Northeast Gulf Science Volume 2 Article 6 Number 2 Number 2 12-1978 Food Habits of the Bay Anchovy, Anchoa mitchilli, in Apalachicola Bay, Florida Peter F. Sheridan Florida State University DOI: 10.18785/negs.0202.06 Follow this and additional works at: https://aquila.usm.edu/goms Recommended Citation Sheridan, P. F. 1978. Food Habits of the Bay Anchovy, Anchoa mitchilli, in Apalachicola Bay, Florida. Northeast Gulf Science 2 (2). Retrieved from https://aquila.usm.edu/goms/vol2/iss2/6 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf of Mexico Science by an authorized editor of The Aquila Digital Community. For more information, please contact [email protected]. Sheridan: Food Habits of the Bay Anchovy, Anchoa mitchilli, in Apalachicola 126 Northeast Gulf Science Vol. 2, No.2 December 1978 opinion that the tag would be retained Marion T. Fannaly, Research Associate in successive molts. III, Coastal Ecology Lab, Center for In summary, the method described Wetland Resources, Louisiana State above of tagging crabs by internally University, Baton Rouge, LA 70803. anchoring an external spaghetti tag seems promising based on laboratory FOOD HABITS OF THE BAY trials. The only drawback observed in ANCHOVY, Anchoa mitchilli, IN the laboratory is that the tag some­ APALACHICOLA BAY, FLORIDA what hinders molting and may therefore Ontogenetic, spatial and temporal increase the susceptibility to predation aspects of the food habits of the bay of the crab during this vulnerable time. anchovy, Anchoa mitchilli, were exa­ It is possible that this drawback could be mined in fish collected from Apalachicola avoided by hand insertion of a con­ Bay, Florida. Calanoid copepods were ventional dart tag which has no leader the major constituent of the anchovy and would offer less resistance to molt­ diet, but their importance declined with ing. However, this type of tag would fish growth as larger zooplankters such also be more difficult to insert and re­ as mysids were consumed. Special­ quire punching a larger hole in the mem­ ization upon copepods led to moderate brane. The gun produces a small hole diet similarity among sites in the estuary, only about one mm in diameter and mini­ except in areas near the mouth of the mizes trauma to the crab. Apalachicola River where mysids, insect larvae, and cladocerans were major food ACKNOWLEDGEMENTS items. Copepods were the dominant prey in all months but were markedly less I would like to thank Dr. Frank Trues­ abundant prey in October, December, dale for his advice and assistance and Dr. and February when other crustaceans and James Bishop for the use of the aquaria. insect larvae became relatively more abundant. LITERATURE CITED INTRODUCTION Cargo, D. G. 1958. The migration of adult 'female blue crabs, Callinectes The bay anchovy, Anchoa mitchilli, sapidus Rathbun, in Chincoteague Bay IS one of the· most abundant fishes in and adjacent waters. J. Mar. Res. South Atlantic and Gulf coast estuaries, 16(3):180-191. ranking first in numerical abundance in Cronin, L. E. 1949. Comparison of many areas (Gunter, 1945; Perret, 1971; methods of tagging the blue crab. Swingle, 19 71; Gallaway and Strawn, Ecology 30(3) :390-394. 1974; Subrahmanyam and Drake, 1975; Fiedler, R. H. 1930. Solving the question Cain and Dean, 1976). An extended of crab migrations. Fishing Gazette spawning season has been indicated 47:18-21. (Gunter, 1938; Springer and Woodburn, Tagatz, M. E. 1968. Biology of the Blue 1960; Haese, 1973), and one study crab, Callinectes sapidus Rathbun, in (Dunham, 1972) found planktonic eggs the St. Johns River, Florida, U. S. and larvae throughout most of the year. Fish and Wildl. Serv. Fish. Bull. This accounts for the collection of 67(1) :17-33. juveniles less than 30 mm in length Published by The Aquila Digital Community, 1978 1 Gulf of Mexico Science, Vol. 2 [1978], No. 2, Art. 6 Short papers and notes 127 during many months in southern paper is concerned with refining pre­ estuaries. Major abundance peaks are vious observations on anchovy feeding generally observed in late summer by examining ontogenetic, spatial and through early winter, and the aforement­ temporal differences in feeding habits. ioned studies indicate that anchovies are able to exploit all habitats from marshes MATERIALS AND METHODS to open waters. In the Apalachicola estuary of northwest Florida, anchovies Anchovies were collected monthly by are the numerical dominant, comprising trawling with a 16' (5 m) otter trawl at 33% of the total catch of trawl-sus­ ten sites in the Apalachicola Bay - East ceptible fishes over five years of study Bay complex (Figure 1). Details of (Livingston e tal., 19 7 6, and unpublished field methods and area descriptions are data). Peak abundances are noted in given in Livingston et al. (1976). After October and November, with occasional field preservation in 10% Formalin, spring and summer peaks of lesser anchovies were rinsed and stored in 40% intensity. isopropanol until analysis. At such time, Apalachicola Bay is a relatively un­ fish were sorted into 10 mm (SL) size polluted, shallow, barrier island estuary classes by station and date of collection. dominated by the Apalachicola River. Stomachs of up to 25 individuals (as Much of the information concerning the collections permitted) from each size Apalachicola drainage basin has been re­ class were resected and their contents viewed by Livingston et al. (1974) and pooled. Stomach contents were then in Livingston and Joyce (1977). This analyzed as percent dry weight com- apalachicola river I I tate's hell swamP I gulf of mexico kilometers 0 6 Figure 1. Map of the Apalachicola estuary showing permanent sampling locations. https://aquila.usm.edu/goms/vol2/iss2/6 2 DOI: 10.18785/negs.0202.06 Sheridan: Food Habits of the Bay Anchovy, Anchoa mitchilli, in Apalachicola 12"8 Northeast Gulf Science Vol. 2, No.2 December 1978 Table 1. Stomach contents (%of total dry weight) of Anchoa mitchilli relative to standard length groups. Size (rnm) Material recovered 10-19 20-29 30-39 40-49 50-59 60-69 Avg. 10-69 Sand grains <.1 <.1 0.1 0.1 <.1 Detritus 2.2 2.5 2.3 2.4 1.6 Diatoms 0.7 1.0 0.8 0.4 0.2 0.5 Plant remains <.1 0.7 0.2 1.0 0.5 0.4 Scyphozoans <.1 <.1 <.1 Polychaete larvae 1.1 0.3 0.2 0.3 0.3 0.3 0.4 Polychaetes 0.2 0.2 2.2 0.3 0.5 Gastropod veligers <.1 0.4 0.2 0.2 0.1 Gastropods <.1 0.4 1.2 1.0 1.6 0.7 Bivalve veligers 0.3 0.5 0.8 0.6 0.8 0.5 Bivalves 1.3 <.1 0.3 0.4 0.2 0.4 Unassigned mollusc larvae <.1 0.1 <.1 Hydracarinids <.1 <.1 <.I Cladocerans 2.8 3.9 1.5 0.8 3.1 2.0 Ostracods 0.4 1.0 0.9 1.8 2.6 1.1 Calanoid copepods 97.8 82.3 72.7 60.6 52.7 49.3 69.2 Barnacle nauplii 0.2 4.8 4.2 1.2 0.4 1.8 Cumaceans <.1 <.1 0.2 0.1 0.2 <.1 Isopods <.1 <.1 <.1 Amphipods <.1 0.5 1.3 1.0 0.7 0.6 Mysids 1.1 1.7 3.1 17 .o 16.5 15.3 9.1 Shrimp zoeae 0.2 0.5 0.4 0.4 0.2 Shrimp postlarvae 2.1 1.6 0.4 0.2 0.7 Shrimp 0.2 0.3 2.3 0.7 0.6 Crab zoeae 0.2 0.4 0.9 0.5 0.3 Crab megalopae <.1 2.1 0.4 Unassigned decapod larvae 0.4 0.6 0.5 0.4 0.3 0.4 Insect larvae 4.5 2.6 2.2 4.3 12.0 4.3 Insects 0.4 <.1 <.1 <.1 <.1 Chaetognaths 0.6 0.1 Invertebrate eggs 2.0 3.2 2.1 1.5 0.6 1.6 Fish eggs 0.1 0.4 1.0 0.6 0.4 Fish larvae 1.1) <.1 Fishes 0.2 2.6 6.7 1.6 Number of individuals 28 851 1055 839 525 101 3399 Number of samples (after pooling) 44 69 62 56 18 250 Number of dates (maximum~31) 26 28 28 25 10 31 Number of stations (maximum~ 10) 8 9 9 10 8 10 positiOn by a gravimetric method de­ was obtained (due to mesh size of the scribed by Carr and Adams (1972, 1973). trawl), the apparent specialization upon copepods is thought to be real since RESULTS lab oratory studies of larval anchovies (Detwyler and Houde, 1970) indicated A total of 3,399 anchovy stomachs selection of copepods over other zoo­ were examined in the present study, plankters. Foods which increased in spanning the dates December, 1973, importance with growth of anchovies through October, 1976. When pooled included mysids (predominantly My­ as described above, 250 discrete station­ sidopsis bahia, occasionally M. bigelowi, date-size combinations were formed. M.- almyra, and Taphromysis bowmani), Calanoid copepods (Acartia spp.) were insect larvae (Dicrontendipes sp.), and the major food item of all size classes larval/juvenile fishes. of A. mitchilli (Table 1), although pre­ Spatial comparison of anchovy feed­ dation upon copepods decreased steadily ing indicated specialization on calanoid with growth of anchovies. Although copepods in most areas of the estuary only one sample of 10-19 mm anchovies (Table 2). Anchovies collected near the Published by The Aquila Digital Community, 1978 3 Gulf of Mexico Science, Vol.