A quantitative analysis of the phytoplankton of the Gulf of Panama II. On the relationship between C14 assimilation and the diatom standing crop

ENGLISH: The Inter-American Tropical Tuna Commission has maintained a hydro-biological station in the Gulf of Panama located at 8°45'N, 79°23'W in connection with their ecological investigation of the anchoveta (Cetengraulis mysticetus), a tuna baitfish (see Peterson, 1961, for references) . The depth is approximately 42 meters at mean low water at this station. Routine hydrographic and biological observations have been made (Schaefer, Bishop and Howard, 1958; Schaefer and Bishop, 1958; Forsbergh, 1963), including the collection of quantitative phytoplankton samples from November 1954 through May 1957 (Smayda, 1959; unpublished). The seasonal and regional variations in phytoplankton growth in the Gulf of Panama have also been investigated (Smayda, 1963). The relationships existing between C1 4 assimilation as determined by 24 hour in situ experiments and diatom standing crop at 10 meters when expressed as cell numbers, cell volume, cell surface area and cell plasma volume have been assessed for 30 observations made between November 1954 and May 1957 at 8°45'N, 79°23'W. The average cell volume and cell surface area characteristics for 110 diatom species and varieties are presented. SPANISH: Las relaciones existentes entre la asimilación del C14 , determinadas después de 24 horas de experimentos in situ, y la cosecha estable de las diatomeas a 10 metros, expresando el número de células, volumen celular, área de la superficie celular y volumen del plasma celular, han sido determinadas por medio de 30 observaciones hechas entre noviembre de 1954 y mayo de 1957, a los 8°45'N, 79°23'W. Se presenta, para 110 especies y variedades de diatomeas, el promedio de las características del volumen celular y del área de la superficie celular. (PDF contains 67 pages.)

Adaptation of coastal communities in the Philippines to the impacts climate change

The Quedan and Rural Credit Guarantee Corporation (Quedancor) of the Philippine Department of Agriculture has the critical responsibility of providing and improving credit assistance to fishers, it also has the task of helping its beneficiaries meet the repayment obligations of their loans. One reason for defaults can be attributed to the devastating impact of natural calamities. Schemes in place are still insufficient to help safeguard lending programs and operations from non-repayment of loans due to production losses and damages to personal properties.(PDF contains 5 pages) Natural calamities include the uncertainties and vagaries of weather and climate that bring about typhoons, floods, and drought; earthquakes; volcanic eruption as well as pests and diseases that affect the productivity of fisheries. When natural calamities occur, small fishers are unable to pay their loans from Quedancor, moreover they have difficulty renewing their loan applications from Quedancor or accessing credit from other sources. Failure to access credit could disable them to continue venture on fishing activities and could eventually jeopardize the welfare of their entire household. The inability of creditors to pay their loans and meet their obligations also impair, to a large extent, the financial operation and viability of the lending institutions. Risk management schemes currently employed include price stabilization measures, targeted relief` to typhoons and drought victims, and crop insurance systems, to name a few. Some of these schemes are becoming very expensive to implement. Moreover, they fail to enable fishers regain sufficient resources so that they may continue production.

The potential for crop rotation in controlling diseases in shrimp culture

The use of antibiotics and other chemicals in controlling shrimp pathogens become ineffective as the strains grow more resistant to these chemicals. Moreover, the bacterial pathogen (Vibrio harveyi) produced biofilm coating that protects it from dying and disinfection procedures that are followed during pond preparation. Biological control is being considered as an alternative means of preventing shrimp disease outbreak. The main principle behind biological control is to enhance the growth of beneficial microorganisms which serve as antagonists or target pathogens. The paper discusses shrimp and tilapia crop rotation as a form of effective biological control, a technique which is already being practiced in Indonesia and the Philippines.

Rice-fish and rice mono-crop production at Gouripur, Mymensingh: an economic analysis

This study examines the relative profitability of rice-fish culture and rice mono-crop production at Gouripur thana of Mymensingh district. The results of the study show that the rice-fish farming was economically more rewarding than the rice mono-crop farming, although both the farming activities were found profitable over cash as well as full costs. In addition to extra earnings from fish, the rice-fish farming produced significantly a higher yield of rice requiring very minimum extra cost for fish. Rice-fish farming also reduced variability in yield of and return from rice.

Prospects of integration of aquaculture with animal husbandry and land crop culture in Tripura State

Tripura is a densely populated small state with meagre water resources. 47.51% of the population is constituted by socio-economically backward, illiterate, orthodox, tribal and scheduled castes. Some of them are nomad and a majority of the rest of the population is refugees from Bangladesh, but almost 100% is fish eater. Settlement of tribes in villages, provision of nutritious food and employment therefore calls for proper utilization of every resource they have. The State is poor in water resources but recently has created 21,636.23 ha of new water area. Tripura is rich in pig population, besides poultry birds. Paddy is the main crop cultivated in arable lands. An integration of livestock raising and land based agriculture with pisciculture practices around mini barrages will help in solving the problems to a great extent. The paper is an attempt to outline the prospects of integration of aquaculture with animal husbandry and land based crop culture in Tripura State.

Factor intensity and economic returns of alternate shrimp crop and shrimp-salt farming in the coastal areas of Bangladesh

The paper examines the factor intensity and economic returns of alternate shrimp-crop and shrimp-salt farming in the coastal areas of Bangladesh. Data were collected from 30 shrimp-crop and 30 shrimp-salt farmers, 30 shrimp farmers and 30 rice farmers from three selected coastal districts of Bangladesh. Cobb-Douglas production function model was used to determine the effect of various factors on alternate shrimp-crop farming. The chosen variables were stocking of juveniles, paddy seed, labour, fertilizers, feed and farm size of respective type of farming. The results indicated that the production function exhibited increasing remrns to scale for alternate shrimp-rice, alternate shrimp-salt and year round shrimp farming while it indicated decreasing returns for year round rice farming. Economic analysis of same system of farming indicated that higher amount of input use produced higher level of yield, gross return and net return for each type of production system.

Fish-makhana (Euryale salisb) integration: a case study of sustainable aquafarming system in north Bihar

The paper deals with a technique to synchronize two crops, fish and makhana (Euryale ferox Salisb) in a pond. In such eco-friendly integration both crops are mutually benefited. Decomposed plant parts of makhana crop form organic matter that releases nutrients in the water to enhance plankton population. Organic detritus not only acts as food for bottom dwelling fishes (mrigal and common carp) but also provides a suitable substratum for the growth of zooplankton, insect larvae, nematodes and gastropods. Fishes contribute to the control of makhana pests. Their faecal matter acts as organic manure for makhana crop. Plankton population fluctuated between 1260 u/l to 4030 u/l in the control pond and 1630 u/l to 4722 u/l in the experimental pond. During the grand growth period of makhana crop (April to July) the dissolved oxygen content fluctuated between 5.02 mg/l to 6.68 mg/l in the covered areas and 6.04 mg/l to 6.92 mg/l in uncovered areas. Makhana leaves acting as blanket barrier over the water surface brought down the D.O. content in the covered areas of the pond. Free CO sub(2) content showed wider fluctuation in the experimental pond (25.2 mg/l to 30.9 mg/l) than in the control pond (25.1 mg/l to 28.6 mg/l). This could be due to decomposition of plant parts of the presiding crop lying as debris at the pond bottom. Autochthonous supply of nutrients enhanced the content of nitrogen, phosphorous and organic carbon in the soil of experimental pond. The experimental pond covering an area of 0.40 ha yielded 852 kg fish and 200 kg pops whereas the control pond covering the same area produced 777 kg fish only. The net profit per ha came out to be Rs.1,04,700 and Rs. 66,200 in integrated and non-integrated system respectively. Owing to crop diversification, the present integrated system was found to be more viable than the non-integrated system in terms of production and net profit.

Croton tiglium (Linn) seed as an ideal eradicant of pests and predators in fish farms

The toxicity of Croton tiglium seed is very effective in the eradication of most of the aquatic fauna except a few species of hard shelled crustaceans such as crabs and prawns which are resistant to even very high concentrations of it. Its toxicity ranged between 0.4 and 2.2 p.p.m. for different species of fishes. Application of homogenized C. tiglium seed at the rate of 10 kg/ha (0.5 m depth) is found effective for the eradication of aquatic pests and predators of fish farms. While its toxicity lasts for 5-8 days in still water ponds, it is only for 1-3 days in tidal ponds with frequent replenishment of water. This method is thus most useful for the initial preparation of the ponds for pisciculture.