Bay anchovy, continued 



water masses (Hoese 1965, Bechtel and Copeland 

 1970, Sabins and Truesdale 1974, Perry and Boyes 

 1977, Jones et al. 1978, Ward and Armstrong 1980). 

 Spawning has been observed in higher salinity por- 

 tions of estuaries with ranges of 30 to 37% and <45%> 

 (Bechtel and Copeland 1 970, Swingle and Bland 1 974, 

 Dokken et al., 1984). Spawning by large schools 

 usually occurs in the early evening, between 6 and 9 

 pm, during warm water (>19°C) periods (Kuntz 1913, 

 Hoese 1965, Jones et al. 1978, Ward and Armstrong 

 1 980). Egg densities peak at different times depending 

 on location. Based on studies of gonads and collection 

 of juveniles and larvae, reported spawning seasons 

 are: February to March, and June to August in the Gulf 

 near Port Aransas, Texas and the latter part of March 

 in Copano and Aransas Bays (Gunter 1945, Hoese 

 1965, Allshouse 1983); summer months (June and 

 July) in East Bay, Texas; February to October in 

 Galveston Bay, Texas (Bechtel and Copeland 1970); 

 spring and summer with peak spawning from March 

 through October in Louisiana (Dugas 1970, Wagner 

 1973, Sabins and Truesdale 1974); and February 

 through October with a July peak along the Mississippi 

 coastline (Edwards 1 967, Christmas and Waller 1 973, 

 Perry and Boyes 1 977). Based on collection of larvae, 

 the spawning season in the north-central Gulf of Mexico 

 is March through September/October (Ditty pers. 

 comm.). In Tampa Bay, spawning begins after water 

 temperatures have reached 20°C and stops by No- 

 vember (Phillips 1981). Some additional spawning is 

 reported to occur throughout the year in some areas 

 (Miller 1 965, Perret 1 971 , Swingle 1 971 , Wagner 1 973, 

 Ward and Armstrong 1980, Dokken etal. 1984). This 

 may be attributable to the Gulf's usually short and mild 

 winters that sometimes allow shallow water winter 

 temperatures to approach and exceed 20°C (Hoese 

 1 965, Dokken et al. 1 984). In Biscayne Bay, Florida, it 

 is suggested that spawning occurs all year, but is 

 uncommon in December and January (Jones et al. 

 1978). 



Fecundity : Data using fish from Chesapeake Bay indi- 

 cate that during the peak spawning period females 

 spawn a batch of 400 to 2000 eggs every four days 

 (Luo and Musick 1 991 ), with the actual number directly 

 related to the weight of the female (approximately 400 

 eggs per g ram of wet weight female). This can conceiv- 

 ably result in a female producing 30,000 to 50,000 eggs 

 during the four month season in Chesapeake Bay 

 (Houde pers. comm.). 



Growth and Development 



Egg Size and Embryonic Development : Eggs have a 

 barely elliptical shape, and are 0.84 to 1.11 mm in 

 diameter (Farooqi et al. 1 995). Average egg size tends 

 to decrease with increasing salinity (Jones et al. 1 978). 

 Eggs are transparent with no oil globule and the yolk is 



composed of separate masses appearing as large 

 cells with an overall volume of 0.15 mm^ (Kuntz 1913, 

 Hildebrand 1943, Houde 1974, Farooqi et al. 1995). 

 Eggs float at or near water surface until near hatching 

 and then gradually sink (Kuntz 191 3, Hildebrand 1943). 

 Incubation takes approximately 24 hours at 27.8°C 

 (Kuntz 1913, Farooqi et al. 1995) 



Age and Size of Larvae : Larvae are 1 .8 to 2.7 mm total 

 length (TL) at hatching and weigh 1 7.6 \ig (Kuntz 1913, 

 Detwyler and Houde 1970, Houde 1978, Ward and 

 Armstrong 1980, Farooqi et al. 1995). The yolk sac is 

 comparatively large and greatly elongated tapering to 

 a point posteriorly. It is completely absorbed 1 5 to 1 8 

 hours after hatching (AH). The body is elongate, 

 slender, and nearly transparent with little pigmentation. 

 Larvae are 2.6 to 2.8 mm TL at 12 hours AH. Develop- 

 ment of mouth and gut, pigmentation of eyes, and yolk 

 exhaustion are completed simultaneously at 36 hours 

 after hatching at 26.2°C and 30.9%o (Kuntz 1913, 

 Hildebrand 1943, Detwyler and Houde 1970). The 

 critical period in which the larvae must begin to feed is 

 2.5 days after hatching (Houde 1974). Size when 

 feeding was initiated was 2.9 mm SL (Houde 1 978). A 

 growth rate of 0.70 mm/day was reported for the fourth 

 day (AH) (Detwylerand Houde 1 970) reaching a weight 

 of 236.0 ug after 1 6 days (Houde 1 978). Larval survival 

 in the laboratory is highest from 24 to 28°C, with faster 

 growth at the higher temperatures (Houde 1974). 



Juvenile Size Range : Metamorphosis into juvenile 

 form begins at 1 5.5 mm SL, and is essentially complete 

 by 22.5 mm SL (Jones et al. 1 978, Ward and Armstrong 

 1 980). A length of 1 8 mm TL is attained during the first 

 month (AH) and a growth rate of 1 mm/month occurs 

 overthe following 2 months (Edwards 1 967, Christmas 

 and Waller 1 973). Juveniles mature rapidly, becoming 

 sexually mature within their first year. 



Age and Size of Adults : The bay anchovy matures in 

 approximately 2.5 months (Hildebrand 1 963, Jones et 

 al. 1978) at 34 to 45 mm TL (Gunter 1945, Edwards 

 1 967, Ward and Armstrong 1 980). Reported sizes for 

 adults in the study area range from 34 to 93 mm TL 

 (Gunter 1 945, Renfro 1 960, Franks 1 970, Perret 1 971 , 

 Dunham 1972, Wagner 1973, Pineda 1975, Tarver 

 and Savoie 1 976) with a recorded mean of 56.3 mm TL 

 for males and 60.0 mm TL for females (Ward and 

 Armstrong 1 980). Two and possibly three size classes 

 have been observed in populations, but they are virtu- 

 ally indistinguishable due to the occurrence of spawn- 

 ing throughout the year (Gunter 1945, Miller 1965, 

 Perret 1971, Cornelius 1984). 



Food and Feeding 



Trophic mode : Bay anchovies are primary consumers, 

 feeding primarily on zooplankton in currents at night 



156 



