摘要:

Abstract.Atlantic salmon kelts were successfully reconditioned in salinities of 16% and 28%o using a moist pellet diet. Two groups of reconditioned kelts were re‐acclimated to fresh water in the autumn tu prevent super chitling in salt water during the winter. The feeding response and growth of salmon kelis. both years, was highest when salinities were maintained at 28% during the winter and 16%during the summer. However, other salinities also provided acceptable growth rates. Two‐sea‐winter salmon kelts reconditioned at a slower rate in all groups than 1‐sea‐winter salmon kelts. Kelt survival was 93.1% the first year and 82.7% the second year. Gonnd maturation occurred in 17.9% of the female 1‐sea‐winter kelts and 40.6% of the male 1‐sea‐winter kelts after the first year. At the end of the second year. 83.3% of the 1‐sea‐winter female kelts and 96.3% of the l‐sea‐winter male kelts matured and spawned. Reconditioned salmon kelts with a mean fork length of 68.4 cm produced 7261 eggs per fish with a mean egg diameter of 5.70 mm and a fecundity of 2262 eggs.kg−1, Survival (Fl) from the green egg stage to the alevin and smolt stages was 73.5% and 38.8% respectively. The smolt to adult return rule based on unadjust

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1987.tb00321.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.Post‐spawning Atlantic salmon.Salmo salar L., were obtained from a salmon enhancement project in the autumn of 1984, These salmon were overwintered in submerged cages in fresh water, retrieved in the spring of 1985, and transferred to a marine cage after vaccination forVibrio anguillarum. Salmon mortality was highest immediately after their retrieval from overwintering cages, Mortality through the duration of the marine cage interval was 0.22% per day. Growth reached a maximum of 1.76% per day. Average final weight reached by reconditioned kelt in the 101 days of marine cage confinement was greater than the average weight of natural repeal spawners in the stock that provided kelt to the aquaculture experiment. Reconditioned salmon were slaughtered in November and marketed, both fresh and smoked. The incidence of maturation among slaughtered salmon was less than 2%. Consumer response to reconditioned kelt indicated that flesh colour was inferior but thai the products were acceptable and that 84% of the consumers polled would purchase the product agai

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1987.tb00322.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.Two 6‐week experiments were conducted with age‐0 striped bass,Morone saxatilis(Walbaum). In the first experiment, fish were fed isocaloric diets that contained 20–65% protein. In the second experiment, fish were fed isonitrogenous diets (42–46% protein) that contained 6–29% dextrin or 8–25% cod liver oil.Maximum weight gain, feed efficiency and protein efficiency ratio were achieved with a 52% protein diet. Net protein utilization was inversely related to dietary protein concentration.In the second experiment, maximum growth was achieved with a 33% carbohydrate diet (based on nitrogen free extract); and with a 17% lipid diet (based on ether extract). Increasing dietary lipid beyond 17% resulted in growth depression. No negative impacts on carcass composition as a result of increasing dietary dextrin or lipid were judged to ha

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1987.tb00323.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.As currently practiced, freshwater prawn,Macrobrachium rosenbergii(de Man), aquaculture in Hawaii requires large inputs of supplementary feed, water and labour. The high cost of these inputs greatly restricts profit potential. An experiment was conducted to compare an alternative prawn production system which used lower feeding rates and fish polycultures to reduce inputs. Three treatments were run in quadruplicate: (1) control—prawns stocked at standard densities (11.5 per n2) in monoculture and fed standard prawn pellets at the commercial ration recommendations by New&Singholka (1982); (2) low feed—prawns at standard densities and fish [silver carp,Hypophthalmichthys molitrix(Valenciennes), grass carp,Ctenopharyngodon idella(Valenciennes), and grey mullet,Mugil cephalus(L.)] fed one‐half commercial ration; and (3) maintenance feed—prawns at standard densities and fish fed one‐tenth commercial ration. Although prawn yield characteristics (mean weights, harvestable sizes, survival, net yields) were not significantly different (P>0.05) based on an analysis of variance in the three treatments over the approximately 9.5‐month culture period, this lack of significance most likely resulted from interpond variability and the lack of a large number of replicates. The relatively poor survival (60–63%) of gray mullet and an almost twofold difference in prawn yields in the control and maintenance feed treatments suggest that there was in fact competition for resources in the nominally polyculture systems. Nevertheless, the wet weight yield of biomass from all species was twice as high in the low feed ponds as in the

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1987.tb00324.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.The system for reporting fishery statistics in Indonesia, a developing country with a large marine fishery, provides an example of the problems of using fishery statistics as the basis for stock assessment and other fishery management work. The statistical system now used was first instituted in 1976. In spite of the millions of pieces of information processed by the system annually, provincial and national reports are produced on a reasonably timely basis. A field review on parts of the island of Java revealed, however, that data from the system are of limited use to the cautious analyst. Significant inaccuracies are present. A brief review of the system, its general accuracy and possible sources of inaccuracies arc given.

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1987.tb00325.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.The status of the fishery of Pimburctlewa wewu, a man‐made lake in Sri Lanka, was studied from January 1985 to January 1986. The annual fish yield in the reservoir is 441 kg/ha, one of the highest in the south‐east Asian region.Oreochromis mossambicus(Peters) is the dominant species in the fishery and accounted for about 90% by weight of the total catch. Although there were monthly variations in catch per unit effort, the daily catch per fisherman was not adversely affected. A possibility of having a more productive fishery is suggested In reducing The minimum permissible mesh size in the gillnet fishery during the peak recruitment season in May–June. The possible effects of reducing the mush size are discussed. Using the length‐frequency data ofO. mossambicus, the asymptotic length and the growth constant were estimated to be 39.3cm and 0.34 respectively. The estimates of total mortality (2.42). natural mortality (0–82) and mean selection length (24.6 cm) were based on these growth parameters Yield‐per‐recruit analysis indicated that theO. mossambictusfishery in the reservoir was optima

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1987.tb00326.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1987.tb00327.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY