Ration, Growth, and Measures of Somatic and Organ Condition in Relation to Meal Frequency in Winter Flounder, Pseudopleuronectes americanus, with Hypotheses Regarding Population Homeostasis

Abstract

Six ration levels were established among 120 large, adult winter flounder (Pseudopleuronectes americanus) by setting different feeding frequencies, but with unlimited feeding at each meal. All fish were maintained at 7 C. With decrease in feeding frequency, fish ate less food per month but more food per meal — i.e. ration compensation was attempted. At the lowest frequency, two meals per month, fish did not compensate. At any one feeding frequency, fish ate progressively more per meal from the first to the fourth (final) month of the experiment.Maintenance ration was 7.9 gcal/g per day. Weight loss on starvation was equivalent to 2.14–2.35 gcal/g per day. Gross conversion efficiency ranged from 1 to 16%, and was positively correlated with ration. Net conversion efficiency averages 24.3% and was not related to ration.Positive correlations were found between mean calories consumed per day and condition, liver weight, percent fat in the liver, percent of fish with yolk-bearing ovaries, ovary weight, and percent of ovarian follicles with yolk. The decrease in proportion of yolked oocytes with decrease in ration was not due to increased follicular atresia, but to a decrease in number of oocytes starting vitellogenesis.Comparisons with flounders sampled directly from Passamaquoddy Bay, N.B. showed that the negative correlation between condition index and percentage of oocytes not in vitellogenesis was the same for Bay and laboratory fish, the range of response being greater in the laboratory fish. The existence of this relationship was interpreted as evidence that some flounders within the Bay were not getting all the food they could use. In the face of food scarcity, the winter flounder’s adaptive reproductive strategy seems to be to sacrifice egg production and maintain body weight, and so when a good year comes its body will be large and able to carry a larger ovary.

Balıkesir, Çaygören Baraj Gölü’ndeki Alburnus alburnus (L.) inci balığı populasyonunun boy-ağırlık ilişkileri, kondisyon ve üremesi üzerine bir araştırma

“…As shown on Table 2, the spawning period in Çaygören Dam Lake is similar to the previous investigations [30,[41][42][43], except for those in Keddara Dam Lake [23] and Keith and Allardi [44]. The hepatosomatic index is an indicator of feeding activity of fish [45]. It shows an allocation of energy to the liver during every period except reproduction, when part of the energy is used for gonad maturation [46].…”

<b>The use of biomarkers for assessing effects of pollutant stress on fish species from a tropical river in Southeastern Brazil

“…According to Tyler and Dunn (1976) Adams et al, 1992). Rypel and Bayne (2010) evaluated growth rates of six fish species correlated with PCB concentrations in a moderatelyto-heavily polluted freshwater ecosystem, and concluded that at the range of concentrations investigated, these PCBs do not exert negative impacts on growth.…”

Response of the Asian Sea Bass Lates calcarifer Fingerlings to Different Feeding Rates and Feeding Frequencies Reared in Hyper Saline Condition

“…Simple regression analyses on growth showed significant coefficient of determination (R 2 ) in the three feeding rates, in relation to final weight (R 2 = 0.84), final length (R 2 = 0.82), ADGR (R 2 = 0.80) and SGR (R 2 = 0.84), indicating that growth can still be improved with increasing amount of food. Tyler and Dunn (1976) Seenappa and Devaraj (1991) also observed increases in the growth of Chanos chanos and Cirrhinus mrigala with increased feeding rates. Nour, et al, (1993) also found similar trend in Mugil cephalus fingerlings.…”