Alabama shad, continued 



about 17°C, and then drops as water temperatures 

 increase (Laurence and Yerger 1967, Mills 1972). 

 Males, especially older ones, enter freshwater earlier 

 and at lower temperatures than females, but when 

 water temperatures reach 19.5°C, females begin to 

 outnumber males at the spawning areas (Laurence 

 and Yerger 1967, Mills 1972). After spawning the 

 adults return downriver to estuarine and marine wa- 

 ters. 



Reproduction 



Mode : Species in the herring family (Clupeidae) have 

 separate male and female sexes (gonochoristic), and 

 fertilization is external through the broadcast of milt and 

 roe. 



Spawning : Eggs are partially developed when females 

 arrive in spawning areas, then complete maturation 

 (Mettee et al. 1 995). Spawning occurs in the headwa- 

 ters of the major drainages along the northern Gulf of 

 Mexico during spring months (March-April) when water 

 temperatures are 1 9° to 23°C. It takes place in fresh- 

 water rivers and streams over coarse sand and gravel 

 with water currents of 0.5-1.0 m/sec (Laurence and 

 Yerger 1967, Mills 1972). Alabama shad are repeat 

 spawners, but some spawning mortality occurs. The 

 spawning population is dominated by two year old fish. 

 This group produces the most viable offspring and its 

 dominance has been interpreted as an adaptation to 

 increase populations (Laurence and Yerger 1 967, Mills 

 1972). 



Fecundity : Reported fecundity estimates range from 

 46,400 to 257,655 eggs produced by female shad 

 (Laurence and Yerger 1 967, Mills 1 972). Fecundity will 

 vary considerably with total length, weight, and age. A 

 decrease in the number of repeat spawners present in 

 the population results in an increase in overall fecun- 

 dity (Laurence and Yerger 1967, Leggett 1969, Mills 

 1972). 



Growth and Development 



Egg Size and Embryonic Development Embryonic 

 development is oviparous. Well developed uterine 

 eggs averaged 1.159 mm in diameter (Mills 1972). 

 Eggs are released in the spring with partially and 

 completely spent females being collected December 

 through April (Laurence and Yerger 1 967, Turner 1 969). 



Age and Size of Larvae : Little information is available 

 on the age and size of larval Alabama shad. 



Juvenile Size Range : This stage ranges in size from 25 

 to 142 mm FL. Modal growth of most juveniles varies 

 from 1 to 30 mm/month. Maturity in males is reached 

 during their first year or shortly after. One fish measur- 

 ing 128 mm FL was collected with mature gonads, but 



was considered atypical (Laurence and Yerger 1967, 

 Mills 1972). 



Age and Size of Adults : Alabama shad are reported to 

 live up to 4 years, based on scale aging studies 

 (Laurence and Yerger 1967, Leggett 1969). Average 

 sizes for these age classes are: 269 mm total length 

 (TL) for Class I males; 340.4 mm TL for Class II males 

 and 368.3 mm for Class II females; 365.8 mm TL for 

 Class III males and 388.6 mm TL for Class III females; 

 and average measurements for Class IV fish were 

 383.5 and 408.9 mm TL for males and females respec- 

 tively (Laurence and Yerger 1967). This information 

 corresponds well with Mills (1972) who reported aver- 

 age size for males as Class 1-219 and 155 mm FL, 

 Class II - 316 and 326 mm FL, Class III - 334 mm FL; 

 and for females as Class I - unknown, Class II - 340 mm 

 FL, Class III - 356 and 370 mm FL. Females are larger 

 than males in every year class (Laurence and Yerger 

 1 967, Mills 1 972). Average sizes and weights for this 

 shad are 31 2 mm FL and 474 g for males, and 347 mm 

 FL and 737 g for females. The largest reported fish 

 measured 450 mm TL (Douglas 1974). A length/ 

 weight equation has been derived by Laurence and 

 Yerger (1967). Recent otolith aging studies of Ala- 

 bama shad in the Choctawhatchee River suggest that 

 fish may live up to six years (Mettee et al. 1995). 



Food and Feeding 



Trophic Mode : The feeding habits of the Alabama shad 

 are not well known. Stomach contents of adults and 

 juveniles suggest that they are opportunistic carni- 

 vores (Hildebrand 1963, Laurence and Yerger 1967, 

 Mills 1972). Adults generally do not feed during their 

 spawning migration (Hildebrand 1963, Laurence and 

 Yerger 1967, Mills 1972). 



Food Items : Stomach contents of some migrating 

 adults show insects, plant material, and detritus 

 (Hildebrand 1963, Laurence and Yerger 1967). Juve- 

 niles are opportunists and will feed on whatever is 

 available, especially fish and larval, pupal, and adult 

 insects (Laurence and Yerger 1967). They also feed 

 on copepods, Cladocera (waterf leas), worms, spiders, 

 detritus, and plant material. Food habits of shad in 

 marine and estuarine environments are not well known. 



Biological Interactions 



Predation : All shad species are important forage fish 

 for piscivorous fish and birds. 



Factors Influencing Populations : Declines in popula- 

 tions may be at least partially due to dams barring this 

 species from its historical spawning grounds, and 

 possibly also to channelization of rivers and siltation of 

 spawning areas (Hildebrand 1963, Lee et al. 1980). 



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