1957). This difficult task has seldom been carried 

 out completely and usually oxygen consumption 

 alone is used to measure metabolism (Fry 1957). 



To date, few researchers have studied any por- 

 tion of the energy budget of penaeid shrimp. The 

 most complete attempt was that of Qasim and 

 Easterson (1974), who ascertained energy in- 

 gested, assimilated, and egested by Metapenaeus 

 monoceros . Condrey et al. ( 1972) tested conversion 

 efficiencies of selected diets of P. aztecus and P. 

 setiferus, and Nose (1964) obtained protein digest- 

 ibility for P. Japonicus. Finally, assimilation 

 efficiencies of P. aztecus feeding naturally were 

 determined by Jones (1973). 



A number of investigators have studied penaeid 

 oxygen consumption ( Rao 1958; Egusa 1961; Kader 

 1962; Subrahmanyam 1962, 1976; Zein-Eldin and 

 Klima 1965; Weerasinghe and Arudpragasam 1967; 

 Steed and Copeland 1967; Kutty 1969; Ikeda 1970; 

 Kutty et al. 1971; Venkataramiah et al. 1975, see 

 footnote 3; Green et al. 1976; Venkataramiah et 

 al. ). Subrahmanyam (1962) has shown that one 

 shrimp. P. indicus, is an oxygen conformer and 

 that its oxygen-consumption rate depends upon 

 the partial pressure of oxygen, even at saturation 

 levels. Thus, as the ambient oxygen concentration 

 in a closed chamber decreases from respiration, 

 the shrimp's respiratory rate will also decrease. 

 Because all previous investigators, except Egusa 

 (1961), Subrahmanyam (1976), and Ven- 

 kataramiah et al. (footnote 4) used static situa- 

 tions to measure oxygen consumption of shrimp, 

 their results may not be representative of res- 

 piratory rates in natural or culture conditions. 



Shrimp of the genus Penaeus in the Gulf of 

 Mexico exhibit a complex life cycle that includes a 

 distinct migration between deep offshore waters 

 and shallow estuarine waters. Shrimp enter es- 

 tuaries as postlarvae and may grow from an initial 

 size of 12 mm to lengths >100 mm before returning 

 offshore (Williams 1965; Perez Farfante 1969). In 

 estuaries, shrimp experience daily and seasonal 

 changes in salinity and temperatui-e and, prior to 



^Venkataramiah, A., G. J. Lakshmi, and G. Gun- 

 ter. 1974. Studies on the effects of salinity and temperature 

 on the commercial shrimp, Penaeus aztecus Ives, with special 

 regard to survival limits, growth, oxygen consumption, and ionic 

 regulation. U.S. Army Engineer WES, Vicksburg, Miss., Con- 

 tract No. DACW 39-71-C-008, 134 p. 



•'Venkataramiah, A., G. J. Lakshmi, R Biesiot, J. D. Valleau, 

 and G. Gunter. 1977. Studies on the time course of salinity 

 and temperature adaptation in the commercial brown shrimp 

 Penaeus aztecus Ives. U.S. Army Engineer WES, Vicksburg, 

 Miss., Contract No. DACW 39-73-C-0115, 370 p. 



FISHERY BULLETIN: VOL. 78, NO. 3 



emigration, are one of the most abundant and im- 

 portant macroinvertebrates. In this paper we re- 

 port the effects of selected environmental factors 

 influencing the shrimp's metabolic rate and (or) 

 osmoregulation. We also estimate energy budgets 

 for animals under typical environmental condi- 

 tions. Experimental conditions were selected to be 

 applicable to the shrimp's natural environment, 

 i.e., typical estuarine salinities and temperatures 

 (St. Amant et al. 1966), or to provide knowledge 

 relevant to their intensive culture. 



METHODS 



Experimental Procedure 



Brown shrimp, Penaeus aztecus Ives, were cap-, 

 tured in a 4.9 m otter trawl in Airplane Lake, 

 Jefferson Parish, La., between 1 September 1973 

 and 30 June 1974 (from November 1973 to January 

 1974, some pink shrimp, P. duorarum, may have 

 been included among the test animals). After cap- 

 ture shrimp were selected for size and transported 

 to Louisiana State University (LSU) in Baton 

 Rouge. One of two size classes, 3.7 ±0.6 g (73-82 

 mm total length, TL) and 6.7 ±0.9 g (90-100 mm 

 TL), of shrimp were used in all tests. The 3.7 g 

 shrimp are typical of estuarine shrimp popula- 

 tions (St. Amant et al. 1966), and 6.7 g shrimp are 

 frequently among the size range emigrating from 

 estuaries (Parker 1970). 



In the laboratory, shrimp were placed in 

 polyethylene holding tanks and acclimated to test 

 salinity and temperature combinations for a min- 

 imum of 1 wk(Sick etal. 1973) prior to any experi- 

 ment. Acclimation and test temperatures were 

 maintained to within ±1.5° C. Salinity was main- 

 tained to within ±1.5%o (refractometer readings) 

 with artificial sea salt. Photoperiod was kept at 12 

 h light, 12 h dark ( 12:12 LD); the photophase began 

 at 0630 and ended at 1830 h central standard time 

 (c.s.t.). Shrimp were starved 24 h before testing 

 but otherwise fed daily an excess amount of an 

 extruded pellet ( EST 21-5/72A).5 Uneaten food was 

 removed daily. Chopped fresh shrimp or Tetra 

 Werke's TetraMin*^ was occasionally included in 

 the diet. 



^Obtained from S. P Meyers, Professor, Department of Food 

 Science and Technologv, Louisiana State University, Baton 

 Rouge, LA 70803. 



^Reference to trade names does not imply endorsement of that 

 product by the National Marine Fisheries Service, NOAA. 



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