roM Technical ManorandwnNMFS-SER::-181
Species profile of round scad Decapterus punctatus (CUVier1829)
Steven P. Naughton Carl H. Salanan and
Rosalie N. Vaught
July 1986
u.S. Deparbnent of Carmerce National Oceanic and Atmospheric Administration National Marine Fisheries Service Southeast Fisheries Center PanamaCity Laboratory 3500 DelwoodBeach Road PanamaCity, FL 32407-7499 NOAA Technical Memorandum NMFS-SEFC-181
Technical Memorandums are used for documentation and timely communication of preliminary results, interim reports, or special-purpose information, and have not received complete formal review, editorial control, or detailed editing.
ATM
Species profile of round scad
D=apt,erus V=tatus (Cuvier 1829)
Steven P. Naughton
Carl H. Saloman
and
Rosalie N. Vaught
July 1986
U.S. DEPARTMENT OF COMMERCE Malcolm Baldrige, Secretary NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION Anthony J. Calio, Administrator NATIONAL MARINE FISHERIES SERVICE William G. Gordon, Assistant Administrator for Fisheries INTROWCTION
Members of the genus Decapterus usually occur in schools and are distributed throughout the world in tropical and subtropical waters. Decapterus is found generally in inshore waters, although larvae and young may occur in oceanic waters (Berry 1968). Fishes of this genus are important both for human consumption and for bait. In the Philippines, the round scad (Decaplerus spp.) is the largest commercial fishery, reaching over 100,000 tons per year (Ronquillo 1970).
The increasing demand for protein for humans has put additional pressure on fish species not formerly exploited to the fullest. This species profile will attempt to bring together information on aspects of Decapterus pmctatus so future management and research plans can be developed. Emphasis will be centered on the species in the Gulf of Mexico.
TAXONOMY
Current scientific name: Decapterus; V=tatus (Cuvier) Previous scientific names: Scomber hiWQs (non Linnaeus) Mitchell 1818 Caranx Vmctatus Cuvier 1829
Caranx rx=tatus Agassiz in Spix 1831 Caranx punctatus Cuvier in Cuvier and Valenciennes 1833 Preferred common name: Round scad
MORPHOLOGY
The round scad is a small carangid with a slender and rounded body with a slender caudal peduncle. The eye is moderate with a well- developed adipose eyelid. Gill rakers on upper gill arch range from 11- 16, teeth are minute and are in a single row in both jaws. There are two well developed and separate dorsal fins including a finlet. The body is well covered with cycloid scales. Total scales and scutes in the lateral line number 77-98. The lateral line is curved and contains 12-14 black spots, usually formed when the fish reaches 10 cm fork length.
The color is greenish to greenish blue above, silvery on the sides and a narrow bronze stripe extends from the tip of the snout along the
1 lateral line to the caudal peduncle. A small black spot is on the margin near the upper edge of the opercle.
IDENTIFYING CHARACTERISTICS
In the western Atlanticr three species of D=apterus occur: _Q, lxmctatus,l D.- macarellusf and D, tabi (Fig. 1). The following key to the three species is from Berry (1968).
KEY TO WESTERN ATLANTIC DECAPTERUS
1A. Dark spots (10-14) present along curved lateral line (at sizes larger than ca. 90 mm SL). Curved lateral line strongly arched. Curved lateral line with 37-56 scales and usually 1-5 scutes. Total lateral line scales and scutes (excluding peduncle scales) 72-98. Vertebrae 10 + 15 ...... DecapterUa ounctatus (Fig. 1A)
1B. No spots in curved lateral line. Curved lateral line moderately to weakly arched. Scales in curved lateral line 61 or more. No scutes in curved lateral line. Total lateral line scales and scutes 103 or greater. Vertebrae 10 + 14 ...... 2
2A. Curved lateral line moderately arched. Anterior scales in straight lateral line 0-8. Scutes in straight lateral line 34-44...... Decapterus ±&-bi (Fig. 1B)
2B. Curved lateral line weakly arched. Anterior scales in straight lateral line 19-33. Scutes in straight lateral line 23-32 ...... o....Decapterus Macarellus (Fig. 10
Larval identification is illustrated with morphological changes from 2.3 mm standard length to 23.0 mm standard length in Figure 2.
DISTRIBUTION AND RANGE
Adults
The round scad occurs in the western Atlantic from Massachusetts through Bermuda, southviard through the Gulf of Mexico, the Caribbean and West Indies to Rio de Janeiro (Fig. 3). According to Berry (1968) this areal distribution is continuous. The species is probably most abundant. in the' eastern Gulf of Mexico (Aprieto 1974, Finucane et al. 1978, Leak 1977, and Montolio 1976). The occurrence of schooling adults and the ' largest commercial fishery of round scad are also from the eastern Gulf of Mexico (Juhl 1966, Klima 1971, Klima and Wickham 1971, Wickham and Russell 1974, and Hastings et al. 1976). Records of adults west of the Mississippi River are scarce (Roithmayr 1965, Chittenden and McEachran 1976).
2 Most of the fishing for adult round scad in the Gulf of Mexico occurs along the northwest Florida coast. The annual catch in pounds f rom Florida's west coast has gradually increased from 1952 to 19E2. In 1982 the catch yielded 1,756,000 pounds (Fig. 4). Records of adult abundance from areas of the Gulf of Mexico are available f rom NMPS, Pascagoula Laboratory in Pascagoula, Mississippi. Data from their shrimp and fish trawls (40 ft head rope) f rom 1950 to 1985 reveal that adult round scad are abundantly concentrated off Florida's west coast in the winter. In the spring, abundance shifts northward with highest concentrations off Mississippi and Alabama. In the summer, abundance has shifted farther west to Louisiana and Te-xas. In the fall, the fish are still concentrated in the northern gulf (Figs. 5, 6, 7, and 8).
Larvae
Larvae of round scad have been found during all seasons. Larval abundance is probably highest in the eastern Gulf of Mexico, based on collections by Aprieto (1974), Montolio (1976), Leak (1977), and Finucane et al. (1978). Larval abundance changes with season, as Montolio (1976) found highest concentrations of larvae in the eastern Gulf of Mexico in the spring, lesser concentrations in the northern, eastern, and southern gulf in the summer, and high concentrations in the north central gulf and off Yucatan in the fall (Fig. 9). A larval survey in the western Gulf of Mexico by Finucane et al. (1978) noted D, punctatus larvae from April through September, with highest abundances in August 1977 (Fig. 10). Larval surveys in the Yucatan and Florida straits indicated round scad larvae to be numerous in October 1962, April 1963, May-June 1968, and May 1969. Larvae were collected at water temperatures between 21-310C (Lyons 1978). Thus, recruitment from the Caribbean into the Gulf of Mexico also occurs.
Along the south Atlantic coast of the United States, larvae were collected from May through November with abundance high from July to September (Hildebrand and Cable 1930). In another survey (Fahay 1975) larval D, punctatus were collected during all seasons with peak abundance in the spring between New River, North Carolina, and Palm Beach, Florida. While sampling larval carangids along the Florida coast and northward to the Carolinas, Aprieto (1974) found larval and juvenile D punctatus in all months with their greatest abundance in the eastern area of the Gulf of Mexico (Fig. 11). Dooley (1972) also found D,_ punctatus from November through May with a peak in March. These specimens were associated with sargassum. In a larval survey of the eastern Gulf of Mexico Cbring 1971- 74, Houde, et al. (1979) found that the abundance of -D-,- pu=tus larvae was highest in September 1972, with secondary peaks of abundance in May 1971, 1972, and 1973 (Fig. 12).
3 REPRODUCrICN
The spawning areas of round scad include almost the entire continental shelf from approximately North Carolina southward throughout the Gulf of Mexico and Caribbean (Hildebrand and Cable 1930, Aprieto 1974, Montolio 1976, Johnson 1978, Finucane, et al. 1978, Reintjes 1979, Lyons 1978, Leak 1981, Houde, et al. 1979,, and Herrema, et al. 1985). Larvae beyond the continental shelf are less abundant, except possibly in the Caribbean (Montolio 1976).
Information on reproductive biology is sparse. In a survey of the coastal waters of northwest Florida, round scad appeared to have a spawning season that extended throughout the year. Ripe males and females (Stage IM were present from April through October. Peak spawning based on GSIs probably occurred in the spring and fall (J.H. Finucane, personal communication). Males matured at a smaller size than females with 50% of the males and females maturing at 125-129 mm fork length. All males were mature at 145-149 mm and all females at 130-134 mm. Estimates of batch fecundity of 20 fish ranged from 21,000 ova for a 146 mm female to 146,000 for a 188.mm female. P, V=tatus are believed to be serial spawners. The size-at-maturity of round scad in the Gulf of Mexico was estimated to be 140 mm (J.H. Finucane, personal communications), while Leak (1981) reported mature females as small as 107 mm. Houde, et al. (1983) stated that fish 135 mm are less than one year of age and may contribute significantly to spawning in the eastern gulf.
AGE AND ^!H
Age and growth information on D, Punctatus is limited to the work of Houde and Berkeley (1981, 19E2a, 1982b, 1982c), and Houde, et al. (1983). Specimens of D,, p=tatus for these reports were collected in the Gulf of Mexico from Port St. Joe to Destin, Florida.
To determine the age and growth of D. Dunctatus, the alternating tryaline and opaque zones on otoliths were judged to be annual marks. Fork length-otolith radius relationship was FL -1.08 + 75.75 R, where n = 2019, and r2 = 0. 80 (FL f ork length in mm, R otolith radius in mm, n = sample size, and r2 coef ficient of determination). The von Bertalanffy growth model was fitted using Beverton's method (Ricker 1975) to the mean back calculated lengths at age for combined 1981-82 data. The equation for round scad was Lt = 221.78(.1-e-0.32(t + L914)) where Lt length (mm) at time; t = time in yrs.'^'^' Estimated mean back calculated fork lengths at age were: Age 1, 136.0 mm; Age 11, 159.7 mm; and Age 111, 176.9 mm (Fig. 13).
4 MORTALITY
The instantaneous rate of total mortality (Z = 0.92) is Considered to approximate closely natural mortality. Annual mortality rate is estimated to be 60% and the annual survival rate is estimated to be 40% (Berkeley and Houde 1984). Based on spawning surveys of egg abundance of about 350 kilotons (Leak 1981, Houde and Berkeley 1982b), and present catches comprising about 1% of this total, Houde, et al. (1983) indicated that highest yields could be attained from these stocks under a high rate of exploitation, if recruitment could be sustained at the high F values that give maximum yield-per recruit. For round scad the theoretical maximum yield-per-recruit at recruitment length of 105 mm FL would be at high rates of exploitation (F = 0.85). At the respective FMax the yield- per-recruit for round scad was 19.5 g. The yield-per-recruit curves were flat topped, with little gain in yield expected beyond F levels of 1.5 (Fig. 14). Round scad grows fast, reaching 50-65% of their estimated asymptotic length at one year of age. This fast growth and high natural mortality (M = >0.82),, indicates that optimum harvesting is best at a young age. As 0+ round scad contribute substantially to spawning in the eastern Gulf of Mexico, round scad may be less susceptible to recruitment overfishing. The percent of the population for 1981-82 in the following age groups were 0+, 75.1%; I+r 19.0%; 2+ 5.8%; and 3+,, 0.1%.
LENGTH-WEIGHT RELATIONSHIP
The length-weight relationships of round scad were determined by Houde and Berkeley (1982b) and later summarized by Berkeley and Houde (1984). Samples are from the eastern Gulf of Mexico collected daring 1981-82. The estimated lengths and weights at age for round scad for males and females are presented in Table 1. The relationship of weight (g) to length (mm fork length) for 1981-82 and by sex for both years combined is presented in Table 2.
TEMPERATURE RELATIONSHIPS
Adult round scad have been caught in surface water temperatures of 12 to 300C and in bottom water temperatures of 13 to 270C. The percent frequency of occurrence and the average pounds of round scad in trawl catches varied considerably over the temperature ranges (Fig. 15 and 16). However, when considering the commercial catches of round scad from northwest Florida, production was the highest during the spring and summer months when water temperatures were the highest (Fig. 17). Catch rates during December, January, February, and March were the lowest and represent less than one percent of the total catch.
5 DEPTH REIATICNSHIPS
In experimental trawls by the NMFS, adult round scad were caught at depths ranging from 1 to 200 fathoms in the Gulf of Mexico. The frequency of occurrence of individuals appearing in the trawls increased as the depth increased to 65 fathoms and then decreased thereafter (Fig. 18). In the commercial fishery of round scad in northwest Florida, the principal gear used is the beach seine, and catches are made in depths of 1 to 2 fathoms. However, with the advent of the purse seine, commercial catches in deeper water may become more common.
EUM HABITS
Information on food habits of D. punctatus in the Gulf of Mexico is restricted to preliminary work by the authors on specimens from northwest Florida. The diet consists mainly of planktonic forms, with various larval crustaceans (mainly crab larvae), copepods, ostracods,' and mysids leading the list of frequency of occurrence. Other items frequently occurring were radiolarians, fish eggs, gastropods, pelecypods, amphipods, Amphioxus, scaphopods, and shrimp. In the Caribbean, Randall (1967) found the stomach contents of 10 round scad 131 to 171 mm to be 60% copepods, 18.5% gastropod larvae by volume with the remainder being ostracods, pteropods, shrimp larvae, and unidentified remains. Schekter (1972) examined the stomachs of 12 larval and juvenile round scad, 7.1 mm to 37.2 mm SL, from the Miami area of the Florida Current, and found 188 food organisms, all copepods.
The consumption of P, punctatus by coastal pelagic predators is fairly common and in food studies, the round scad is often listed. The main predator in northwest Florida on pecW-terus is the king mackerel. Examination of king mackerel stomachs revealed a frequency of occurrence of 25.6% and-a percentage volume of total stomach contents of 29.9% for D., p=tatus(Saloman and Naughton 1983a). The presence of round scad was also common in Spanish mackerel, bluefish, and crevalle jack collected in northwest Florida (Saloman and Naughton 1983b, 1984; Naughton and Saloman 1984).
SEX RATIO
The ratio of females to males varied between months, with females dominating in collections from northwest Florida. In 1980 females comprised more than 59% of the population in 6 of 7 months and in 1981 females comprised more than 64% in 6 of 8 months (Fig. 19). This information differs from the work of Berkeley and Houde (1984)1, as they found males were more abundant in 1981 and 1982 (Table 3). The difference could be attributed to sample size, as the number of specimens
6 examined by Berkeley and Houde (1984) were approximately 1/3 the number we examined. Examination of sex in relation to size of D.- o=tatus reveals that the larger fish M65 mm FL) had a higher proportion of males than females (Fig. 20).
AGE STRJCTURE
The age structure of the population of round scad in northwest Florida varied from year to year and also within months of each year. The mode of the length-frequency distribution of the population for the years 1980 to 1982 changed from 155 mm EL in 1980 to 165 mm EL in 1981 and to 145 mm FL in 1982 (Figs. 21, 22, and 23). In 1980 the size grouping at 155 mm EL was the highest in 5 of 6 months sampled. In the other two years (1981 and 82) the mode changed from month to month. Based on the length-frequency distribution of the population and age estimates by Berkeley and Houde (1984) where age I fish are 136.0 mm EL and age 11,, 159.7 mm FL, the modal frequency of the population was between ages I and II.
FISHERIES
The commercial fishery for round scad is primarily located in northwest Florida. The product is used almost exclusively for bait. The annual catch of round scad from northwest Florida has shown an increasing trend since the 1950s. Production reached its peak in 1982 with over 1,700,000 pounds (Fig. 4).
Methods of capture are primarily the beach seine and the purse seine. With more boats equipped with a purse seine, the production should increase as schools in deeper water can be harvested.
Handling of the catch for the bait market includes the following steps. The fish are iced upon capture; on arrival at the fish house, they are boxed in five pound boxes and frozen. The next day the boxes are opened and water is sprayed on the fish and then are immediately ref rozen. This process creates a glaze of ice on the fish which results in a higher quality product.
CDMPOSITION
Hale (1984) gave the proximate composition of round scad from gulf waters as: protein - 22.6%; fat - 2.6%; moisture - 73.95%; ash - 2.60%. Sidwell (1981) listed the following microelements from raw muscle (in ppm): zinc - 4.61; arsenic - 0.46; cadmium - 0.03; copper - 0.51; and mercury - 0.10. Additional information regarding the proximate composition of round scad is given in Tables 4 and 5.
7 MARKETING
The following information was obtained from M.E. Smith (NMFS, Pascagoula, MS, personal communication).
Domestic Market - The only known market at this time for these fish is as bait by sportsmen. The value of the fish at the wholesale level, packed in five pound cartons is about $.35 per pound.
EWQrt Market - The relatively small size of the gulf round scad limits the use of the fish as an export item. The same genus of fish has been seen in the Orient and are marketed heads-on, split, salted, and dried. In Hong Kong the dried form, depending on the degree of quality of the product, is valued at about $.82 per pound at the wholesale level. The product is imported from countries having very low wage scales; therefore, it is doubtful U.S. producers could be competitive.
The larger red tail scad (p, jab_Jl is also available from the gulf and ranges in size from 10" to 147. This species closely resembles red finned scad which is sold fresh in Japan. It is possible that this species would be equally acceptable by Japanese markets. A value cannot be placed on the red tail scad at this time.
INFICRMATICN NEEDS
More information is needed on the distribution and abundance of the adults. The fishery in northwest Florida occurs during the warm months. During the winter, round scad migrate to unknown areas, most probably to offshore waters. Mark and recapture studies would be futile, since no fishery exists in other areas for recaptures to be made. Needed biological information includes reproductive biology (especially fecundity), effort data from the commercial fishery, recruitment and mortality estimates (McIlwain 1983). Economic and marketing information on this fishery is also desired.
LITERATURE CITED
APRIETO, V. 1974. Early development of five carangid fishes of the Gulf of Mexico and the south Atlantic coast of the United States. U.S. Nat. Mar. Fish. Serv., Fish. Bull. 72(2):415-444.
BERKELEY, S.A., and E.D. HOUDE. 1984. Age, growth and mortality of coastal herrings in the eastern Gulf of Mexico. Final report to Gulf and South Atlantic Fisheries Development Foundation, Inc. GASAFDFI Project No.: 21-12-32272.
BERRY, F.H. 1968. A new species of carangid fish (Decapterus Jtabl) from the western Atlantic. Contrib. Mar. Sci., Univ. Tbx. 13:145-167.
8 OIITl'ENDEN,M., and J. McEACHRAN.1976. COmposition, ecology, and dynamics of demersal fish communities on the northwestern Gulf of Mexico continental shelf with a similar synopsis for the entire Gulf. Texas A&MUniv. Sea Grant Publ. No. TAMU-OO-76-208.104 W.
OCOLEY,J.H. 1972. Fishes associated with the pelagic sargassum complex, with a discussion of the sargassum community. COntrib. Mar. Sci., Univ. Texas 16:1-32.
FAHAY,M.P. 1975. An annotated list of larval and juvenile fishes captured with a surface-towed meter net in the South Atlantic Bight during four IN Dolphin cruises between May 1967 and February 1968. roM Tech. Rep. NMFS-SSRF-685, 39 pp.
FINUCANE,J.H., L.A. COLLINS,L.E. BARGER,and J.B. McEACHRAN1978. Ichthyoplankton/mackerel eggs and larvae. roM Final Report to BLM. Environmental studies of the south Texas outer continental shelf 1977. BLMCOntract AA550-1A7-21, xxI. plus 504 pp.
HALE,M.B. 1984. Proximate chemical composition and fatty acids of three small coastal pelagic species. Mar. Fish. Rev. 46(1):19-21.
HASTINGS,R.W., L.H. OGREN,and M.T. MABRY.1976. Observations on the fish fauna associated with offshore platforms in the northeastern Gulf of Mexico. U.S. Nat. Mar. Fish. Serv., Fish. Bull. 74(2):387- 402.
HERREMA,D.J., B.D. PEERY,N. WILLIAMS-WALLS,andJ.R. WILCOX. 1985. SPawning periods of commoninshore fishes on the Florida east coast. Northeast Gulf Sci. 7(2):153-155.
HILDEBRAND,S.F., and LeE. CABLE. 1930. Development and life history of fourteen te1eostean fishes at Beaufort, N.C. Bull. U.S. Bur. Fish. 46:384-488.
HOUDE,E.D., and S.A. BERKELEY.1981. Age, growth and mortality of coastal herrings in the eastern Gulf of Mexico. Interim Report, 30 July 1981. Gulf and South Atlantic Fishery Development Foundation, Inc. 7pp.
HOUDE,EoD., and S.A. BERKELEY.1982a. Age, growth and mortality of coastal herrings in the eastern Gulf of Mexico. Progress report, August 1981 to December 31, 1981. Gulf and South Atlantic Fisheries Development Foundation, Inc. Ref. No. UMCEES82-46 CBL, 10 pp.
HOUDE,E.D., and S.A. BERKELEY.1982b. Assessment of coastal herring resources in the eastern Gulf of Mexico. Interim report, May 1, 1982 to October 31, 1982. Gulf and South Atlantic Fisheries Development Foundation, Inc. Ref. No. UMCEES82-155 CBL, 11 We
9 HOUDE, E.D., and S.A BERKELEY. 1982c. Gulf of Mexico "Coastal Herrings.0 Summary document prepared for Southeast Fisheries Center Stock Assessment Workshop, Miami, Florida 3-7 August 1982. SEFC/SAN/MCH/5, 17 pp.
HOUDE, LD., C. GRAIL, and S.A. BERKELEY. 1983. Population parameter estimates for three shoaling pelagic fishes in the eastern Gulf of Mexico. ICES C.M. 1983/H:43, 7 pp.
HOUDE, E.D.F J.C. LEAK, C.E. DOWD, S.A. BERKELEY, and W.J. RICHARDS. 1979. Ichthyoplankton abundance and diversity in the eastern Gulf of Mexico. Report to 13LM, Contract No. AA550-M-28.
JCHNSON, G.D. 1978. Development of fishes of the mid-Atlantic bight, an atlas of egg, larval and juvenile stages. U.S. Dept. Int. FWS, Biol. Serv. Prog. Vol. IV Carangidae through Ephippidae, FWS/ OBS- 78/12, 314 pp.
JUBL, R. 1966. Experimental trawling survey along the Florida west coast. Comm. Fish. Rev. 28(6):1-5.
KLIMA, LF. 1971. Distribution of some coastal pelagic fishes in the western Atlantic. Comm. Fish. Rev. 33(6):21-34.
KLIMA, E.F., and D.A. WICKHAM. 1971. Attraction of coastal pelagic fishes with artificial structures. Trans. Am. Fisheries Soc. 100(l):86-99.
LEAK, J.C. 1977. Distribution and abundance of Carangidae (Pisces, Perciformes) larvae in the eastern Gulf of Mexico, 1971-1974. Univ. Miami, Master's Thesis. 83 pp.
LEAK, J.C. 1981. Distribution and abundance of carangid fish larvae in the eastern Gulf of Mexico, 1971-1974. Biological Oceanography l(l):1-28.
LYMS, J.M. 1978. Distribution and abundance of the larvae of Decapterus punctatus (Pisces, Carangidae) and Bothus spp. (Pisces, Bothidae) in the Florida and Yucatan Straits. Master's Thesis, Florida State University, 85 pp.
McMWAIN, T.D. 1983. Research needs for information leading to full and wise use of fishery resources in the Gulf of Mexico. Office of Representative Trent Lott, Washington DC, 20515, 26 pp.
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10 NAUGHTONF S.P.r arid C.H. SALOMAN. 1984. Food of bluefish (Pomatomus saltatri from the U.S. south Atlantic and Gulf of Mexico. NOAA Tech. Memo., NMFS-SEFC-150, 37 pp.
RANDALL, J.E. 1967. Food habits of reef fishes of the West Indies. Stud. Trop. Oceanogr. Miami 5:665-847.
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11 Table 1. Estimated lengths and weights at age for D. punctatus based on 1981 and 1982 samples. Lengths were back^-_calcul`ated rom fork length-otolith relationships and weights were then determined from length-weight relationships (Berkeley and Houde 1984).
A. Fork lengths (mm)
Year Age 2 3 Males Females Males Females Males Females
1981 135.5 136.7 16o.4 159.3 169.4
159.4 - 171.7-1982 155.5 150.9 176.6
Means 145.5 143.8 168.5 159.4 169.4 171.7
Combined male and female means 144.7 164.o 170.6
B. Weights (9)
Year Age 1 2 Males - --re-ma-i-es Males Fema I es Males Fema I es
1981 30.5 31.3 52.0 50.9 61.8 -
1982 47.9 43.4 73.4 52.1 - 66.8
Means 39.2 37.4 62^7 51.5 61.8 66.8
Combined male and female means 38.3 57.1 64.3
12 Table 2. Length-weight relationship for D. punctatus in the eastern Gulf of Mexico (W = weight in g-; L = fork length in mm) (Berkeley and Houde 1984). Year Relationship n rz
1981 W = 5.00 X 10-60*18 3,683 0.92
1982 W = 2.93 X 10-60.29 3,624 0.95
Sex FL 3.34 Fema I e W 2.25 X 10- 6 935 0.92
Male W 2.96 x io-6 FL3.28 IP041 0.95
13 Table 3. Sex ratio of D. punctatus collected off northwest Florida (Berkeley and Ho-u-d-77-997.
Male - Fema-I e Mon th No. % No. 7. Male:Female 1981
Apr 77 49.7 78 50.3 0.99:1
May 82 49.7 38 50.3 9.99:1
Jun 193 54.5 161 45.5 1.20:1
Jul 71 46.7 81 53.3 0.88:1
Aug 21 65.6 11 34.4 1.91:1
Sep 43 43.0 57 57.0 0.75:1
Oct 51 57.3 38 42.7 1.34:1
Nov 37 92.5 3 7.4 12-3:1*
Total 575 52.9 512 47.1 1.12:1
1982
Ma r 34 54.8 )8 45.2 Apr
May 92 52.8 83 47.2 1.12:1
Jun 165 52.6 149 47.4 1.11:1
Jul 44 40.4 65 49.6 0.68:1
Aug 55 55.6 44 44.4 1.25:1
Sep 35 72.9 13 27.1 2.69:1
Oct 54 45.0 66 55.0 9.82:1
Nov
Total 480 100.0 448 100.0 1. 07: 1
*Many specimens were too young to be sexed.
14 Table 4. Seasonal proximate chemical composition of three product forms of D. punctatus. (Data from M. Hale, NMFS, Charleston Laboratory.)
Month of Number of Average Moisture Protein Ash Fat, ZI Product form harvest Sample^S Individuals weight, 9 % % % Ether SAK
Whole Sep 1978 4 20 38.3 75.44 19-95 2.98 2.05 2.72 Whole Apr 1979 1 7 27.5 72.90 19-53 4.30 3.56 4.o8 Whole Aug 1979 3 12 37.0 73-32 20.46 4.82 1.56 2.13 Whole Jan 1980 1 4 48.7 71-05 19-99 3.97 5.79 6.31 Whole Jul 1980 2 16 27.6 74.27 20-39 4.o6 2.15 3.19 Range: 14.2-48.7 71.1-76.8 19.6-20.8 3.0-5.1 0.9-5.8 1.7-6.3 Overall average: 35.95 74.18 20.03 3.89 2.25 2.96
Headed & Gutted Sep 1978 3 30 29.9 75.48 22.01 2.52 0.89 1.64 Headed & Gutted Apr 1979 1 9 34.9 72.10 21.28 3.26 3.30 4.03 Headed & Gutted Aug 1979 3 13 39.6 73-38 22.05 3.61 1.22 1.85 Headed & Gutted Jan 1980 2 55.0 71-145 22.27 3.24 3.21 4.07 Headed & Gutted Mar 1980 - - 73.72 20.10 2.58 3.50 5.46 Headed & Gutted Jul 1980 2 27 23.9 75.44 21.13 3.41 1.35 2.34 Range: 13.0-55.0 71.2-76.3 20.1-22.6 2.1-3.8 0.6-3.5 1.4-5.5 Overall average: 35-13 74.06 21.64 3.12 1.75 2.52
Fi I lets Sep 1978 3 26 29.9 76.09 22.12 1.41 .87 1.34 Fillets Apr 1979 1 15 27.5 74.49 21.87 1.38 2.31 3.25 Fillets Aug 1979 1 13 33.6 75.64 22-35 1.56 .51 1.29 Fillets Jan 1980 1 9 55.8 74-72 23-07 1.37 1.53 2.78 Fillets Mar 1980 1 - - '.1, ' 1 75^39 21.50 1.17 2.94 1.87 Fillets Jul ig8o 2 44 25.4 76.45 22.41 1.54 .21 1.53 Range: 12.7-55.8 74.5-77.2 21.5-23.0 1.2-1.6 0.2-2.3 0.9-3.3 Overall average: 31-93 75-71 22.22 1.42 1.03 1.90
*Ether fat = triglycerides; SAK = total lipids by chloroform/methanol. Table 5. Seasonal fatty acid composition of D. _punctatus flesh. (Data from M. Hale, NMFS, C^`arleston Laboratory.)
Season and number of composite samples Spring Summer Fall Fatty acid 0 ) (3) (3)
14 :0 2.15 2.74 3.20
16:0 20.13 ig.6o 18.12
18:0 8.77 11.49 9.94
16:1 6.63 4.90 4.22
18:1 15-78 lo.49 7.69
20:1 0.93 0.54 1.51
22:1 0.19 0.15 -
18:2W6 1.82 1.59 2.00
18:3W3 1.09 0.72 o.96
18:4W3 1.22 1.27 0.79
20:4W6 2.38 3.22 3.99
20:5W3 6.72 6.14 7.59
22:5W6 1.59 1.93 2.21
22:5W3 2.05 2.15 2.o4
22:6W3 20.63 23-74 26.26
Total Saturated 34-52 37-18 33-32
Total Monoenes 25.64 17.76 15-03
Total PUFA 39-84 45.06 51.65 (Polyunsatura(t.ed fatty acids)
16 Decapterus punctatus (A)
go ;0,
0 3.2cm
Decapterus tabl
0 4.8cm
Decapterus macarellus (C)
Oo 4cm
Figure 1. Three species of Decapterus in the western Atlantic.
17 ......
...... 8-O.-SIL 2.3 mm SL
10.5 mm SL 3.1 mm SL
I
12.0 m m SL
4.2 mm SL
175 mm SL 5.2 mm SL
m m S L 20.0 mm SL
6.5 mm SL 23.0 mm SL
Figure 2. Larvae of D. punctatus. (A, D, H, and K taken from Hildebrand and Cable 1930; B, C, E, F, G, 1, J, and L taken from Aprieto 1974.) • BERMUDA
o 20
Figure 3. Ojstribution and range of round scad (D. punc~atus) in the western Atlantic. -.
19 1800 - 450 o----o POUNDS
1600 DOLLARS - 400
1400 - 350
1200 - 300 Z z D tA 0 D 1000 - 250 0
800 - 200 z D 0 0 CL 600 - ISO
400 C^ - 100
200 - 50
0 0 I t I I 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 YEARS
Figure 4. Annual catches and values of D. punctatus in pounds and dollars from the west coast of Florida, 1952-1982. 31 t T
TEXAS LOUISIANA IVI S. AA L. FLORIDA
30[ 0 0 0 0 00 00 00 29 00 0
0 00
28 0 0 0 0 0 0 000 0 00
27 000O^ 0 DECEMBER- FEBRUARY 0 0 0 26 MEAN CATCH RATES 0 1-50 6-100 11-200 0 25 21-500 GULF OF MEXICO 51-1000 >1000
2416 I I I I I I I I I I I 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81
Figure 5. Abundance and distribution of adult D. punttatus collected by trawl in the winter. 31 Ms. AL.,' LOUISIANA FLORIDA TEXAS 0 30 1" 0 0 0 000 00 9 0 000 0 00
29 - 0 00 0 0 0
0 0 0 0 0 28 - 0 0
0 27 - 0 MARCH - MAY 0 0 MEAN CATCH RATES 26 - 0 1-5 0 0 6-10 0 11-20 0 21-50 0 GULF OF MEXICO 51-100 0
>100 0
I I I I --- -I - ---A' 6 --1 1 AM=" 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81
Figure 6. Abundance and distribution of adult D. punctatus collected by trawl in the spring. 31 T TEXAS LOUISIANA M S. k"L.,L0 FLORIDAFLORIDA
30[ 0 00
29 0 0 0 00 0 00 00 0 ,70 0 000 OO00C()O0O 0 000 00000000 0 0 00 28 ^/,n 1 0 V)
27
JUNE-AUGUST MEAN CATCH RATES 26 1-50 6-100 11-200 21-500 25 51-10ou GULF OF MEXICO 1 >1000 I
241( 98 97 96 95 94 93 92 ^l 90 89 88 87 86 85 84 83 82 81
Figure 7. Abundance and distribution of adult D. punctatus collected by trawl in the summer. 31 I I I I TEXAS I LOUISIANA MS. AL.: FLORIDA I I i I
30 0 t.jk-T-"U 0 0 00 000 0 o8o 0 29 0 00 000 0 0 000 000 00 000
28 0 0 0
27
SEPTEMBER- NOVEMBER 26 MEAN CATCH RATES 1-50 6-100 11-200 25 21-500 GULF OF MEXICO 51-1000 >1000
2 4 LL....J -- - -1 1 1 1 1- 1 I I I I I I I I - A 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81
Figure 8. Abundance and distribution of adult D. punctatus collected by trawl in the fall. APRIL-MAY AUGUST- SEPTEMBER
I T I
MAY-JUNE OCTOBER - NOVEMBER ......
CO
NUMBER LARVAE PER 100 m2
1 -100 H++H+H+H+i 1 10 1 - 3 0 0 >300
Figure 9. Abundance of larval D. punctatus in the Gulf of Mexico. Data taken from Montolio (1976). 97 0 30' 97 0 96 0 30' 96, 95 0 30, I I I NAUTICAL MILES 0 0 10 20 30 28, §NNff=:D0MNC7:3N0ffi= 30 20 40 60 KILOMETERS
SAN ANTONIO BAY f N W1 U
45H\ 28 I OZ (7 3.1) CORPUS BAY CHRISTI (21, 2.4 - 2.8) go M *1 ^6 0, 2.0 - 3 " 5) 3 27 40 (55,,2.4 - 1.4) 30 42(^f208/1.6-3.5) / *506(214, 2.1-3.6) 93 (50, 2.2-3.7)
*(106, 1.6-73)
SIZE (0) (6, 4.2) (3, 4.1) 27 NO. RANGE 61 92 *3 MONTH LARVAE MM APR. 168 2.1-4.7 MAY 40 3.1-5.0 JUL. 124 2.0 -7.3 04 26 AUG. 2,367 1.6 - 3.5 30' ^r_ 4 37 2,
(0) (0) 92 03(6, 3.3- 5.0) 91 IV I N
Figure 10. Abundance and size of larval D. punctatuscollected in the Gulf of Mexico off the Texas coast in 1977. Data taken from Finucane et a]. (1978).
26 0 OCTOBER- NOVEMBER 1970 35 AUGUSTOCTOBER, NOVEMBER 1971 0
0 31-99 0 0>100
3 C^
0 0 0 25
2 C^ -7-
35 MAY-AUGUST 1972 0 31-99 0>100
3C^
doft ^
25 1^k - I N I
0 20 0 0 0 95 0 90 85 80 7^
Figure 11. Abundance of larval D. punctatus in the south Atlantic and Gulf of Mexico. Data taken from Aprieto (1974).
27 60
LU 5 0 D t^
,ujA 4 0
LL. 0 C14 E 11 n
(z LU 0 z :5 20 oe U.1 ca z 10
t I I I L- I I I I I I I I I I I I I I I I I I I I I I I I 0 I I M J J A S 0 N D J F MAMJ J A S 0 N D J F MAM J J A S ON 1971 1972 1973 CRUISE DATE
Figure 12. Abundance of larval D. punctatus in the eastern Gulf of Mexico, September 1972 November 1973 (Houde et al. 1979). 190 W-
E E
160 I-- z
^e ad 0 130 U.
100
2 3 4 AGE
Figure 13. Back calculated lengths at age and fitted von Bertalanffy growth model line for D. punctatus from the eastern Gulf of Mexico (Houde et a]. 1^'83).
29 30
-3 20 UU
LU CL. a 10 ..j LU
I --- I -- I t 1 0 6 8 10 F
Figure 14. Predicted yield-per-recruit as a function of fishing mortality for D. punctatus from the eastern Gulf of Mexico (Houde et al. 1983). 34-
70 le 0 FREQUENCY OF OCCURRENCE
6 AVERAGE NUMBER OF POUNDS Uj 60 cx U D z CAUGHT PER HOUR 0 X cz ex 5 50 'C"L 0
LA. 0 4- 40 < z z D LOU 3- 30 0 LA. CL cz US z . 2- r 20 D CL z LU
1 10 LU
0 0 I I. I I I I I I I 1 12 14 16 18 20 22 24 26 28 30 SURFACE TEMPERATURE ('C)
Figure 15. Percent frequency of occurrence of D. punctatus and the average number of pounds caught per hour of trawling in relation to sur-face water temperature when D. punctatus were present in shrimp or fish trawls in the Gulf of Mexico from 1950-1985. DaTa provided by NMFS, Mississippi Laboratory, Pascagoula, MS. 8 0--^^ PERCENT FREQUENCY OF OCCURRENCE - 40
AVERAGE NUMBER POUNDS CAUGHT 7 PER HOUR 35
W D 0 6 30 3: z cz Uj CL I D I 5 I 25 0 U- 0 4 20 z z D 0 LU ad 3 U- 15 Uj I.- z D 2 10 z UU
UU I 5
0 0 I t I 1 1 13 15 17L 19L- L21 -j23 25L- 27 BOTTOM TEMPERATURE (OC)
Figure 16. Percent frequency of occurrence of D. punctatus and the average number of pounds caught per hour of tr"awling in relation to bottom iAster temperatures when D. punctatus were present in shrimp or f ish trawls in the Gulf of k'e-xi-jo-, 1950-1985. Data provided by NMFS, Mississippi Laboratory, Pascagoula, MS.
32 40 200 PERCENT
35 175 00-% P 0 U N D S 0 0 0 30 150 x
z 25 125 D 0 CL
2 0 0 100 U- Ui 0 15 75 3: z LU
OLIU 10 50 LU 0-
5 25
0 I --I I I I I I I I I I 0 F M A M i i A S 0 N D MONTHS
Figure 17. The percent and average weight of monthly catch of D. punctatus from the west coast of Florida, from 1952-1982. 10
9
8
7 Ui U Uiz Im 6
0 U_ 5 0 z 4 LU
ZLU 3
2
0
5 25 45 65 85 105 195 FATHOMS (MID-POINTS)
Figure 18. Percent occurrence of D. punctatus caught in shrimp and fish trawls at depths rang'ing Trom I to 200 fathoms in the Gulf of Mexico from 1950-1985. Data provided by NMFS, Pascagoula Laboratory, Pascagoula, MS.
34 80 200 70 1980 100 200 200 200 1,100 60 200 r-.-.l 50
40
30
20
10
1981 Z 100 MALES LU 100 Uj 90 0. 0 FEMALES 80 300 200 70 400 100 1597 60 100 100 297 50
40 1 __j 30
20
10
0 I APR. MAY JUN. JUL. AUG. SEP OCT. NOV. ALL MONTHS
Figure 19. Monthly sex ratios of D. Punctatus from northwest Florida during 1980 and 1981. Sample-size is recorded above monthly columns, 1980 50[ F] MALES (439)
40 FEMALES (661 )
30
20
LZ 10 U od LU CL
30 1981 MALES (566)
1_ 20 FEMALES (1,031)
-4-1 10
C= =0 1 -1 I I I I I 1 -1 =011im 105 ]is 125 135 145 155 165 175 185 195 TOTAL LENGTH MID-POINTS (mm)
Figure 20. Sex ratio of D. punctatus by size groups from northwest Florida (sample size Tin 'parentheses). 60
40 MAY (228) 20 r--- I F-1 r--1
60 JUNE (469)
40
20 - F-1
60 JULY (473)
40
20
60 AUGUST (744)
40
20 I.- Z
60 SEPTEMBER (1,126) CL 40
20
60 OCTOBER (1,020)
40
20
r_^ F] r7=
60 ALL MONTHS (4,060)
40 20 F-1
105 115 125 1 5 145 155 165 175 185 TOTAL LENGTH MIDPOINTS (mm)
Figure 21. Length frequency distribution of D. punctatus from northwest Florida in 1980 (sample size in parentheses).
37 40
20 APRIL (1,180) o -LL1lo. n 11_Ll
40 MAY (1922)
20 o JUNE (2,051) 40
20 o .~._[l ..ll.._D 40 JULY (803)
20 o ~[l AUGUST (358) 40
t- 20 Z ~U 0 SEPTEMBER (970) ~ 40
20 o
60 OCTOBER (870)
40
20 o
60 NOVEMBER (510)
40
20 o
40 ALL MONTHS (8,664)
20 o
85 95 105 115 125 135 145 155 165 175 185 195 205 TOTAL LENGTH MID-POINTS(mm)
Figure 22. Length frequency distribution of D. punctatus from northwest Florida in 1981 (sample size in parentheses).
38 60 MARCH (500)
40
20
0
60 APRIL (870)
40 20 F1 40 MAY (1,010)
2or -
0 D F-i F1 E-71
40 - JUNE (1,267)
20 r= F] F-^ F-1 F-i F-i
40 JULY (1,410)
"_ 20 Z 0 F1 F^ Uj a. 40 AUGUST (1,200)
20
40 SEPTEMBER (1,200)
20
0 F^
40 OCTOBER (1,340)
20 E^ E-1 El F1
40 NOVEMBER (400)
20
r__,
40 ALL MONTHS (9,197)
20 E-1
95 105 115 125 135 145 155 165 175 185 195 TOTAL LENGTH MID-POINTS (mm)
Figure 23. Length frequency distribution of D. punctatus from northwest Florida in 1982 (sample-size in parentheses).
39