stunted seed production & culture practices
TRANSCRIPT
Need of the hour- Seed production
Spawn6-8 mm
Fry20-25mm
Fingerling100-150mm
YEARLING100-200 GM
632 million fry (1986-87)
18.5 billion fry (2002-03)
20 billion today
2.5 m ha ponds &
Tanks
2.0 m ha reservoir
31 billion fingerling
Need for seed
• Target of 12mmt during 2020 to meet the protein requirement of huge human population.
• The high stocking density, etc resulting in detrimental consequences in aquatic organisms (Reubush and Heath, 1996).
• Production of stunted fingerlings of Indian major carp (IMC) has become a general practice where fish are stocked at high density with restricted ration.
Need for seed
• Rearing of these fingerlings is adopted by the farmers with an assurance of low mortality and compensatory growth during the grow-out phase.
• The subsequent growth of the stunted fingerlings up to marketable size is believed to be rapid (Nandeesha et al., 1994).
• No systematic work has been carried out yet to understand the stress caused due to food deprivation on fish.
Why use fingerlings?High
survival
Short culture period
Multi cropping
Can fetch good price
Superfast growth
How to produce large sized fingerlings?
1-Nurturing spawn in high density, followed by thinning of fry which are then raised to fry and fingerlings.
2-Nursing spawn at low density ,which makes fry grow faster. In 1-2 months fingerlings are there from fry.
3-Producing spawn through early breeding before onset of monsoon to maximize time available for growth.
4-Rearing fry at higher densities for 10-12 months to get stunted fingerlings/ yearlings.
5-Supply of quality food and low density helps to ensure healthy seed with fast growth and survival of fingerlings.
Seed production
Fingerling
Spawn
Egg
Yearling
3 days
15-20 days
60-90 days
7-8 months
Reasons behind Stunted seed Technology
• The gap between demand and supply of quality seeds, by and large, remains a daunting task in aquaculture development.
• Carps are known to grow rapidly during the second year of their age.
• To address the problems related to fish growth and yield.
History
• Yearlings are produced traditionally in village ponds. When farmers fail to sale their fingerlings and they continue to rear them up to May-June. Before monsoon, when ponds are prepared for next fry rearing crops, farmers harvest stunted fish for consumption as they are grown with reduced nutrient uptake.
History
• Nikolsky (1963), reported that partial or complete starvation of tropical fish species is followed by a voracious feeding period and subsequent restoration of growth during the ensuing more favourable conditions.
• Stunted populations are frequently observed in fishes (Roff, 1992).
• stunted fish seed = aged, but have not yet attained full growth potential.
• A stunted population as consisting of individuals that grow slowly and mature early and at a small size, in which growth is restricted by density-dependent mechanisms, and the diminished maximum size is not genetically determined.
What is stunted seed????
Causes
1. Resource limitation (arising from intraspecific density dependence)
2. size- or age-dependent survival probabilities• Fish whose growth was arrested as juveniles under
controlled conditions can subsequently compensate growth when suitable conditions return.
• Level of this compensation is mediated by the quality of the grow-out environment.(Ylikarjula etal 1999)
Causes
• Several ecological factors, including increased survival from reduced predation and decreased food availability, may influence the development of individuals in stunted populations (Roff, 1992; Ylikarjula et al., 1999; van Kooten et al., 2007).
• Stunting is a phenotypic change resulting from unfavourable environmental conditions, such as overcrowding and limited food availability (Noakes & Balon 1982; Björnsson etal. 1988).
• Overwintering
Procedure
Rearing pond of 0.4-3.0 ha
Fry stocking @ 50,000-70,000 seed/ha.
Manuring @5000-10,000 kg/ha
6-12 months fry will become fingerling of 100-200g
Feeding@ 0.5-1.0%
Procedure
• Stocking spawn at shallow water depth (35-45 cm) followed by phased increase of water level at 3 - 4 days intervals, results higher fry recovery of 50-70 %.
Orissa
• Some of the village fish farmers produce yearlings and/or stunted fingerlings with improved management on commercial scale. In this, the fingerlings stocked in well prepared ponds at high density July-August.
• During culture period ponds are fertilised monthly once.
• Complete harvesting of yearlings is done by repeated netting from May-June.
• The farmers of Kantapada and Bhatpadagarh are producing 3-5 tonnes of yearlings every year.
Feeding
• Fingerlings are fed with the mixture of ground nut oil cake and rice bran in the ratio of 1:1.
• Fortification of micro-nutrients in artificial feeds is also enhances the growth and survival of fry. A commercially available multiplex pre-minerals mixture with vitamins accelerates plankton production and fry survival in nursery ponds.
Feeding
• Farmers in Andhra Pradesh incorporate salt along with feeds to improve the growth of fish @ 0.5 to 2 percent along with the feed.
• Used in many parts of Asia. • It is possible to improve the growth of carps
by incorporating the salt at 0.5 to 2 percent for different species (Gangadhara et al., 2004).
Changes
• Metabolic depression seems to be an important strategy developed by fish in response to periods of food scarcity (Cook et al., 2000; O'Connor et al., 2000; Rios et al., 2002).
• When the fish is deprived of food, it tries to cope with the change by reducing the energy expenditure and this is reflected by lower oxygen consumption.
• A decline in oxygen consumption may be a consequence of lower activity by the fish in an attempt to conserve body energy reserves during periods of food shortage.
Changes
• L. rohita fingerlings can tolerate the stressor arising out of feed deprivation up to 3 weeks (Cara et al. 2005).
• He Demonstrated that food-deprived trout larvae were more tolerant to thermal shock than its fed counterparts because of the protection conferred by fasting-induced Hsp.
• The reduced oxygen consumption by L. rohita fingerlings in the 3rd week of starvation may suggest reduced metabolic needs for energy so that the fish can sustain limited nutrient supply from body reserves.
Changes
• Under normal growing conditions, energy is available for allocation to somatic growth, which has the effect of increasing the somatic tissue at a similar rate to the continuous growth of the bony structures.
• Alternatively, stunted fish may allocate less energy to somatic growth because of food limitation, resulting in a body that remains undifferentiated compared to the bony structures in the head.
Compensatory fish growth
• Compensatory growth in fish is a phase of fast growth, which occurs after the re feeding of fish following a period of feed deprivation or after abnormal conditions such as low temperature.
• Compensatory growth is usually accompanied by hyperphagia (an increase in appetite).
• Compensatory growth in fish is regulated by many environmental factors such as water temperature, Water quality , social aggression and dietary protein and energy contents during re-alimentation period.
Compensatory fish growth
• The period of feed deprivation that elicits compensatory growth varies among fish species (Jobling et al.).
• Carassius auratus gibelio, which showed improved feed efficiency and preferential protein growth during compensatory growth.
Advantages
• Overwintering and ‘stunting’ has economic significance. Brood fish and fry/fingerlings may be stunted intentionally through manipulation of feed and stocking density to reduce costs of feed and space and to service market demand better for both seed and table fish.
• The culture of stunted Indian major carp has become established in parts of India because the subsequent growth of the fish is believed to be rapid (Nandeesha, Dathathri, Krishnamurthy, Vargese, Gangadar & Umesh 1994).
Advantages
• Stunted fingerlings/ yearling are the most preferred stocking material by grow out farmers and fetch a higher price than the normal fingerlings.
• High survivability of stunted fish (95%).• Farmers are now able to obtain, most
commonly an average yield of 8 tonnes/ha and some of the progressive farmers obtain a yield of more than 15 tonnes/ha/year.
Applicability
• Used for herbivores fishes.• High mortality• Not applicable for prawn.• Fishes having fast growth not in first year.• Seed should be in appropriate quantity.
•Growth of carp fingerlings during prolonged nursing (5 or 12 months) was stunted compared with fish nursed over a conventional duration of 3 months but showed superior growth subsequently.
•This trial indicates that fish whose growth was arrested as juveniles under controlled conditions can subsequently compensate growth when suitable conditions return, and that the level of this compensation is mediated by the quality of the grow-out environment.
Case study
• The economic viability of stunting juvenile fish has been established for milkfish (Baliao, Franco & Agbayani 1987) and tilapia (Dan & Little 2000) for conditions in the Philippines and northern Vietnam, respectively, but the viability of stunting carps is likely to be system and site specific.
Case study
• Stunting or retarding the growth of milkfish for fingerling production has been practiced in the Philippines for some time.
• This practice has been necessitated by the irregularity of fry supply from the wild, which adversely affects continuous production of the ponds. Stunting has also been shown to be a profitable activity in milkfish culture operation.
Stocking duration
6 months 9 months 12 months
A- fixed costs
Depreciation of nylon substrates
50.00 50.00 50.00
Salary of pond care taker
25.92 25.92 25.92
Repair and maitenance
61.10 61.10 61.10
B- Variable costs
Pond preparation
Lime 22.03 22.03 22.03
Chicken manure 17.05 17.05 17.05
16-20-0 5.76 5.76 5.76
45-0-0 2.88 2.88 2.88
Economics
Stocking density
6 months 9 months 12 months
Installation of substrates
Stocking
2 months old fingerlings
(At P0.31/each) 892.80 892.80 892.80
Stunting operation
feeding
Trash fish 42.88 64.32 85.76
Rice bran 21.44 32.16 42.88
Harvesting
Labor for harvesting
12.50 12.50 12.50
Interest charges 71.09 106.64 142.18
Economics
Stocking density
6 months 9 months 12 months
Total cost 1226.25 1306.92 1387.58
No. of fingerling harvested
2505.00 2274.00 1499.00
Cost/piece 0.49 0.57 0.92
Net income/pieceP700/thousand
0.21 0.13 (0.22)
Total net income 526.05 295.62 (329.78)
Average rate of return
33.50 18.87 (21.06)
Economics
Conclusion
• Fisher community sells off as much as they can to satisfy current year demand and then go for producing stunted fingerlings.
• No systematic work has been carried out yet to understand the stress caused due to food deprivation on fish.