Is the Trout Industry Ready for Welfare Assessment?

By Craig MacIntyre and Jimmy Turnbull, Institute of Aquaculture, University of Stirling and published by CEFAS Finfish News - Issue 3, Winter/Spring 2007


Like it or not, fish welfare legislation is on the horizon. The actions that the trout industry takes now may influence the measures that are introduced by legislators in the future. Whilst it is common knowledge throughout the industry that fish have to be well cared for if they are to thrive, there is a need to demonstrate this to consumers/legislators. It has therefore been recognised that fish welfare will have to be assessed, although the form that any assessment takes has still to be agreed.

Welfare assessment could be for legislative reasons, as part of a quality assurance/ certification scheme, such as Quality Trout UK, or as a management/advisory tool(1). Although the specific nature of an on-farm welfare assessment scheme has yet to be agreed, certain information is central to safeguarding and assessing welfare. As part of a project funded by Defra and the BTA, we have tried to find out what information is currently measured on commercial UK trout farms and what additional measurements are possible.

This study followed on from a series of focus groups that were held in 2004/2005 involving stakeholders in the UK trout industry (see 2 for more details). The purpose of these focus groups was to ask how should we assess fish welfare. There was general agreement that information was required on:

  • Environmental quality
  • Farm records (including mortality data, production data, disease treatments)
  • Targeted fish sampling
  • Demonstration of good stockmanship
  • Harvest measures

It was stressed that the use to which the information was put depended upon the context of the welfare assessment, i.e. whether it be for daily welfare monitoring, for retrospective analysis of welfare or demonstration that good welfare standards were adhered to.

In 2005, we contacted 109 trout farmers by telephone and obtained brief details of the farming operation. Out of these 109 farmers, we visited 58 from May to July 2005 to obtain more detailed information about the farming operation, including many of the criteria identified by the stakeholders as important to contribute to welfare assessment. The results are displayed related to the categories above.

Environmental Quality

Farming for the table market or for restocking/ fishery purposes often leads to differences in production techniques, therefore our findings differentiate between the two, with farms classified according to the primary purpose of production.

Water quality was recognised to be fundamental to welfare, with dissolved oxygen (DO) and temperature having the most influence. Whether it be for daily monitoring, retrospective analysis or demonstration of good welfare, measurement of water quality was considered to be important.

From the telephone questionnaires, 37% of restocking farmers and 78% of table farmers measured DO, while 43% of restockers and 83% of table farmers respectively measured temperature. The same question asked during the farm visits for restocking farmers resulted in different percentages. From the farmers we visited, 74% of restockers and 80% of table farmers measured DO, and 78% of restockers and 80% of table farmers measured temperature. A possible explanation is that there were more smaller farms (<50 tonnes per annum production) in the respondents to the telephone study than were visited, who were less likely to measure water quality than those who ran larger farms.

Other water quality parameters, such as suspended solids and ammonia, were monitored by the Environment Agency or SEPA, although the frequency of the visits varied. Of all the farmers, 95% received the results of this regular monitoring from the respective environment agencies.

Farm Records

The stakeholders suggested that accurate records allowing individual batches of fish to be tracked was likely to reflect good husbandry practices. Such records also provide transparency and traceability for the production process, both of which are necessary to facilitate external auditors’ assessment of the welfare of the fish. Table 1 describes the percentages of farmers that can track the performance of individual batches of fish, that record biomass, the food conversion ratio (FCR), mortalities and disease treatment, with records of the latter two required to be kept by law.

Table 1. Percentages of farmers that can track the performance of an individual batch of fish, that record biomass, FCR, mortalities and disease treatment
(results from farm visits component of study).
  Track Performance (%) Biomass (%) Food Conversion Ratio (%) Mortality (%) Disease Treatment (%)
Primarily restocking 78 63 67 78 81
Primarily table market 92 92 80 96 96
Total 86 76 72 88 90

Targeted Fish Sampling

The data collected from targeted fish sampling was considered to be useful by the stakeholders for a post-mortem assessment of fish welfare. A total of 74% of restockers and 88% of table farmers either sampled fish themselves or appoint a vet to do this on their behalf. The frequency of sampling varied, with the bulk of sampling being conducted on an ad hoc basis.

Demonstration of Good Stockmanship

There are many possible ways to demonstrate good stockmanship, such as evidence of staff competence, regular maintenance of equipment, protection against predators, fish sampling and keeping accurate farm records, as described above. Also included under this heading was the provision of a veterinary health plan (VHP): from the farm visit component of the study, 33% of restockers and 96% of table farmers had a VHP.

Establishing contingency plans and emergency back-ups also demonstrate good stockmanship, the provision of which are included in the British Trout Association Code of Practice(3)and the Quality Trout UK (QTUK) Farm Standards(4). From the farm visits, 15% of primarily restockers and 84% of table farmers were members of the QTUK scheme, while 67% of primarily restockers and 92% of table farmers were members of the BTA, and thus abide by their Code of Practice. From the telephone questionnaires, 62% of respondents were members of the BTA, split 33% primarily table farmers and 29% primarily restockers (9% of table farmers and 29% of restockers were not members of the BTA). Nonmembership of either the BTA or the QTUK scheme does not mean that those farmers have no contingency plans for emergencies, however we did not ask that specific question during the initial, brief contact with farmers.

Harvest Measures

Feedback from processors was considered to be a potentially useful source for assessing what the welfare of the fish had been, although this is obviously a snap shot of the final condition of the fish and also will not apply to fish reared for restocking/fishery purposes. Out of the 58 farms visited, 35 harvested fish, with 13 farms (37%) processing the fish themselves and 22 (73%) having fish processed off site.


For 2004/5, the estimated annual production for the UK trout industry was around 16,000 tonnes(5). For the 109 respondents to the first component of the study, the telephone questionnaire, the annual production for 2005 was estimated at 13,500 tonnes, accounting for over 80% of UK trout production. The 58 respondents who were visited on site accounted for over 60% of UK trout production (9,750 tonnes). We therefore consider this study to be representative of the industry.

From this study it would seem that providing information relevant to the welfare of farmed trout is possible and need not necessarily involve significant additional work. Parameters such as the condition of the fish, mortality rates, growth, water quality etc, all indicate the welfare status of the stock. We now need to decide what levels of these parameters demonstrate that the welfare of the fish is acceptable and that reasonable precautions are being taken to avoid deterioration in welfare.


Our thanks go to all the farmers who gave up their time to contribute to this study. We also gratefully acknowledge Defra and the British Trout Association for funding this project. Also, thank you to Imogen Hoyle and Chris Pond for help with the data collection.


  1. Main, D.C.J., Kent, J.P., Wemelsfelder, F., Ofner, E., Tuyttens, F.A.M. (2004). Applications for methods of on-farm welfare assessment. Animal Welfare 12: 523- 528.
  2. Macintyre, C., North, B., Nikolaidis, J. & Trunbull, J. (2006). Interactions between water quality and trout welfare (defra project AW1205). Finfish News 1: 9-13.
  3. Anon. (2002). Code of practice for the production of rainbow trout. British Trout Association, London
  4. Anon. (2003). Farm & hatchery certification standards. Quality Trout UK, London.
  5. Anon. (2006). Summary of UK trout production in 2004. Finfish News 1: 43.
Spring 2007

the Fish Site Editor

Learn more