Marine aquaculture modelling
Computer modelling is used as a guide to determining licensed
discharge quantities of anti-parasitic chemicals and organic waste
arising from marine fish-farm operations.
The modelling tools promoted by SEPA provide robust predictions
in most cases, requiring relatively little site-specific
information. Nevertheless, the quality of the model outputs is
dependent upon good quality data and careful implementation of the
models and interpretation of their results.
This page provides access to a variety of software tools, and
reference and guidance materials.
Survey and modelling manuals
This section introduces the parts of SEPA's fish farm manual
that relate specifically to data collection and modelling.
Site-specific data
The robustness of the modelling is highly dependent upon the
quality of the data that is used. Both SEPA and SAMS
(Scottish Association for Marine Science) promote the collection of
the most representative data possible. We encourage
applicants to submit high quality data that exceed the existing
minimum requirements. Due to improvements in equipment, and
the importance of these data, SEPA now require that all new
hydrographic data recorded should have a component that is measured
at a maximum of 3m above the seabed.
Attachment
VIII 
(226k) - Site and Hydrographic
Survey Requirements
Minimising the impact of sea-lice treatment chemicals and of
solid organic waste
Sea-lice are a natural parasite of salmon; in the wild, salmon's
migratory lifestyle means that they only come into contact with
lice sporadically, and are hence unlikely to develop an imperilling
lice burden. Conversely, caged salmon are unable to evade
their parasites, so farm managers use a range of anti-parasitic
chemicals to protect their stock. There are two predominant
modes of treatment:
- a topical 'bath' treatment, where the water in which the salmon
swim is dosed, and the chemical concentration is maintained for a
prescribed period; typically, this entails reducing the volume of a
cage by lifting the base of the nets, enclosing it in tarpaulin to
create a 'bath', and maintaining the dosed volume for one
hour;
- an in-feed treatment, where the stock are fed a precise dose of
pelletized feed impregnated with the anti-parasitic chemical,
typically daily over a period of a week.
Bath treatments result in a release of the treatment chemical in
solution when the tarpaulins are removed, creating a surface plume
that gradually disperses as it is carried away from the site on the
tide. In-feed treatments result in a release of the treatment
chemical bound to solid material, due both to uneaten feed pellets
falling to the seabed, and to faecal material, as the ingested
chemical is gradually excreted. The physical processes that
determine the concentration of the chemicals in the environment
over time, and their eventual fate, are different for the two
treatment types, so different modelling tools are used for
each.
The ongoing release of solid organic material during normal farm
operations, in the form of waste feed and of fish faeces, has the
potential to have a damaging impact on the seabed. This
impact is assessed with the same modelling tool as in-feed
chemicals because the same physical processes govern it. The
two modelling approaches are described in the following annexes to
the Fish-farm Manual:
Annex
G (300k) – Models for assessing the
use of medicines in bath treatments
Annex H
(2.08mb) - Methods for
Modelling In-feed Anti-parasitics and Benthic effects
Training
Chemical modelling
Presentations from a seminar explaining the modelling tools used
for predicting the impacts of bath and in-feed treatments are
listed below.
Biomass modelling
A workshop was held in March 2005 to herald the introduction of
the new approach to setting site biomass limits from modelled
benthic impact due to organic wastes, and of the associated
additional functionality in the AutoDEPOMOD modelling
tool. The material and exercises presented have subsequently
been developed for the AutoDEPOMOD training courses that have been
run periodically by the model's primary author, Chris
Cromey. Copies of the presentation, notes, and model data from
these courses are available via the AutoDEPOMOD section of
http://www.mapandmarine.co.uk 
Data analysis, modelling, and reporting
tools
Current meter and wind data analysis
SEPA has produced a MS-Excel workbook that facilitates the
analysis and reporting of current meter and wind data.
In addition to the in-built instructions and cell notes, some
further usage notes are available in a technical guidance note
Bath treatment models
The bath treatment models described in Annex
G to the Fish-farm Manual are
available as an MS-Excel workbook and an executable,
Gillibrand and Turrell's paper describing the long-term model is
available from the FRS website: Gillibrand
& Turrell, 1999
In-feed and biomass models
AutoDEPOMOD is a development of the DEPOMOD aquaculture impact
model that integrates site configuration, load scenario iteration,
results visualisation, and EQS testing tools into a single
package. It has been developed by the Scottish Association for Marine
Science (SAMS), in
conjunction with SEPA and industry partners, and may be obtained
from Chris Cromey of Map and Marine
Ltd. who provides
distribution and technical support on behalf of SAMS.
To use AutoDEPOMOD, it is also necessary to install the
Microsoft Excel spreadsheet program and Golden Software's Surfer
contouring program (either v.7 or v.8).
Users are advised to check that they have the following most
recent versions of the program executables installed:
- autodepomod_srf7.exe - version 2.0.51 (22/04/05)
- autodepomod_srf8.exe - version 2.0.52 (17/08/05)
NB: the version number and compilation date may be found either
in the title bar of the user interface, or on the 'Version' tab of
the file properties, obtained by right-clicking the executable file
icon and selecting 'Properties'.
Modelling results summary
Current data summary statistics and the results of the biomass
and chemical modelling are reported using a MS-Excel workbook
template.
Download Marine_sum_v3.xls 
(106k - version 3.2)
NB: No hard copy of the Marine Summary workbook is required
as part of an application; however, an electronic copy of this is
essential.
Both the 'chemical' and 'biomass' sheets incorporate a
calculation of the minimum area required to disperse exported
material to the far-field EQS concentration. Importantly, the
workbook invites the modeller to provide an estimate of the
available area downstream – with respect to the near-bed residual
current direction of the farm site - over which any exported carbon
or in-feed chemicals may be distributed. This is included to
give the applicant a better idea of the relationship between the
required distribution area with respect to exported material and
the distribution area available to the site.
Additional technical guidance
Over time, as an increasing number of sites have been modelled, a
variety of more complex scenarios have been confronted and tackled,
and certain limitations of the modelling tools have been identified
and, often, addressed. This has resulted in a number of
guidance notes being issued, certain of which will be incorporated
into revisions of the 'Fish-farm Manual' documents when these are
reviewed.
Read the technical guidance notes
Modelling methods reports and 'test site' results
submissions
Modelling predictions form part of the supporting information
accompanying a CAR application, for which the applicant is legally
responsible; information that is entered onto the Public Register
must meet certain scientific and reporting standards. To
reduce the amount of information required for each application,
SEPA promotes a scheme whereby a modelling practitioner, who
intends to undertake modelling for many sites, need only submit a
single copy of their modelling method. This is held as
'Environmental Information' on the Public Register and referenced
in any further modelling results submissions.
The modelling produces license limit recommendations, and
throughout the process any errors generate an environmental
risk. To give the modeller, their client, and SEPA some basic
confidence that the modelling techniques and tools are understood,
SEPA requires that standard demonstration sites are modelled and
reported. This gives the modellers an opportunity to produce
a valid report template, and makes it easier for SEPA to identify
any errors in the modelling process.
Read the methods and test site
information
Submitting data and modelling results
In order to offer applicants a consistent and efficient service,
SEPA requires an electronic copy of all raw, extracted, and
processed data, site survey and hydrographic data reports, and
modelling reports. Ideally, these reports should be in PDF
format, with 'Content Copying or Extraction' set to 'Allowed'; this
enables the reviewing and feedback process. The raw data,
modelling files, reports, and an electronic copy of the Marine
Summary MS-Excel workbook should be submitted on a CD.
Please include only the files relevant to final compliant model
runs; AutoDEPOMOD v2 includes the facility to delete failing model
runs automatically.
Pre-application process
The information supporting a CAR application has to be checked
before the application is considered valid. To reduce the
likelihood of an application being rejected due to insufficient or
inadequate scientific information, SEPA promotes the phased
submission of data and reports prior to making an application.
Read about the pre-application
process for fish-farms (21k)
Application CD
Apart from signed copies of the application forms, the entire
application and its supporting information can be submitted
electronically, on CD. If SEPA's favoured pre-application
process is followed, a single application CD will be populated in
stages. It is advisable to construct the skeleton directory
structure for the various pieces of information at the outset, as
this helps to reduce omission or repetition of the required
information.
Read about the preferred structure for
application CDs.
External links
Position fixing, bearings and projection conversions
Read about position-fixing using the national GPS
network
The grid convergence angle (for correcting bearings to True
North) at any specified location may be obtained with a useful
facility, amongst other transformations between projections, within
the free spreadsheet tool available from the national GPS website:
www.gps.gov.uk/additionalInfo/gpsSpreadsheet.asp
Further information about conversions between Magnetic, Grid,
and True North may be found on
the Ordnance Survey website
A freeware OSTN02 converter (Grid InQuest) for converting
between positions recorded by longitude and latitude and the
National Grid references (NGR) is available from Quest Geo Solutions
Ltd.
Software for modelling
Distribution and technical support for DEPOMOD and AutoDEPOMOD
is provided by Chris Cromey of Map and Marine
Ltd. on behalf of
the Scottish
Association for Marine Science.
The contouring software package, Surfer, is produced by
Golden
Software and marketed
in the UK by GeoMEM
Electronic charting software and licensing of electronic
Admiralty chart data may be discussed with SeaZone
Ltd.