and are, for the most part, sexually inactive 

 (Beaumariage 1973, Finucane et aL footnote 7). 

 Immature fish form a large proportion of the Florida 

 winter catch but are proportionately less abundant 

 along the North Carolina, South Carolina, and Texas 

 coasts. For example, percent compositions of king 

 mackerel between 300 and 600 mm FL in the rec- 

 reational catches by area and year were as fol- 

 lows: 



Location 



South Florida 



South Carolina-Georgia 



North Carolina 



Northwest Florida 



Texas 



King mackerel<600 mm FL were not observed from 

 Louisiana. Members of the immature group are 

 caught in abundance in areas other than south 

 Florida only during summer months. They are pro- 

 portionately abundant in the catches in July- August 

 in northwest Florida, in August in Texas, and in Sep- 

 tember in North Carolina. 



The Spawning Group 



Members of this group include the sexually mature 

 individuals (usually >600 mmFL) of the Florida win- 

 ter groups and, during warmer months, are dis- 

 tributed throughout the coastal zone of the 

 southeastern United States and along the northeast 

 U.S. coast. In the Gulf of Mexico, most members of 

 this group residing in south Florida during winter 

 apparently migrate north earlier or faster than do 

 members of the immature group (Trent et aL 1981). 

 Early departure of the larger king mackerel is reflect- 

 ed, for example, in the recreational landings in south 

 Florida during 1979; mean fork lengths decreased 

 from 861 mm in January to 729 mm in March. King 

 mackerel occurring in the early months of each fish- 

 ing season in northwest Florida and Texas are usually 

 the largest. Members of this group that migrate 

 northward along the Atlantic coast in the spring did 

 not reveal the same seasonal size pattern as did those 

 in the Gulf of Mexico. The largest individuals did not 

 arrive in North Carolina until June of each year and 

 were preceded by smaller fish. 



FISHERY BULLETIN: VOL. 81. NO. 4 



Louisiana Group 



This group is characterized by large fish, most of 

 which are female. Of all fish examined only 12.1% in 

 1977 and 2.9% in 1978 were <900 mmFL (about 12 

 lb) and 92.5% of all fish were females. Although king 

 mackerel of both sexes were caught during all 

 seasons, monthly estimates of the proportion of 

 females were never <80%. The highest proportions 

 of males occurred from May through September. 

 Exceptionally large fish (> 1,399 mm FL) were 

 caught in highest proportions from November 

 through March. Fish <800 mm FL were caught only 

 during June, September, and October. 



The range and migration patterns of the Louisiana 

 group are not known. Most of the king mackerel 

 observed from Louisiana were caught adjacent to oil 

 rigs in water depths of 10-20 fathoms about 12-18 mi 

 southeast of Grand Isle. This area is fished heavily by 

 recreational fishermen, because it is within practical 

 range of two ports (Grand Isle and Empire) that pro- 

 duce most of the fishing effort for king mackerel in 

 Louisiana and because king mackerel fishing is 

 known to be good in the area. The oil rigs, however, 

 are numerous at depths from 10 to 50 fathoms from 

 the Mississippi Delta (long. 89°30') westward to 

 areas off the Texas-Louisiana border (long. 93°50'), 

 an east-west distance of about 250 mi. Members of 

 the Louisiana group probably occur throughout the 

 oil field but, evidently, do not participate in extensive 

 north- south migrations as do smaller king mackerel. 

 The presence of large king mackerel off the Louisiana 

 coast in winter (Table 4) suggests that environmental 

 factors are favorable for them there throughout the 

 year. Munro (1943) stated that minimum tem- 

 peratures of 20° C limit the distribution of members 

 of the genus Scomberomorus. Large king mackerel 

 were caught in abundance off the Louisiana coast 

 during the winters of 1977 and 1978, two of the 

 coldest winters on record (Ingham 1979). In 1978, 

 surface water temperatures and their deviations 

 from the 1948-67 mean(°C) in the one-degree square 

 (long. 89°-90° and lat. 28°-29°) just south of the area 

 where king mackerel were caught averaged 19.4°C 

 (-1.3) in January, 18.7°C (-1.8) in February, and 

 18.6°C (-2.4) in March. Data collected during 

 January-March 1976 indicated that bottom tem- 

 peratures are about 1°-2°C higher than surface tem- 

 peratures where depths are between 10 and 20 

 fathoms off Louisiana (Ragan et al. 1978); thus a 

 habitat in which temperatures were 20° C or greater 

 could have been available to king mackerel in 

 1978. 



Atlantic croaker; longspine porgy, Stenotomus ca- 



720 



