trawl efficiency devices (TED's). A 

 National Marine Fisheries Service (NMFS) TED 

 equipped with finfish deflector"^ was installed in 

 one net, a Georgia TED^ in a second net, and a 

 third net acted as a control. The TED's were 

 fished against each other and against the control 

 for a total of 30 tows on the first cruise (July-Au- 

 gust 1986) and 15 tows on the second (September- 

 October 1986). 



Tongue nets, also known as bib, falcon, cobra, 

 or mongoose trawl nets, have become widely used 

 by commercial shrimpers in some areas during 

 recent years (Edwards 1987). The major differ- 

 ence between these and other common towed 

 gears used in the penaeid shrimp fishery is a mod- 

 ified and elongated headrope that is held well 

 above the footrope by attachment to the trawl 

 warp with a third bridle. A large float, usually 

 attached to the center of the headrope, produces a 

 high, vertical mouth opening. The result is a net 

 that fishes a larger portion of the water column 

 than other common nets with similar footrope 

 and door configurations. 



Results 



During years when semiballoon nets were used, 

 catch per unit effort of mackerels was relatively 

 low (king mackerel: 0.2-0.4 individuals/net-hour; 

 Spanish mackerel: 0.3-2.2 individuals/net-hour). 

 Tongue trawl nets on four 1986 cruises gave 

 cruise-specific average catches of 2.5-8.7 individ- 

 uals/net-hour for king mackerel and 12.4-115.2 

 individuals/net-hour for Spanish mackerel, using 

 catches of control [unmodified] nets for TED 

 cruises (Table 1). Both species were taken as late 

 as 30 October, except for two king mackerel 

 caught in December 1982. Approximately 79% of 

 king and 91% of Spanish mackerel were caught in 

 depths <9 m during the two years in which sam- 

 ple depths extended to 18 m. 



Mackerels taken in shrimp trawls were almost 

 entirely juvenile fishes. Rather than pool catches 

 between cruises that often differed in time of 

 year, geographic area, and sampling strategy, ex- 

 amples of length frequencies of Spanish and king 



iContribution No. 244 of the South Carolina Marine Re- 

 sources Center. 



^South Atlantic Fishery Management Council, Council Meet- 

 ing Summary, 27-29 April 1987, Charleston, SC. 



3Described and illustrated in the Federal Register, vol. 52, no. 

 124; Monday, June 29, 1987 - Rules and Regulations; p. 24244- 

 24262. 



394 



FISHERY BULLETIN: VOL. 86, NO 2, 1988. 



