Earlier Life Stages: Initial Study Findings
- Paul Monaghan
- 10 hours ago
- 5 min read
Summary
Earlier this year, we launched a study that focused on identifying potential areas around which we could consider developing interventions to improve the welfare of fishes at stages of the fish farming process before the “grow-out” stage, which is the stage that FWI primarily focuses on. This blog post summarises the key findings of this study and the path forward (full report can be found here).
Ultimately, we have decided not to further pursue exploring nurseries just at the moment, as we weren’t convinced that any of the ideas for interventions we identified were sufficiently promising to proceed with. However, we remain open to reconsidering if and how we can have an impact at nurseries in the future. We are now considering developing a study to explore hatcheries, the life stage that precedes nurseries. This is spurred by our study showing that nursery farmers often distrust the hatcheries from which they source their spawn.
Background
FWI’s current core program, the Alliance for Responsible Aquaculture (ARA), primarily focuses on the final life stage—the “grow-out” stage—of the farm cycle of Indian major carps (IMC). Before fishes are stocked into grow-out ponds, they are generally transported through two to three different stages:
Hatcheries: where the baby fishes hatch from their eggs in tanks and live for about the first three days of their lives,
Nurseries: where the ~3-day-old fishes are transported in bags to a nursery pond, growing for 3–6 weeks, transforming from tiny larvae into fry about 2–2.5 cm long,
Rearing ponds: where the fishes are transported to rearing ponds in tanks, usually by truck, growing for about 2–3 months, into fingerlings roughly 10–15 cm long.
In this study, we chose to focus on the nursery stage. We may consider similar studies at hatcheries and/or rearing ponds in the future.
Overview of Study
The study used semi-structured interviews and on-site observations with 20 nursery farmers across West and East Godavari districts. The study was structured around a two-phase, mixed-methods approach to systematically identify practices detrimental to fish welfare and to determine if there was a viable path towards developing and implementing a suitable intervention for nurseries:
Phase 1 involved structured qualitative interviews combined with preliminary observational assessments to identify practices and interventions that may warrant further investigation.
Phase 2 was planned to consist of more detailed observational studies focused specifically on the shortlisted practices identified during Phase 1.
A midpoint review was included to decide whether the shortlisted practices warranted moving to Phase 2. If the practices identified during Phase 1 held sufficient promise for developing a potential cost-effective and scalable intervention, the intention was to further explore these in a follow-up Phase 2 study.
The study was designed and led by Teja Sangeetha, FWI’s R&D Project Manager.
Key Findings
The full report of the study can be found here. The survey was structured to gather information from nursery farmers about operations at their nurseries throughout a full cycle. Findings are predominantly based on information provided by the farmer, supported by on-site observations (when and where possible). We probed into practices that nursery farmers follow: preparing their pond before stocking spawn, sourcing their spawn, stocking their ponds, managing water quality, feeding, and disease management and biosecurity. Key findings are as follows:
Compliance with pond preparation steps before stocking is quite good, with 60% of the surveyed farmers carrying out at least one key step—such as drying, desilting, liming, or initial sanitizing measures—before stocking.
Concerns about the quality—and inaccurate counting of spawn—sourced from hatcheries are common.
Stocking densities varied widely, from 10 lakh (1 million) to 50 lakh (5 million) spawn per acre, although we found no correlation between stocking density and survival. Only two of the twenty surveyed farmers follow any form of acclimatization step before releasing the spawn into their pond.
Only 40% of the surveyed farmers conduct proactive water quality testing before stocking or routinely during the cycle, with the majority of farmers testing water quality only when problems arise. 40% routinely use aerators as part of their water quality management strategy, as large capital and electricity costs present barriers to wider adoption.
All farmers use low-quality feed formulated as a mash. Feeding quantities and frequencies are guided by experience and intuition rather than measurements.
To treat disease occurrences, 75% of the surveyed farmers rely on self-diagnosis and self-medication using products from local shops. 40% utilize some form of bird deterrent to minimize predation of spawn by birds, with cost being the major factor limiting wider adoption. Over 80% utilize mesh screens over water inlets to minimize predation of land/water-based predators (e.g. frogs, snakes, other fishes such as tilapia).
High mortality at earlier life stages (particularly at hatcheries and nurseries) is well known. This survey confirmed that mortality is extremely high at nurseries, with a mean survival rate of 27%, ranging from 10% to 70%.
From these findings, some practices emerged as potentially promising areas for FWI to consider to try to reduce mortality and improve welfare at nurseries:
Verified counting of spawn and stocking density management
Acclimation at stocking
Proactive water-quality routines
Path Forward
Mortalities at nurseries are high—much higher than mortalities reported at the grow-out stage of IMC fish farming, where FWI currently focuses. However, as we highlighted in our earlier blog post when we launched this study, it’s worth noting that, as a r-selecting group of animals, fishes naturally have high mortality rates in their young, at least to our human eye. The real question for us as fish advocates is how much of this mortality is inevitable, and how much reflects poor welfare on the farm. In other words, how much can we realistically improve mortalities by working with farmers to improve processes? The answer to this question is difficult to determine. But there is unlikely to be a single “magic bullet” approach to improving mortality levels at nurseries.
The shortlisted ideas that emanated from this study were considered as part of the study’s midpoint review. However, it was ultimately decided not to take them forward, as the path ahead was considered not sufficiently promising, and there were question marks about the tractability amongst nursery farmers, scalability, and the likely impact of any program based around these ideas.
While we won’t proceed to a Phase 2 for this nursery study at this point in time (we may reconsider if or how we can have an impact on nurseries in the future), we are currently considering developing a study to explore hatcheries. This is spurred by the current study showing that nursery farmers have distrust in the hatcheries from which they source their spawn. Farmers don’t trust the numbers of spawn provided to them, which potentially impacts stocking densities, or, more fundamentally, the quality of the spawn (which potentially impacts mortalities and overall welfare of the fishes as they live their lives in nurseries, rearing ponds, and grow-out ponds).